Renal Blood Flow and Glomerular Filtration (Rao) Flashcards
Explain how renal failure can lead to death.
- Loss of the ability to balance water and Na
- Edema
- inc work load of heart
- heart failure and pulmonary edema
- adicemia
- hyperkalemia
- death
What is ESRD?
end stage renal disease = little or no kidney function = cannot survive without hemodialysis or kidney transplantation
Urine from a calyx flows into __(structure)___
the renal pelvis
The kidney vasculature is ___% of body mass but receives ___% of total cardiac output
less than 5% but receives greater than 20%
What named blood vessels does bblood travel through as it travels from the renal artery to the renal vein?
renal artery-> interlobar a -> arcuate a -> radial a -> afferent arteriole -> glomerular capillary beds -> efferent arteriole -> peritubular capillary bed -> renal vein
the __(blood vessel)___ forms the glomerular capillary bed and the __(blood vessel)__ forma the peritubular capillary bed
afferent arteriole -> glomeriular capillary bed
efferent arteriole -> peritubular capillary bed
What is the vasa recta?
blood supply to the medullary region (plays a role in concentration of urine)
Describe the pressure profiles (hydrostatic) of the renal vasculature.
there are 3 drops in pressure that maintain a high hydrostatic pressure in the glomerular capillary beds (needed for filtration)
- afferent arteriole (90 -61 mmHg)
- efferent arteriole (59-29 mmHg)
- peritubular capillaires (25-6 mmHg)
dropping the HP slowly allows for more filtration (high capillary HP is needed for filtration)
*normally HP drops (from 90 to 25 mmHg) very quickly when blood travels from artery to vein, but due to the control of the smooth muscle in the renal vasculature, this drop can be slowed down = necessary for filtration to occur
T or F: High hydrostatic pressure and high oncotic pressure (in glomerular capillaires) drives glomerular filtration.
F: high hydrostatic and low oncotic
What is there an increase in oncotic pressure in the glomerular capillaries compared to the afferent arteriole?
because almost everything is being filtered out of the blood–leaving protein behind (bc it is too larger to be filtered)
Bc protein is pretty much the only thing left, it inc in conc in the blood which inc oncotic pressure
What are the 3 processes of urine formation?
- glomerular filtration
- tubular reabs
- tubular secretion
What is an example of a substance that is…
freely filtered, partially reabs, but not secreted
urea
What is an example of a substance that is…
freely filtered and completely reabs
glc, amino acids, and organic acids
What is an example of a substance that is…
freely filtered, no reabs, but secreted
creatinine
Describe the composition of glomerular filtrate
- NO cells or large proteins
- low levels of some small molecules bound to proteins (calcium and fatty acids)
- more antions than cations due to Gibbs Donnan effect
What is the average GFR of a healthy person?
130 mL/min
180 L/day
T or F: glomerular filtration increases with age and renal disease
F: decreases
What is the avg filtration fraction of a healthy indiv?
20%
What effect does a urethral obstruction have on GRF and FF?
decreases both GFR and FF
What effect does renal artery stenosis have on GFR and FF?
decreases GFR and inc FF (dec renal plasma flow)
What are the filtration barriers in glomerulus?
- capillary endothelium
- basement membrane
- epithelium or podocyte monolayer
What solute properties determine filterability?
size and charge
small and + charge filtered more
What are the determinants of GFR?
GFR = Kf x Net filtration pressure
net filtration pressure = forces that favor filtration - forces that oppose filtration
= (HPgc - HPbs) - OPgc
What is Kf?
filtration coefficient = hydraulic conductivity X surface area of glomerular capillary
= 0.08 nL/s/mmHg
hydraulic conductivity = ease at while fluid can flow thru the pores
How does Kf value change with diabetes?
Kf is determined by hydraulic conductivity (ease at while fluid can flow thru the pores). With DM, the basement membrane thickens and capillaries are damaged… both reduce the hydraulic conductivity and reduce the Kf
What effect does inc resistance in the afferent arteriole have on GFR and RPF?
reduces GFR and RPF
What effect does inc resistance in the efferent arteriole have on GFR and RPF?
inc GFR and dec RPF
What effect does dec resistance in the efferent arteriole have on GFR and RPF?
dec GFP and inc RPF
What effect does dec resistance in the afferent arteriole have on GFR and RPF?
inc GFR and inc RPF
What is a measure of the resistance of a nephron and the rate of urine flow?
HP of bowman’s space
What are some conditions that would inc HP bowmans space?
kidney stone, hypertrophic prostate, tumor
What effect does an inc HP bowman’s space have on GFR?
decreases it
Why do men with enlarged prostates pee all the time?
by emptying their bladder frequently the HP of bowman’s space decrease and GFR can increase (compensation for inc HP with hypertrophy)
What is the relationship between renal plasma flow, oncotic pressure, and GFR?
If RPF decreases, oncontic pressure inc, and GFR will decrease
What would happen if GFR was not autoregualted and BP increased?
GFR would increase -> urine output would increase -> blood volume would be depleted
What changes in order to auto regulate GFR?
afferent arteriolar resistance via…
1) myogenic mechanism
2) tubuloglomerular feedback
What does the juxtaglomerular complex sense in order to autoregulate GFR? Why?
NaCl conc (as a sensor for GFR change)
Inc Cl- at macula densa = GFR has inc -> tells aff art to inc resistance and dec the GFR
dec Cl- at macula densa = GFR as dec –> tells aff arteriole to dec resistance –> GFR will inc
When there is an inc in Cl- at the macula densa, what happens?
the JG apparatus releases ATP and ara c metabolites –> [Ca2+] inc –> smooth muscle contraction -> dec GFR
When there is an inc in Cl- at the macula densa, what happens?
renin is secreted from JG cells which decreases [Ca2+] -> ang I -> ang II -> constricts arterioles and leads to aldosterone secretion -> Na+ retention and H2O retention -> inc BP -> inc GFR
T or F: renal bood vessels are richly innervated by sympathetic nerve fibers
T
What hormones and/or substances secreted by endothelial cell will cause the arterioles to constrict? What affect do they have on GFR?
adrenaline, endothelin-1
decrease GFR
What hormones and/or substances secreted by endothelial cell will cause the arterioles to decrease vascular tone? What affect do they have on GFR?
NO and prostaglandins
What are the 2 general causes of proteinuria?
glomerular barrier failure
abnormal circulating protein
What type of barrier breakdown will result in albumin and cells filtered into the urine?
visible barrier breakdown/large pore
What type of barrier breakdown will result in albumin but not cells filtered into the urine?
invisible barrier breakdown/loss of selectivity
When there is an abnormal circulating protein in the urine, it is usually small, medium, or large in size?
medium
What causes an abnormally circulating protein to be found in the blood in the first place?
breakdown of tissue or turmor cell production
