urinarysystem - LECTURE NOTES ANATOMY & PHYSIOLOGY II...

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© LECTURE NOTES – ANATOMY & PHYSIOLOGY II (A. IMHOLTZ) URINARY SYSTEM P1 OF 7 I. Function of the urinary system a. The organs of the urinary system ( kidneys , ureters , urinary bladder and urethra ) all play a role in urine formation, storage, or expulsion. b. However the function of the urinary system cannot be simply defined as “urine production” or “waste removal.” c. The primary functions of the urinary system include: i. Regulating blood volume. ii. Regulating the chemical make-up of blood. d. Secondary functions include: i. Metabolism of vitamin D ii. Regulation of acid/base balance. iii. Production of renin . iv. Production of EPO . II. Basic pathway of urine i. Urine is formed in the renal cortex ii. Travels thru collecting ducts in the renal medulla iii. Continuously drips out of the renal papillae into the minor calyces iv. Flows into major calyces v. Flows into the renal pelvis vi. Flows into the ureter vii. Flows into and is stored in the urinary bladder viii. Exits the body via the urethra. b. The walls of the calyces, pelvises, ureters, bladder, and urethra all contain smooth muscle to propel urine. III. Basic pathway of renal blood flow a. Since the kidney’s main function is regulating the volume and composition of the blood, it requires an extensive blood supply (≈ 25% of cardiac output). b. This is the basic pathway of renal blood flow: c. The glomerular capillaries are the sites of filtration d. The peritubular capillaries are the sites of reabsorption and secretion . IV. The Nephron a. The functional unit of the kidney is a set of tubules known as the nephron . b. Each kidney contains 1 million nephrons. Abdominal Aorta Renal Artery Segmental Artery Interlobar Artery Arcuate Artery Cortical Radiate Artery Afferent Arteriole Glomerular Capillaries Efferent Arteriole Peritubular Capillaries or Vasa Recta Cortical Radiate Vein Arcuate Vein Interlobar Vein Renal Vein IVC
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© LECTURE NOTES – ANATOMY & PHYSIOLOGY II (A. IMHOLTZ) URINARY SYSTEM P2 OF 7 c. Each nephron begins with a ball of capillaries known as a glomerulus . i. Blood filtration occurs here. The filtered fluid is known as filtrate . d. The filtrate travels through the renal tubules of the nephrons and is modified and turned into urine. e. The renal tubules run alongside the peritubular capillaries, so exchange may take place between the two. f. Any substance that was filtered but should not be excreted in urine will be reabsorbed – transported from the filtrate within the renal tubules to the blood within the peritubular capillaries. g. Any substance that was not filtered but should be excreted in urine will be secreted – transported from the blood within the peritubular capillaries to the filtrate within the renal tubules. h.
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This note was uploaded on 11/10/2011 for the course LS 101 taught by Professor Abdul during the Spring '11 term at Montgomery College.

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urinarysystem - LECTURE NOTES ANATOMY & PHYSIOLOGY II...

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