Physiological correlates of renal disease I

Question 1

what % of CO do the kidneys receive?

Answer 1

20%

Question 2

how often is the entire blood supply filtered through the kidneys?

Answer 2

30 minutes

Question 3

what are the major functions of the kidney?

Answer 3

• excretion
• body fluid / electrolyte balance
• elaboration of endocrine hormones
• gluconeogenesis

Question 4

what three layers make up the glomerular membrane?

Answer 4

• endothelium of capillary
• basement membrane
• podocytes (epithelial cells)

Question 5

the high filtration rate across the glomerular capillary is supported by what 3 factors?

Answer 5

• perforation of the endothelium (fenestrae)
• meshwork of the basement membrane
• podocytes

Question 6

what is the main underlying problem in nephrotic syndrome?

Answer 6

increased glomerular permeability to large proteins such as albumin

Question 7

plasma in the glomerular capillaries must pass through which 3 structures before it becomes glomerular filtrate?

Answer 7

• capillary endothelium
• basement membrane
• bowman’s capsule epithelium

Question 8

what impedes the movement of proteins into the glomerular filtrate?

Answer 8

negatively charged basement membrane

Question 9

what are the two types of nephrons?

Answer 9

• cortical

- juxtamedullary

Question 10

what are the differences between the cortical and juxtamedullary nephrons in terms of 1) glomeruli location and 2) loop length?

Answer 10

cortical:
- glomeruli in outer cortex
- shorter loop

juxtaglomerular:
- glomeruli deep in cortex
- longer loop

Question 11

which nephrons are surrounded by peritubular capillaries?

Answer 11

cortical

Question 12

what are the two types of capillary beds in the kidney?

Answer 12

• glomerular

- peritubular

Question 13

the glomerular and peritubular capillaries are arranged in series and separated by what structure?

Answer 13

efferent arteriole

Question 14

the juxtamedullary nephrons are surrounded by specialized peritubular capillaries known as what?

Answer 14

vasa recta

Question 15

what capillary network has an essential role in the formation of concentrated urine?

Answer 15

vasa recta

Question 16

what is the tonicity of the glomerular filtrate in comparison to the plasma?

Answer 16

isotonic

Question 17

the GFR is determined by what two factors?

Answer 17

• net filtration pressure

- glomerular capillary filtration fraction coefficient

Question 18

what two components / forces make up the net filtration pressure?

where does this take place?

Answer 18

• hydrostatic forces
• colloid osmotic forces
• takes place across glomerular membrane

Question 19

what force favors filtration?

Answer 19

glomerular hydrostatic

Question 20

what forces oppose filtration?

Answer 20

• glomerular colloid oncotic

- bowman’s capsule pressure

Question 21

what is the effect of afferent arteriole constriction on GFR?

Answer 21

decreased

Question 22

what is the effect of efferent arteriole constriction on GFR?

Answer 22

increased

Question 23

what is the effect of afferent arteriole dilation on GFR?

Answer 23

increased

Question 24

what is the effect of efferent arteriole dilation on GFR?

Answer 24

decreased

Question 25

60-70% of sodium is reabsorbed in which part of the nephron?

Answer 25

PCT

Question 26

why filter amino acids, oligopeptides, and glucose carboxylates if they are not going to be excreted?

Answer 26

- filtration is not specific enough | - filtration is based on rate (selectivity does not occur during filtration)

Question 27

which substances have a fractional excretion over 1 (excreted more than filtered)?

Answer 27

- potassium - protons - organic acids and bases - urea - urate

Question 28

definition: alkalosis

Answer 28

- reduction in extracellular fluid proton concentration | - kidney fails to reabsorb filtered bicarb, increasing bicarb excretion

Question 29

what is responsible for the selectivity of tubular reabsorption / secretion?

Answer 29

- luminal membrane | - tight junctions

Question 30

what are the two pathways for reabsorption of filtered fluid and solutes from the tubular lumen into the blood?

Answer 30

- transcellular | - paracellular (diffusion)

Question 31

the transcellular pathway of reabsorption comprises which two transport types?

Answer 31

- primary active | - secondary active

Question 32

what type of solutes are transported transcellularly?

Answer 32

metabolic substrates: - glucose - amino acids - fatty acids

Question 33

what are the pathological steps involved in nephrotic syndrome?

Answer 33

- glomerular injury - proteinuria - reduced colloid oncotic pressure - edema - reduced plasma volume

Question 34

pathogenesis: nephrotic syndrome

Answer 34

- disturbance in forces that normally partition fluid into various subcompartments of extracellular fluid space - blood volume remains contracted even though extracellular fluid volume is expanded