tubule transport Flashcards
what is primary effect of angiotensin 2 binding to AT1 receptors
increasing speed of Na/K ATPase
paracellular reabsorption help together by _____ ______
tight junctions
transcellular reabsorption is ______ transport via _____ or ______
active transport (primary or secondary)
via channels or transporters
tight junctions at the proximal tubule are _____ than other tight junctions in the tubule
looser
what gets dragged or reabsorbed via the paracellular pathway?
chloride
lots of Na via transporters… and Cl typically wants to follow Na
aquaporins are a _____ route
transcellular
places in the kidney that are impermeable to water, have _____ tight junctions and typically lack aquaporins too
tighter
reabsorption occurring at the proximal tubule as a result of starling forces in the peritubular capillaries creates a NRP _____. This is also called _____ ______.
NRP 100 mmHg
Bulk Flow
combines both paracellular and transcellular reabsorption
in absence of aquaporins, water reabsorption occurs following solutes. This is called _____.
osmosis
both transcellular and paracellular
______ is in abundance in the interstium and provides and osmotic gradient for water to follow
*urea
also proteins and filaments
______ _____ is really evident in the proximal tubule (on luminar side). It increases the surface area x20 to promote greater reabsorption. Also allows MORE ion channels/transporters.
brush boarder
proximal tubular epithelial cell membrane potential is ______ vs. tubular lumen membrane potential is ______.
-70 mV
secondary to Na/K APTase pumps creating electrochemical gradient which are activating secondary active transporters
-3 mV
Na, K, Cl… if more Cl -> more (-) charge
first half of proximal tubule ____ Cl reabsorption vs the second half of the proximal tubule.
less
in healthy kidneys, how much protein get filtered per day?
How much is reabsorbed?
how mu excreted in urine?
1.8 g
1.7 g
100 mg
reabsorption of protein in the proximal cells is via _____ or ______.
endocytosis or pinocytosis
*PT cells grab protein from inside tubular brush boarder, bring it inside, destroy them into amino acids… then reabsorb them
2 condition for proteinuria
sepsis, DM
whats a big protein that gets filtered?
what are 2 small proteins that get filtered?
- protein
- growth hormones
- peptides: signaling compounds in blood that have micro proteins…. small string of 10-20 amino acids
what transporter is the primary reabsorption of Na in the PT?
sodium hydrogen exchanger
3 places in tubule where carbonic anhydrase is found
- implanted in epithelial cell membrane
- tethered to cell membrane
- suspended in the tubule
carbonic anhydrase takes a water out of carbonic acid, this is called a _______ process
anhydrase
H+ gets put back into the lumen via ______ exchanger. H+ can then form with bicarb, or get excreted if no bicarb available, or attach to a larger compound forming ________.
sodium hydrogen exchanger
ammonium
*buffers the acidity of our urine
H+ + ammonia -> ______
ammonium
effects of carbonic anhydrase inhibitor
- bicarbonate not reabsorbed via Na bicarbonate symporter -> wasting bicarbonate in UO -> acidosis***
- decrease Na hydrogen exchanger -> more Na and H2O in tubule -> increase UO (weak diuretic)
what is glutamine, where is it produced, what effect on kidney?
glutamine is an amino acid produced in the liver
used in epithelial cells of PT to produce bicarb
glutamine + 1 glucose molecule -> 2 HCO3- + 2NH4+ (ammonium)
why do liver failure patients have a hard time balancing acid base balance?
their liver can’t produce enough glutamine
glutamine can be supplemented through another source
2 urinary buffers
ammonium NH4+
phosphate PO4-3
phosphate concentration is ______ inside the cell vs outside the cell
higher
- lots of phosphorylation inside cells BUT also found outside cells (tubular lumen)
calcium reabsorption in the tubules occurs where?
PT, TAL, DT
calcium reabsorption in PT occurs _____ and _____ pathways.
transcellular and paracellular
- gets drug along with everything else
what drives Ca++ reabsorption in the PT?
negative charges inside the tubular cells and low Ca+ levels
calcium bound to albumin in the plasma _____ get filtered
won’t
in acidosis there is ____ ionized Calcium that will get freely _______.
more
filtered
in alkalosis there is _____ ionized calcium that will be freely filtered.
less
_______ gland monitors calcium levels in the extracellular fluid
parathyroid
- located on the sides of the thyroid gland
low calcium in the blood, leads to release of _____
parathyroid hormone
increase in PTH leads to what 3 things
- increase vit D action -> increase intestinal Ca+ reabsorption
- increase renal Ca+ reabsorption -> increase number of apical membrane Ca channels in PT and DT
- increase Ca release from bones -> increase osteoclast and reduce osteoblast activity
osteoclasts work by…
breaking calcium phosphate bonds (bone) to release Ca into bloodstream -> osteoporosis
osteoblast work by….
binding calcium and phosphate to build stronger bones
long term vs short term storage places in the body
short term = SR
long term = bone
what year did first person take PNC
1942
who discovered in WW2 that hippurates added to PNC was competative secretion via using the same transporters -> PNC lasting longer in circulation
Alexander fleming
most powerful diuretic class and where they act on tubule
loop diuretics
- furosemide
- ethacrynic acid
- butetanide
they GREATLY reduce the renal interstitium conc. -> reducing water reabsorption via osmosis
highest conc that the renal insterstitium can have
1200 mOsm
reabsorbs most water at this mOsm
also urine conc would be 1200 mOsm
what 2 things account for the renal interstium conc.
KCL and urea
how conc. can lizards make their renal interstitum
3000 mOsm
electrolyte reabsorption in tubule
- PT: 2/3
- Thin AT: 25%
- late DT and Collecting duct via principle cells: determines remaining electrolytes for reabsorption or not
principle cells location and what they are sensitive to
late DT and collecting duct
ALDO
principle cells and intercalated cells are sensitive to ______
ADH: water reabsorption
what two parts of the tubule have a high metabolic rate
proximal tubule and thick ascending limb
where do thiazide diuretics work and how?
apical distal tubule blocking the Na/Cl co-transporter
*speeds up the Na/Ca exchanger on basolateral side -> increase Ca reabsorption (tx osteoporosis or prevent kidney stones)
careful not to take _____ supplements while taking thiazide diuretics
calcium
could get hypercalcemic
aldersterone is a ________ and increases ______ reabsorption and increases ________ excretion
mineralocorticoid
Na+
K+
ALDO is a _______ derivative, thats why the receptor is inside the distal tubule. It has no issue getting through the cell wall
cholesterol
3 primary effects of ALDO in order
1: increase pumping of Na/K/ATPase
2. plants addiction ENAC on apical surface
3. increases K channel opening on apical membrane, increasing K secretion (both opening of ROMK and BK)
what are the 2 potassium channels called in principle cells
ROMK (renal outer medullary K) channel
BK (big K) channel
osmotic diuretics MOA
conserve water in early parts of tubule?
Inhibition of Na reabsorption from ANYWHERE upstream from the principle cells will have ______ Na conc. reaching the principle cells (DCT and collecting duct) -> more _____ reabsorption at principle cells and more ______ excretion from ______ activity of the Na/K/ATPase pump
increased
Na+
K+
increased
***K+ wasting diuretics
what diuretic is commonly given with Triamterene to inhibit K+ wasting
hydrochlorothiazide
