Exam 3 Kirk 6: Mechanisms of Local Regulation

Question 1

Explain the factors that affect TPR

Answer 1

TPR is affected by blood viscosity and arteriolar radius

The arteriolar radius is affected glocally and locally

Global/extrinsic: baroreceptor, hormones, SNS

Local: myogenic response, Endothelium mediated regulation, local metabolic changes

Question 2

Blood flow is primarily controlled by the ____ vessels

Vascular smooth muscle is responsible for the control of ______

Multiple mechanism govern vascular resistance and thus blood flow.

Name the four LOCAL mechanisms

Answer 2

Blood flow primarily controlled by resistance vessels: artery side

Vascular smooth muscle is responsible for the control of total peripheral resistance, artery and venous tone and distribution of blood flow throughout the bodu

Four local mechanisms: Myogenic, Metabolic, Mechanical, Endothelial

Question 3

Explain myogenic control

Explain metabolic control

Answer 3

Myogenic Control: (it does opposite of what global says), aka it constricts when it’s supposed to dilate

Metabolic: metabolic activity produces metabolites that act on VSMC to cause local vasodilation

Question 4

Explain endothelial control

Explain mechanical control

Answer 4

Endothelial local control: endothelial cells produce several substances that act on VSMC to cause constriction or relaxation

Mechanical: exterior tissues pushing down on local blood vessels

Question 5

_______ is an intrinsic property of an organ or tissue to maintain constant blood flow despire changes in arterial perfusion pressure

Answer 5

AUTOREGULATION: maintaining constant blood flow locally to tissues

Question 6

Draw the graph explaining how autoregulation controls resistance and how that relates to flow

Answer 6

Question 7

Autoregulation is accomplished through two mechanisms: ______ and _______

Answer 7

Autoregulation is accomplished via myogenic and metabolic responses

Question 8

Where is there strong autoregulation?

No autoregulation?

Answer 8

Strong autoregulation: brain, heart, kidney, skeletal muscle

Little to none: skin, lungs

Question 9

Metabolites from a tissue act locallt to ________ to increase blood flow to that tissue

Further, a reduction in O2 delivery to a tissue stimulates the formation of metabolites that are ______

What is adenosine? (vasoconstrictor or vasodilator)

Answer 9

Metabolites from tissue act locally to dilate resistance vessels to increase blood flow to the tissue

Further, a reduction in 02 delivery to a tissue stimulates the formation of metabolites that are vasodilators.

Adenosine is a vasodilator (slow down, vaseline)

Question 10

Explain active hyperemia

vs reactive hyperemia

Answer 10

Active hyperemia: increased blood flow caused by increased tissue activity

Reactive hyperemia: transient increase in blood flow following a brief arterial occlusion…. during this occlusion metabolic debt increases, creating an increase in blood flow

Question 11

Name the endothelial vasodialtors:

Name the endothelial vasoconstrictors:

Answer 11

Vasodilators: EDRF/NO , Protacyclin, Nitroprusside

Constrictors: Endothelian (comes from Arg II)

Question 12

Explain the production of NO starting from calcium activating NOS

Answer 12

NOS gets activated, turns arginine into NO into endothelial cell

NO then travels to smooth muscle cell and activates guanylyl cyclase, which converts GTP into cGMP

that cGMP causes relaxation

Question 13

Which vasodilator does NOT need the endothelium to work?

Answer 13

Nitroprusside is a vasodilator that bypasses the endothelial layer

Nitroprusside (endothelial layer, step aside i don’t need you)