Topic 7: Glomerular Filtration and Renal Bllod Flow

Question 1

Three renal processes

Answer 1

1. Glomerular filtration (From glomerular capillaries to Bowman’s capsule) 2. Tubular reabsorption (From renal tubules to peritubular capillaries) 3. Tubular secretion (From peritubular capillaries to renal tubules)

Question 2

Excretion equation?

Answer 2

Excretion = Filtration–Reabsorption + Secretion

Question 3

Excretion Rate: Filtration Rate

Answer 3

Excretion = Filtration Waste products (creatinine)

Question 4

Excretion Rate: Filtration, partial reabsorption

Answer 4

Excretion = Filtration–Reabsorption Electrolytes (sodium, chloride)

Question 5

Excretion Rate: Filtration, complete reabsorption

Answer 5

Nothing excreted Nutritional substances (amino acids, glucose)

Question 6

Excretion Rate: Filtration secretion

Answer 6

Excretion = Filtration + Secretion (no reabsorption) Organic acids & bases

Question 7

Increased sodium; increased filtration; decreased reabsorption all equal what?

Answer 7

increased excretion

Question 8

Small changes in filtration and/or reabsorption will produced significant changes in what?

Answer 8

excretion rate

Question 9

High Filtration Rate allows what? (3)

Answer 9

-Allows rapid removal of waste products -Allows multiple passes of the blood volume through the kidneys each day -Allows rapid and precise control of body fluid volume and composition

Question 10

GFR average amount

Answer 10

180 L/day (125 mls/minute) versus 3 to 4 liters of plasma volume

Question 11

How many times is the plasma volume completely filtered on average each day?

Answer 11

plasma volume 6 times each day

Question 12

Renal Blood Flow average mls/min

Answer 12

1100 mls/minute RBF

Question 13

Filtration Fraction = equation?

Answer 13

GFR / Renal Plasma Flow

Question 14

Filtration Fraction average %

Answer 14

20%

Question 15

Normal reabsorption ≈

Answer 15

178.5 Liters/day (123 mls/minute)

Question 16

Normal urine output ≈

Answer 16

180–178.5 ≈ 1.5 Liters/day

Question 17

Normal urine output ≈

Answer 17

125-123 ≈ 2 mls/minute

Question 18

Glomerular Capillary Membrane layers?

Answer 18

Endothelial cell layer Basement membrane layer Epithelial cell layer

Question 19

Epithelial Cell Layer consists of what?

Answer 19

Foot like processes - Podocytes: surround outer surface of basement membrane, that have slit pore-gaps, which glomerular filtrate moves through

Question 20

Endothelial cell layer has what?

Answer 20

perforated by thousands of fenestrations (small holes) Protein passage prevented by negative charge on surface of endothelial cells

Question 21

Basement membrane layer allows what? and prevents what?

Answer 21

allows movement of water and small solutes Protein passage prevented by proteoglycan mesh and negative charge

Question 22

Epithelial lay is not continuous bc of what?

Answer 22

-Slit pores present between adjacent podocytes–allow free movement of water and small solutes -Negative charge of surrounding epithelial cells hinders protein filtration

Question 23

Overall pore size is approximately what?

Answer 23

Overall pore size approximately 8 nanometers (80 angstroms)

Question 24

Filterability of 0.75 means what?

Answer 24

filtered 75% as quickly as water Filtrate concentration <plasma></plasma>

Question 25

Albumin size compared to pore size?

Answer 25

Albumin smaller than pore size (6 nm vs. 8 nm) but negative charge prevents passage

Question 26

Dextrans

Answer 26

Polysaccharides that can be made with specific charges - can be neg or positive to test things

Question 27

Renal diseases where the negative charge of basement membrane is lost before any histological changes are seen has an early indicator of what?

Answer 27

Proteinuria or Albuminuria appearance of albumin in urine is an early indicator

Question 28

Graph

Answer 28

Positivly charged ions are much easier to be passed through bc kidney layers have so many negative charges

Negatively charged large molecules are filtered less easily than positive charged molecules or equal Molecular Weight