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PHGY 210 Study Set Exam
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PHGY 210 Study Set ExamKidney Functions - Answer 1. regulation of water, inorganic ion balance, acid-base
balance
2. removal of metabollic waste products from blood and excretion in urine
3. removal of foreign chemicals from blood and excretion in urine (ex. antibiotics)
4. production of hormones/enzymes
- erythropoietin: controls erythrocyte production
- renin: controls angiotensin formation and BP, Na balance
- 1,25-dihydroxyvitamin D: active vitamin that influences Ca balance
kidney weight - Answer 150 g each
kidney location - Answer behind peritoneum on either side of vertebral column against
posterior abdominal wall
kidney anatomy - Answer renal cortex, renal medulla, renal pelvis, renal artery, vein,
ureter
renal artery - Answer interlobar arteries (passes from pelvis to medulla; branches into
cortex)
arcuate arteries (perpendicular to interlobar)
nephron - Answer - gets blood from interlobar artery
- ~1 million per kidney
- consists of renal corpuscle (glomerulus (capillary loops + Bowmans capsule) and
tubule
nephron passage - Answer from corpuscle in cortex --> proximal tubule --> loop of Henle
(descending and ascending) --> distal tubule (touches on glomerulus) --> cortical
collecting duct --> medullary collecting duct
renal corpuscle - Answer - glomerulus punching into Bowman's capsule
Bowmans capsule - Answer parietal layer, space, visceral layer (podocytes)
podocytes - Answer cell processes and cell body in glomerular capillary wall
glomerular capillary wall - Answer filtration barrier
- entangled capillary loops surrounded by Bowman's capsule
,- filters blood to make urine
filtrate flow - Answer endothelial cells --> GBM (Glomerular Basement Membrane) -->
podocytes
renal corpuscle - Answer glomerulus (cortex)
Bowman's capsule (cortex)
proximal tubule - Answer proximal convoluted tubule (PCT) - cortex
proximal straight tubule (PST) - cortex/medulla
Henle's loop - Answer descending thin limb - medulla
ascending thin limb - medulla
thick ascending limb - medulla/cortex
distal convoluted tubule - Answer DCT - cortex
collecting duct - Answer cortical collecting duct (CCD) - cortex
medullary collecting duct (MCD) - medulla
nephron vascular supply - Answer efferent arteriole --> peritubular capillaries --> venous
system
urine formation - Answer 1. glomerular filtration
2. tubular secretion
3. tubular reabsorption
glomerular filtration - Answer filtration of plasma from glomerular capillaries into
Bowman's space
- filtrate is cell-free and except for proteins, has substances as plasma in same
concentrations
tubular secretion/absorption - Answer - as filtrate passes through tubules, composition
altered
- reabsorption: tubules --> peritubular capillaries
- secretion: peritubular capillaries --> tubules
Amount Excreted - Answer Amt excreted = amt filtered + amt secreted - amt reabsorbed
(secretion =/= excretion)
3 substance pathways - Answer - complete secretion (ex. PAH para-amino-hippurate to
,calculate blood flow into kidney)
- some/most reabsorption: Na, H2O, most small molecules, most common
- complete reabsorption (ex. glucose, amino acids, stuff essential to the body)
what is filtered - Answer water, small substances
(not proteins, or protein-bound substances)
- 1/2 Ca reabsorbed b/c bound to albumin
filtration forces - Answer - favoring: glomerular capillary BP (Pgc) ~ 60 mmHg
- opposing: fluid pressure in Bowman's space (Pbs) ~ 15mmHg and osmotic force due to
plasma proteins (PIgc) ~ 29 mmHg
net glomerular filtration pressure - Answer Pgc - Pbs - PIgc ~ 16 mmHg
glomerular filtration rate (GFR) - Answer volume fliud filtered from glomeruli to
Bowman's space per unit time
- regulated by net filtration P, membrane permeability, SA available for filtration
normal GFR - Answer for 70 kg person: 180 L/day (125 mL/minute)
- plasma V of such person is 3.5 L
- plasma filtered 51x/day
GFR regulation - Answer - decreased GFR: constrict afferent arteriole or dilate efferent
arteriole so that Pgc increases
- increased GFR: dilate afferent arteriole or constrict efferent arteriole so that Pgc
decreases
Filtered load - Answer total amount freely filtered substance
= GFR * plasma conc. of substance
- ex. filtered load of glucose = 180 L/day * 1 g/L = 180 g/day
- filtered load > amt excreted --> net reabsorption
- filtered load < amt excreted --> net secretion
- enormous, greater than amt substance in body
, reabsorption tubular lumen --> peritubular capillaries - Answer - basolateral membrane,
tight junction b/w tubular epithelial cells on tubular lumen, luminal membrane, interstitial
fluid
paracellular - Answer through tight junction
transcellular - Answer through tubular epithelial cell
urea reabsorption rate - Answer low (44%) compared to water, Na, glucose (~100%) b/c
is a waste product
- K net 86% reabsorption
2 mechanisms or reabsorption - Answer diffusion and mediated transport
diffusion - Answer across tight junction (paracellular) connecting tubular epithelial cells
- e.g. urea in proximal tubule: urea freely filtered in glomerulus, in proximal tubule water
reabsorption, urea concentration higher, urea diffuses into peritubular capillaries and
interstitial fluid
mediated transport - Answer - transcellular
- requires plasma membrane transport proteins
- usually coupled to Na reabsorption
solute transport mechs - Answer - passive: spontaneous, down electrochemical
gradient (no energy); diffusion, channels, uniport, coupled transport, solvent drag
- active: against an electrochemical gradient (needs energy)
Transport Maximum (Tm) - Answer - when transport proteins in membrane saturated,
tubule cannot reabsorb any more --> limit is Tm
- ex. in diabetes mellitus, plasma conc. of glucose can be very high and filtered load
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