Organ Systems and Homeostasis - Role of the Nephron, Circulatory and Digestive Systems - Coursework Example

ASSIGNMENT 2 OF 3 ORGAN SYSTEMS AND HOMEOSTASIS Name Course: Tutor Institution City and State Date: Assignment 2 of 3 Organ Systems and Homeostasis Part 1 Role of the circulatory system The circulatory system plays an important and unique role in the body of people. It is involved in transport and more so maintaining homeostasis (MANOLIS 2009, p.9). The process of homeostasis is responsible for the maintenance of a balanced internal environment. However, the role of the circulatory system is the transport of blood and other useful substances throughout the body using blood. Also, this system is involved in the carriage of secretions and excretions to facilitate various body functions and support organ systems (MANOLIS 2009, p.11). The circulatory system is indeed necessary as it transports the waste products of metabolism from the cells for instance carbon (IV) oxide. On the other hand, it provides cells with materials such as glucose and oxygen to facilitate cellular activities. The circulatory system is composed of the heart, arteries and capillaries (MANOLIS 2009, p.5). When blood is pumped by the heart, it is taken to the rest of the body through the use of arteries. However, at the cell level, the arteries branch to the capillaries. These are small blood vessels that can reach particular cells. The high blood pressure from the pumped blood forces the liquid portion of this fluid through the membrane of the capillaries forming tissue fluid. This process is called ultrafiltration and the fluid is composed of nutrients and oxygen (MANOLIS 2009, p.6). Once the filtrate is passed from the capillaries, it reaches the cells and replenishes them with fresh nutrients such as glucose and oxygen. In return, the cells pass out waste materials and carbon dioxide to the tissue fluid which is conveyed using the veins. In that way, the internal cell environment becomes balanced as the wastes of metabolism are removed and nutrients supplied. Role of the Respiratory System The respiratory system is composed of organs and tissues to allow people to breathe. This system ensures that cells are supplied with a constant stream of oxygen to support cellular activities (TAYLOR-BUTLER 2009, p.6). Also, the system facilitates the removal of carbon dioxide which is a metabolic poison. In that way, it prevents the products of respiration from accumulating to dangerous levels. The respiratory system is categorized into three key parts the lungs, airways, and muscles. First, the airways comprise the mouth, nose, larynx, pharynx, bronchioles and bronchi (TAYLOR-BUTLER 2009, p.10). Second, the lungs serve as the functional unit of the respiratory system where the contract and relax to pump oxygen to the blood. Lastly, the muscles such as the diaphragm are responsible for pushing air in and out of the lungs in the process of breathing. During breathing, the diaphragm relaxes to allow air into the lungs through the nose. The air passes through the nose, trachea and into the lungs (TAYLOR-BUTLER 2009, p.11). While in the nose it is warmed, moistened and the mucus traps dust. Also, as the air travels through the trachea to the lungs the mucus removes dust particles. Once the oxygen reaches the lungs, it goes to the alveoli where it dissolves in the water and is passed to the large network of blood capillaries for supply to the rest of the body. On the other hand, deoxygenated blood is brought to the alveoli where the red blood cells release carbon dioxide (TAYLOR-BUTLER 2009, p.12). As the level of carbon dioxide increases, the diaphragm contracts to expel this air from the lungs. The cycle continue to provide body cells with oxygen and release carbon dioxide to provide optimum working internal conditions. Function of the Digestive System The digestive system is involved in the provision of nutrients to the body cells to allow the production of energy and survival of people. When food enters the mouth, it is mechanically broken down through mastication (MIFTAHOF & NAM, p.14). The saliva and mucus mix with the food to commence digestion of starch. Then after swallowing, the food is passed down to the stomach through the esophagus through peristalsis. While In the stomach, the broken down food is mixed with various enzymes to continue the digestion of starch, proteins, and carbohydrates. The cells of the stomach produce digestive enzymes and hydrochloric acid which kills germs (MIFTAHOF & NAM, p.17). After sufficient processing, the stomach contents are passed to the small intestines where the digestion of fats completes in the duodenum. In the small intestines, food is absorbed into the blood stream via the villi. Therefore, the cells are provided with energy relevant for cellular activities. At the large intestines, water is absorbed by the body. The rest of the constituents are passed out of the body as stool (MIFTAHOF & NAM, p.21). The anus is the last segment of the digestive system where waste products are excreted from the body. However, it is controlled by a sphincter which ensures that the anus relaxes to let out stool through muscular contractions. In that way, the digestive system is provided with a proper environment for the processing of the food eaten next to complete the homeostatic function of this system. Part 2 Function of the Nephron The nephron forms the basic functional unit of a kidney. A kidney is, therefore, composed of millions of nephrons which are responsible for the removal of toxic wastes found in the body (SUDERMAN & HARRIGAN, p.8). The renal cortex thus has a granular appearance that results from the formation of nephrons. The design of a nephron comprises of a long tube that begins from the cortex to the medulla and then moves back to the cortex before joining the next nephron at the collecting duct. As a nephron starts forming, it creates a cup-shaped structure called the Bowman’s capsule which leads to the proximal convoluted tubule (SUDERMAN & HARRIGAN, p.13). These tubes descend, they form the distal convoluted tubules. These tubules are responsible for draining their contents into the collection duct at the renal pelvis. After the contents of the tubules have collected, they are drained to the ureter as urine. Glomerulus In homeostasis, the nephron is responsible for filtering, absorbing and secreting glomerular filtrates such as carbohydrates. The glomerulus forms the first part of the nephron where all fluids are filtered. It is comprised of two essential portions; a network of capillaries and the Bowman's capsule (SUDERMAN & HARRIGAN, p.15). The former is responsible for the transport of blood, and the latter is the part where the filtered fluids collect. The Bowman's capsule is situated in the renal cortex. Its lining is composed of epithelial cells which allow fluids and some substances to be absorbed into the blood stream. The filtrates of the filtration process are passed to the renal tubules for further processing. Notably, the glomerular capillaries are comprised of thin endothelial cells. In that way, they can allow the fluid that leaves the Bowman's capsule to the tubules. Tubules The connecting, distal and proximal tubules are found in the renal cortex of the nephron. However, the loop of Henle is located at the medulla section. These tubules have thin inner layers composed of epithelial cells. They have thinner sections which form the ascending and descending loop of Henle (SUDERMAN & HARRIGAN, p,17). The other segments of the tubules have thick cells that are rich in mitochondria cells to facilitate active and passive reabsorption of the glomerular filtrate. Most importantly, the tubules and collecting ducts are designed such that they are impermeable to water absorption. However, this property is altered through the presence of the antidiuretic hormone which increases the absorption of water at these parts. When the glomerulus filters the fluid it moves to the proximal convoluted tubule where reabsorption occurs at peritubular capillaries (SUDERMAN & HARRIGAN, p.19). At this juncture, substances such as vitamins, iron, glucose and amino acids are reabsorbed into the blood. As such, the proximal tubule is lined with numerous microvilli to enhance the surface area for the absorption of substances to the blood stream. As the process of absorption occurs, the concentration of elements at the capillaries increases. With that, a lot of water should be absorbed in this tubule through osmosis to create an electrolyte balance. All the absorption of glucose occurs at the proximal convoluted tubule. Formation of Urine As the process of reabsorption continues, the loop of Henle accumulates salts which are added to the components of urine (SUDERMAN & HARRIGAN, p.19). As a result, a high concentration of solutes is created at the medulla. However, the ascending and descending tubules control the situation through the absorption of water and ions. That is made possible through their permeability and thin epithelial lining. The ascending tubule is responsible for absorption of salts through active transport. On the other hand, the high volume of filtrate that leaves the descending tubules results to the creation of concentrated urine (SUDERMAN & HARRIGAN, p.20). The contents of these tubules are passed on to the distal convoluted tubule. This portion is responsible for the maintenance of the pH balance within the blood and urine. After this process, the contents of the distal convoluted tubules are taken to the collection duct. Here, ultrafiltration occurs where useful substances are reabsorbed into the blood. The rest of the solution of passed on to the ureter for excretion as urine. Part 3 The Role of the Nervous and Endocrine Systems in Osmoregulation Osmoregulation is a homeostatic process responsible or the control of water as well as mineral salts in the blood. The nervous system through the hypothalamus notes the change in water levels in the blood. If the level is low, antidiuretic hormone is secreted to trigger the absorption of water at the tubules (SUDERMAN & HARRIGAN, p.22). As a result, less concentrated urine is produced. On the contrary, the pituitary gland reduces the production of antidiuretic hormone to reduce water absorption. The endocrine system has a critical role in homeostasis which is secreting hormones such as antidiuretic hormone in response to the levels of water in the body through the pituitary gland. In the body, osmoregulation is the process that ensures that cells have sufficient water to support various functions (TAYLOR-BUTLER 2009, p.20). Therefore, the osmotic potential of blood is dependent on its solute content. When the water level in the blood is low, the hypothalamus notes the change. The pituitary gland responds by secreting ADH to increase water absorption at the kidneys. As a result, the kidneys work to ensure they absorb as much water to ensure that the concentration of cells becomes hypotonic. The result of successful absorption is that large volumes of dilute urine is produced (TAYLOR-BUTLER 2009, p.21). When that point is reached, the pituitary gland initiates a negative feedback where is reduces the production of ADH. The endocrine plays a crucial part in osmoregulation through the production of two hormones; ADH and aldosterone. First, aldosterone regulates the amount of salts absorbed by the body cells. In that way, the kidneys can adjust their rate of water absorption is the bid to prevent the body from dehydrating (TAYLOR-BUTLER 2009, p.24). When the water level is high, more salts are produced and therefore the concentration of water reduces. In this case, the aldosterone and ADH hormones work together. Aldosterone is produced in high amounts and ADH in low volumes to make the water concentration in the blood to be normal. List of References MANOLIS, K. (2009). Circulatory system. Minneapolis, MN, Bellwether Media. MIDTHUN, J., & HITI, S. (2014). Cells to organ systems. MIFTAHOF, R., & NAM, H. G. (2010). Mathematical foundations and biomechanics of the digestive system. Cambridge, Cambridge University Press. http://site.ebrary.com/id/10388564. SUDERMAN, R & HARRIGAN, J. (2013). The urinary system. TAYLOR-BUTLER, C. (2008). The respiratory system. New York, Children's Press. Read More