Kidneys: Filtration

Question 1

What three mechanisms regulate kidney filtration?

Answer 1

Renal auto regulation
Hormonal
Neural regulation

Question 2

Where is renal autoregulation?

Answer 2

It’s intrinsic to the kidney itself

Question 3

What two mechanisms control renal autoregulation?

Answer 3

Myogenic mechanism- Tendency of vascular smooth muscle to contract when stretched
Tubuloglomerular feedback mechanism- See Macula Densa cells

Question 4

Which two hormones regulate filtration?

Answer 4

Angiotensin II

ADH

Question 5

In general, what does angiotensin II do?

Answer 5

Raise BP

Question 6

Specifically, how does angiotensin II raise BP (4 things)

Answer 6

By causing widespread arteriolar vasoconstriction
Activating thirst centers
Stimulate aldosterone release → makes kidney retain Na+
Stimulates ADH release

Question 7

How does angiotensinogen become angiotensin II?

Answer 7

Angiotensinogen → (via renin) Angiotensin I → (via ACE in lungs) Angiotensin II

Question 8

What is renin?

What does it do?

Answer 8

Renin is a proteolytic enzyme from the JG cells of the kidney
Eventually creates more angiotensin II, so ↑ BP

Question 9

What 2 types of cells are in the juxtaglomerular apparatus?

Answer 9

Juxtaglomerular cells/JG cells/granular cells

Macula densa cells

Question 10

Where is the juxtaglomerular apparatus?

Answer 10

Occurs where afferent arteriole comes in contact with distal convoluted tubule (DCT)

Question 11

Where are juxtaglomerular cells?

Answer 11

Enlarged specialized smooth muscle cells wrapped around afferent arteriole

Question 12

What do juxtaglomerular cells do?

Answer 12

Secrete renin when they detect a low BP

Question 13

Where are macula densa cells?

Answer 13

Closely packed cells in the ascending loop of Henle

lie adjacent to JG cells

Question 14

What do macula dense cells do?

Answer 14

Are chemoreceptors that respond to changes in NaCl of filtrate

Question 15

Macula dense cells release a ________, to slow glomerular filtration rate (___). This slowdown allows more time for the _______ to filter blood.

Answer 15

vasoconstrictor
GFR
Glomerulus

Question 16

What is a Tx for hypotension?

Answer 16

Tx for hypotension is ACE-inhibitors which blocks the formation of angiotensin II, so no vasoconstriction.

Question 17

What is the RAAS system? And what does it do?

Answer 17

RAAS (Renin, Angiotensin, Aldosterone System) plays an important part in regulating blood volume and systemic vascular resistance, which together influence cardiac output and arterial pressure

Question 18

Where does ADH come from?

Answer 18

Posterior pituitary

Question 19

When is ADH released? What does it do?

Answer 19

Release in response to dehydration, ↑blood osmolarity (more particles in blood)
Results in ↑BP by ↑H2O resorption by collecting ducts

Question 20

Without ADH what disease occurs?

Answer 20

Diabetes insipitus

Question 21

What kind of neural regulation occurs: at rest; under moderate stress; under severe stress?

Answer 21

At rest- Sympathetic nervous system is minimal
Moderate stress- Both afferent and efferent arterioles constrict the same
Extreme stress- Vasoconstriction of the afferent predominates- blood to brain/heart

Question 22

What two substances are produced by the kidneys, and what do they do? (Enzyme and hormone)

Answer 22

Renin- A proteolytic enzyme
Erythropoietin- A hormone that regulates the production of RBCs. Stimulated whenever the delivery of O2 is less than normal

Question 23

What is GFR, how much does it amount to?

Answer 23

Glomerular filtration rate- The total amount of filtrate formed per minute by the kidneys
Normal amount is 120 mL/minute
Equivalent to 150 L/day