Physiology and Human Anatomy

Questions: 1. a) Filtration, secretion and excretion b) Clearance , excretion and glomerular filtration rate 2. a) What types of anabolic steroids would they use b) What could be some undesirable effects of taking such steroids? 3. Why is the endocrine system considered one of the integrative systems of the body? Answers: 1. a) Filtration, secretion and excretion Filtration Filtration is the movement of water and solutes from plasma to the renal tubule that occurs in the renal corpuscle. at any given time about 20% of the plasma volume passing through the glomerulus is filtered. In other words, about180 litersof fluid are filtered by the kidneys every day. That means, the entire plasma volume (which is about 3 liters) is filtered almost 60 times a day. Filtration is primarily driven in the capillaries of the glomerulus by fluid pressure (blood pressure). It has to be remember that kidneys filter much more fluid than the actual amount of urine excreted (which about 1.5 liters per day). This is essential for the kidneys to rapidly remove waste and toxins from the plasma efficiently. Secretion After filtration has occurred, secretion of additional substances into the tubular fluid by the tubules continues. This enhances the kidney's ability to eliminate certain wastes and toxins. It is also essential for the regulation of plasma potassium concentrations and pH. Excretion The result of the above processes is excretion, which goes into the urine. Initially the original concentration of a substance in the tubule fluid may be close to that of plasma, subsequent filtration, re-absorption and secretion can dramatically alter the final concentration in the urine. The amount of a particular substance that is excreted is determined can be written in simple formula: E.g. amount filtered - amount reabsorbed + amount secreted= amount excreted b) Clearance , excretion and glomerular filtration rate Renal clearance is a measurement that allows one to analyze the activity of the kidney. The definition for clearance could be defined is thevolume of plasmafrom which a substance is completely removed by the kidney in a minute. As an example if we say, the clearance for urea is 65 ml/min. This means that the kidney removes all of the urea in 65 ml of plasma in one minute. Every minute approximately 625 ml of plasma goes to the kidney. This is called the renal plasma flow. Some of the fluid leaves the kidney in the plasma while some leaves the kidney as urine. There are only two ways for a substance to end up in the urine: the substance either it isnot filtered but issecretedby from theperitubular capillariesinto thetubules or it is filteredat theglomerulusand then notreabsorbedfrom thetubules,. In either instance, the substance ends up in thecollecting ductand has been excreted into the urine (de Souza and Hallak, 2011). Of the 625 ml/min of plasma that goes to theglomerulus, 125 ml/min are filtered intoBowman's Capsuleforming the filtrate (this is known as the glomerular filtration rate). The remaining 500 ml/min remain in the blood and enter into theperitubular capillaries. Of the 125 ml/min which was filtered initally , almost all of the water in this fluid is reabsorbed and put back into the blood. It is important to remember that the composition of the filtrate inBowman's Capsuleisidenticalto the composition of the plasma except that the filtrate has no or very few proteins. It has to be remember that this is not true for the urine. This means, for example, that the concentration of glucose in the filtrate inBowman's Capsuleis the same as that in the plasma. Glomerular filtration rate GFR - glomerular filtration rate is the test to measure ones level of kidney function and which determine if there are any kidney disease is present or not. It can be calculated from the results of age, body size blood, gender, and creatinine test. If the GFR number is low, kidneys are not working properly as they should. The glomerular filtration rate is 125ml/min in a normal person but person with diabetes, high blood pressure or any other cardiovascular diseases shows altered rate of glomerular filtration. 2. a) What types of anabolic steroids would they use Anabolic steroids are synthetic hormones, which mimics the structure and function of male hormone testosterone and androgens (Bowman, 1990). Types of anabolic steroids used by athelets are Testosterone Nandrolone Boldenone Stanozolol Dan azol Mesterolone b) What could be some undesirable effects of taking such steroids? Kidneys are involved in filtration and removal of metabolic byproduct from the body. When steroid compounds cause strains in the renal structure. Because of anabolic steroids blood pressure most likely to rise in the body as well as in the kidney and this high blood pressure glomerular filtration rate are severely hampered. Along with kidney dysfunction prostate enlargement, testicular atrophies, liver dysfunction, hair loss, depression , gyncomastia , cardiovascular disease are also observed because of abuses or misuses of anabolic steroids(de Souza and Hallak, 2011). 3. Why is the endocrine system considered one of the integrative systems of the body? The endocrine system is considered one of the integrative systems of the body because the hormones produced by the system act locally as well as different other parts of the body. Hormones from the endocrine system, they cross talk to the cell and tissues of different organs and systems of the body and maintains integrity throughout the system. As per George P Chrousos Cells communicate with each other through molecular messengers, the hormones. The simple definition of a hormone as an intercellular messenger is much more inclusive than the original one, which limited the hormones to substances produced by specialized multicellular organsthe glandsthat circulated in blood and acted on distant target organs. This simplification allowed single cells to be considered glands or targets of hormones, or both, and eliminated blood circulation as a prerequisite. The concept of endocrine function thus was expanded to paracrine, autocrine, juxtacrine, and intracrine functions, whereas the classic endocrine system, which included the traditional endocrine axes, was expanded to every organ and cell in the body that produced and responded to hormones. (Chrousos, 2007) References: Astor, B., Shaikh, S. and Chaudhry, M. (2013). Associations of endogenous markers of kidney function with outcomes. Current Opinion in Nephrology and Hypertension, 22(3), pp.331-335. BASELINE TOTAL KIDNEY VOLUME IS ASSOCIATED WITH WORSENING OF KIDNEY FUNCTION INDEPENDENTLY OF BASELINE GLOMERULAR FILTRATION RATE IN PATIENTS WITH AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE. (2014). American Journal of Kidney Diseases, 63(5), p.B90. Hori, Y., Murayama, T., Fukushima, K. and Takahashi, H. (2011). Relations between Glomerular Filtration Rate of Chronic Kidney Disease with Cardiac Size and Function in Patients with Chronic Atrial Fibrillation. J Arrhythmia, 27(Supplement), pp.PJ3_023. JOHNSON, D. (2005). Use of estimated glomerular filtration rate to assess level of kidney function. Nephrology, 10(s4), pp.S140-S156. Stevens, L., Coresh, J., Greene, T. and Levey, A. (2006). Assessing Kidney Function Measured and Estimated Glomerular Filtration Rate. New England Journal of Medicine, 354(23), pp.2473-2483. Bowman, S. (1990). Anabolic steroids and infarction. BMJ, 300(6726), pp.750-750. de Souza, G. and Hallak, J. (2011). Anabolic steroids and male infertility: a comprehensive review. BJU International, 108(11), pp.1860-1865. Chrousos, G. (2007). Organization and Integration of the Endocrine System: The Arousal and Sleep Perspective. Sleep Medicine Clinics, 2(2), pp.125-145.