Category: Anatomy

Introduction

The human body comprises different parts that perform distinct and coordinated functions. In conjunction with the brain, the body parts respond accordingly to both internal and external environments. The excellent functionality of the different parts of the body, including the hand, thigh, neck, girdle, pectoral, and legs, are critical for the normal functioning of a human being. The brain is considered the command center of the body. According to Ramadan and Vasilakos (2017), it is equal to the computers central processing unit (CPU) because it controls everybodys duty and action. This paper aims to understand how the human hand and the specific muscles work in partnership with the brain.

Types of Muscles

Interossei Muscles

The interossei have both the palmar and dorsal small muscles. The muscles commence between the bones of the hand, towards the fingers. The muscles allow the bending of the metacarpophalangeal joint, where the finger bones intersect the hand ones. Burin et al. (2017) opine that the dorsal interossei enable people to spread their fingers away from each other while the palmar interossei pull their fingers together. It is regarded as the first muscle to shrink among patients with cubital tunnel syndrome (Urits et al., 2019). The dorsal interosseous pulls the thumb close to the index finger, providing stability when pinching. Therefore, the interossei muscles are part of the muscles which form the human hand.

Hypothenar

The hypothenar muscles are the other muscles which form part of the hand. The flexor digiti minimi, opponens digiti minimi, and equally the abductor digit minimi from the hypothenar muscles (May, 2020). These muscles form a bulk on the small finger. Specifically, the abductor allows the little finger to pull sideways from the ring finger (May, 2020). The opponents enable a person to cup hands, bringing the small and thumb fingers together.

Elbow Muscles

The elbow contains four muscles, including the biceps, brachialis, triceps brachii, and lacertus. According to Gaspar et al. (2018), the biceps help an individual rotate the palm down and up. They equally help the brachioradialis and the brachialis to bend the elbow. The brachialis is another muscle that is deep and large in the arms front, lying beneath the biceps muscle, attaching to the ulnas coronoid process (Van Den Bekerom et al., 2016). The triceps are three-headed in the arms back, delivering the critical role of elbow strengthening (Alves et al., 2018). Therefore, a person can throw items and push up a chair due to the strength of the triceps.

Sensory Stimulus Pathways

There are several unconscious processes that an individual goes through to sense an external stimulus. Whether in the presence or absence of light, the human hand skin must feel different external stimuli, including the crawling of bugs on the hand. First, skin on the human hand has multiple anodes that help one develop a feeling that something has touched them. Anodes are at the epidermis and dermis, which are the topmost layers of the skin. Villard et al. (2017) allude that receptors are small in size, collecting accurate information regarding touch. Conduits often sense pain, pressure, friction, temperature, and even stretch.

The idea of feeling a bug crawling on the skin allows an individual to flick it off before biting the skin. According to Yu and Smith (2017), the hairs that project from the follicles in the hand skin sense different environmental changes. It is the root plexus that surrounds the follicle base that senses any interference and disturbance on the skin (Yu & Smith, 2017). As a bug crawls on the skin, it touches the hairs on the hand and sends a signal to the follicles, simultaneously transferring the same signals to the plexus and back to the skin that something is crawling. The hair root plexus sends the received information to the central nervous system (CNS), which incorporates the brain and the backbone. Subsequently, the CNS responds by activating the eyes skeletal muscles and removing the bug.

The skin acts as a critical sense organ due to the dermis, epidermis, and hypodermis, containing the nerves specialized sensory structures, sensing and detecting touch. These receptors are concentrated on the fingertips, especially the Pacinian corpuscle, which responds to skin vibrations (Yu & Smith, 2017). The Merkel cells in the stratum basale are equally regarded as the touch receptors. Sensory nerves are connected to each hair follicle throughout the hand skin. The motor nerves innervate the glands and arrector pili muscles, which helps humans sense the bug. The initiation point of the tracts starts at the epidermis and its termination is at the peripheral nerves where neurons are located. Chemical synapses occur in the epidermis, releasing neurotransmitters which bind receptors on the postsynaptic cell, making the hand quick to respond to external stimuli.

Adduction Movement

Adduction is one of the multiple hand muscle movements which take place in the fingers. As Assi et al. (2016) assert, adduction is a critical motion that brings all the hand fingers towards the middle finger. In other words, the movement involves the act of closing the finger together, for example, when one wants to slap another or when holding an object tight. Palmar interossei are the prime mover in adduction, helping humans to make a fist, whereas the antagonist for this kind of movement is the dorsal interossei. Extensors of the wrist form part of the synergist muscles that help and coordinate the movement of the fingers, whereby one of them is the extensor carpi radialis longus. For example, when one makes a fist flexed forwards towards their palm and equally makes another while the wrist is extended back, it becomes evident that the fist becomes strong when the wrist is extended back. Thus, it becomes clear that the wrist extensors aid the palmar interossei to close the hand fingers, hence considered to be palmar interossei synergists.

Stroke

In the primary somatosensory cortex and the primary motor cortex, the stroke will not affect the hand regions anatomy. It will affect the functioning and ability of the hand. The hand becomes feeble in case of a stroke, because of the weakness of the biceps, triceps, and the other muscles. In the scenario of a stroke in the primary somatosensory cortex, the hands ability to sense different somatic sensations, including pain, vibration, touch, heat, and pressure, will be impaired. The hand becomes paralyzed, hence unable to sense different internal and external stimuli, for example, an internal cache, which enables a person to seek medical attention. Externally, the hand cannot sense pain or the crawling of a bug on the skin. An individual will realize that an insect is crawling on their hand when they only see it. A person cannot respond to external stimuli including excessive heat. Stroke is a devastating incident that can occur in the human body considering that it makes people susceptible to bodily danger because they cannot sense external stimuli apart from becoming weak to respond.

Conclusion

In conclusion, it is paramount to note that the removal of a crawling bug on the hand involves the sensory input and the motor output to respond. The nervous system has a tremendous impact on the muscular system. The hand has critical muscles including the elbow, hypothenar, and interossei muscles. Moreover, adduction is one of the movements that take place in the hand. It allows a person to bring fingers together to form a fist.

References

Alves, D., Matta, T., & Oliveira, L. (2018). Effect of shoulder position on triceps brachii heads activity in dumbbell elbow extension exercises. The Journal of Sports Medicine and Physical Fitness, 58(9), 12471252.

Assi, A., Bakouny, Z., Karam, M., Massaad, A., Skalli, W., & Ghanem, I. (2016). Three-dimensional kinematics of upper limb anatomical movements in asymptomatic adults: Dominant vs. non-dominant. Human Movement Science, 50(1), 1018.

Burin, D., Garbarini, F., Bruno, V., Fossataro, C., Destefanis, C., Berti, A., & Pia, L. (2017). Movements and body ownership: Evidence from the rubber hand illusion after mechanical limb immobilization. Neuropsychologia, 107(4), 4147.

Gaspar, M. P., Adams, J. E., Zohn, R. C., Jacoby, S. M., Culp, R. W., Osterman, A. L., & Kane, P. M. (2018). Late reconstruction of the interosseous membrane with bone-patellar tendon-bone graft for chronic essex-lopresti injuries: Outcomes with a mean follow-up of over 10 years. The Journal of Bone & Joint Surgery, 100(5), 416427.

May, C. A. (2020). Long abductor digiti minimi muscle: Variation of the hypothenar muscles and clinical consequences. Clinical Anatomy, 33(5), 643645.

Ramadan, R. A., & Vasilakos, A. V. (2017). Brain computer interface: Control signals review. Neurocomputing, 223(1), 2644.

Urits, I., Gress, K., Charipova, K., Orhurhu, V., Kaye, A. D., & Viswanath, O. (2019). Recent advances in the understanding and management of carpal tunnel syndrome: A comprehensive review. Current Pain and Headache Reports, 23(10), 70.

Van Den Bekerom, M. P. J., Kodde, I. F., Aster, A., Bleys, R. L. A. W., & Eygendaal, D. (2016). Clinical relevance of distal biceps insertional and footprint anatomy. Knee Surgery, Sports Traumatology, Arthroscopy, 24(7), 23002307.

Villard, C., Eriksson, P., Kronqvist, M., Lengquist, M., Jorns, C., Hartman, J., Roy, J., & Hultgren, R. (2017). Differential expression of sex hormone receptors in abdominal aortic aneurysms. Maturitas, 96(1), 3944.

Yu, C., & Smith, L. B. (2017). Multiple sensory-motor pathways lead to coordinated visual attention. Cognitive Science, 41(1), 531.

Introduction

The muscles of the head and neck (Fig. 1) are divided into two groups: masticatory and mimic muscles. In some cases, they function together for articulating speech, chewing, swallowing, and yawning. The masticatory muscles are four paired muscles located on the sides of the skull. They all start on the bones of the skull and attach to the lower jaw, setting it in motion (Bordoni & Varacallo, 2022). The masticatory muscle begins from the lower edge of the zygomatic bone, the zygomatic arch; attaches to the masticatory tuberosity of the outer surface of the lower jaw. She raises the angle of the lower jaw.

Discussion

The temporal muscle begins from the temporal surface of the frontal bone, the parietal bone, the scales of the temporal bone (temporal fossa), the large wing of the sphenoid bone, the temporal fascia; attaches to the coronal process of the lower jaw. It raises the lower jaw (the biting muscle); the posterior tufts pull the jaw back. The medial pterygoid muscle begins from the pterygoid fossa of the pterygoid process of the sphenoid bone (Georgakopoulos & Lasrado, 2021). It attaches to the pterygoid tuberosity of the inner surface of the lower jaw. The medial pterygoid muscle raises the angle of the lower jaw.

The lateral pterygoid muscle begins from the suspensory crest of the large wing of the sphenoid bone, the outer surface of the lateral plate of the pterygoid process. It attaches to the neck of the lower jaw, the intra-articular disc and the capsule of the temporomandibular joint. With unilateral contraction, it shifts the jaw in the opposite direction, and with bilateral contraction, the lower jaw moves forward (Abuhaimed et al., 2022). Facial muscles are located under the skin, start from the bones of the skull and are woven into the skin. During contraction, the skin is shifted, changing its relief, forming facial expressions.

The neck muscles are topographically anatomically divided into superficial, medium, and deep. The superficial muscles are the subcutaneous muscle of the neck and the sternocleidomastoid muscle. The subcutaneous muscle of the neck is located directly under the skin, covering the entire front surface of the neck. It tightens the skin; pushing it forward, the muscle promotes the expansion of veins and the outflow of blood from the head (Powell et al., 2022). The subcutaneous muscle begins from the thoracic fascia, the skin of the upper chest at the level of the second rib (Bordoni & Varacallo, 2019). It attaches to the chewing fascia, the edge of the lower jaw, the corner of the mouth. The subcutaneous muscle of the neck pulls the corner of the mouth down, pulls the skin of the neck, prevents compression of subcutaneous veins.

Conclusion

The middle, or muscles of the hyoid bone, include: the muscles lying above the hyoid bone lie between the lower jaw and the hyoid bone. They are part of a complex apparatus, including the lower jaw, hyoid bone, larynx, windpipe, and play an important role in the act of articulate speech. Deep muscles include lateral muscles attached to the ribs. The anterior rectus muscle of the head starts from the anterior surface of the lateral mass of the atlas (Flynn & Vickerton, 2020). It attaches to the lower surface of the basilar part of the occipital bone. The lateral rectus muscle of the head begins from the transverse process of the atlas; it attaches to the lower surface of the jugular process of the occipital bone. It tilts his head to the side.

References

Abuhaimed, A. K., Alvarez, R., & Menezes, R. G. (2022). Anatomy, head and neck, styloid process. National Journal for Biotechnology Information, 40(13), 942945.

Bordoni, B., & Varacallo, M. (2022). Anatomy, head and neck, sternocleidomastoid muscle. National Journal for Biotechnology Information, 42(2), 17.

Bordoni, B., & Varacallo, M. (2019). Anatomy, head and neck, temporomandibular joint. Europe PMC, 234(8), 540547.

Flynn, W., & Vickerton, S. (2020). Anatomy, head and neck, larynx cartilage. Europe PMC, 382(21), 1941 1960.

Georgakopoulos, B., & Lasrado, S. (2021). Anatomy, head and neck, inter-scalene triangle. National Journal for Biotechnology Information, 36(6), 397402.

Powell, V., Esteve-Altava, B., Molnar, J., Villmoare, B., Pettit, A., & Diogo, R. (2018). Primate modularity and evolution: First anatomical network analysis of primate head and neck musculoskeletal system. Scientific Reports, 8(2341), 1543.

Heart anatomy

The heart consists of four chambers through which blood inconsistent flows. They are divided by heart walls that are made of cardiac muscle as the whole structure. The upper compartments are called atria (singular: atrium), and the lower ones are ventricles. Atlas of Human Cardiac Anatomy interactively shows that the right atrium contains the sinusoidal node, which is vital for the hearts electrical conduction. The tricuspid valve connects the right atrium with the right ventricle. A similar function is carried out by the mitral valve, which bridges the left atrium to the left ventricle. Semilunar valves are leading the blood from ventricles to blood ways. There are also more helpful diagrams and animations in the named resource that give detailed and up-to-date information.

The electrical conduction system of the heart

The electrical conduction starts from the sinoatrial node, which is sometimes called a pacemaker for its functions. The propagation of the electrical activity across the atrial muscle fibers brings uniform atrial contraction. The action potential travels down to the atrioventricular node, projecting further to the Bundle of His. The latter is located in the aforementioned heart wall between two ventricles. Conduction of the electrical signal to Purkinje fibers results in ventricular contraction, in other words, systole. The video and overview by Chen and the A.D.A.M. Editorial team provide a concise and useful description of the named mechanism. Electrical activity can be checked by taking an electrocardiogram from the patients.

Blood flow through the heart

The vena cava carries the blood from body tissues and brings it to the right atrium. As it fills with blood, the sinoatrial node fires the action potential, causing the contraction. It results in the opening of the tricuspid valve, which brings the blood to the right ventricle. The high level of pressure inside the ventricle closes the tricuspid valve preventing the flow of the blood in a backward direction. Ventricular systole pumps the blood to the pulmonary circuit, after passing which blood flows to the left atrium. As accessibly pictured in the diagram of 18.7G: Blood Flow in the Heart by Medicine Libretexts, the analogous algorithm is accomplished in the left half of the heart, but the blood is sent to the body tissues. The blood flow through the heart is closely related to its proceeding through body vessels.

Blood flow through the body

Leaving the right ventricle, the deoxygenated blood enters the pulmonary artery, which leads it to the lungs. The closer the blood gets to the lungs, the narrower the vessels become, transforming to arterioles and capillaries. As oxygen diffuses to blood replacing carbon dioxide, a saturated liquid is passed through venioles towards the pulmonary vein fused with the left atrium. Afterward, blood leaves the heart from the left ventricle and flows through the main body artery  artery, which leads it to smaller blood vessels directing to all body tissues. The process has only a single direction, which is explicitly depicted in the animation by Pearson Education called Pathway of Blood through the Pulmonary and Systemic Circuits. The uniformity prevents disruptions and allows blood to flow to all organs.

The cardiac cycle

The cardiac cycle is divided into two phases: diastolic and systolic. The electrocardiogram, pressure readings, and heart sound altogether assist in understanding the cardiac cycle the most (Chambers et al. 118). During the diastolic interval, the atria are filled with blood, and as the atrioventricular valves remain open, the ventricles are slowly filled with blood. Atrial contraction attributes to the P wave in the electrocardiogram and results in the fast filling of ventricles. As the action potential is transmitted through Purkinje fibers and ventricular muscles, the systole starts. The pressure in the aorta raises significantly because of the large amount of blood passing to the blood vessel.

Works cited

Atlas of Human Cardiac Anatomy. U of Minnesota, 2020. Web.

Chambers, David, et al. Cardiac cycle. Basic Physiology for Anaesthetists, Cambridge University Press, 2015, pp. 117-119.

Chen, Michael A. Cardiac conduction system. Medline Plus, 2020. Web.

18.7G: Blood Flow in the Heart. Medicine Libretexts, 2020. Web.

Pathway of Blood through the Pulmonary and Systemic Circuits. Pearson Education, 2020. Web. 

The skin is the outer vertebrates guarding and protecting the underlying muscles, internal organs, ligaments, and bones. Different body locations have different skin layers which support diverse appendages and subsequent functioning. The hand skin aids in preventing the inner body against harm and regulating body temperatures. Therefore, the hands skin contains the epidermis, the dermis, and the subcutaneous tissue, including different appendages adapted to their roles.

Notably, the epidermis is the superficial layer of the human hand. According to Metral et al. (2017), the epidermis is a thin coat of the skin. The hand epidermis helps in detecting touch sensations and protecting the body against microorganisms and external harm. In terms of adaptability, the hand skin has melanocyte cells preventing the skin from harmful UV radiation. Moreover, the epidermiss thinness augments quick detection of touch, enhancing response.

Additionally, the dermis forms a part of the hand skin. Cole et al. (2018) opine that the dermis contains blood vessels which enhance skin nourishment. The dermis aids in thermoregulation apart from protecting the deeper layers. The dermis is adapted to its function through its ability to distribute blood, hence, consuming the harmful impurities or toxins, including bacteria. The dermis contains phagocyte cells consuming the toxins within the skin (Cole et al., 2018). Connectedly, the ability of the dermis to habiting the blood vessels makes it adaptable to its functioning.

Besides, the subcutaneous tissue is the other hand skin layer which plays a critical role in maintaining body temperature and absorbing shock. Herlin et al. (2015) allude that the subcutaneous tissue contains the nerves and blood vessels. Adaptatively, the subcutaneous film contains fat layers which aid in moderating the body temperature. Correspondingly, the fat layers within the subcutaneous sheet help absorb physical shock to internal organs, bones, and muscles (Herlin et al., 2015). Therefore, the subcutaneous layer is adapted to its functioning of maintaining body temperature and absorbing shock through the fat layers.

Distinctively, skin on the hand contains the eccrine sweat glands. According to Cole et al. (2018), the eccrine sweat secretors aid in thermoregulation. The eccrine secreters are adapted to their function, considering that they excrete sweat from the skin when the internal temperatures are high. Excreting sweat is the primary form of enhancing thermoregulation as it maintains the internal temperature moderate. In addition, when the external temperatures are high, the eccrine glands release sweat to cool the skin. Thus, the skin contains the eccrine sweat glands that keep the body at moderate temperatures.

Moreover, the pilosebaceous apparatus is the other appendages present in the skin of the hand. As Marvdashti et al. (2016) mention, the pilosebaceous apparatus contains the hair follicles, erector pili muscles, and the sebaceous gland. It is adapted to maintaining optimal body temperature by enhancing the reaction of the hand hairs as per the environmental temperatures. The arrector pili muscles contract at once, making the skin air to stand and vice versa. Holistically, the pilosebaceous apparatus is adapted to maintaining body temperature by dictating the state of the hair on the skin.

Furthermore, the hand joints are the radiocarpal and carpometacarpal. The Arthritis Foundation (2020) highlights that the radiocarpal joint connects the radius and the carpus in the wrist. Within the wrist, there are the carpal bones, the midcarpal joint, and the intercarpal articulations. First, the radiocarpal joint allows for proper hand movement, including extension and flexion of the wrist. Second, the carpometacarpal joint connects the carpal bones to the metacarpal bones at the intermetacarpal articulations (Arthritis Foundation, 2020). The radiocarpal joint, the carpometacarpal joint allows for motion in adduction, abduction itself, and extension. Together, the carpometacarpal joint arrangements allow the movement of the thumb, such as retro-pulsion and opposition.

Conclusively, the hand skin contains the epidermis, the dermis, and the subcutaneous layers adapted to their functioning. The hand skin equally contains appendages, including eccrine sweat glands and the pilosebaceous apparatus, which are equally modified to their roles. The hand contains the radiocarpal and carpometacarpal joints which aid in hand movement. Thus, understanding the human hands anatomy is excellent as it develops peoples knowledge regarding the human body.

References

Arthritis Foundation. (2020). Hand and wrist anatomy. Web.

Cole, M. A., Quan, T., Voorhees, J. J., & Fisher, G. J. (2018). Extracellular matrix regulation of fibroblast function: Redefining our perspective on skin aging. Journal of Cell Communication and Signaling, 12(1), 35-43.

Herlin, C., Chica-Rosa, A., Subsol, G., Gilles, B., Macri, F., Beregi, J. P., & Captier, G. (2015). Three-dimensional study of the skin/subcutaneous complex using in vivo whole-body 3T MRI: A review of the literature and confirm a generic organization pattern. Surgical and Radiologic Anatomy, 37(7), 731-741. Web.

Marvdashti, T., Duan, L., Aasi, S. Z., Tang, J. Y., & Bowden, A. K. E. (2016). Classification of basal cell carcinoma in human skin using machine learning and quantitative features captured by polarization-sensitive optical coherence tomography. Biomedical Optics Express, 7(9), 3721-3735.

Metral, E., Bechetoille, N., Demarne, F., Rachidi, W., & Damour, O. (2017). ±6 integrin (±6high)/Transferrin receptor (CD71) low keratinocyte stem cells are more potent for generating reconstructed skin epidermis than rapid adherent cells. International Journal of Molecular Sciences, 18(2), 282. Web.

Introduction

During sprint races among sportspeople, the most crucial emphasis is placed on the time for which an athlete can run. A short distance does not mean easy performance professional sprinters must demonstrate incredible coordination and speed performance to be the first among their competitors. Every hundredth of a second is of enormous importance, and studies show that there are specific anatomical patterns in this environment. This research work aims to discuss anatomical factors that directly affect the performance of sprinters.

Sprint Anatomy

There is no doubt that among the two athletes involved in a sprint, the one with the more beneficial body anatomy will have the advantage. At the dawn of the sports development, it was thought that the fundamental formula for achieving efficiency in races was a high frequency of leg movements with an athletes high height. It was assumed that a high sprinter would spend significantly more time and distance at the same speed as a slower athlete. However, research shows that height is not the only factor behind high performance among elite sprinters (Hennessy, 2017). Even athletes with average or low height rates can win. In addition, high stature can even be a significant disadvantage when it comes to instantaneous body coordination and acceleration.

Formula 1. The dependence of the runners speed on the frequency of steps, the average force applied to the ground, body weight, and contact length (Tuttle, 2018)

In addition to height, the athletes weight makes a significant contribution to achieving high results. The vast majority of studies confirm the need for a sprinter to be free of excess fat because, as shown in formula 1, bodyweight is inversely proportional to speed. Another important indicator is the repulsive force with which the lifter acts on the stadium track (Ae, 2017). It seems evident that the higher the ground force of the sprint, the faster the movement is. However, it is impossible to achieve the maximum force and expect ideal results because there is a limit to the force. Blazevich is further developing this issue and shows that the key to success in races is to generate more forces in less time, as shown in Figure 1.

An important characteristic is the ability to stabilize the body during a sharp movement by shortening the muscles. First of all, it should be noted that studies have repeatedly pointed to the differences in the anatomical structure of proximal leg muscles  the volume and length of muscle fibers are more noticeable when tested with sprinters (Bex et al., 2017; Aikawa et al., 2020). Nevertheless, the structure of the foot bones also has a significant effect on achieving faster speed characteristics. Although the nature of the cause-and-effect relationship between foot length and high performance is still unknown, Tanaka et al. (2017) show that long bones in the foot are advantageous for the athlete. In terms of muscular development of the arms, the limbs anatomy implies a low mass  this will help less effort to move the arms to stabilize the body.

An athlete with large muscle volume, long legs, and low body weight will use more energy to achieve high speeds. Thus, the athlete breathes more actively while running, allowing their heart to pump more blood. Moreover, during the race, lactate production begins to exceed its neutralization rate, which is characterized by the activation of the anaerobic energy generation process (Mangini & Fábrica, 2016). For example, elite athletes have an increased content of lactate or lactate degradation products in their biochemical blood analysis.

Conclusion

It is known that anatomical factors play an essential role in achieving the high results of sprinters. Research on this issue is continuing, but the determinants of an effective race are already apparent. Typically, these include developed muscles, lack of excess weight, higher height at higher step frequencies, good blood circulation, and increased lactate levels in the blood. In general, these indicators do not rule out winning an atypical athlete, but statistical studies show such an anatomical portrait of an elite sprinter.

References

Ae, M. (2017). Sprint Running: Running at Maximum Speed. In M. Bertram & S. Wolf (Eds.), Handbook of Human Motion (pp. 1-29). Springer.

Aikawa, Y., Murata, M., & Omi, N. (2020). Relationship of height, body mass, muscle mass, fat mass, and the percentage of fat with athletic performance in male Japanese college sprinters, distance athletes, jumpers, throwers, and decathletes. The Journal of Physical Fitness and Sports Medicine, 9(1), 7-14. Web.

Bex, T., Iannaccone, F., Stautemas, J., Baguet, A., De Beule, M., Verhegghe, B.,& & Derave, W. (2017). Discriminant musculoskeletal leg characteristics between sprint and endurance elite Caucasian runners. Scandinavian Journal of Medicine & Science in Sports, 27(3), 275-281. Web.

Blazevich, A. (2016). What makes a winning sprinter? The Conversation. Web.

Hennessy, L. (2017, January 12). Physical characteristics of sprinters and runners. Setanta College. Web.

Mangini, F. L., & Fábrica, G. (2016). Mechanical stiffness: a global parameter associated to elite sprinters performance. Revista Brasileira de Ciências do Esporte, 38(3), 303-309. Web.

Tanaka, T., Suga, T., Otsuka, M., Misaki, J., Miyake, Y., Kudo, S.,& & Isaka, T. (2017). Relationship between the length of the forefoot bones and performance in male sprinters. Scandinavian Journal of Medicine & Science in Sports, 27(12), 1673-1680. Web.

Tuttle, W. M. (2018). Relationship of maximal strength and relative stride length in sprinters (Publication No. 10840459) [Doctoral dissertation, Indiana State University].

Introduction

Embryos have different stages depending on organisms for instance, in humans, it is a newly developing being up to the ninth week of development. In organisms with multiple cells, the term embryo broadly describes the life cycle or early stage of development before hatching or birth. The embryonic development process starts with fertilization, where a zygote is created. A zygote is a single cell that results from the union of both male and female gametes. Zygotes develop into a multicellular embryo, proceeding into a sequence of identifiable stages including cleavage, blastula, gastrulation, and organogenesis. An embryo of good quality must show the required kinetics and simultaneous division. Normal developing embryos have cell division taking place every eighteen to twenty hours.

Germinal Stage

The entrance of the spermatozoon into the ovum and the fusion of the two sets of genetic materials contained in the gametes form the zygote, which is a single diploid cell. The process is referred to as fertilization and happens at the ampulla part of the fallopian tube. The zygote is made up of amalgamated genetic materials of both the female and male gametes, consisting of 23 chromosomes from the nucleus of sperm, and 23 chromosomes from the nucleus part of the ovum (Gardner & Balaban, 2016). The 46 (23+23) chromosomes go through changes before mitotic division, leading to the formation of the embryo with 2 cells (Wang et al., 2018). Three processes that enable fertilization to happen include chemotaxis, adhesive compatibility between the egg and sperm, and acrosomal reaction.

Cleavage Stage of Development

A single cell of a zygote goes through rapid cell division among organisms with multiple cells. Cleavage refers to the fast, numerous rounds of cell division that take place with a single zygote. The cleavage process produces more than a hundred cells, resulting in a new embryo termed as blastula (Wang et al., 2018). At the cleavage stage, cell division takes place without increasing the mass of the cells. For example, multiple cells result after the division from one large single cell. Cleavage happens either partially or fully, commonly referred to as holoblastic, or meroblastic respectively. Yolk amount and distribution influence the cleavage type that a zygote undergoes (Gardner & Balaban, 2016). Isolecithal cells are cells that are evenly and fairly distributed throughout the cell. In holoblastic cleavage, blastomeres and zygotes completely divide during the process of cleavage.

Blastula Formation

Blastulation is a stage in embryonic development where blastula is produced. The blastula is a hollow sphere of cells that surround the blastocoel (an inner cavity filled with fluid). When a zygote undergoes numerous cleavages, a ball of cells named morula develops. The early embryo develops into blastula only when the blastocoel forms. The morula becomes blastula after the seventh cleavage produces 128 cells. At this stage, Wang et al. (2018) point that blastocyst is formed among mammals, with a distinct inner mass from the surrounding blastula. Blastocyst and blastula have different fates, with a similarity in terms of their structure. The process of cell differentiation also takes place during this stage i.e., into the outer and inner layers. The inner cells undergo differentiation, forming polarize and embryoblast, which closes together to form gap junctions.

Gastrulation

During the gastrulation stage, the blastula reorganizes into numerous layers called the gastrula. Before the process, the embryo is initially an unending sheet of cells. However, as gastrulation ends, the embryo begins differentiating, establishing specific cell lineages (Gardner & Balaban, 2016). The second process following differentiation involves setting up basic body axes such as posterior-anterior, and internal types of cells e.g. the gut. Gastrulation occurs after cleavage and blastula formation and begins when primitive streak forms (Wang et al., 2018). The primitive streak, a line band made up of cells at the mid-embryo, forms by the migrating epiblast cells. Their formation takes the form of bilateral symmetry, giving the embryo the orientations of the front-to-back and head-to-tail.

Composition of an Entire Organism

Every embryos germ layer gradually gives rise to various distinct cells, tissues, and organs which make up a whole organism as illustrated. The ectoderm for instance gradually forms cells of numerous internal organs and glands such as the thyroid, intestines, bladder, lungs, and pancreas. The mesoderm (mid-layer) eventually forms the cells of the muscles, kidneys, blood, heart, and bones. The ectoderm layer forms nervous system cells, eye cells, epidermal cells, and other connective tissues (Wang et al., 2018). The primitive gut forms in the last gastrulation phase, eventually developing into the gastrointestinal tract. Blastopore forms on one side of the embryo and deepens to finally develop into the anus. The tiny hole (blastopore) continues tunneling through the embryo to the remaining side, forming an opening that eventually becomes the mouths. The gastrulation process is known for completing with a working digestive tube.

Neurulation

Neurulation commences when notochord stimulates the formation of the Central Nervous System (CNS). The stimulation signals the ectoderm above it to a flat and thick neural plate (Wang et al., 2018). The plate folds upon itself, forming a neural tube that later becomes the brain and spinal cord, gradually forming the CNS. Two processes form various parts of the neural tube and they include; primary neurulation, and secondary neurulation (Gardner & Balaban, 2016). In the former, the neural plates fold inwards till the edges meet, hence fusing, while in secondary neurulation, the formation of tubes takes place with the solid precursors interior hollowing out (Wang et al., 2018). Primary neurulation also refers to the process where the flat neural plate folds into a cylinder-like neural tube.

Organogenesis

By definition, organogenesis refers to the process where the 3 layers of the germ tissue develop into internal organism organs. The differentiation process results in the formation of the endoderm, ectoderm, and mesoderm. The differentiation process takes place when cells with less specialization become more specialized and can happen numerous times as the zygote develops into a full organism. The embryos stem cells express specific genes that later determine their type of cell. For instance, ectoderm cells help in expressing the genes to cells in the skin (Gardner & Balaban, 2016). As a result, these cells later undergo differentiation, becoming epidermal cells.

Environmental and Generic Dangers to Development of the Embryo

The activities that happen in the embryo are fundamental for different cells, tissue, organs, and organ systems of the body. Defects resulting from genes or hazardous exposures from the environment during the embryonic stage have fatal effects on the organism. According to Gardner & Balaban (2016), such risks may lead to the eventual death of the embryo. In case the embryo survives and grows as a fetus, chances of it having birth defects are usually high. Examples of the environmental dangers include; consumption of strong drinks such as alcohol by the mother. Exposing an embryo to such strong drinks from the mothers blood results in fetal alcohol spectrum disorder (Wang et al., 2018). Diagnostics X-ray: Expectant mothers going for radiation therapy risk both their lives and the embryos. Radiation is linked to the damaging of DNA and causing mutation in germ cells of the embryo.

Conclusion

The embryogenesis process involves the division of cells and differentiation, leading to embryo development. A human being (mammals) develops a zygote (a single-cell), resulting from the fertilization of an ovum by a sperm. The zygote goes through cleavage, where the number of cells increases in the zona pellucid. The degeneration of zona pellucid allows the embryo to increase volume, which proceeds for four to six days. It leads to the formation of blastocyst, and cells that undergo differentiation into trophoblast and an inner cell mass. At the gastrulation stage, the primitive streak forms, and the process reorganizes the embryonic layers.

References

BioNinja. (n.d.). Neurulation | BioNinja. Web.

Embibe. (n.d.). Learn Blastulation meaning, concepts, formulas through Study Material, Notes  Embibe.com. Web.

Gardner, D. K., & Balaban, B. (2016). Assessment of human embryo development using morphological criteria in an era of time-lapse, algorithms and OMICS: Is looking good still important? Molecular Human Reproduction, 22(10), 704718. Web.

Graham, J. (2010). Photographs of human embryos at five stages of gestation& ResearchGate. Web.

inviTRA. (n.d.). Beginning of organogenesis in the embryo. InviTRA. Web.

Uday, L., & Mandira, P. (2016). What is the process of gastrulation? | Socratic. Socratic.Org. Web.

Wang, C., Liu, X., Gao, Y., Yang, L., Li, C., Liu, W., Chen, C., Kou, X., Zhao, Y., Chen, J., Wang, Y., Le, R., Wang, H., Duan, T., Zhang, Y., & Gao, S. (2018). Reprogramming of H3K9me3-dependent heterochromatin during mammalian embryo development. Nature Cell Biology, 20(5), 620631. Web.

Yakhin, I. (2016). Types of Tissues. Web.

The skin may be regarded as one of the most important organ of the human body due to its multiple indispensable functions. It protects a person from all challenges that may come from the environment and assists in the regulation of inner processes as well. This paper is dedicated to the examination of the skin, its gross and microscopic anatomy, functions, and the most common diseases.

Gross Anatomy

The skin is the largest vital organ in the human body. It covers the bodys entire external surface, forming a highly efficient initial protective barrier against mechanical injuries, pathogens, heat, UV light, chemicals, and other threats from the environment (Yousef et al., 2020). In general, the skin covers an area of 1.5 to 2 square meters and weighs between 3.5 and 10 kilograms depending on a persons body mass and height (How does skin work? 2019). It is closely integrated to the underlying fascial endoskeleton through retinacular ligaments, blood vessels, nerves. and lymphatics (Wong et al., 2016, p. 92). Besides protection, the skin has other essential functions, including the regulation of body temperature and water release and gathering sensory information concerning environmental conditions. Moreover, it plays an ultimate role in the protection from diseases by the immune system and stores vitamin D, water, and fat.

The texture, thickness, and color of the skin differ over the body regions. In general, there are two major types of the skin on the basis of the thickness of the epidermal and dermal layers  thin hairy and thick hairless skin (Yousef et al., 2020). The first type is prevalent on the human body, while the second one is found in the hands palms and the feet soles as these parts endure excessive friction and are used heavily.

The skin consists of three layers that have completely different anatomy and functions  the epidermis, the dermis, and the hypodermis (Yousef et al., 2020). The epidermis, or the outer layer, is the primary protection of the whole body that contains melanocytes responsible for the production of melanin. The dermis contains sweat and oil glands, nerve endings, and hair follicles. The hypodermis, or the subcutis, is a subcutaneous tissues fatty layer.

Microscopic Anatomy

The first level of the skin, the epidermis, has several layers that include the stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum (Yousef et al., 2020). Stratum basale, or stratum germinativum, is the skins deepest level separated by basal lamina, the basement membrane, from the dermis. At this level, cells are cuboidal to columnar mitotically active stem cells that produce keratinocytes (Yousef et al., 2020).

Stratum spinosum has 8-10 cell layers and contains irregular polyhedral and dendritic cells. Stratum granulosum with 3-5 cell layers contains keratohyalin and lamellar granules with keratin precursors and glycolipids in diamond-shaped cells. Stratum lucidum made from eleidin is presented in a hairless skin of soles and palms. Finally, the uppermost layer, stratum corneum, consisted of 20-30 cell layers and made up of anucleate squamous cells and keratin, participates in the bodys first immune defense.

The main cells that form the epidermis are melanocytes, keratinocytes, Merkels cells, and Langerhans cells (Yousef et al., 2020). Melanocytes produce melanin responsible for the skins pigment during tyrosines conversion to DOPA, and the secretion of melanin stimulated by UVB light protects against UV radiation (How does skin work? 2019). Keratinocytes are the epidermiss predominant cell type that produces keratin and forms the epidermal water barrier through the secretion of lipids.

Merkels cells are the most populous in the palms, soles, fingertips, genital, and oral mucosa  they are functioning as mechanoreceptors and sensitive for light touch as their membranes are connected with the skins free nerve endings. In turn, Langerhans cells play a highly essential role in the bodys defense and antigen presentation. At the same time, the dermis consists of a thinner papillary layer and a thicker reticular layer merged together. The dermis houses hair, the sweat glands, muscles, hair follicles, blood vessels, and sensory neurons. The hypodermis, the deepest skin layer, contains adipose lobules and some skin appendages, including blood vessels, sensory neurons, and hair follicles as well.

Physiology/Functions

The human skin has multiple immeasurably essential functions, and every layer is responsible for particular ones.

Epidermis

It serves as a primary barrier to microorganisms, water, chemical and mechanical trauma, and damaging UV light. To be precise, it is melanin in the epidermis that defends the organism against ultraviolet radiation. In addition, Langerhans cells are involved in the immune system and protects the body against multiple infections. In addition, this layers turgor, color, and general appearance may indicate the bodys general health and the existence of particular diseases (How does skin work? 2019).

Dermis

The skin is responsible for the sensation of heat, cold, touch, and pain due to the nerve endings in the dermis. Moreover, this layer preserves homeostasis through the regulation of water loss and temperature with the help of sweat glands, hair follicles, and blood vessels. As a matter of fact, the skin is highly responsive to the changes in temperature and helps to regulate the bodys processes according to these changes. In addition, oil from the dermiss sebaceous glands keep the skin moisturized and serves as a barrier to unknown external substances.

Hypodermis

As a fat layer, hypodermis protects the organism from extreme temperatures regulating its temperature as well, serves as the skins energy storage area, and provides protective padding.

Skin Diseases

In general, there are multiple types of skin diseases, and although the majority of them are non-fatal, they put a burden on almost 2 billion people worldwide (Liu et al., 2020). The most common ones include acne, rosacea, psoriasis, vitiligo, hives, ichthyosis, and eczema. In addition, the alteration of the skin may be a part of more serious general illnesses, such as measles or chickenpox, or the result of mechanical exposure, for instance, in the case of a blister. Temporary skin disorders include keratosis pilaris, the formation of small rough bumps, and contact dermatitis, the irritation of the skin due to contact with particular materials. In turn, psoriasis, rosacea, and vitiligo are among permanent, incurable skin diseases, the causes of which are still unknown.

References

How does skin work? (2019). Web.

Liu, Y., Jain, A., Eng, C., Way, D. H., Lee, K., Bui, P., Kanada, K., de Oliveira Marinho, G., Gallegos, J., Gabriele, S., Gupta, V., Singh, N., Natarajan, V., Hofmann-Wellenhof, R., Corrado, G. S., Peng, L. H., Webster, D. R., Ai, D., Huang, S. J.,&Coz, D. (2020). A deep learning system for differential diagnosis of skin diseases. Nature Medicine, 26, 900-908. Web.

Wong, R., Geyer, S., Weninger, W., Guimberteau, J. C., & Wong, J. K. (2016). The dynamic anatomy and patterning of skin. Experimental Dermatology, 25(2), 92-98. Web.

Yousef, H., Alhajj, M., & Sharma, S. (2020). Anatomy, skin (integument), epidermis. NCBI. Web.

Introduction

Anatomy is the foundation of medicine, the basis of its theory and practice. With this science, the process of knowledge of medical disciplines begins. Its comprehension forms the beginning of clinical thinking in medical students. This was perfectly understood by outstanding scientists at the dawn of the formation of medicine as a science. In the Renaissance, anatomy, like other sciences, stepped far forward. A particularly significant contribution to the development of anatomy was made by Leonardo da Vinci (1452-1519) and Andreas Vesalius (1514-1564) (Habbal 18-19). In particular, thanks to Leonardo da Vinci, earlier primitive knowledge about the structure of the human body was put on a scientific basis.

The formation of scientific anatomy in Renaissance Europe

The history of medicine as a science that studies the development of medical knowledge and medical activity in various fields of medicine during different historical periods is characterized by certain milestones and key moments when a particular achievement or discovery not only deepens and expands the world perception but also leads to the formation of paradigms and new methodological approaches to the study of various processes and phenomena. In this regard, the history of the study of human anatomy and the formation of its scientific foundations not only occupy a special place in the field of medicine, but also reflect the dynamics in the knowledge of a person as a multidimensional and, at the same time, unique being in his relationship with the environment.

The formation of any scientific theory, concept, the doctrine does not occur at the zero level, but is born based on previous teachings, paradigms, and discoveries. In the history of science, the continuity of scientific ideas and the fundamental methodological principles underlying particular scientific approaches are important. This is fully reflected by the history of the creation of the human anatomy scientific foundations.

The first anatomical autopsy of human bodies to study their structure began in the 3rd century in Alexandria. This was done, in particular, by Herophilus and Erasistratus. However, for the first time, a systematic and holistic description of the anatomy of the human body was given by the ancient Roman physician and researcher Galen in his classic work on the designation of parts of the human body (De usu partium corporis humani).

One of the main values of this work is that, in it, the anatomical characteristics of various organs were given in their inextricable connection with physiological functions: all parts of the body are in agreement with each other, that is, they all mutually support each other when doing any action (Rifkin and Ackerman 26). Therefore, in the historical and medical literature, the creation of an anatomical and physiological system by Galen is rightly emphasized.

Galen created a system of ideas about the human body, built on certain principles, the main of which were the following: a) a presentation of material and conclusions based on logical reasoning; b) the use of philosophical teachings on the relationship of the natural environment and human (natural philosophy). He, along with Hippocrates and other doctors of the period of antiquity, began to consider issues of anatomical and physiological nature, taking into account environmental factors (Rifkin and Ackerman 62).

For almost fourteen centuries, the concept of human anatomy, based entirely on the provisions and conclusions of Galens anatomy dominated in medicine. One of the main reasons for this stability was the religious and philosophical basis of his anatomical and physiological teachings, which, in essence, served him as the main methodological guide in substantiating his ideas and opinions (Clayton 30-31).

In other words, in anatomical and physiological studies, Galen put at the forefront an experimental observation method based on anatomical dissections and experiments. However, in the explanations of what he saw, he used, first of all, teleological and natural philosophical ideas about the nature of humans. Therefore, the anatomical and physiological doctrine of Galen harmoniously fit into the theological nature of medicine and the scholastic philosophy of the early and classical Middle Ages, which made him one of the indisputable medical authorities.

Anatomists of the Renaissance were the first after ancient healers to attempt to study the structure of the human body and the processes occurring in it and laid the foundation for scientific medicine and anatomy. They obtained permission to perform autopsies. Anatomical theaters for public autopsies were created. In the second half of the 15th and throughout the 16th century, there was a significant increase in the interest of representatives of painting in anatomy, which pursued the goal of a more realistic depiction of a person, especially the exposed parts of his body (Rifkin and Ackerman 19).

However, artists study of anatomy went beyond the framework of purely anatomical knowledge of the human body and fit into the general idea of the close relationship of humans as a microcosm and the environment, primarily the natural one.

This was facilitated by the revival of interest in the heritage of ancient culture and the understanding of the human as a unique being (Habbal 20). In contrast to the periods of the early and classical Middle Ages, the static vision of the Human as a Divine creation, subject to Gods will, was replaced by a dynamic perception of him as a unique individual in the manifold manifestations of his inner world and spiritual values.

In this regard, the need for practical knowledge of anatomy has prompted many Renaissance artists to observe the processes of anatomical dissections, and some of them directly engaged in the anatomy of bodies. So, Leonardo da Vinci not only personally performed the autopsy but also compiled a series (about 750) of sketches under the general name Anatomical Drawings (early 16th century) (Capra 38-39). Combining science and art in their mission to know nature, he, being actively engaged in anatomy (as a scientist), solved (as an art theorist) the problem of proportion as a link between the scientific study of natural phenomena and their artistic representation.

Contribution of Leonardo da Vinci to the development of anatomy

Leonardo da Vincis revealing of general laws of human body structure, topographic relationships between organs, and the identification of functional and structural relationships turned empirical anatomy into a scientific one and made him the founder of systemic, plastic, topographic, and functional anatomy. Excellent knowledge of anatomy helped the artist create world masterpieces, including a portrait of the Mona Lisa with a mysterious smile (Clayton 28). In his anatomical drawings, Leonardo da Vinci first reflected the actual structure of the human body. He noted several features of the childrens and senile organism, proposed his canon of ideal body proportions (Jose 187).

Muscle function, respiration, and heart function were explained by him from the standpoint of mechanics. Leonardo da Vinci, making autopsy the corpses, made a detailed and thorough description of the anatomical structures, immediately sketched everything, supplemented with measurements. He injected vessels, ventricles of the brain, and created organ models to understand their function.

One can rightfully say that Leonardo da Vinci was the first to study the functional anatomy of the motor apparatus. Leonardo was the best anatomist of his time in the world  this is how the distinguished English doctor, surgeon, and anatomist Professor William Hunter (1718-1783), a student of the Edinburgh professor of anatomy Monroe and the London professor Douglas appreciated his personality (Capra 63).

Leonardo da Vinci made sections of a stereometric body formed by regular pentagons, and each time received rectangles with the aspect ratios in the golden division. Therefore, he gave this section the name Golden Section, which is still held as the most popular. To fully appreciate the importance of the anatomical works of da Vinci, one must understand that science in his time was constrained by scholasticism and deeply rooted mysticism. With his clear, free from prejudice thoughts, the scientist was far ahead of his contemporaries.

Leonardo described and sketched many muscles, bones, nerves, and internal organs. His anatomical sketches in their accuracy and skill surpass not only his contemporary works but also many subsequent ones. An example is the sketch of the position of the fetus in the uterus with gluteal Previa. The work of Leonardo da Vinci for half a century ahead of the research of the founder of modern scientific anatomy Andreas Vesalius, but remained unknown to contemporaries.

After the death of Leonardo da Vinci, all the encrypted notebooks and manuscripts with a volume of about 7 thousand sheets were inherited by his student, friend, and companion Francesco Melzi, who systematized only what was related to art. The rest in various ways fell into private collections and libraries of Italy and other countries of Western Europe and for a long time was not published (Capra 79). Over time, Leonardos manuscripts began to be collected, researched, and systematized, and in the second half of the 17th century, 13 volumes were compiled from his notes and drawings. Thus, the works of Leonardo da Vinci on anatomy gained fame only in the 18th century (after the light of the fundamental work of A. Vesalius), and were published even later.

In Da Vincis drawings, for the first time, an image of the frontal, sphenoid, and maxillary sinuses, sesamoid bones of the foot was given. He was the first to correctly determine the number of vertebrae in the sacrum of a person  five (previously, it was believed that the sacrum consists of three vertebrae), correctly described the lordosis and kyphosis of the spinal column, the angle of the sacrum (previously, the sacrum was considered straight, hence the name of the rectum) (Pevsner 217 -219). He tried to study the structure of muscles and joints in a load and close relationship, proposed a classification of muscles according to the size, strength, shape, and nature of tendons and the method of attachment of the bones to the skeleton, expressed innovative ideas about muscle antagonism.

Leonardo da Vinci paid great attention to the quality of the anatomical drawing, which should be as informative and understandable as possible. For the first time, he was offered the image of bones in different angles and projections, and later it began to be used by other anatomists, and this principle underlies modern tomography.

Leonardo da Vinci cannon

Leonardo da Vinci created the so-called canon, based on the works of the Roman architect Vitruvius, author of the treatise Ten Books on Architecture, who lived in the second half of the 1st century BC. Each volume was devoted to separate sections of architecture, construction, and mechanics. In the preface, Vitruvius demonstrated the canonical proportions of the human body (Laurenza 17).

In 1450, the Italian architect Leon Battista Alberti turned to the works of Vitruvius, creating the foundations of the theory of Renaissance architecture. In 1486, the first edition of Vitruvius was published; in 1511, the Dominican priest and architect Giovanni Giocondo made up for the lost drawings. The text of Vitruvius was translated for Leonardo, and he embedded his version of the method proposed by the ancient Roman for determining the exact proportions of a male body that fits into a circle and a square (Laurenza 19). The canon of Leonardo da Vinci represents a modification of the ancient square.

It turned out that if a figure inscribed in a square raises and spreads arms and spreads legs, then it will easily fit into the circle, the center of which is the navel. Leonardo took the head in a unit of measure, laying it in the figure eight times. In the head, he distinguished the cerebral and facial parts, considering them to be the border of the upper eye region. The human body, depicted by the canon of Leonardo da Vinci, has a significant leg length, low navel, somewhat elongated face, especially the nose.

The drawing and explanations for it are sometimes called canonical proportions (Clayton 70). The Vitruvian man tried to solve the problem of squaring the circle. It is impossible to do it exactly (squaring a circle is a metaphor for the impossible), but Leonardo da Vinci managed to get as close as possible to this. He was not interested in the geometric relationship between a circle and a square, and the two geometric figures in his drawing are not connected. Based on his results, he corrected the errors in Vitruvius measurements, being guided by his empirical knowledge of human dimensions.

The rediscovery of the mathematical proportions of the human body in the 15th century, made by da Vinci and other scientists, was one of the great achievements of the Italian Renaissance. As one can see when examining the drawing, the combination of the arrangements of the arms and legs gives two different positions. A pose with arms spread apart and legs brought together is inscribed in a square. On the other hand, a pose with arms and legs spread out to the sides is inscribed in a circle. In more detailed studies, it turns out that the center of the circle is the navel of the figure, and the center of the square is the genitals.

Subsequently, according to the same method, Corbusier compiled his proportionality scale, Modulor, which influenced the aesthetics of 20th-century architecture. The drawing itself is often used as an implicit symbol of the internal symmetry of the human body and, further, the Universe as a whole. Unfortunately, only subsequent generations recognized Leonardo as a great anatomist, although his anatomical work was ahead of time. The whole history of medicine is inextricably linked with the name of a person whose genius has become a symbol of the Renaissance.

Works Cited

Capra, Fritjof. The Science of Leonardo: Inside the Mind of the Great Genius of the Renaissance. Doubleday, 2007.

Clayton, Martin. Leonardo Da Vinci: The Anatomy of Man. Little Brown & Co, 1992.

Habbal, Omar A. The Science of Anatomy: A historical timeline. Sultan Qaboos University Medical Journal, vol. 17, no. 1, 2017, pp. 18-22.

Jose, Antony Merlin. Anatomy and Leonardo da Vinci. Yale Journal of Biology and Medicine, vol.74, 2001, pp. 185-195.

Laurenza, Domenico. Art and Anatomy in Renaissance Italy: Images from a Scientific Revolution. Metropolitan Museum of Art.

Pevsner, Jonathan. Leonardo da Vinci Contribution to Neuroscience. Trends in Neurosciences, vol. 25, no. 4, 2002, pp. 217-220.

Rifkin, Benjamin A., and Michael A. Ackerman. Human Anatomy: From the Renaissance to the Digital Age. Harry N. Abrams, 2006.

Anatomical Structure and Functions

Having a rather complicated structure, the human digestive system consists of eight distinctive parts, namely, the mouth, the esophagus, the stomach, the small intestine, and the large intestine (Kibble & Halsey, 2020, p. 321). The nature of the anatomical structure of the digestive system allows obtaining nutrients from food in the most effective way possible. Specifically, the structure of the digestive system is specifically designed for splitting food into its key components so that the nutrients contained in it could be released and delivered to the respective organs. Namely, the saliva allows starting the process of breaking the food down into its primary components. Afterward, the food is transported through the esophagus with the help of peristalsis into the stomach, where it further decomposes with the help of the acidic components and enzymes that help to turn the food into the form that can be absorbed and transported further. In the small intestine, the food is affected by the enzymes released by the pancreas and the bile from the liver. Finally, the waste left from the processed food is transported into the larger intestine, where it is released from the body through the rectum (Kibble & Halsey, 2020).

Accessory Organs in Digestion

Apart from the organs mentioned above, accessory ones also play a major part in the digestion process. These include teeth, which allow grinding the food into smaller particles, the tongue, which pushes the food down the digestive tract, and salivary glands, which release the saliva needed to split the food into its components. Furthermore, liver and gallbladder are also regarded as the accessory organs since they release the enzymes that lead to faster digestion and the decomposition of the food so that it could be split into the primary elements that will be, later on, delivered to respective organs.

Chemical Reactions

Finally, one should mention the complexity of the chemical reactions that occur during the digestive process. Namely, the in the course of digestion, larger molecules are split into simpler ones, therefore, allowing the body to absorb essential nutrients. Specifically, a process known as hydrolysis occurs within the digestive system once food passes through it. Hydrolysis is typically defined as the chemical reaction in the course of which molecular bonds are broken with the help of water (Lovegrove et al., 2017). The specified process serves as the catalyst for the digestion process and increases the speed of food processing.

Delving into the process of hydrolysis will help to realize that after it occurs, the food processed in the human body is transformed into glucose. Although the shapes that hydrolysis may take may vary extensively depending on the type of food consumed and the components and elements that it contains, the general formula for the process is rather basic. Specifically, if representing the compound that is being split in the course of hydrolysis as AB, and depicting water as HOH, the formula for the process will look the following way: AB + HOH Ì AH + BOH (Lovegrove et al., 2017). As seen in the specified template for the analysis of the digestion process, the compounds may be released as hydroxides. However, the specified formula is not the only possible way of describing the reactions occurring during digestion. Since the reactions in the specified process include hydrolyses of acids, the following formula, where R represents a combining group, apply: RCOOR (Lovegrove et al., 2017).

References

Kibble, J. D., & Halsey, C. R. (2009). Medical physiology: The big picture. Singapore Medical Journal, 50(8), 833. Web.

Lovegrove, A., Edwards, C. H., De Noni, I., Patel, H., El, S. N., Grassby, T.,& Shewry, P. R. (2017). Role of polysaccharides in food, digestion, and health. Critical Reviews in Food Science and Nutrition, 57(2), 237-253.

Abstract

The experiment at hand is investing on the safe usage of the microscope as vital tool in the study of cell biology. It is focusing on two main microscopic techniques used in the many biological laboratories. These are bright-field and phase-contrast microscopy. To achieve this its looks at the different method employed in the preparation of microscopic slide materials as well as examines the best most correct method of focusing the prepared slides in using the microscope.

Introduction

The study of biology entails getting of the insight information for both large and minute biological objects. The study of very small objects has not been possible with unaided eye. Therefore, the invention of the microscope is viewed as major break through in cell biology. The microscope is the most significant basic tool for a cell biologist, which enables the study of minute biological object that cannot be seen with naked eyes (Rudolph 4). Since its invention in the late 16^th century by Janssen, the microscope developed as useful magnifying equipment in biological laboratories. Whereas earliest microscopes depended on the visible light in their functions, several advancements have been made leading to production of more sophisticated ones. The compound microscope which comprises of more lenses than the simple light microscope is the most common in biological laboratories for the study of microbes and other minute biological objects such as animal and plant tissues and cells (Cox 47).

In the study of minute biological objects, the different microscopic techniques are employed depending on the required depth of details or information. Four types of microscopic techniques that are commonly used include phase-contrast, dark-field, bright-field and fluorescence microscopy. The bright-field and phase contrast microscopic techniques are widely used in today’s biology laboratories particularly in microbiological work (Carpenter et al 3). These various microscopic techniques are suited for particular applications of study. Thus, each type has its advantages and disadvantages over the others. In order to use the microscope for the various studies in the microbiological work, cells, tissues and other biological objects undergo different treatments to reveal the necessary features required. Microbial cells such as bacteria, protozoa as well as plant and animal cells are treated with dyes, which contain either colored charged positive ions or negative ions- “(chromatophores)”. If a biological object has most of its components negatively charged, it’s stained with basic dyes such as crystal violet and methylene blue which have the cations being the chromatophores. However, for biological object that has its components being positively charged, it’s stained with acidic dyes which have the anions acting as the chromatophores (Bregman 47). The results of microscopic work depend on the adherence to the recommended procedure. This entails precision and accuracy in dispensing reagents in the entire process with the use of the appropriate apparatus or equipments.

Objectives

To study and understand the different characteristics of light microscopy employed in cell biology in studying the structural and physiological characteristics of the cells and their components.

To study and understand the proper use and care of the compound microscope.

Materials and Equipment

Plant cell from Elodea, human epithelial cell, Paramecium culture , automatic pipettes, glass slides, slide cover slips, brilliant crystal blue, methylene blue, alizarin red, janus green, Congo red, neutral red, and bismark brown, light compound microscope and its accessories, Toothpick visco-elastic resin

Methodology

Preparation of wet mount of paramecium

Using a sterilized pipette, a drop of paramecium culture medium was placed on a glass slide. 10 μl of visco-elastic resin was added and mixed with the culture medium using a toothpick. A slide cover slip was placed on top and then the slide was observed under bright-field microscopy at the different magnifications of the microscope. A sketch of the image observed was made of drawing paper. The slide was then observed under the phase-contrast microcopy and a sketch diagram was made on a piece paper.

Preparation of stained slide

Using a sterilized pipette, a drop of paramecium culture medium was placed on a glass slide. 10 μl of visco-elastic resin was added and mixed with the culture medium using a toothpick. A slide cover slip was placed on top and crystal blue stain added on one edge of the cover slip. Using a piece of “Kimwipe”, the stain solution was drawn into the wet mount. The prepared slide was observed under bright –field microscopy and the observed microscopic image was drawn. Similarly, the slide was also observed under the phase-contrast microscopy and the microscopic observed structured of the paramecium was drawn on a paper.

Examination of plant cell

Elodea leave was obtained from the plant body and placed on a clean glass slide. A drop of distilled water was added and a cover slip placed on top. The slide was then observed under the microscope using the bright-field microscopy. A clear diagram of the observed microscopic image was drawn

Examination of human cell

An epithelial cell was obtained from the cheek using a clean toothpick. The cells were mixed with a drop of distilled water on clean glass slide. A drop of methylene blue stain was added and mixed with the contents on the slide. A cover slip was placed on the top and then, the slide was observed under the microscope. The results of the observed bright-field and phase contrast microscopic images were drawn on a piece of paper.

Results

Magnification

Discussion

The microscope comprises of various parts which are coordinated with each to aid in the study of minute and complex structure found on the biological objects such a cells. The most important factor in the study of minute microscopic biological objects using the microscope is the ability of the microscope to attain high resolution. This depends on the contrast displayed by the objects. The microscope has several objective lenses which aids in the magnifying the tiny objects under study. When lens of the power of 10x is focused on the objects, the structures seen are less in number and also unclear than when a higher powered lens is used. Thus, the objective lens of 40x has gives greater resolution than 10x. The images of cells observed under 10x objective lenses were blurred. For instance, the epithelial cell nucleus was only seen when observed under 10x objective power but these were very unclear. Furthermore, it appeared as without of cytoplasm content with just the cell membranes surrounding it. This infers that it structure resembled that of single-celled organism or the prokaryotes. The plant cells observed under the bright-field microscopy also reveal important structures including the cell-wall which was absent in the epithelial cell and the paramecium cells. The cell-wall thus suggested the slight difference found in the epithelial cells which are of animal origin from the plant cells. The cell-wall found in plant cells are believed to be of significant important as it give the shape of plant cell as well as increasing support to the plant

Conclusion

Generally, the microscope is used for various studies in the biological field. This include the study of plant cells, animal cells as well as the study of unicellular cells such as the paramecium, which is a unicellular eukaryotic. Microscope is very delicate equipment, which needs a lot of care on the lenses. The microscope helps the observation of the biological object at different resolution, hence the preparation of the biological material together with the ability to scan the microscope is an important skills needed in the operation of the microscope.

Works Cited

Bregman, Allan. Laboratory exercises in cell and molecular biology. New York: Wiley ,1996

Carpenter et al. Biology Lab. Manual. University of Texas, 2007

Cox, Guy. Optical Imaging Techniques in Cell Biology. Boca Raton: CRC Press, 2007.

Rudolph, W. Biological microscopy with ultrashort laser pulses, in Tunable Laser Applications. New York: CRC press, 2009