CVS

Question 0

What does blood transport

Answer 0

Oxygen,
Metabolic substrates
Co2
Waste products

Question 1

What is diffusion affected by

Answer 1

Area
Diffusion resistance
Concentration gradient

Question 2

Where does exchange of oxygen and nutrients occur

Answer 2

Capillaries

Question 3

How do hydrophilic substances diffuse through the capillary endothelial cells?

Answer 3

Through pores
E.g. S,all water soluble molecules such as AA, glucose, and lactate

Lipid soluble molecules e.g. Co2 and O2 pass straight through

Question 4

How does the area of the capillaries affect diffusion rates

Answer 4

More area available for exchange faster diffusion
Determined by capillary density (capillaries per unit volume)
Varies tissue to tissue
Higher in more metabolically active tissues- increases rate of diffusion
Branching can increase density
Not all capillaries are always perfused

Question 5

How does diffusion resistance occur

Answer 5

Diffusion resistance affected by
Nature of molecule: size (small e.g. Glucose diffuse, large e.g. Proteins don’t (stay in blood :)) ) and lipophilic or hydrophilic
Nature of barrier: large pores?
Path length: longer path decreases rate

However resistance is generally quite low, and is NOT A. RATE LIMITING FACTOR

Question 6

How does concentration gradient affect diffusion

Answer 6

Drives diffusion, greater concentration gradient between capillaries and tissues greater rate of diffusion.
Must be maintained for diffusion to continue
Affected by flow of blood through capillary. Blood supply must be at an appropriate rate to maintain.

Question 7

Know is blood flow controlled

Answer 7

By arterioles and pre capillary sphincters: resistance vessels
Directs blood to other harder to diffuse to areas of the body