Renal Physiology (3B)

Question 1

Glomerular filtration rate is the

Answer 1

volume of fluid filtered from the glomerulus into the Bownman’s space per unit time

Question 2

The GFR is **

Answer 2

125 mL/min (180L/day) in a 70kg man

Question 3

Is the GFR a fixed value?

Answer 3

No

Question 4

How many times does the GFR allow plasma filtration throughout the day?

Answer 4

About 60 times

Question 5

What are the 4 factors that affect GFR?**

Answer 5

1. net glomerular filtration pressure is positive
2. permeability of the corpuscular membrane
3. surface area available for filtration
4. neural and endocrine control on the afferent + efferent arteriole resistance

Question 6

Are podocytes bridged?

Answer 6

Yes, by slit diaphragms

Question 7

Surface area determines the GFR specifically by ___ cells

Answer 7

mesangial

Question 8

Are mesangial cells a part of the filtration layers

Answer 8

No

Question 9

Mesangial cells are found between the __ and __ arterioles

Answer 9

afferent, efferent

Question 10

How do the mesangial cells affect surface area of glomerular capillaries?

Answer 10

Contraction of the cells reduces the SA and as a result GFR decreases

Question 11

Mesangial cells are unique because they are ___ muscle and pull the capillaries together to ___ the size of the bed.

Answer 11

smooth, decrease

Question 12

Resistance changes in renal ____ alter renal blood ___ and GFR.

Answer 12

arterioles, flow

Question 13

Most of the blood entering the renal system also will flow to ___ organs.

Answer 13

other

Question 14

With an increased resistance in the afferent arteriole, there is a ___ in renal blood flow, decreased ___ and ___ capillary blood pressure.

As a result, there will be an ___ in blood flow to other organs.

Answer 14

decrease, GFR, decreased, increase

Question 15

With an increased resistance in the efferent arteriole, there is a ___ in renal blood flow, ___ GFR and ___ capillary blood pressure.

As a result, there will be an ___ in blood flow to other organs.

Answer 15

decrease, increase, increase, increase

Question 16

Decreased GFR occurs when (2)

Answer 16

1. constricted afferent arteriole
2. dilated efferent arteriole

Question 17

Increased GFR occurs when (2)

Answer 17

1. constricted efferent arteriole
2. dilated afferent arteriole

Question 18

When the GFR goes up, so does the

Answer 18

pressure in the glomerular capillaries

Question 19

When the GFR goes down, so does the

Answer 19

pressure in the glomerular capillaries

Question 20

GFR remains relatively ___ despite any large and sudden changes in ___ pressure and or renal blood ____.

Answer 20

constant, arterial, flow

Question 21

How is GFR maintained fairly constant?**

Answer 21

by changing the renal blood vessel resistance (mainly the afferent arteriole) to compensate for any changes in blood pressure

Question 22

One of the autoregulations of GFR includes:

Answer 22

myogenic response that constricts and expands the smooth muscle lining when blood pressure changes

Question 23

The second autoregulation processes that maintains GFR is

Answer 23

tubuloglomerular feedback effect

Question 24

What are the principles of tubuloglomerular feedback effect?

Answer 24

1. increased tubular flow cause constriction of the AA to reduce GFR
2. regulated by the paracrine actions of the juxtaglomerular apparatus
3. paracrine control of afferent arteriole resistance

Question 25

Is autoregulation independent of neuronal and hormonal control?

Answer 25

YES

Question 26

The importance of autoregulation stems from the protection of the ____ capillaries from trauma related to ____ (high blood pressure) and ___ (low blood pressure).

Answer 26

glomerular, hypertension, hypotension

Question 27

Autoregulation takes place over a ___ variety of blood pressures.

Answer 27

wide

Question 28

Autoregulation maintains nearly constant GFR when the ____ is between ___ and ____ mmHg.

Answer 28

MABP, 80, 180

Question 29

TRUE or FALSE: Autoregulation will not function well if it is was too high or low the MABP point?

Answer 29

True

Question 30

MABP formula **

Answer 30

DP + 1/3 (SP- DP) DP: diastolic pressure SP: systolic pressure

Question 31

What is the juxtaglomerular apparatus comprised of? (3)

Answer 31

macula densa, juxtaglomerular cells, mesangial cells

Question 32

The macular densa are longtitudinal cells on the wall of the ____ tubule. They can sense the _____ fluid flow through the tubules via [ ] and [ ]. It secretes ____ compounds such as adenosine. Paracrine effect changes the ___ arteriolar resistance and thus signals to the juxtaglomerular cells.

Answer 32

distal, increased, Na+, Cl- vasoactive, afferent

Question 33

The juxtaglomerular cells are also known as ___ cells. They are on the wall of the ___ arteriole and it controls ___ hormone release based on [ ].

Answer 33

granular, afferent, renin, Na+

Question 34

Mesangial cells are in between the __ and __ arterioles and are outside of the ______ bed. It serves to regulate the ___ ____ available for filtration process.

Answer 34

afferent, efferent, glomerular, surface area

Question 35

Role of macula densa in the tubuloglomerular feedback (step by step)

Answer 35

1. GFR increase 2. Flow through the tube will increase 3. Flow past the macula densa in the distal tubule increases 4. Paracrine from macula densa to afferent arteriole (adenosine will cause vasoconstriction of the afferent arteriole4 5. Afferent arteriole will constrict 6. Resistance in the afferent arteriole increase 7. Hydrostatic pressure in the glomerulus will decrease 8. GFR will decrease

Question 36

Filtered load is known as the

Answer 36

total amount of non-protein or non-protein bound substance that is filtered through the Bowman's space

Question 37

Formula: Filtered load

Answer 37

GFR x [substance in plasma]

Question 38

Ie. glucose's filtered load is

Answer 38

180g/day

Question 39

When substance excreted in urine < filtered load

Answer 39

reabsorption occured

Question 40

When substance excreted in urine > filtered load

Answer 40

secretion occured