Lecture 2 - Renal Blood Flow, Glomerular Filtration And Clearance

Question 1

What is the distribution of renal blood flow in the kidney, brain, muscles, and coronary in ml/100g tissue/min?

Answer 1

Kidney = 340, coronary = 84, brain = 54, muscle = 3

Question 2

Where does the 93% of the renal blood flow confined to the cortex come from?

Answer 2

Superficial and mid-cortical glomeruli

Question 3

What region of the kidney is the most superficial?

Answer 3

The renal cortex

Question 4

Where is the blood supply found in the kidney?

Answer 4

In the glomerulus

Question 5

Describe the vasa recta in the kidney

Answer 5

It is small compared to the glomerulus blood supply, it has small arterioles than enter the medulla and small venules that leaves the medulla

Question 6

What is the order of nephrons located in the kidneys?

Answer 6

Superficial nephrons are located near the surface, mid cortical nephrons found in the middle of the cortex, and juxtamedullary nephrons

Question 7

What is the % renal blood flow that comes from the juxtamedullary nephrons?

Answer 7

7%

Question 8

Describe the diffusion pressure - along the glomerular capillary

Answer 8

The diffusion pressure is held relatively constant

Question 9

what is the glomerulus a site of?

Answer 9

Filtration

Question 10

Where does the filtration barrier sit?

Answer 10

On the podocytes, close to the basal laminate and urinary space-line of the bowman’s capsule

Question 11

Where are the distal convoluted tubules found in the renal corpuscle?

Answer 11

They are found wrapped along the top

Question 12

Can you control filtration pressure?

Answer 12

Yes - if you increase the Afferent resistance by decreasing the lumen then you decrease overall renal blood through the capillary and glomerulus - this leads to a decrease in filtration pressure

Question 13

What happens if you decrease Afferent resistance?

Answer 13

Renal blood flow will increase and the overall filtration pressure will increase

Question 14

What happens if you increase efferent resistance?

Answer 14

Renal blood flow will decrease and the overall filtration pressure will increase

Question 15

What happens if you decrease efferent resistance?

Answer 15

Renal blood flow will increase and the overall filtration pressure will decrease

Question 16

How is renal blood flow kept?

Answer 16

It is kept relatively constant

Question 17

What does a change in Afferent resistance do?

Answer 17

It controls blood pressure and glomerulus filtration

Question 18

How does a nephron respond to an increase in arterial pressure?

Answer 18

It will increase resistance

Question 19

What is the myogenic reflex?

Answer 19

When blood vessel contracts, pressure increases, when the blood vessels relax pressure decreases

Question 20

What are the two mechanisms of autoregualtion of renal blood flow?

Answer 20

Myogenic reflex and glomerular tubular feedback (GTF)

Question 21

What is the glomerular tubular feedback (GFR) known as?

Answer 21

A secondary mechanism

Question 22

Describe the glomerular tubular feedback mechanism

Answer 22

When there is ani increase in NaCl to the distal tubule, the macula dense senses and increased flow rate and constricts the Afferent arterioles, decreasing pressure in the single GFR

Question 23

What is the macula densa in close contact with?

Answer 23

The Afferent arteriole

Question 24

How can you measure the response of a single GFR pressure?

Answer 24

Blocking the nephron with wax - will perfuse the distal tubule and you can measure the response

Question 25

Increased delivery of isotonic Nacl =

Answer 25

An autoregulation effect on Single nephron GFR

Question 26

What is the effect on SNGFR when there is an increased delivery of isotonic mannitol?

Answer 26

There is no autoregulation

Question 27

What is the effect on SNGFR when there is an increased delivery of isotonic NaCl + furosemide?

Answer 27

There is no autoregulation

Question 28

What is the autoregulation method? - cellular mechanisms of TGF

Answer 28

High levels of na+ need to be pumped out, adenosine causes a ca2+ release and vasoconstriction which increases the Afferent arteriole and brings the blood pressure back down

Question 29

What are some hormonal vasoconstrictors?

Answer 29

Noradrenaline, adrenaline, angiotensin II and endothelin

Question 30

What are some local vasodilators?

Answer 30

Prostaglandins, nitric oxide, brandykinin and dopamine

Question 31

What is the renal response to a haemorrhage?

Answer 31

Arterial pressure decreases, renal secretion increases, which activates angiotensin II and the renal arteries constrict. There is also an increase in renal sympathetic nerves which releases noradrenaline

Question 32

What is required to maintain vasoconstriction?

Answer 32

Very low hormones, only catastrophic levels of blood loss is when GFR is abandoned

Question 33

What vessels is more sensitive to hormones, Afferent or efferent?

Answer 33

Efferent vessels are more sensitive

Question 34

When will Afferent vessels increase?

Answer 34

Afferent vessels will increase resistance when adrenaline gets very high

Question 35

What does a high concentration of adrenaline lead to?

Answer 35

Renal blood flow decreasing, GFR decreasing and the control of GFR is abandoned as blood is delivery to the systemic circulation

Question 36

What does low concentrations of adrenaline lead to?

Answer 36

A slight decrease in renal blood flow, GFR drops only slightly or is maintained despite a fall in renal blood flow

Question 37

What does prostaglandin release maintain?

Answer 37

Renal perfusion

Question 38

What does a decrease in renal blood flow and oxygen delivery cause?

Answer 38

Release of prostaglandins

Question 39

What does prostaglandin cause?

Answer 39

It causes both the Afferent and efferent arterioles to vasodilation

Question 40

What can the prostaglandin release mechanisms be inhibited by?

Answer 40

NSAIDS - leading to possible renal damage

Question 41

What leads to a nitric oxide release?

Answer 41

Shear stress, histamine, bradykinin and ATP

Question 42

What does a nitric oxide release lead to?

Answer 42

Renal and peripheral vasodilation

Question 43

Where can you find an abnormal production of NO?

Answer 43

In diabetes mellitus or hypertension - these can contribute to vascular damage

Question 44

What are the first layer of cells in the fenestrated endothelium?

Answer 44

Podocytes

Question 45

Describe podocytes

Answer 45

They have large pores, very little resistance to diffusion - the red blood cells can pass through

Question 46

What is the next layer of cells after podocytes?

Answer 46

Basal lamina - has a mesh size of 4nm, red blood cells cannot pass through

Question 47

What are pedicels?

Answer 47

Foot processes of the podocytes

Question 48

What can be filtered through the filtration barrier?

Answer 48

Water, ions, glucose, urea, creatinine and uric acid

Question 49

What cannot be filtered through the filtration barrier?

Answer 49

Red blood cells and serum albumin

Question 50

What is nephrin?

Answer 50

It is the major TM molecular, mutations in the nephrin gene can lead to abdominal pore sizes which means proteins can get through

Question 51

What is inulin?

Answer 51

It is a polysaccharide

Question 52

What is the collagen phase?

Answer 52

It is a negatively charged phase - negatively charged molecules become less permeable as they are repelled by the collagen