Lecture 4: Glomerular Filtration

Question 1

What is the first step in forming urine?

Answer 1

Glomerular filtration

Question 2

What is the initial first step of GFR?

Answer 2

Renal plasma flow

Question 3

GFR is siphoned from

Answer 3

RPF

Question 4

Ultrafiltrate contains

Answer 4

Water and small solutes

Question 5

There should be absolutely no what in ultrafiltrate?

Answer 5

Proteins

Question 6

Starling’s forces cause

Answer 6

Filtration

Question 7

The ______ rate is much higher than in rest pf the capillaries

Answer 7

Filtration

Question 8

What is the filtration rate much higher than in the rest of capillaries?

Answer 8

Because surface area in glomerulus is higher

Question 9

What are the two types of cells in the glomerulus?

Answer 9

1. Endothelial cells
2. Mesangial cells

Question 10

Which of the glomerulus cells have large pores and decrease GFR

Answer 10

Endothelial cells

Question 11

Modified smooth muscle cells located between capillaries

Answer 11

Mesangial cells

Question 12

Mesangial cells contract in response to what?

Answer 12

Angiotensin 2

Question 13

Cells found in between afferent and efferent arterioles

Answer 13

Extraglomerular mesangial cells

Question 14

Cells found inside glomerulus and in between capillaries

Answer 14

Intraglomerular mesangial cells

Question 15

Jobs and properties of extraglomerular mesangial cells and intraglomerular mesangial cells

Answer 15

• Remove trapped residue/debris from basement membrane
• Contractile properties

Question 16

Name the 3 layers of the glomerular capillary

Answer 16

1. Endothelium
2. Basement membrane
3. Epithelium

Question 17

Describe the endothelium

Answer 17

Relatively large pores in which fluid, dissolved solutes, and plasma proteins can easily enter

Question 18

What does the endothelium not filter?

Answer 18

Red blood cells

Question 19

Name the 3 layers of the basement membrane

Answer 19

Lamina rara interna
Lamina dena
Lamina rara externa

Question 20

Name the two characteristics of the basement membrane

Answer 20

• No filtration of plasma proteins
• Significant barrier, keeps proteins out

Question 21

Epithelium has what attached to the basement membrane of foot processes?

Answer 21

Podocytes

Question 22

Small filtration slits between foot processes which add an additional barrier to larger substances. Which layer of the glomerular capillary?

Answer 22

Epithelium

Question 23

Filtration depends on

Answer 23

Size and charge

Question 24

What serves as a charge barrier on every layer of the glomerulus besides the lamina dena?

Answer 24

Negatively charged glycoproteins

Question 25

What does the negative charge attract and repel?

Answer 25

- Repels large solutes w/ negative charges (proteins) - Attracts solutes with positive charges - Small solutes w/ negative charges can still filter

Question 26

Locations of the two hydrostatic (fluid) pressures of glomerular capillary

Answer 26

1. Capillary blood 2. Interstitial space (Bowman's space)

Question 27

Locations of the two oncotic pressures of glomerular capillary

Answer 27

1. Interstitial blood 2. Bowman's space (but should be zero)

Question 28

Kf =

Answer 28

Water permeability of glomerular capillary wall

Question 29

What makes up Kf

Answer 29

Total surface area of capillary + permeability per unit SA

Question 30

Pgc =

Answer 30

Force favoring filtration

Question 31

Relative to systemic capillaries, Pgc is

Answer 31

Very high

Question 32

Pgc changes are produced by

Answer 32

Changes in resistance of afferent and efferent arterioles

Question 33

Pbs =

Answer 33

Force opposing filtration

Question 34

Pbs significance

Answer 34

Not very significant

Question 35

πgc =

Answer 35

Force opposing filtration

Question 36

What is πgc due to?

Answer 36

Blood protein

Question 37

πgc changes throughout length of capillary

Answer 37

Increases due to fluid leaving

Question 38

Filtration equilibrium

Answer 38

When net filtration out of capillary stops, driving force for reabsorption, filtration and force opposing filtration are equal

Question 39

Net ultrafiltration pressure

Answer 39

Always favors filtration out of capillaries