Human Physiology and Anatomy: Functions of the Kidney - Essay Example

Essay 2 – Renal (Human Physiology and Anatomy) Introduction: The kidneys represent important organs in the body of human beings. It has the responsibility of urine preparation, thereby allowing toxic substances and water to get removed from the body. Thus the primary roles of kidneys in the body include removal of metabolic products and deadly substances from the body, upholding the concentration of electrolyte in the body, and taking the responsibility of circulation and formation of blood with the production of substances of renin and erythropoietin that are hormone like products in the body (Faller et al, 2004, p.442). The present study focuses on the various functions of kidney, the anatomy of the organ, as well as the dialysis treatment and management of other functions by the kidney. Functions of the Kidney: Excretion of waste products from the body is the most important function of the kidney within the body. Urea is the main product that gets excreted in the process. Also, the kidney has the responsibility to regulate water in the body as well as balance the acid base and electrolytes levels within the body. In the recent years, studies have obtained that kidney has an endocrinal responsibility as well. This is so because the kidney helps in secretion of a variety of materials like renin and erythropoietin into the stream of blood, leading to several effects external to the kidney as well (Moffat, 1975, p.48). The role of the kidneys involves processing blood such that waste products and excess water can be removed from the body. The waste materials are eliminated in the form of urine as a result of this process. If kidneys did not allow the elimination of the waste products, then these products would accumulate in the blood leading to damage to the human body as a whole. In terms of function, renal function and kidney function are the same. A person having both kidneys active enables the functions of the kidney effective. Several nephrons are present in each kidney that allows intertwining of small blood vessels and tubes that collect the urine. The tubules get hold of the materials and chemicals that the body would make use of from which the kidneys filter the toxic products and return the materials that are needed in the blood within the body, thus balancing the levels of different products in the body (Chiras, 2011, pp.170-182). Thus in particular, the functions of the kidney include: maintaining balance of water in the body; maintaining balance of other body fluids occurring as a result of water balance in the body; monitoring regulation of the absorption and quantity of ions and minerals in the body, maintaining volume of plasma; maintaining acid balance of the body; excreting end products like urea, uric acid, creatinine, bilirubin, and metabolites of hormones; allowing excretion of foreign materials; enabling stimulation of red blood cells through production of erythropoietin; enabling conservation of salt in the kidneys through production of renin; and allowing active form of Vitamin D to perform in the body (Sherwood, 2008, p.512). Anatomy of the Kidney: The anatomy of the kidneys can be represented by structures that retroperitoneal and paired in form. The kidneys are in general positioned flanked by the crosswise progressions of T12-L3 vertebral column. The left kidney is in a fairly higher position than the right. The poles in the upper side of the kidneys are slanting in a median position as well in a posterior manner than the poles at a lower position (Hansel et al, 2012, p.7). Viewing internally, there is an external layer of external cortex on the kidney that encloses the inner medulla of the kidneys. There are several medullary pyramids contained in the medulla. Their names arise from their shapes that are triangular in forms. These medullas contain coiled tubes called nephrons that are microscopic in structure and size. Nephrons are the functional unit of the kidney (Schrier, 2007, pp.34-35). Figure 1: The Structure of Nephron (Physiology of Adult Homo sapiens – Urinary Apparatus, 2001). Renal corpuscle and renal tubule are the two main parts of a kidney nephron. Blood plasma is filtered in the corpuscle of the nephron. The corpuscle, again, has two parts of which one is the glomerulus, constituting a network of blood vessels small in size called capillaries. Bowman’s capsule is the other part the shape of which is a double-walled epithelial cup. The glomerulus is contained within this Bowman’s capsule. The tubule is the second part of the nephron through which the filtrate from the glomerulus passes after it has passed through the Bowman’s capsule (Vize, Woolf & Bard, 2003, pp.156-159). Excretion of Hypertonic Solute Load: There are several factors that determine the most favorable renal concentrating capability determining the organization of the concentration gradient within the structures of renal medulla as well as ADH which is another hormone. The kidney plays the role of managing the excretion of hypertonic solute load. When NaCl in the absence of water is transported actively through the ascending limb of the loop of Henle, there is a resultant “interstitial osmolal gradient from 285 mosmol/kg (in the cortex) to 1200 mosmol/kg in the medulla at the tip of the renal papilla” (Urine Concentrating Ability, n.d.). The medullary concentration gradient is usually obtained through the renal tubules that are present in the loop of Henle where the blood vessels also function representing a process referred as countercurrent exchange. This may be represented through the diagram: (Urine Concentrating Ability, n.d.). Figure 2: Establishment of Medullary Concentration Gradient (Medullary Tonicity) (Urine Concentrating Ability, n.d.). There is a significant need for maintaining the osmolality of the body fluids keeping a constant balance. With the purpose of regulating for extensive discrepancies in solute and water intake, the kidneys need to be proficient to excrete urine of wide-ranging concentrations. Here the tubules play their roles by dissociation of the salt and the water. The urine is referred to as hypertonic when the level of solute in the urine exceeds the level present in the plasma water (Schrier, 2007, p.324). Thus kidney function with the presence of antidiuretic hormone (ADH), renin-angiotensin-aldosterone system, norepinephrine and through the use of thirst mechanism regulates the water and tonicity in the body (Polak et al, 2011, pp.270-271). Dialysis Treatments: Kidney dialysis is mainly of two types: hemodialysis and peritoneal dialysis. In hemodialysis, a special type of filter is used that allows removal of excess water and waste materials from the human. On the other hand in case of peritoneal dialysis, a fluid is used that is put into the hollow space of the stomach in the patient with kidney disorder. This is done with the help of a particular tube made of plastic that enables the elimination of excess water and waste products out of the body. During the process of hemodialysis, a filter is utilized that allows blood to pass through from the body of the patient into the machine of dialysis that is referred as dialysis membrane. To achieve this, sometimes the arteries and veins are directly connected or the use of a particular plastic tube is made for the connection, in the arm or leg. Once this part is achieved needles are located in the graft and blood is allowed to pass through the dialysis machine, get filtered and returned to the patient (Shiel, 2012). In peritoneal dialysis, a membrane referred as the peritoneal membrane is used in the body of the patient. This membrane performs the task of a filter allowing clearance of wastes and extra body fluids such that the levels of electrolytes in the body may return to normal levels. The technique is also referred as exchange. Generally a patient undergoes four to sex of such exchanges every day that involves entry of dialysis fluid into the peritoneal cavity of the patient’s body. This stage is called the ‘fill’ stage. While this stage gets performed, the excess water and materials needed to be excreted move across the membrane and mix with the dialysis fluid. This stage is referred as the ‘dwell’ stage. Following this is the ‘drain’ stage where the fluid of the dialysis is allowed to get drained thereby excreting the waste products. New fluid then replaces this drained dialysis fluid (Poinier & Rosner, 2011). The most important similarity between the two types of dialysis lies in the fact the purpose lies in removal of waste products and excess water from the body of patients and hence tries to treat the kidney disorders in such patients. However both the processes have their own advantages and disadvantages as well depending on which patients need to choose the process they would undertake. For both the processes, certain diet measures are needed to be followed by the patients, also monitoring the intake of fluids within the body, intake particular vitamins and undergo medications to keep the pressure in the blood at normal levels as well as keep other minerals like calcium and phosphorous balanced in the body (Shiel, 2012). The dialysis methods are used in the body of patients because the kidneys become unable to filter the wastes and excrete them out of the body. However both the processes have certain differences as well in their functions and purposes. For example, hemodialysis is used in patients where the kidneys are still capable of functioning minimally. However peritoneal dialysis is particularly for patients where the kidneys have failed completely. These are patients where the kidneys would require transplantation. Another difference is that in hemodialysis, a machine is used for the filtration of wastes, while in case of peritoneal dialysis, the wastes are filtered in the abdomen (Henrich, 2009, pp.687-689). There are similarities and differences in the two dialysis methods also in terms of the diet that patients would require to follow while undergoing these processes. With both the processes, the diet plan needs to be kidney friendly in the patients. The diet during dialysis is also largely dependent on weight, age, and other related conditions as associated with different patients. Calories, protein, sodium, potassium, phosphorous, calcium, fluid balance, and fiber are required in both the cases, however the degree of intake of each of these generally vary with the process being applied on the patient (Stanfield, 2009, p.312). The process of dialysis is an artificial process to eliminate excess water and waste products from the body of humans particularly when the kidneys do not function or undergo complete failure. Normally this function is performed by the kidney. Thus dialysis can be said to replace the function of excretion that is otherwise done by the kidney. It can be said that dialysis is an artificial replacement of the kidney in the body of a patient where the kidneys do not function any more. The endocrine functions of the kidneys are not completely performed through the process of dialysis. Only some of the functions of the kidney are replaced with the dialysis. Dialysis is mostly necessary because excretion of excess water and waste products from the body is highly essential without which human being would die (Stein, Wild & Auer, 2002, pp.12-13). When kidneys do not function properly or fail to function, the excess water and waste materials are normally accumulated in the blood thus creating excess pressure in the blood which is harmful for human bodies. With dialysis, this problem is tried to be removed otherwise which the accumulations of wastes and excess water in the blood would increase to a level that might lead the patients to coma or even death. Hemodialysis may be used by patients who would prefer to perform it at home, who reflected stable conditions after the process, who do not pose the risks of other diseases affecting them that in turn might affect the dialysis, whose blood vessels are suitable for insertion of catheters, and who have caregivers to serve the patient in the correct manner with the dialysis (Stein, Wild & Auer, 2002, pp.14-26). Considering the effectiveness of the process, it has been obtained that although the process may be used to treat patients having kidney failures, yet the process cannot be considered to be as efficient as kidneys function on their own. Generally several patients are capable of living their normal lives after going through dialysis. However in some cases the conditions of the patients may become different. Thus, it can be said that certain functions of the kidney are and may be replaced by the methods of dialysis. However, it may not be considered to be the most efficient solution though. Dialysis are not as efficient as are the normal kidneys, hence patients need to be more careful with the process they choose as well as their lifestyles and diets (Depner, 2005, pp.241-254). Conclusion: From the above study, learning on the anatomy and functions of the kidney could be obtained. The functional unit of the kidney could be studied and how the structures function towards elimination of excess water and waste products from the body. It has been learnt from the study that such excretion of wastes from the body is highly essential for an individual to live. With kidneys not functioning properly, this function gets hampered which is then tried to be corrected to some extent by the methods of dialysis. The methods of dialysis hence prove to be significant in treating patients when kidneys fail to work. However, it has also been learnt that dialysis cannot replace the normal kidneys but can only correct the functions to some extent. Hence patients need to be very careful with their kidneys and treatment methods. References Chiras, D. (2011), Human Biology, Massachusetts: Jones & Bartlett Learning Depner, T.A. (2005), Hemodialysis adequacy: Basic essentials and practical points for the nephrologist in training, Hemodialysis International, Vol.9, pp.241-254 Faller, A. et al (2004), The Human Body: An Introduction to Structure and Function, Germany: Thieme Hansel, D.E. et al (2012), The Urinary Tract, New York: Springer Henrich, W.L. (2009), Dialysis, Philadelphia: Lippincott Williams & Wilkins Moffat, D.B. (1975), The Mammalian Kidney, Cambridge: CUP Archive Physiology of Adult Homo sapiens – Urinary Apparatus (2001), UFRGS, available at: http://www.ufrgs.br/imunovet/molecular_immunology/kidney.html (accessed on December 25, 2012) Poinier, A.C. & M.H. Rosner (2011), Peritoneal Dialysis, webmd, available at: http://www.webmd.com/a-to-z-guides/peritoneal-dialysis-4391 (accessed on December 27, 2012) Polak, A.N. et al (2011), Critical Care Transport, Massachusetts: Jones & Bartlett Learning Schrier, R.W. (2007), Diseases of the Kidney & Urinary Tract, Philadelphia: Lippincott Williams & Wilkins Sherwood, L. (2008), Human Physiology: From Cells to Systems, Connecticut: Cengage Learning Shiel, W.C. (2012), What are the advantages of the different types of dialysis?, medicinenet, available at: http://www.medicinenet.com/dialysis/page4.htm#5whatare (accessed on December 27, 2012) Shiel, W.C. (2012), When do patients require dialysis?, medicinenet, available at: http://www.medicinenet.com/dialysis/page2.htm#3whattypes (accessed on December 27, 2012) Stanfield, P. (2009), Nutrition and Diet Therapy: Self-Instructional Approaches: Self-Instructional Approaches, Massachusetts: Jones & Bartlett Learning Stein, A., Wild, J. & J. Auer (2002), Kidney Dialysis and Transplants: The ‘at Your Fingertips’ Guide, United Kingdom: Class Publishing Ltd Urine Concentrating Ability (n.d.), VET, available at: http://ahdc.vet.cornell.edu/clinpath/modules/ua-rout/usg.htm (accessed on December 26, 2012) Vize, P.D., Woolf, A.S. & J.B.L. Bard (2003), The Kidney: From Normal Development to Congenital Disease, Massachusetts: Academic Press Read More