Vascular Control--Nordgren

Question 1

What ion depolarizes smooth muscle?

Answer 1

Ca²⁺

Question 2

Unique contractile feature of vascular smooth muscle

Answer 2

needs to maintain some level of tone at all times

Question 3

Myosin light chain function

Answer 3

*when phosphorylated

causes contraction of smooth muscle

Question 4

Phosphorylated myosin light chain vs. Myosin light chain

Answer 4

phosphorylated myosin light chain activates smooth muscle contraction

unphosphorylated myosin light chain inactivates smooth muscle contraction

Question 5

RMP of vascular smooth muscle

Answer 5

-40 mV to -65 mV

Question 6

Electromechanical coupling mechanism

Answer 6

VG Ca²⁺ open in response to depolarization

basal tone present

Question 7

Pharmacomechanical coupling mechanism

Answer 7

Receptor operated Ca²⁺ channels open

G-protein coupled receptor

form inositol triphosphate, opens Ca²⁺ channels on SR

Question 8

Electromechanical relaxation mechanism

Answer 8

hyperpolarization

Question 9

Pharmacomechanical relaxation mechanism

Answer 9

G-protein coupled receptors

stimulate Ca²⁺ efflux

Question 10

What does Ca²⁺ bind to when it enters the smooth muscle cell?

Answer 10

calmodulin

Question 11

What causes basal tone?

Answer 11

stretch in response to having any volume of blood present

Question 12

What is the most important means of local tissue flow control?

Answer 12

local metabolic influences

Question 13

How do endothelial cells affect the tone of surrounding smooth muscle?

Answer 13

produces NO

diffuses across cell membrane

cGMP inhibits Ca²⁺ entry

activates K+ channels

Question 14

What do prostaglandins do to local tissue flow/smooth muscle?

Answer 14

depends on which prostaglandin

Question 15

Transmural pressure: local change mechanism

Answer 15

arterioles actively and passively repsond to transmural pressure (pressure across vasculature)

Question 16

What is hyperemia?

Answer 16

blood flow across organ

Question 17

Active hyperemia

Answer 17

flow to organ controlled by metabolic rate (sk and cardiac muscle)

Question 18

Reactive hyperemia

Answer 18

increased blood flow after removal of restriction (ie tourniquet)

Question 19

Autoregulation (like hyperemia)

Answer 19

organs tend to keep blood flow constant despite variations in arterial pressure

Question 20

What most important means of reflex control in vasculature?

Answer 20

neural influences

release of NE

Question 21

Neural influences on vasculature

Answer 21

NE release

α-1 androgenic receptor

Question 22

How does autoregulation function?

Answer 22

change in resistance when change in pressure occurs to maintain constant flow

Question 23

T/F

Venous system is under the control of local metabolic needs

Answer 23

false

Question 24

Important outside physical influence on venous system

Answer 24

skeletal muscle pump (veins)

Question 25

T/F

NE activates α1 receptors in veins, leading to vasocontriction

Answer 25

true

but veins don’t respond to local changes

Question 26

How does arteriole constriction affect capillary hydrostatic pressure?

Answer 26

decreases capillary hydrostatic pressure

Question 27

How does the lung vasculature respond to hypoxia?

Answer 27

vasoconstriction

*lungs sense hypoxia in capillaries

*this means that the area of the lungs where these capillaries are going through is not well perfused with oxygen

*shunting of blood away from poorly perfused area to area that has better perfusion