CV Control 3: Reg. of SVR and Flow Distrib.

Question 0

You know that smooth muscle cells have gap junctions, too, right?

Answer 0

Sure do.

Question 1

How can capillary networks be bypassed despite high CO?

Answer 1

Metarterioles can bypass capillary beds….

Question 2

What’s vascular autoregulation?

Answer 2

Vascular beds will adjust in response to metabolic need.

Question 3

3 effector mechanisms of vascular autoregulation? What’s the molecular mechanism for each?

Answer 3

Myogenic: Increased BP -> increased SMC tone via stretch-activated Ca++ channels.
Endothelium-mediated: Sheer stress -> NO -> SMC relaxation.
Metabolic: Metabolic need (adenosine?) -> vasodilation

Question 4

2 main external inputs vascular tone?

Answer 4

Adrenergic

Renin, A-II, aldosterone system (RAAS)

Question 5

Effect of adrenergics on the vascular beds of heart, brain, gut, renal, skin, and skeletal muscle?

Answer 5

Heart and brain: little change.
Renal, cutaneous, gut: vasoconstriction.
Skeletal muscle: vasodilation.
“Fight or flight.”

Question 6

Vascular beds are in parallel… so how do you add the resistances? (Who ever thought any of E&M physics would be useful?)

Answer 6

1 / R(total) = Sum of reciprocals of resistances

Question 7

What do the vascular beds do in sepsis?

Answer 7

They all dilate too much.

Question 8

When managing a patient shock, what’s one thing you should worry about once you restore systemic arterial pressure?

Answer 8

Are they making enough urine? - i.e. has been blood been shunted away from kidneys to preserve overall bloodflow?