Lecture 10- Renal- Ion and Water balance Flashcards
after filtration, tubular fluid is subject to reabsorption or secretion. these processes involve transport of substances across the tubular epithelial cells in a nephron. there are 2 modes of transport, what are they?
transcellular- molecules move through tubular cells
paracellular- molecules move between tubular cells
… diffusion requires a specific membrane protein and they can be 3 different types
uniporter
symporter
antiporter
… transport is against the gradient and is coupled with ATP
active
sodium can be reabsorbed in all but this segment of the nephron
thin descending limb of loop of henle
you get pretty much 100% of reabsorption of glucose and amino acids in the ….
proximal tubule
there is a about 65% (2/3) reabsorption of Na in the ….
proximal tubule
about … % of Na is reabsorbed in the thin ascending limb
7
about …% of Na is reabsorbed in the thick ascending limb
20
about … % of Na is reabsorbed in the distal convoluted tubules
5
about …% of Na is reabsorbed in the collecting ducts
2-3
4 ways sodium is reabsorbed in the proximal tubule
- symporters with glucose
- active transport on basal side to keep intracellular sodium low
- moves with water and other solutes paracellularly
- Na/H antiporter which is indirectly associated with bicarb reabsorption
are drugs freely filtered?
no, they are too big, must be secreted in the proximal tubule
the proximal tubule has …. for organic cations and anions (drugs)
transporters
drugs are commonly bound to …. so they are not filtered at the glomerulus and must be secreted in order for them to be excreted in the urine
plasma proteins
in the loop of henle, … of filtered NaCL and … of water is reabsorbed
25%
15%
the descending thin limb is … to salt but … to water
impermeable
permable
the ascending thin limb is … to salt but …. to water
permeable
impermeable
reabsorption in the thin descending and ascending limbs is ….
passive
in the ascending limb, fluid becomes … due to …. symporter in apical membrane and …. in basolateral membrane
diluted
Na/K/2Cl
Na/K ATPase
fluid leaving the loop is… but the renal … mechanism has established an … gradient required for formation of hyperosmotic urine.
hypoosmotic
countercurrent
osmotic
concentration of the tubular fluid will occur in the …. if …. is present
collecting duct
ADH (vasopressin)
the initial segment of the distal tubule reabsorbs about …% of filtered NaCl via a …. symporter in apical membrane and … in basolateral membrane
Na/Cl
Na/K ATPase
sodium reabsorption in the latter half of the distal tubule and collecting duct is …
similar
there are 2 types of cells in the collecting duct and late distal tubule
principal cells that have epithelial sodium channels (ENaC) that reabsorb Na and secrete K
intercalated cells involved with acid-base balance; can also reabsorb K
ADH (vasopressin) is released from the …
posterior pituitary
ADH increases the … of the late distal tubuler and the collecting duct to water by increasing…. into the apical membrane (basolateral membrane is freely permable to water)
permeability
aquaporins
the release os ADH is stimulated by changes in …. of body fluids and changes in …
osmolality
blood volume/pressure
ADH responds to an osmolality above a set point of …mOsm/kg H2O
275-290
…. baroreceptors in the LA and Pulm vessels respond to a … in blood volume and this stimulates ADH secretion
low pressure
decrease
… baroreceptors in aortic arch and carotid sinus respond to a …. in blood pressure and this stimulates ADH secretion
high pressure
decrease
ADH also increases permeability of medullary collecting duct to…
urea
if ADH is low, solutes are reabsorbed in distal tubule and collecting duct but no water reabsorption so urine is as dilute as …
50 mOsm/kg H2O
if ADH is high, water is reabsorbed as passes through collecting duct and urine can be concentrated up to …
1200 mOsm/kg H2O
the renin-angiotensin-aldosterone system stimulates events that increase reabsorption of …. to combat volume…
Na and water
contraction (low BV)
renin converts…
angiotensinogen to angiotensin I
Angiotensin I is converted to angiotensin II by ….
angiotensinogen converting enzyme (ACE)
what are the 4 effects of angiotensin II?
vasoconstriction
stimulate release of ADH
increase sympathetic activity
stimulate aldosterone secretion
renin is released in response to a drop in …., decreased …. delivery to the macular densa or … input to the juxtaglomerular cells
perfusion pressure
NaCl
sympathetic
aldosterone from the … acts to increase …. reabsorption in the distal tubule and collecting duct by increasing …
adrenal cortex
NaCl
transport protein synthesis
… are hormones that are secreted when the heart dilates (during volume expansion)
natriuretic peptides
atrial natriuretic peptide is from the …
brain natriuretic peptide is from the …
atria
ventricles
are aldosterone’s effects immediate?
no
4 effects of natriuretic peptides
vasodilation of afferent arterioles
vasoconstriction of efferent arterioles
inhibition of renin/aldosterone
inhibition of ADH secretion
net effect of natriuretic peptides is to increase secretion of … and …
NaCl and water
the main location where we see a decrease in Na reabsorption due to natriuretic hormones is in the ….
proximal tubules
hypokalemia will …. membrane voltage
hyperpolarize
hyperkalemia will … membrane voltage
depolarize
ingested K+ is … shifted into cells and this is mediated by … , … and …
fast
insulin, epi, aldosterone
kidneys typically excrete …% of ingested K+
90-95%
