L2: Renal Circulation

Question 1

Peritubular Capillaries

Answer 1

Electrolyte reabsorption and secretion and delivery of substances

Question 2

Vasa Recta

Answer 2

Important for osmotic gradient - linked to H2O reabsorption

Question 3

many nephrons share..

Answer 3

a collecting duct

Question 4

Renal blood flow is denoted as

Answer 4

RBF or QR

Question 5

Assume the total RBF __% of C.O. of _L so _ to each kindey

Answer 5

25%, 5L so 12.5% to each kidney

Question 6

25% of 5L is

Answer 6

1250mL/min

Question 7

What is RBF?

Answer 7

Flow of blood through both kidneys
20-25% of C.O. (1/4) delivered from the abdominal aorta to renal arteries
Kidney cortex receives 90% and medulla 10%

Question 8

Blood flow to the kidney 3

Answer 8

Allows for filtration of plasma
Indirectly determines GFR
Delivers O2 and nutrients to tubules for reabsorption and secretion

Question 9

Blood flow to the kidney cont 3

Answer 9

Returns HCO3-, electrolytes and H2O to the bloodstream
Delivers substances to the tubule for urinary excretion
Delivers drugs to tubular sites of action

Question 10

Where fo the two major pressure changes occur?

Answer 10

afferent and efferent arterioles

Question 11

Describe the vascular pressure changes along the kidney

Answer 11

Sharp decreases in the afferent and efferent to maintain high hydrostatic pressure aling the glomerular capillary

Question 12

What is the equation for QR

Answer 12

QR=P/R

Question 13

How can we reduce the hydrostatic pressure coming into the glomerular capillaries?

Answer 13

constrict the afferent

Question 14

How can we increase the pressure?

Answer 14

constrict the efferent

Question 15

Assume that renal vein pressure is

Answer 15

2-3mmHg

Question 16

Renal plasma flow eq

Answer 16

RPF = [1-Hct] x RBF (Hct is the RBC conc.)

Question 17

Filtration fraction

Answer 17

FF=GFR/RPF

Question 18

What is the average FF

Answer 18

125ml/min

Question 19

Autoregulation occurs where ______ remains constant despite..

Answer 19

organ blood flow remains constant despite fluctuations in arterial pressure

Question 20

Autoregulation of RBF occurs above

Answer 20

80mmHG

Question 21

Renal autoregulation refers to the regulation of both

Answer 21

RBF and GFR

Question 22

RBF is controlled by:

Answer 22

Renal sympathetic nerves
Vasoconstrictors (angiotensin II, endothelin-1)
Vasodilators (nitric oxide, prostaglandins)

Question 23

Nerve plexus

Answer 23

branching of network of intersecting nerves composed of afferent and efferent fibres

Question 24

Renin-angiotensin pathway

Answer 24

Angiotensinogen
Renin
Angiotensin I
ACE
Angiotension II
AT1Rs/AT2Rs (receptors)

Question 25

Why does NO need to be created locally?

Answer 25

It is a gas and thus, only effective for a short period of time

Question 26

Synthesis of NO

Answer 26

L-arginine to L-citrulline

Question 27

Endothelin (ET-1)

Answer 27

Like snake venom - extreme vasoconstrictor
Low levels normally
Buffered by NO
Endothelial-derived
Increase in ET-1 in hypertension, coronary arter disease

Question 28

Prostaglandins (PGs)

Answer 28

Low levels normally
Increase in PGI2 and E2 in dehydration and stress (buffers AngII)
Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit PGs (ibuprofen,aleve,aspirin)
NSAIDs contraindicated if RBF is low - will shut kidney down if NSAIDs are administered when RBF is low

Question 29

Endothelial cells produce local factors that cause vasodilation.cons in adjeacent

Answer 29

smooth muscle cells