(DSA) Introduction to Renal Blood Flow and GFR | (Pierce)

Question 1

What is this structure?

Answer 1

Glomerulus

Question 2

In order for filtration to occur, what three layers must the particulate cross through?

Answer 2

1. Capillary Endothelium
2. Glomerular basement membrane
3. Podocyte epithelium

Question 3

Describe the movement of fluid from the capillary lumen…

Answer 3

Capillary lumen –>

Capillary endothelium –>

Glomerular basement membrane –>

Podocyte epithelium –>

BOWMANS CAPSULE

Question 4

What is shown in this image?

Answer 4

View seen from the capillary side

Holes = fenestrea of the endothelial cells

Question 5

What are the arrows pointing at?

Answer 5

*fuzzy border = Biogel

Glomerular endothelium glycocalyx forms a biogel in the endothelial lumen

Question 6

What is the major cell adhesion molecule that specifically functions in the glomerulus?

Function?

Answer 6

NEPHRIN

Nephrin blocks Larger proteins from entering bowmans space

*frequently absent in diseased renal states

Question 7

Any molecule less than _____ angstroms are freely filtered

Answer 7

20

Question 8

Any molecule greater than _____ angstroms are not filtered

Answer 8

42

Question 9

What are podocytes?

Answer 9

Cells in bowmans capsule that wrap around capillaries of the glomerulus

Question 10

What passes through the filtration barrier?

Freely filtered?

Answer 10

Water

Small solutes (glucose, amino acids, electrolytes)

Question 11

What is not freely filtered through the filtration barrier?

Answer 11

• Large molecules (proteins)
• Formed elements (cells)
• Miniscule amounts of protein are filtered

*Tamm-Horsfall protein

Question 12

What molecules are more freely filtered,

Cations or Anions?

Answer 12

CATIONS!!! ++++++++++

Question 13

What does the cortex contain?

How are they organized?

Answer 13

Renal corpuscles, coiled blood vessles, coiled tubules

Intertwined randomly like plate of spaghetti

Question 14

What does the medulla contain?

How are they organized?

Answer 14

Straight blood vessels and Straight tubules

Organized in parallel array like bundles of pencils

Question 15

RBF is regulated…

Answer 15

Minute-by-minute oversight

*For example: during intense exercise, the renal fraction of blood flow decreases because blood is shunted to the musculature

Question 16

What is filtered load?

Answer 16

The amount of a substance that is filtered into the bowman’s space per unit time (mg/min)

Question 17

How do you calculate filtered load?

Answer 17

FL = GFR x Px

Question 18

Equation for urinary excretion?

Answer 18

Amount filtered - Amount reabsorbed + amount secreted = Urinary Excretion

Question 19

Equation for tubular reabsorption?

Answer 19

Glomerular filtration - Urinary excretion + Amount secreted

Question 20

If excretion > filtration then…

Answer 20

Tubular secretion must have occured!!!

Question 21

Equation for urine exretion rate?

Answer 21

Urine excretion rate of x = Ux x V

Ux= the concentration of that substance in the urine in a given volume

V=Urine flow rate, rate at which urine is produced

Question 22

How do you calculate Ux?

Answer 22

Ux= concentration of X (Ux) = the concentration of that substance in the urine in a given volume

Question 23

How do you calculate V?

Answer 23

V= Urine flow rate, the rate at which urine is produced

Question 24

What is renal clearance?

Answer 24

Renal Clearance (C) is the rate at which substances are removed (cleared) from plasma)

IT’S A FLOW RATE

Question 25

What are the units for renal clearance (C)?

Answer 25

Volumer per unit time

(mL/min, L/hour, L/day)

Question 26

What is the equation for renal clearance?

Answer 26

Question 27

What is the glomerular filtrate?

Answer 27

Volume of plasma filtered into combined nephrons of both kidneys per unit time (mL/min)

Question 28

What is the equation for filtration fraction?

Answer 28

FF = GFR / RPF

GFR= glomerular filtration rate

RPF = renal plasma flow

*FF is typically 20% of RPF

Question 29

Describe the relationship between filtration fraction and glomerular oncotic pressure

Answer 29

Question 30

What is filtered load?

Answer 30

A rate in mg/min

Question 31

What is filtration fraction (FF)?

Answer 31

A ratio of GFR to RBF

Question 32

What percentage of the filtered load of sodium is reabsorbed per day?

Answer 32

Question 33

GFR is directly proportional to renal clearance under these conditions:

Answer 33

1. Substance must be freely filterable in the glomeruli
2. Substance must be neither reabsorbed nor secreted by the renal tubules
3. Substance must not be synthesized, broken down, or accumulated by the kidney
4. Substance must be physiologically inert

Question 34

What is an example of a substance that has the GFR = C?

Answer 34

Inulin

Creatinine

Question 35

In clinical situations, the GFR of a patient is usually determined by measuring the __________

Answer 35

Clearance of creatinine

Question 36

Sympathetic stimulation causes:

Answer 36

Vasoconstriction

Renin release + RAAS

Na-K ATPase activity; Increased Na+ reabsorption

INCREASED BLOOD PRESSURE

Question 37

What are the receptor subtypes for:

Answer 37

Question 38

Plasma creatinine concentration and GFR are _________ proportional

Answer 38

Inversely

Question 39

What is BUN?

Answer 39

Blood urine nitrogen

Question 40

What can PAH (Para-aminohippuric acid) be used for?

Answer 40

Estimating renal plasma flow

*We can assume that all the PAH presented to the kidney appears in the urine