4: reabsorption and secretion Flashcards
in ____ ____, water and solutes can travel thru the tubular epi, either thru the __ route (thru cell memb) or the __ route (bt cells via tight jxn)
tubular resorption
transcellular
paracellular
in tubular resorption, water is always absorbed by ___ mechanism (osmosis)
passive
__ __ is the limit to the rate at which a solute can be transported during active reabsorption or secretion
transport maximum
some substances that are passively absorbed don’t demo a transport maximum, rate dep on other things, is then called __ __ transport
gradient time
transport type in which the rate dep on:
- electrochem gradient
- perm of memb to substance
- time the fluid containing the substance in tubule
gradient time
some actively transported substances can exhibit characteristics of gradient time transport , such as:
Na reabsorption in prox tubule
sodium transport in the PROX tubules obey __ __ transport principles
- greater [Na] in prox tubule, greater reabsorp rate
- slower flow rate, more Na reabsorbed
gradient time
65% of filtered water and Na are reabsorbed in ___ ___ before reaching the _ _ _
proximal tubule
loop of henle
thin descending segment
thin ascending segment
thick ascending segment
–are the three parts of the :
loop of henle
the THICK ASCENDING segment of loop of henle is made of thick epi cells and functions in active resorption of (3):
Na
Cl
K
transport mechanism found in the thick ascending part of loop of henle
sodium-hydrogen counter-transport (mechanism)
late distal tubule and cortical collecting tubule is composed of what 2 cell types
principal
intercalated
in late distal tubule & cortical collecting tubule, reabsorp of Na and secretion of K is controlled by ____
aldosterone
permeability to water in late distal tubule and cortical collecting tubule is dependent on __
ADH
hormone that increases water reabsorp in resp to dehydration
ADH
w/o ADH, distal tubule & collecting ducts aren’t v. permeable to ___, and we would excrete large quantities of __ ___
water
dilute urine
two net reabsorptive forces that FAVOR reabsorption
plasma colloid OP (32mmHg)
hydrostatic P in interstitium (6mmHg)
two net reabsorptive forces that OPPOSE reabsorption
peritubular hydrostatic P (13mmHg)
OP of the renal interstitium (15 mmHg)
net reabsorptive forces AND glomerular cap net filtration forces both =
10mmHg
Kf (filtration coefficient) influences movement of fluid across caps and involves ___ __ and ___ of the capillary
surface area
permeability
Kf x net reabsorptive forces =
reabsorption
-if peritubular capillary hydrostatic pressure is raised, reabsorption rate is ____. if it is lowered, reabsorption rate ___
decreased
increases
Na+ excretion in urine is called ____, and water excretion to reg BP is called __ __
- increases arterial P
- increase in urinary excretion of Na & H2O
natriuresis
pressure diresis
___ is secreted by the zona glomerulosa cells of adrenal corex, and regs Na reabsorption and K secretion
aldosterone
___ is released in resp to increased extracell [K] and angiotensin II levels
aldosterone
___ increases water permeability and its primary fxn is to conserve water when bod is dehydrated
ADH
___ is released in the cardiac atria when distended, inhibits the reabsorp of Na & water, and counteracts the renin-angiotensin system
ANP
hormone that increases Na & water reabsorp and increases when BP is low/low extracell vol
angiotensin II
hormone that stim aldosterone secretion, constrict efferent arterioles
angiotensin II
hormone that directly stim Na resabsorp in prox tubule, loop of henle, distal tubule, collecting tubule
angiotensin II
