Urinary Phys #2- GFR Flashcards
(35 cards)
GFR =
Glomerular filtration rate
what two factors allow renal corpuscle to filter blood at high/rate
due to glomerular capillary pressure and attenuated filtration membrane
what is the glomerular capillary blood pressure? in glomerulus? in normal capillaries?
50-90 mmHg in glomerulus ; 35 mmHg normal BP of capillaries
what percentage of plasma that enter the glomerulus is filtered?
20%
citrate same as plasma - except lacks large proteins
the attenuated filtration membrane
how much water a day does a person filter? how much per minute?
180L water/ day ; 125 ml/ min
how many grams of salt a day does a normal person filter
1200 gm of salt
how many gm of glucose does a person filter per day
300 gm of glucose
how much small protein is filtered each day
3.6 gm of small protein
how much water a day is excreted in urine
1.5 L / day
how much salt is excreted per day in urine
10-15 gms of salt
how much glucose is excreted per day?
none
how much trace of protein is excreted in urine each day?
100 mg / day
what is the equation of calculating glomerular filtration rate?
GFR = Kf X Net Filtration Pressure *rate of filtration
filtration coefficient is what? what are the two factors associated?
Kf
a. how much glomerular surface area is available for penetration
b. how permeable the glomerular membrane is
What is the equation for calculating net filtration pressure?
Glomerular capillary pressure - (plasma colloid osmotic pressure + Bowmans capsule hydrostatic pressure)
standard: 55 mmHg - (30 mmHg + 15mmHg) = 10mmHg
what is the most important factor in the GFR?
net filtration pressure
Normal control of GFR is a function of what?
Glomerular capillary blood pressure
Normally about _____ of the plasma that enters the glomerulus is filtered at the net filtration pressure of ______ , producing collective through all glomeruli ______ liters of glomerular filtrate each day for an average of GFR = _____ in males and ____ in females
20% Net filtration rate = 10 mm Hg Glomeruli = 180 LIters of Glomerular filtrate each day Average GFR = 125 ml / day men Average GFR = 160 ml / day women
What are the two factors that influence Glomerular filtration rate that are normally constant?
- plasma colloid osmotic pressure
2. hydrostatic pressure of filtrate
T/F The filtration coefficient Kf can change.
true
How can the filtration coefficient change?
Mesangial cells and Podocytes can contract in response to sympathetic input causin ga decrease in Kf and a decrease in GFR
What is the mechanism for auto regulation of GFR?
myogenic mechanism
T?F An increase in MAP, causes GFR to increase.
false. regardless if MAP is increased, GFR remains relatively constant because the afferent arterioles increase resistance
