Physiology-Microcirculation

Question 1

Where does oxygen diffusion into tissues begin in the cardiovascular system?

Answer 1

The microcirculation (arterioles, capillaries and venules). These vessels only have one layer of endothelium.

Question 2

How do you measure net movement across the capillary?

Answer 2

*

Question 3

What forces determine flux across the capillary membrane?

Answer 3

The equilibrium between factors favoring fluid loss (capillary hydrostatic pressure, interstitial fluid colloid osmotic pressure) and factors favoring reabsorption (interstitial fluid hydrostatic pressure, capillary colloid osmotic pressure)

Question 4

How do veins play a role in cleaning up the extravascular space?

Answer 4

Arteries have a net outward force of 8 mmHg, pushing fluid out of the vessel. Veins have a net inward force of -7 mmHg, pulling interstitial fluid into the vessel.

Question 5

What property of our lymphatic vessels make them great collectors of interstitial fluid?

Answer 5

They have tethered endothelial cells that flap open and shut. When interstitial fluid pressure is high, it pushes fluid into the vessel. When fluid fills the vessel, the valves shut and contract, compressing the fluid towards the thoracic duct via valves.

Question 6

What structures are responsible for keeping the interstitial fluid osmotic force low?

Answer 6

Lymphatics. They absorb cellular debris, bacteria and protein to keep the interstitial osmotic force low.

Question 7

What factors contribute to edema?

Answer 7

*