16.1 Physiology- Kidney function 1

Question 1

What ions need to be tightly regulated? 4)

Answer 1

K+
Ca2+
Mg2+
Cl-

Question 2

What is the acid-base balance controlled by?

Answer 2

Kidney in tandem with lungs

Question 3

What is a filtration unit of the kidney?

Answer 3

Glomerulus

Question 4

Do we see albumin normally in the kidney? Why?

Answer 4

Doesn’t appear in health kidney, negative charge repels albumin from slits

Question 5

What is the GFR /day, /min?

Answer 5

180L/day, 120mL/min

Question 6

What is the order of structures in a nephron? (7)

Answer 6

Glomerulus (Bowman's capsule)
Proximal tubule
Descending limb of loop
Loop of Henle
Ascending limb of loop
Distal tubule
Collecting duct

Question 7

What is the junction where the thick ascending loop meets the distal tubule?

Answer 7

Macula densa (contact point where distal dephron gets feedback)

Question 8

Where does the bulk of reabsorption take place?

Answer 8

Proximal tubule

Question 9

What sections of the nephron concentrate?

Answer 9

Thin descending and ascending limb of loop of Henle

Question 10

Where does dilution take place?

Answer 10

Thick ascending limb

Question 11

What is the macula densa part of? Where specifically is it located? What does it do?

Answer 11

Part of the JGA

Located in between efferent/afferent arterioles emerging from glomerulus

Important regulatory role

Question 12

Where in the nephron does the fine-tuning take place?

Answer 12

Distal tubule

Question 13

Where is the Aldo-dependent equilibrator? What does it do?

Answer 13

Collecting duct

Equilibrates osmolarity of total solute

Question 14

How does water move from the collecting duct to the interstitium?

Answer 14

Via aquaporins (single water molecule channels)

Question 15

Where is bulk flow taking place?

Answer 15

Bowman’s capsule

Question 16

What are the 2 types of glomeruli? What is the diference?

Answer 16

Superficial cortical glomeruli (90%)

Juxtamedullary glomeruli (10%) (penetrates deep into the medulla)

Question 17

What are the JM glomeruli responsible for?

What do their efferent arterioles become?

Answer 17

Medullary concentration gradient (increasing osmolarity

Become the vasa recta (capillaries that accompany loops of Henle)

Question 18

Where does and doesn’t reabsorption take place?

Answer 18

Takes place throughout the nephron,

EXCEPT tALH and glomerulus

Question 19

Is movement between capillary and interstitium active or passive?

Answer 19

Passive

Question 20

Where does secretion occur? What does the pumping work?

Answer 20

PT
DT
CD

Epithelial cells lining the tubule

Question 21

What is the formula for the amount of solute excreted?

Answer 21

Amount filtered- amount reabsorbed + amount secreted

F - R + S =E

Question 22

What is normally filtered? (4)

Answer 22

Small ions, organic solutes (free), drugs (free) and very small amount of albumin

Question 23

What surrounds each capillary? What is the relevance of this?

Answer 23

Podocyte foot processes (slits in between allowing filtration)

Question 24

What is the filtration fraction (%)?

Answer 24

FF: 20% of renal plasma flow

Question 25

What are the forces that effect GFR (4)?

Answer 25

``` Hydrostatic pressure (Glomerular capillary): 50mmHg Hydrostatic pressure (Bowman's capsule): 10mmHg Oncotic pressure (Glomerular capillary) 25-->40mmHg Oncotic prsesure (Bowman's capsule): 0mmHg ```

Question 26

What happens to the pressure as we go across?

Answer 26

Resistance means that pressure drops (Pra=100 --> Pg=50--> Pcapp=10

Question 27

How does RBF autoregulation work? How does GFR autoregulation work?

Answer 27

Altering resistance of afferent arteriole (glomerular pressure is held constant, hence GFR autoregulation)

Question 28

What happens to GFR when the afferent arteriole constricts? (and capillary blood pressure)

Answer 28

GFR decreases (capillary blood pressure decreses)

Question 29

What happens to GFR when the efferent arteriole constricts?

Answer 29

GFR increases (increased P (H))

Question 30

What happens to GFR when MAP increases from 90-110mmHg?

Answer 30

GFR doesn't change (due to autoregulation)

Question 31

When does autoregulation maintain a constant GFR?

Answer 31

When MAP is 80-180mmHg

Question 32

What is the myogenic response of the renal arteries?

Answer 32

Inherent property, afferent arteriole opposes distention (by contracting)

Question 33

What is the tubuloglomerular feedback sensed by?

Answer 33

TGF: sensed by the macula densa (afferent contact)

Question 34

What do macula densa cells respond to? How do they respond?

Answer 34

Chloride concentration (not flow), respond by opening calcium channels

Question 35

What does calcium entering the macula densa cells trigger? What does this act on?

Answer 35

A paracrine signal into the nest of cells (e.g. adenosine), acts on granular cells

Question 36

What are granular cells? What do they do?

Answer 36

Cells abutting against afferent arteriole. They have adenosine type I receptors, vasoconstrict and release renin

Question 37

What is the purpose of the JBA?

Answer 37

Tubuloglomerular feedback

Question 38

What are the steps in TGF negative feedback (e.g. GFR increases) (8)?

Answer 38

1. GFR increases 2. Flow though tubule increases 3. Flow past macula densa increases 4. Paracrine from MD to afferent arteriole 5. Afferent arteriole constricts 6. Resistance in afferent arteriole increases 7. Hydrostatic pressure in glomerulus decreases 8. GFR decreases