Urinary 2 Flashcards
Renal corpuscle
Filters blood plasma
Glomerulus - capillary network
Glomumerular capsule - double walled cup surrounds glomerulus
renal tubule
proximal convoluted tubule
loop of henle -1 .thin descending limb and 2. ascending limb with thin and thick segments
distal convoluted tubule
fenestration of glomerular endothelial cell
prevents filtration of blood cells but allows all components of blood plasma to pass through
basal lamina of glomerulus
prevents filtration of larger proteins
slit membrane between pedicels
prevents filtration of medium sized proteins
flow of fluid thrpugh a juxtamedullary nephron
glomerular capsule proximal convoluted tubule descending limb of the nephron tuble ascending limb .... distal convoluted tubule (which drains into collecting duct )
what layers are in the glomerular capsule
visceral and parietal
visceral layer of glomerular capsule
consists of modified simple squamous epithelial cells called podocytes
parietal layer glomerular capsule
simple squamous epithelium
outer wall of capsule
where is the fluid filtered from the glomerular capillaries
the fluid enters capsular space ,the space btw the two layers of glomerular capsule ,which is continuous with the lumen of the renal tubule
cells in the proximal convoluted tubule
simple cuboidal epithelial cells with a prominent brush border of microvilli on their apical surface
cells in the descending limb and thin ascending limb of nephron limb
simple squamous epithelium
thick ascending limb of nephron loop is composed of what cells
simple cuboidal to low columnar epithelium
what two cells are in the DCT and continuing into the collecting ducts
principal cells that have receptors for both antidiuretic hormone and aldosterone
intercalated cells which play a role in homeostasis of blood pH
What does the JGA help with
regulate blood pressure inside the kidneys
macula densa
specialized cells lining the wall of the distal tubule ,at the point where the thick ascending limb meets the distal convulated tubule
juxtaglomerular cells
modified smooth muscle fibers found in the walls of afferent and efferent arterioles
glomerular filtration
in the first step of urine production ,water and most solutes in are filtered and move into the glomerular capsule
tubular reabsorption
as filtered fluid flows through the renal tubules and through the collecting ducts ,tubule cells reabsorb about 99% of the filtered water and many useful solutes
tubular secretion
as filtered fluid flows through the renal tubules and collecting ducts ,the renal tubule and duct cells secrete other materials ,such as wastes ,drugs and excess
filtration membrane
endothelial cells of glomerular capillaries and podocytes encircling capillaries.It permits filtration filtration of water and small solutes .prevents filtration of most plasma proteins ,blood cells and platelets
3 barriers to cross in the filtration membrane
glomerular endothelial cells fenestration’s ,basal lamina btw endothelium and podocytes and pedicels of podocytes create filtration slits
why is the volume of fluid filtered large ?
large surface area
thin and porous membrane
high glomerular capillary BP
Glomerular filtration rate
the amount of filtrate formed in all renal corpuscles of both kidneys each minute
male 125 mL/min
female 105 mL/min
what three mechanisms regulate GFR
renal auto regulation
neural regulation
hormonal regulation
myogenic mechanism
occurs when stretching triggers contraction of smooth muscle cells in afferent arterioles -reduces GFR
tubuloglomerular mechanism
macula densa provides feedback to glomerulus ,inhibits release of NO from cells in the JGA ,causing afferent arterioles to constrict and decreasing GFR (slower than myogenic mechanism )
neural regulation
kidney blood vessels supplied by sympathetic ANS fibers that release norepinephrine causing vasoconstriction
moderate stimulation -both afferent and efferent arterioles constrict to same degree and GFR decreases slightly
greater stimulation - constriction of afferent arterioles predominates blood flow into the glomerular capillaries is greatly decreased and GFR drops
hormonal regulation
angiotension II reduces GFR (potent vasoconstrictor )
atrial natriuretic peptide increases GFR - stretching of atria causes ANP release ,ANP causes relaxation of intra-glomerular mesangial cells increases capillary surface area for filtration
net filtration depends on what pressures
glomerular blood hydrostatic pressure
capsular hydrostatic pressure
blood colloid osmotic pressure
capsular hydrostatic pressure
pressure exerted against the filtration membrane by fluid in the capsular space and renal tubule
glomerular blood hydrostatic pressure
BP in the glomerular capillaries
blood colloid osmotic pressure
due to the presence of proteins in blood plasma
net filtration pressure formula
NFP=GBHP-CHP-BCOP
Reabsorption
return of most filtered fluid and substrate from the tubular lumen to the peritubular capillaries
secretion
from the peritubular capillaries to the tubular lumen
paracellular re-absorption
fluid can leak between the cells in a passive process in proximal convoluted tubules
trans-cellular re-absorption
substances passes from the tubular lumen through the apical membrane of a tubule cell ,across the cytosol and out into interstitial fluid through the basolateral membrane
primary active transport
energy derived from hydrolysis of ATP is used to pump a substance across a membrane
secondary active transport
energy stored in an ions electrochemical gradient ,rather than hydrolysis of ATP ,drives another substance across a membrane
symporters
are membrane proteins that move two or more substances i the same direction across a membrane
antiporters
move two or more substances in the opposite directions across the membrane
oobligatory water reabsorption
water reabsorbed with solutes in tubular fluid because water is obliged to follow solutes when they are reabsorbed (occurs in convulated tubule and descending limb of the nephron loop )
faculatative water reabsorption
re-absorption of the final 10 percent of water
regulated by - anti-diuretic hormone
occurs in collecting ducts
reabsorption in the proximal tubule
65 % of filtered water ,sodium and pottasium reabsorbed
100 % of most filtered organic solutes
80% of filtered bicarbonate
reabsorption of loop henle
reabsorption of glucose ,amino acids ,other nutrients ,water and solutes balanced
15% filtered water
20-30% filtered sodium and potassium
why is the reabsorption of water NOT coupled automatically to reabsorbtion of solutes
part of the loop of henle is relatively impermeable to water
how much water is absorbed in the ascending limb
none ,because osmolarity progressively decreases as fluid moves towards end of ascending limb
what does the early distal convoluted tubule do
reabsorbs 10%-15% of the filtered water ,the major site where parathyroid hormone stimulates reabsorption of Ca+ depending on bodys needs
reabsorption and secretion in the late distal convoluted tubule and collecting duct
90-95% have been returned by now
principal cells reabsorb Na + and screte K+
intercalated cells reabsorb K+ and HCO3-
