Vascular Tone

Question 1

how do a2 agonists help lower BP?

Answer 1

they inhibit NE release and block the baroreflex and decrease peripheral vascular resistance

Question 2

how do beta blockers lower BP?

Answer 2

reduce HR and contractility

Question 3

angiotensin blockers decrease _____ ________ ________ and _____ ______

Answer 3

peripheral vascular resistance, blood volume

Question 4

Ca antagonists relax _______ smooth muscle and decrease ______ _____ _____

Answer 4

arteriolar, peripheral vascular resistance

Question 5

what is the mechanism of action of direct vasodilators such as hydralazine and minoxidil?

Answer 5

hydralazine reduces intracellular calcium in vascular smooth muscle cells
minoxidil causes potassium efflux with smooth muscle relaxation
both cause arteriolar dilation

Question 6

describe the cardiac action potential

Answer 6

1. influx of sodium causes rapid depolarization
2. sodium channels close and slow calcium channels open causing a plateau
3. slow calcium channels close causing repolarization
4. potassium channels close

Question 7

list the layers of an artery from most outer to most inner

Answer 7

tunica externa -> External elastic lamina -> Tunica media (smooth muscle) -> Internal elastic lamina -> Basement membrane -> Tunica Interna (Endothelium)

Question 8

list the layers of a vein from most outer to most inner

Answer 8

Tunica externa -> Tunica media (smooth muscle) -> Basement membrane -> Tunica interna (endothelium)

Question 9

list the layers of a capillary from most outer to most inner

Answer 9

Basement membrane -> Endothelium

Question 10

T/F capillaries allow only a handful of RBCs to pass at a time

Answer 10

false, only a single RBC to pass at a time

Question 11

what is another term for afterload?

Answer 11

systemic ventricular resistance

Question 12

blood circulation is described by what 3 parameters?

Answer 12

flow
pressure
resistance

Question 13

the volume of blood flowing through a vessel or an organ is equivalent to?

Answer 13

cardiac output

Question 14

mean arterial pressure is determined by what parameters?
what is the formula calculation?

Answer 14

cardiac output, systemic vascular resistance, and central venous pressure
MAP = (CO x SVR) + CVP, but CVP is usually at or near 0, so…
MAP ~= CO x SVR

Question 15

vascular smooth muscle contraction is dependent on?

Answer 15

intracellular calcium and myosin light chain phosphorlyation

Question 16

agents that relax vascular smooth muscle ______ intracellular calcium and myosin light chain phosphorlyation

Answer 16

decrease

Question 17

in smooth muscle contraction, what does calcium bind to after it enters cell or is released from sarcoplasmic reticulum?

Answer 17

calmodulin

Question 18

after calcium binds to calmodulin, what is activated?

Answer 18

myosin light chain kinase

Question 19

what does myosin light chain kinase do?

Answer 19

phosphorylates light chains and increases myosin ATPase activity

Question 20

what do active myosin crossbridges do?

Answer 20

slide along actin and create muscle tension

Question 21

what is the first step of smooth muscle relaxation?
how do you describe the consequential steps of relaxation?

Answer 21

removal of calcium from the cytosol by pumping it out of cell or back into sarcoplasmic reticulum
the reverse process of contraction to decrease muscle tension