Lecture 58 - Collecting Ducts Flashcards
what are the 3 basic renal processes
- glomerular filtration
- tubular reabsorption
- tubular secretion
why is there reabsorption?
because it is impossible and metabolically wasteful to intake the water and electrolytes needed to replenish waste
glomerular capillary bed
- specialized for filtration
- produce ultrafiltrate under high blood pressure
peritubular capillaries
- from efferent arterioles
- associated w renal tubules
- low-pressure and high oncotic pressure
- reabsorption of solutes and water
proximal convoluted tubule
- responsible for the majority of reabsorption
- large # of mitochondria
- microvilli increases surface area
how are tubular cells connected
via tight junction and trans-/para-cellular pathways
what barriers must a transcellular pathway pass between
- luminal membrane of tubular cells
- basolateral membrane of tubular cells
- endothelium of capillary
what is reabsorbed in the PCT
- water
- sodium
- chloride
- bicarb
- glucose
- amino acids
water reabsorption is driven by
starling forces
what stimulates water reabsorption
- high oncotic pressure
- low hydrostatic pressure
glomerulotubular balance
constant fraction of the filtered load is reabsorbed at the proximal tubules
Give examples of increased GFR
constriction of efferent arteriole increases the amount of blood that is filtered
Give examples of increased reabsorption
higher oncotic pressure in the blood in the peritubular capillary will increase the amount of fluid reabsorbed from filtrate to capillary
water moves through
aquaporins
T/F: the resting state of aquaporins can be “open” or “closed”
TRUE
where are aquaporins always open
proximal convoluted tubule
where are aquaporins always closed
collecting ducts
glucose is reabsorbed with ____ in the PCT
Na+
what 2 carrier proteins are required for glucose transport in the renal system
- SGLT-2
- GLUT-2
SGLT-2
Na+ and glucose
Na+ out by APTase
Glucose in due to concentration/electrical gradient
GLUT-2
glucose from cytoplasm to interstitial fluid
passively reabsorbed
what can you give a cat with insulin-non-dependent diabetes
SGLT-2 inhibitor
when glucose exceeds the renal threshold it “spills over” to
urine
T/F: glucose cannot change osmolarity
FALSE