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Physiology Lecture 16- Urinary System
Study Set Exam
kidney - Answer consists of 3 distinct areas: cortex (outer), medulla (middle), and renal pelvis (inner)
cortex - Answer contains ~1,000,000 renal corpuscles, which filter the blood
medulla - Answer once the blood is filtered, the filtrate is sent through the nephron and then into the collecting ducts of this. it consists of 8-15 renal pyramids and each pyramid has a renal papilla; around each renal papilla is a funnel-like tube=minor calyx. The minor calyces fuse together to form major calyces and those fuse to form the renal pelvis; middle of kidney
nephron - Answer the microscopic unit that modifies the blood filtrate to form urine; the functional unit of the kidney
renal corpuscle - Answer contains a mass of capillaries =glomerulus, surrounded by a spherical structure=Bowman's (glomerular) capsule;
made up of the glomerulus and the glomerular capsule
glomerulus - Answer a mass of capillaries in the renal corpuscle of the nephron
glomerular (Bowman's) capsule - Answer a spherical structure that surrounds the glomerulus which is part of the renal corpuscle in the nephron
renal tubule - Answer consists of: proximal convoluted tubule, loop of Henle, and distal convoluted tubule
loop of henle - Answer has descending and ascending limbs; makes up renal tubule along with PCT and DCT
juxtaglomerular apparatus - Answer a site at which a portion of the DCT comes in contact with the adjacent arterioles, 2 parts: macula densa and juxtaglomerular cells
macula densa - Answer DCT cells which monitor sodium concentration
juxtaglomerular cells - Answer release renin in response to decreased sodium
renin - Answer a hormone released by the juxtaglomerular cells in response to low sodium levels; increases production of sodium
basic exchange process - Answer 3 types: glomerular filtration, tubular secretion, tubular reabsorption
glomerular filtration - Answer the filtering of the blood through the wall of the glomerular capillary into surrounding glomerular space; the blood is brought in to the glomerular
capillaries through the afferent arteriole. once in the capillary, the difference in Starling's forces dictates the glomerular filtration pressure
net filtration pressure - Answer filtration pressures - absorption pressures
glomerular filtration pressure (GFP) - Answer the difference in starling's forces dictates this;
___ = (GCHP + BCOP) - (BCHP + GOP)
= 16 mmHg;
so, there is 16mmHg pushing fluid out of the glomerular into the glomerular capsule
glomerular filtration rate (GFR) - Answer the volume of plasma filtered per unit time; this is equivalent to 125ml/min = 180L/day;
since the body has approximately 2.75 liters of plasma, the GFR indicates the entire volume of plasma is filtered every 22 minutes
factors affecting GFR - Answer if there wasn't any compensation, as our MAP increased or decreased, the glomerular capillary hydrostatic pressure would increase or decrease, and the GFR would increase or decrease, consequently our GFR would constantly be changing (thats not desirable); however, due to several control mechanisms, as our MAP varies from 80-180mmHg, our GFR stays essentially the same (~125ml/min)
intrinsic controls affecting GFR - Answer myogenic regulation and juxtaglomerular apparatus
myogenic regulation - Answer an intrinsic control; when the MAP rises, the afferent arteriole is stretched, and the GFR rises. In response, the arteriole vasoconstricts to help maintain a normal GFR and vice versa
juxtaglomerular apparatus - Answer an intrinsic control; if the volume in the DCT increases (perhaps due to increased GFR), the cells of the macula densa release chemicals to vasoconstrict the afferent arteriole and the GFR decreases
extrinsic control affecting GFR - Answer in response to decreased MAP perhaps due to hemorrhage or excessive fluid loss, the sympathetic nervous system contracts efferent arterioles, which increases resistance and increases GFR
tubular reabsorption - Answer refers to the removal of substances from the filtrate in the renal tubule and their return to the plasma of the peritubular capillaries; if this wasn't done, then everything that was filtered would leave the body. it would take only 8 minutes to lose 1 L of fluid. most reabsorption takes place in the PCT and some in the loop and DCT
active reabsorption - Answer requires energy and carriers or pumps to move
