physiology Flashcards
what area the starling forces that oppose filtration?
hydrostatic interstitium(bowman’s space) pressure
oncotic glomerular capillary pressure
what area the starling forces that favors filtration?
hydrostatic glomerular capillary pressure
urine concentration is regulated by …….?
vasa recta
the renal corpuscle is made up of?
glomerulus and bowman’s capsule
glomerulus contains what type of capillary?
fenestrated
what is the glomerular filtration rate?
125ml/
180L/
why is the glomerular basement membrane important?
it is made up of 3 layers
: 2 layers of negatively charged heparin sulfate glycosaminoglycans called lamina Rera interna and Rera externa and in the middle is a type 4 collagen lamina densa layer
–
proteins are -vely charged–>repelled by basement membrane
Where does the glomerulus bowmans capsule drain?
The filtrate that has passed through the three-layered filtration unit enters Bowman’s capsule. From there, it flows into the renal tubule—the nephron—which follows a U-shaped path to the collecting ducts, finally exiting into a renal calyx as urine.
which layer of the glomerulus filtrate barrier does not permit the filtration/passing of plasma proteins?
basement layer
the basement layer doesn’t allow for the passing of the plasma proteins creating …….?
ultrafiltrate fluid(has no plasma proteins or blood cells)
what are the molecules that are freely filtered through the basement membrane?
glucose
amino acids
lipids
Ca2+
Cl-
Na+
K+
HCO3-
Mg2+
H2O
creatinine
urea
which molecules are repelled away from the basement membrane is absorbed back into the blood?
plasma proteins are not filtered (absorbed back into blood): albumin, fibrinogen, IgG globulin
Filtration fraction=
GFR/RPF
As filtration fraction increase, GFR increase and renal plasma flow decrease
What occurs to the RPF,GFR,& Filtration fraction when afferent arterioles constrict?
RPF: dec
GFR: dec
Filtration fraction: no change
What occurs to the RPF,GFR,& Filtration fraction when efferent arterioles constrict?
Rpf: dec
Gfr: inc
Filtration fraction: increase
What occurs to the RPF,GFR,& Filtration fraction when there’s increased plasma protein concentration?
Rpf: no change
Gfr: dec
Filtration fraction: decrease
What occurs to the RPF,GFR,& Filtration fraction when there’s decreased plasma protein concentration?
Rpf: no change
Gfr: inc
Filtration fraction: increase
What occurs to the RPF,GFR,& Filtration fraction when there’s constriction of the ureter?
Rpf: no change
Gfr: dec
Filtration fraction: dec
Low levels of angiotensin 2 results in …… bcz……
High levels of angiotensin 2 results in …… bcz …..
1) inc GFR bcz it’s only affecting the efferent arterioles
2) decrease GFR bcz it’s spreading to both efferent and afferent arterioles
Podocytes are found in which layer?
Epithelialof glomerular filtration barrier
Nephrotic syndrome results from…..
Loss of charge barrier in glomeruli causing albuminuria, edema hyperlipidemia
Where is heparen sulfate found and what charge does it posses?
It is found in the basement membrane and it has a negative charge which repels negatively charged proteins
The clearance of …… is used to estimate renal plasma flow
The clearance of …… is used to estimate GFR
Para-aminohippurate
Inulin
If filtration > excretion =
If filtration < excretion =
Reabsorption
Secretion
Glucose is filtered across glomerular capillaries and reabsorbed by the epithelial cells of the …….
proximal convoluted tubule.
Fill in the channels:
Glucose reabsorption is a two-step process involving ……….. across the luminal membrane and ………. across the peritubular membrane.
Na+-glucose cotransport (in the membrane of tubule)
facilitated glucose transport (in the blood vessel)
………..—> Na+-glucose cotransporter channel
……….—> Na+-K+ ATPase and the facilitated glucose transporter channel
Luminal membrane of the epithelial cells
Peritubular membrane(blood vessel)
The proteins involved in ………….. of glucose are called GLUT 1 and GLUT 2, which belong to a larger family of glucose carriers.
facilitated diffusion
…….. patients have glucose plasma concentration that exceeds Tm causing Glycosuria(glucose in urine)
Diabetes
Filtered load. Glucose is freely filtered across glomerular capillaries, and the filtered load is the product of GFR and plasma glucose concentration (filtered load = GFR × [P]x).
• Thus, as the plasma glucose concentration is increased, the filtered load ………
increases linearly.
Reabsorption.
At plasma glucose concentrations less than 200 mg/dL, all of the filtered glucose can be ……. because Na+-glucose cotransporters are plentiful.
At plasma concentrations above 350 mg/dL, the carriers are completely saturated and reabsorption levels off at its maximal value, Tm.
reabsorbed
……. plasma glucose concentrations of 200 mg/dL, all of the filtered glucose is reabsorbed and none is excreted.
• At plasma glucose concentrations above 200 mg/dL, the carriers are nearing the saturation point.
—>Most of the filtered glucose is reabsorbed, but some is not; the glucose that is not reabsorbed is excreted.
• The plasma concentration at which glucose is first excreted in the urine is called threshold, which occurs at a lower plasma concentration than does Tm. phenomenon called splay.
• Above 350 mg/dL, Tm is reached and the carriers are fully saturated.
Below
Because of …….., glucose is excreted in the urine (i.e., at threshold) before reabsorption levels off at the Tm value.
splay
In contrast to glucose, which is reabsorbed by carrier-mediated (facilitated)mechanisms, urea is reabsorbed or secreted by ……….
diffusion (simple diffusion and facilitated diffusion).
The rate of reabsorption or secretion is determined by the ……………….. for urea between tubular fluid and blood and by the permeability of the epithelial cells to urea.
concentration difference
Reabsorption occurs mainly in the …….
Proximal convoluted tubule
When medulla cortical duct becomes permeable to urea and there’s high concentration of urea, …… will aid in reabsorption of water, which will automatically cause reabsorption of urea.
ADH (vasopressin);(aids in water reabsorption- > triggering reabsorption of urea)
the greater the ……. reabsorption, the greater the urea reabsorption and the lower the urea excretion.
water
Where are water and urea reabsorbed ?
Proximal convulated tubule
In the ………, urea is secreted.
thin descending limb of Henle’s loop
The ………… limb of Henle, distal tubule, and cortical and outer medullary collecting ducts are impermeable to urea (&water), so no urea transport occurs in these segments
thick ascending
More urea is secreted into the ……………… than was reabsorbed in the proximal tubule; thus, at the bend of the loop of Henle, 110% of the filtered load of urea is present.
thin descending limbs
in the presence of …………, water is reabsorbed in the late distal tubule and the cortical and outer medullary collecting ducts—consequently, in these segments, urea is “left behind” and the urea concentration of the tubular fluid becomes quite high.
antidiuretic hormone (ADH)
Vasopressin creates a (hyper/hypo) osmotic urine?
Hypo-osmotic urine (bcz ADH allows for the reabsorption of water and NaCl back to blood)
in the presence of ADH/vasopressin , water is reabsorbed in the …………….. tubule and the cortical and outer medullary collecting ducts
late distal tubule
in which part of the nephron is urea reabsorbed?
in the proximal tubule, 50% of the filtered urea is reabsorbed by simple diffusion
where is the urea filtered?
glomerulus, which is where filtration occurs
