Chapter 18/19 (Pt. 3)

Question 1

local control of glomerular filtration rate by tubuloglomerular feedback involves what apparatus?

Answer 1

juxtaglomerular apparatus

Question 2

where is the juxtaglomerular apparatus located?

Answer 2

where afferent arteriole, efferent arteriole, and distal tubule come together.

Question 3

what makes up the juxtaglomerular apparatus?

Answer 3

composed of macula densa and granular cells within the distal tubule wall and around the afferent and efferent arterioles respectively

Question 4

what happens when macula densa cells detect an increase in Na+ ?

Answer 4

flow rate is going too fast = increased Na+ = macula densa release a paracring signaling molecule, which diffuses to nearby aff. arteriole = smooth muscle constricts to limit blood flow in = filtration rate stops

Question 5

macula densa cells rely on which type of signaling

Answer 5

paracrine

Question 6

what happens when macula densa cells detect low Na+?

Answer 6

short answer; dilate aff. to get increased blood to go through quicker

filtration rate is too slow, so they release 1. less paracrine signaling molecule, or 2. a different signaling molecule

nephron aff. arteriole dilates

blood flow to glom. increases

filtration rate increases

Question 7

when is local control of GFR needed?

Answer 7

to respond to increased BP during physical activity

Question 8

why is local control of GFR needed to respond to increased BP during physical activity? (3)

Answer 8

• prevent rupture of the glomerular capillary bed due to excessive arteriole hydrostatic pressure
• reducing blood flow through aff. art. makes more blood available to skeletal and cardia muscle
• lowering filtration rate reduces urine production in order to retain greater plasma volume

Question 9

an increase in physical activity stimulates the SNS to increase CO which leads to an increase in MAP and a decrease in glomerular filtration. how is glomerular filtration: decreased by the SNS?

Answer 9

norepinephrine -> alpha receptors -> activates Ca+2 pathway -> arteriole constrict

Question 10

what are two positive effects of glomerular filtration being decreased by the SNS?

Answer 10

• prevent rupture of the glomerular capillary bed due to excessive arteriole hydrostatic pressure
• reducing blood flow through aff. art. makes more blood available to skeletal and cardia muscle
• lowering filtration rate reduces urine production in order to retain greater plasma volume

Question 11

would GFR be increased by constriction of the afferent arteriole?

Answer 11

no

Question 12

would GFR be increased by increased Bowman’s capsule hydrostatic pressure?

Answer 12

no

Question 13

would GFR be increased by a decrease in the concentration of glomerular plasma protein?

Answer 13

yes

Question 14

would GFR be increased by dilation of the efferent arteriole?

Answer 14

no