Renal Function 1

Question 1

What is the functional unit of the kidney?

Answer 1

nephron

Question 2

Nephron:

Answer 2

blind-ended tube that has a cup at one end that holds the capillaries​ which the fluid is filtered

Question 3

Where does the filtering apparatus​ sit?

Answer 3

In the cortex

Question 4

Describe what is happening in red ​circle?

Answer 4

That is where the capillaries​ come up against cup which is blind end to tube

Question 5

Blood supply to the nephron - how is it unique from other tissues?

Answer 5

It has 2 sets of capillaries in a series:
1. Afferent arteriole: that goes to the glomerular capillaries
2. Efferent arterioles: that go​ to the peritubular capillaries

**On either side of capillary bed

Question 6

Resistance inflow:

Answer 6

drops pressure​ in capillaries

Question 7

Resistance outflow:

Answer 7

increases pressure in capillaries

Question 8

Glomerulus capillaries vs capillaries in skin and muscle?

Answer 8

Glomerular capillaries operate at high pressure (5x higher) compared to capillaries in skin and muscle

Question 9

Why is the pressure so high in the glomerular​ capillaries?

Answer 9

It is needed to form a filtrate

Question 10

Which arteriole goes IN?

Answer 10

afferent arteriole

Question 11

Which arteriole goes OUT?

Answer 11

efferent anteriole

Question 12

Term referred to as the “cup”

Answer 12

bowman’s capsule

Question 13

What is contained​ in the glomeruli?

Answer 13

Whole capsule including capillaries inside Bowman’s capsule.

Question 14

Bowman’s capsule is filled with?

Answer 14

tightly​ coiled network of capilaries

Question 15

3 cell types in the glomerulues?

Answer 15

1. Podocytes
2. Endothelial cells
3. Mesangial cells

Question 16

Pododcytes:

Answer 16

• visceral (thin) epithelium)
• stabilize structure​
• make basement membranes
• contract ( can change permeability​ of filter)
• foot processes form ‘silt pores’

Question 17

endothelial cells of glomeruli​ tissues:

Answer 17

• layer gaps between tissues
• permeable to fluid
• make basement membrane
• surface glyco-calyx may be important

Question 18

mesangial cells:

Answer 18

• Phagocytic cells (keep filter clean, prevent clogging)
• located between capillaries
• make mesangial matrix
• contractile

Question 19

Glomerular basement membrane:

Answer 19

• made of structural proteins
• macromolecules present ( Type IV collagen = strength, proteoglycan = repel -VE charged proteins)
• these glycoproteins self-aggregate

Question 20

Determinants of Glomerulus filtration rate: How quickly they form in each tubule

Answer 20

• Hydrostatic pressure
• Colloid osmotic pressure

Question 21

More tissue fluid = more concentration - How does this affect colloid osmotic pressure?

Answer 21

Colloid osmotic pressure rises as it moves along the length of the capillaries

Hydrostatic Pressure drops and fluid is lost from the capillary

Question 22

Where does fluid tend to move back into the capillaries?

Answer 22

Venous end

Question 23

Where is the hydrostatic​ pressure always higher that the colloid osmotic pressure?

Answer 23

At the afferent arterial end of the capillary

Question 24

Hydrostatic preesur​e Is the difference​ between

Answer 24

Is the differnce between the fluid inside the capillary and fluid pressure in the tubule

Question 25

Colloidal osmotic pressure is exerted by?

Answer 25

proteins that remain​ in the capillary ( very little protein in filtrate)

Question 26

What does this graph show?

Answer 26

The net hydrostatic pressure always exceeds the net osmotic pressure **The Single nephron Glomular Filtration rate (SNGFR) is mostly influenced by glomerular capillary hydrostatic pressure and the ultrafiltration coefficient​

Question 27

Filtartion faction =

Answer 27

GFR/ Renal plasma flow (RPF) x 100%

Question 28

Changed in GFR would affect?

Answer 28

tubular​ workload

Question 29

How is GFR stabilzed?

Answer 29

via autoregulation - stable over perfusion pressures of 70 to 120 - see very little change in RPF and GFR

Question 30

Mechanisms for autoregulation: Myogenic tone

Answer 30

afferent​ arteriole constricts in response to stretch (increase in blood pressure) - protects capillaries from 2 high of a rise in pressure

Question 31

What type of ions are sensed by macula densa?

Answer 31

chloride ions

Question 32

Mechanisms for autoregulation: Tubuloglomerular feedback

Answer 32

- Cl sensed by macula densa If high: afferent constricts​ and efferent relaxes If low: afferent relaxes and efferent constricts

Question 33

If resistance on Afferent arterial goes up then?

Answer 33

filtration goes down

Question 34

If resistance on the efferent side goes up then​?

Answer 34

filtartion rate goes up

Question 35

Macula densa mediators/ signals: adenosine

Answer 35

- High Cl increases adenosine release

Question 36

local mediater that constricts afferent arteriole?

Answer 36

adenosine

Question 37

Inhibits renin secretion from afferent arterioles​ cells that have renin stored in granules within them

Answer 37

adenosine

Question 38

What happens if Cl is low?

Answer 38

Nitric oxide and prostaglandins​ are released

Question 39

What affect does nitric oxide have on afferent arteriole​?

Answer 39

- relaxes afferent arteriole - stimulates renin secretion (possibly via prostaglandins​ production)

Question 40

Renin is an enzyme that?

Answer 40

reacts to produce angitension 2 locally within kidney

Question 41

Renin is secreted by ___ in response to ___

Answer 41

modified smooth muscle cells of AA in response​ to stretch

Question 42

Renin is secreted by ___ in response to ___

Answer 42

modified smooth muscle cells of AA in response​ - to stretch - No and prostoglandins - Sympathetic nerves stimulation to kidney

Question 43

Explain the renin-angiotensin​ system:

Answer 43

Renin cleaves angiotensinogen --> forms Angiotensin I Angiotensin I is cleaved by Angiotensin-converting enzyme (ACE) --> forms angiotensin II Angiotensin II constricts the efferent arteriole ONLY, enhances Na+ and water absorptions by proximal convoluted​ tubule

Question 44

Where does fine control of electrolytes and fluid volume happen?

Answer 44

distal tubule

Question 45

PGE2 and PGI2:

Answer 45

- vasodilators (as is Nitric Acid) - signal renin release - protects against vasoconstriction of afferent arteriole when BP drops (maintains Blood flow to the kidney) - important drugs used clinically to inhibit the ​formation of prostaglandins

Question 46

Where does ultrafiltration occur?

Answer 46

via the glomerules: endothelium, basement membrane, and podocytes

Question 47

GFR is a fuctional measure of?

Answer 47

number of nephrons in kidneys ( each one has its own GFR)

Question 48

The kidney filters the amount based on?

Answer 48

the number of functioning nephrons in that kidney

Question 49

Filtration rate is regulated to give ?

Answer 49

a stable filtered load for the tubules to work on

Question 50

concept of renal clearance:

Answer 50

volume of plasma cleared in order to provide amount of substance in the urine per unit of time

Question 51

concept of renal clearance:

Answer 51

volume of plasma cleared in order to provide amount of substance in the urine per unit of time - Used to measue GFR

Question 52

Clearance can be used to measure GFR if the ​substance is:

Answer 52

- freely filtered - not reabsorbed - not secreted

Question 52

Clearance can be used to measure GFR if the ​substance is:

Answer 52

- freely filtered - not reabsorbed - not secreted

Question 53

Clearance can be used to measure GFR if the ​substance is:

Answer 53

- freely filtered - not reabsorbed - not secreted