Renal 2: Tubular Absorption & Secretion Flashcards
filtration from the blood into the nephron occurs in what part of the nephron?
bowman’s capsule
give the formula for renal excretion
E = (filtered - reabsorbed) + secreted
describe the anatomy of the nephron in the order urine passes through them
proximal tubule; loop of henle; distal tubule; collecting duct
most of what is filtered is ____ by the nephron
reabsorbed
glucose in the urine is a sign of ___
diabetes
water is ___%reabsorbed by the nephron
99
sodium is __% reabsorbed by the nephron
99
glucose is ___ % reabsorbed by the nephron
100
substances are reabsorbed and secreted across renal tubular ___ cells
epithelial
substances can be reabsorbed and secreted across renal tubular epithelial cells by what 2 methods?
- paracellular
2. transcellular
transcellular reabsorption / secretion is _____
active
paracellular reabsorption/ secretion is ___
passive
what are the 3 membranes of the nephron epithelial cells?
apical, lateral, basal
passage of solutes by paracellular route is ___
passive
passage of solutes by the transcellular route is ___
active
passage of water by the paracellular and transcellular routes is ___ and driven by __
passive; osmosis
for active transepithelial absorption / secretion, there are ___ located on either side of the cell
specific transporters
t/f transcellular Na reabsorption requires energy
true
the entrance of Na into the epithelial cells is ___ and the exit is __
passive; active
Na enters the __ end and exits through the __ end
apical; basolateral
what transporter is used to actively move Na across the basolateral membrnae?
Na/K pump
t/f sodium can be reabsorbed by both active and passive routes
true
overall, sodium reabsorption is a ___ process (active / passive?
active
t/f other substances can be reabsorbed in a Na-dependent fashion. If so give an example
true; glucose
entrance of glucose to the apical membrane is ___ and its exit across the basolateral membrane is __
active; passive
what transporter is used to bring glucose into the cell in a sodium-dependent manner?
sodium glucose transpoter
what transporter is used to remove glucose from the cell in a sodium-dependent manner?
glucose facilitated diffusion transporter
__% of filtered glucose is reabsorbed by the proximal tubule?
100
water moves in response to ___ pressure difference
osmotic
water moves from __osmotic pressure to ___ osmotic pressure
low; high (yes thats correct, think about it)
water reabsorption to the higher osmolarity is ___ and driven by __
passive; osomosis
most (2/3) of the Na is reabsorbed in the ___
proximal tubule
substances absorbed by the proximal tubule can do so by what 2 methods?
- dependent on Na
2. passive diffusion
t/f Na is reabsorbed in varying amounts in each of the parts of the nephron using different techniques
true
t/f water is reabsorbed by most parts of the nephron, but some parts can be impermeable
true
t/f water reabsorption is secondary to solute reabsorption
true
at the start of the proximal tubule, the solute concentrations are the same as the ___ and filtration is ___
plasma; non-specific
within the proximal tubule, the Na concentration and osmolarity are ____ even though 2/3 of Na and water have been reabsorbed
unchanged
within the proximal tubule Cl is ___ and its [ ] ____
left behind ; increases
in the descending limb of the loop of henle, solutes are reabsorbed ____ water (w/ or w/o?)
with
in the ascending loop of henle, solutes are reabsorbed ____ water ( w/ or w/o)?
without
in the ascending section of the loop of henle, the ___ membrane is water-impermeable
apical
where are NKCC channels located in the ascending loop of henle?
apical membrane
where are Na K atpase found in the ascending loop of henle?
basolateral membrane
reabsorption of salt (NaCl) without water reduces the ___, while maintaining the __
urine osmolarity; urine volume
in the ascending loop of henle, transport of Cl is ___in and ___ out and Na is ___ in and __ out
active; passive; passive; active
reabsorption of salt without water does what to urine osmolarity?
reduces
what is the osmolarity of urine when it eneters the distal tubule?
hypoosmotic
reabsorption of Ca in the early distal tubule is dependent on ___
parathyroid hormone
____ regulated water reabsorption in the late distal tubule means excreted urine can by hypoosmotic or hyperosmotic
ADH
the secretion of K in the late distal tubule is ___ to maintain body fluid balance
variable
a small amount of Na is reabsorbed in the late distal tubule and collecting duct by Na/K pumps, and ion channels stimulated by ___
aldosterone
reabsorption of HCO3 in the late distal tubule / collecting duct depends on ___
H secretion (antiporters
t/f extracellular K concentrations must be very tightly controlled as they can be fatal
true
what are the hormones that regulate the reabsorption of water, Na, Ca, and K?
- ADH / vasopressin
- aldosterone
- atrial natriuretic peptide
- parathyroid hormone
what is the major trigger for ADH
increased osmolarity of extracellular fluid, or decreased blood volume
what is the effect of ADH?
increase water reabsorption
what is the major trigger for aldosterone?
increased angiotensin and K
what is the effect of aldosterone?
increase K secretion and Na reabsorption and increased water reabsoprtion in presence of ADH
what is the trigger for ANP?
atrial stretching
what is the effect of ANP?
increase Na urine excretion and increase urine output volume
what is the trigger for parathyroid hormone?
decreased plasma Ca
what is the effect of parathyroid hormone?
increase Ca reabsorption
how is Na reabsorbed in the proximal tube?
Na dependent co-transporters
how is Na reabsorbed in the loop of henle?
NKCC
how is Na reabsorbed in the distal tubule?
NCC
how is Na reabsorbed in the collecting duct?
ENAC
how is Na reabsorbed in the basolateral membrane?
sodium potassium pump
excretion of Na in the urine is very __
low
excretion of K in the urine is very __
variable
t/f water reabsorption is always passive
true
most water is reabsorbed in the ___
proximal tubule
___ water reabsorption occurs in the late distal tubule and collecting duct
variable
water reabsorption in the late distal tubule and the collecting duct is determined by what hormone?
ADH
___ controls the water permeability of the late distal tuble and collecting duct
ADH
when ADH is high, there is ____ water reabsorption (More or less)
more
