PSIO202 Exam 1 Lecture 5

Question 1

When things cross through the capillary wall, what is on the “other side” from the capillary?

Answer 1

ISF (interstitial fluid)

Question 2

How do oxygen, nutrients, waste, and CO2 move through the capillary (direction)?

Answer 2

oxygen and nutrients move out of the capillary into the ISF, waste and CO2 move into the capillary from the ISF

Question 3

What is a capillary bed?

Answer 3

network of capillaries where exchange of material with the tissue cell can take place

Question 4

How close are tissue cells to capillaries?

Answer 4

All cells are within 2-3 cells from a capillary

Question 5

What are the dimensions of the capillary? Length, diameter, and velocity of flow?

Answer 5

Length: 1 mm
Diameter: 0.8 micrometers
Velocity: 0.1 cm/sec

Question 6

What determines if a tissue has more or less capillaries?

Answer 6

Metabolic activity - more metabolic activity needs more capillaries

Question 7

If capillaries are so small, why does bloodflow slow down so much in them?

Answer 7

The cross sectional area is huge, so there is still more space for the blood even though individual capillaries are tiny.

Question 8

What are the three structures that allow passage of things through a capillary? What do they allow to pass?

Answer 8

intercellular clefts (lines between): water and water soluble solutes
endothelial cell membranes: small molecules and gases
fenestrations (holes, pores): large molecules

Question 9

What are the structures like in a continuous capillary? What passes through them, and where are they located?

Answer 9

They have tight junctions between the endothelial cells, but small molecules and gases can still pass through the intercellular celfts. Located in the lungs, skeletal muscle, and connective tissues.

Question 10

What are the structures like in a fenestrated capillary? What passes through them, and where are they located?

Answer 10

They have pores in the endothelial cells which allow more small molecules to pass. Located in the kidneys, endocrine glands, and small intestine.

Question 11

What are the structures like in a sinusoid capillary? What passes through them, and where are they located?

Answer 11

Big fenestrations, few tight junctions, and wide clefts allow for large molecules like proteins or whole cells to pass through. Located in the liver, spleen, bone marrow, and pituitary gland.

Question 12

What is diffusion? Passive or active?

Answer 12

movement from high concentration to low concentration, passive

Question 13

What is bulk flow? Passive or active?

Answer 13

Passive process. Movement from high pressure to low pressure.

Question 14

What is transcytosis? Passive or active?

Answer 14

Active, vesicles endocytose then exocytose on the other side

Question 15

What forces are involved in bulk flow?

Answer 15

BHP, IFOP, BCOP, and IFHP

Question 16

What is BHP? Reabsorption or filtration pressure?

Answer 16

pushes fluid out through the capillary pores, filtration

Question 17

What is IFOP? Reabsorption or filtration pressure?

Answer 17

Pulls fluid out of the capillary via osmosis. Filtration.

Question 18

What is BCOP? Reabsorption or filtration pressure?

Answer 18

Difference in protein concentration between plasma and ISF that pulls water into the capillary since the proteins can’t get out. Reabsorption.

Question 19

What is IFHP? Reabsorption or filtration?

Answer 19

The pressure of ISF favors movement into capillaries. Reabsorption.

Question 20

Which of the 4 pressures significantly contribute to NFP, vs the ones that are very small?

Answer 20

BHP and BCOP contribute, but IFOP and IFHP are very small.

Question 21

What is the equation for NFP? What is the meaning of it?

Answer 21

NFP is the net movement of fluid (positive is movement out, negative is movement in)

NFP= (BHP+IFOP) - (BCOP+IFHP)

Question 22

How does albumin impact capillary pressures?

Answer 22

Albumin cant move out of the capillary, Na+ is attracted to albumin and moves in too, water needs to move in to balance the Na+ (maintains BCOP)

Question 23

Does more fluid filter or reabsorb from/to capillaries? How much?

Answer 23

More filters out than comes back in. 20 L out, 17 L back.

Question 24

What is the role of filtration from the capillaires?

Answer 24

Constant wash of fluid over cells that brings nutrients and oxygen

Question 25

What is the role of reabsorption into the capillaries?

Answer 25

Return of fluid brings waste and CO2 into the venous blood

Question 26

How does the NFP differ at the arterial and venous end of a capillary? Why does this make sense?

Answer 26

venous: negative NFP (movement in) to bring wastes back to the veins
arterial: positive NFP (movement out) to take the nutrients and oxygen out to the cells