Chapter 7 Vascular control

Question 1

Are these vasodilator or vasoconstrictor substances?

• Prostaglandins
• Histamine
• Bradykinin

Answer 1

• Prostaglandins : certain are potent vasodilators: inflammation, other are vasoconstrictors: PG produced by platelets/endothelial cells, involved in hemostatic vasoconstriction
• Histamine: vasodilator (+ increased vascular permeability)
• Bradykinin: vasodilator (10 times more potent than histamine) (+ increased vascular permeability)

Question 2

Define active hyperemia:

Answer 2

= when the blood flow closely follows the tissue’s metabolic rate. => skeletal muscle blood flow increases within seconds of the onset of muscle exercise and returns to control values shortly after exercise ceases

Question 3

Define reactive hyperemia

Answer 3

Lower than normal blood flow transiently followed by a higher-than-normal blood flow - also known as postocclusion hyperemia
=> flow through an extremity is higher than normal for a period after a tourniquet is removed from the extremity

Question 4

What is the sympathetic vasoconstrictor neurotransmitter?

Answer 4

Norepinephrine, through alpha 1 adrenergic receptor. Normal nasal tonic activity, increasing arteriolar tone in a continuous manner. If decreased tomic activity of sympathetic nerves, causes vasodilation.

Question 5

What protein does Ca+ bind to in smooth muscles and initiate muscle contraction?

Answer 5

Calmodulin

Question 6

T/F Once smooth muscles have contract, it is very cheap (low ATP cost) to maintain the contraction

Answer 6

True

Question 7

What is the main molecule determining the resting membrane potential in a smooth muscle cell

Answer 7

Potassium

Question 8

What is smooth muscle cells’ reaction to high vs low O2 concentration? (in most tissues)

Answer 8

High O2 -> vasoconstrict

Low O2 -> vasodilate

Question 9

Nitric oxide is produced intracellular from which amino acid?

Answer 9

L-arginine