Chapter 7 Vascular control Flashcards
Are these vasodilator or vasoconstrictor substances?
- Prostaglandins
- Histamine
- Bradykinin
- 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)
Define active hyperemia:
= 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
Define reactive hyperemia
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
What is the sympathetic vasoconstrictor neurotransmitter?
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.
What protein does Ca+ bind to in smooth muscles and initiate muscle contraction?
Calmodulin
T/F Once smooth muscles have contract, it is very cheap (low ATP cost) to maintain the contraction
True
What is the main molecule determining the resting membrane potential in a smooth muscle cell
Potassium
What is smooth muscle cells’ reaction to high vs low O2 concentration? (in most tissues)
High O2 -> vasoconstrict
Low O2 -> vasodilate
Nitric oxide is produced intracellular from which amino acid?
L-arginine