Renal Physl 6

Question 1

What do renal functions like glomerular filtration depend on?

Answer 1

Renal blood flow

Question 2

What is renal blood flow modulated by?

Answer 2

Systemic pressure

Question 3

What do renal sympathetic nerves do?

Answer 3

They terminate on renal vasculature and extend to the renal tubules and participate in renal blood control and tubular function

Question 4

What does increased renal sympathetic activity do?

Answer 4

Decreases RBF and GFR

Question 5

How does renal sympathetic activity decrease RBF and GFR?

Answer 5

It causes vasoconstriction causing changes in glomerular hydrostatic pressure

Question 6

What happens if glomerular hydrostatic pressure increases?

Answer 6

GFR increases

Question 7

What is renal auoregulation?

Answer 7

The mechanisms that exist to stabilize renal blood flow and GFR

Question 8

What are the two mechanisms involved in autoregulation?

Answer 8

• Myogenic response

* Tubuloglomerular feedback mechanism (TGF)

Question 9

Why is RBF and GFR relatively stable over a wide range?

Answer 9

Due to the myogenic response and TGF

Question 10

What occurs in the Myogenic response?

Answer 10

Smooth muscle of glomerular afferent arterioles stretch as blood pressure and renal blood flow increases stretch sensitive ion channels open and the muscle cells depolarize causing opening of voltage gated calcium channels which induces vascular smooth muscle contraction increasing vasoconstriction stabilizing GFR

Question 11

What happens in the myogenic response if blood pressure and renal blood flow decrease?

Answer 11

The resting contraction of the afferent arteriole is decreased so the blood vessel becomes dilated and restores glomerular hydrostatic pressure

Question 12

What is the range of BP that the myogenic response can occur?

Answer 12

80 mmHg and 180 mmHg

Question 13

What does active constriction of the efferent arteriole do?

Answer 13

Causes blood to back up into the glomerular capillaries increases glomerular hydrostatic pressure of GFR

Question 14

What is TGF?

Answer 14

A local control mechanism where the rate of fluid flowing through parts of the tubule can initiate changes in renal blood flow which helps to stabilize GFR

Question 15

What passes between the efferent and efferent arteriole?

Answer 15

• Ascending limb of the loop of henle

* Distal tubule

Question 16

What is the Juxtaglomerular apparatus?

Answer 16

The point where the distal tubule makes contact with the afferent and efferent arteriole

Question 17

Where are the macula densa located?

Answer 17

In the wall of the distal tubule

Question 18

What has juxtaglomerular cells?

Answer 18

The portion of the afferent arteriole making contact with the macula densa

Question 19

What do the juxtaglomerular cells secrete?

Answer 19

Renin

Question 20

How does the TGF system work with increased GFR?

Answer 20

• GFR increases and the macula densa sense an increased delivery of sodium and chloride
• Macula densa release a paracrine factor
• Paracrine factor acts on neighboring arterioles causing vasoconstriction and reduces blood flow

Question 21

How does the TGF system work when GFR falls as a result of a drop in arteriole pressure and renal blood flow?

Answer 21

Paracrine factor elicits dilation of the afferent arteriole. A factor from the macula densa also triggers renin release which forms angiostenosis two causing vasoconstriction increases glomerular hydrostatic pressure