Lecture 27 - MicroCirculation

Question 1

Precapillary sphincter?

Answer 1

cuffs of smooth muscle, controls whether flow goes through true capillaries (open) or metarteriole thoroughfare channels (closed)

Question 2

Factors promoting capillary dilation?

Answer 2

decreased oxygen, increased CO2, adenosine and NO, K+ or H+, histamine, inc. temperature, NOT NEURAL

Question 3

Reactive hyperanaemia?

Answer 3

blood flow restoration post-occlusion at a level above pre-occlusion, driven by metabolites

Question 4

Autoregulation?

Answer 4

constant flow despite changes in perfusion pressure e.g. brain, kidney

Question 5

Myogenic Control?

Answer 5

increased pressure leads to vessel constriction so that flow and wall stress can remain

Question 6

Capillary types?

Answer 6

continous, fenestrated, sinusoidal (progressively leakier)

Question 7

Transcapillary exchange types?

Answer 7

diffusion (conc. gradient & diffusibility), filtration (pressure gradient), large molecule movement (pinocytosis)

Question 8

Capillary pressure?

Answer 8

results in greater filtration (oedema) - arterial and venous pressure increase as wel as arterial/venous resistance decrease/increase

Question 9

Lymphatic vessel function?

Answer 9

return blood to circulation, absorption from gut, removal of RBC and bacteria from tissues