Urinary Phys #2- GFR

Question 1

GFR =

Answer 1

Glomerular filtration rate

Question 2

what two factors allow renal corpuscle to filter blood at high/rate

Answer 2

due to glomerular capillary pressure and attenuated filtration membrane

Question 3

what is the glomerular capillary blood pressure? in glomerulus? in normal capillaries?

Answer 3

50-90 mmHg in glomerulus ; 35 mmHg normal BP of capillaries

Question 4

what percentage of plasma that enter the glomerulus is filtered?

Answer 4

20%

Question 5

citrate same as plasma - except lacks large proteins

Answer 5

the attenuated filtration membrane

Question 6

how much water a day does a person filter? how much per minute?

Answer 6

180L water/ day ; 125 ml/ min

Question 7

how many grams of salt a day does a normal person filter

Answer 7

1200 gm of salt

Question 8

how many gm of glucose does a person filter per day

Answer 8

300 gm of glucose

Question 9

how much small protein is filtered each day

Answer 9

3.6 gm of small protein

Question 10

how much water a day is excreted in urine

Answer 10

1.5 L / day

Question 11

how much salt is excreted per day in urine

Answer 11

10-15 gms of salt

Question 12

how much glucose is excreted per day?

Answer 12

none

Question 13

how much trace of protein is excreted in urine each day?

Answer 13

100 mg / day

Question 14

what is the equation of calculating glomerular filtration rate?

Answer 14

GFR = Kf X Net Filtration Pressure *rate of filtration

Question 15

filtration coefficient is what? what are the two factors associated?

Answer 15

Kf

a. how much glomerular surface area is available for penetration
b. how permeable the glomerular membrane is

Question 16

What is the equation for calculating net filtration pressure?

Answer 16

Glomerular capillary pressure - (plasma colloid osmotic pressure + Bowmans capsule hydrostatic pressure)
standard: 55 mmHg - (30 mmHg + 15mmHg) = 10mmHg

Question 17

what is the most important factor in the GFR?

Answer 17

net filtration pressure

Question 18

Normal control of GFR is a function of what?

Answer 18

Glomerular capillary blood pressure

Question 19

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

Answer 19

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

Question 20

What are the two factors that influence Glomerular filtration rate that are normally constant?

Answer 20

1. plasma colloid osmotic pressure

2. hydrostatic pressure of filtrate

Question 21

T/F The filtration coefficient Kf can change.

Answer 21

true

Question 22

How can the filtration coefficient change?

Answer 22

Mesangial cells and Podocytes can contract in response to sympathetic input causin ga decrease in Kf and a decrease in GFR

Question 23

What is the mechanism for auto regulation of GFR?

Answer 23

myogenic mechanism

Question 24

T?F An increase in MAP, causes GFR to increase.

Answer 24

false. regardless if MAP is increased, GFR remains relatively constant because the afferent arterioles increase resistance

Question 25

When MAP increases, what does increased resistance in the afferent arterioles accomplish?

Answer 25

normal glomerular capillary pressure

Question 26

Why do hypertensive patients have normal GFR?

Answer 26

because of myogenic mechanism

Question 27

What hormone can override myogenic mechanism?

Answer 27

Angiotensin II

Question 28

What feedback system helps maintain GFR at a constant rate as fluid and electrolyte intake varies?

Answer 28

Tuloglomerular Feedback ; involves juxtaglomerular apparatus

Question 29

Controls Na+ reabsorption and blood pressure is the function of _________

Answer 29

function of juxtaglomerular apparatus

Question 30

specialized smooth muscle cells in wall of afferent and efferent arterioles, contain secretory granules (renin).

Answer 30

juxtaglomerular cells

Question 31

What does juxtaglomular cells produce:

Answer 31

erythropoietin

Question 32

what stimulates bone marrow to produce red blood cells

Answer 32

erythropoietin

Question 33

what stimulates erythropoietin release in the kidneys

Answer 33

hypoxia

Question 34

____ % of erythropoietin produced in the kidney; ____ % in the liver

Answer 34

90% and 10%

Question 35

special cells in wall of distal tubule wall next to juxtaglomerular cells

Answer 35

macula densa