Lecture 3 Flashcards
Cardiac output
Volume of blood pumped out by each ventricle
per minute
Regulating blood pressure
Short term (seconds)
Cardiac output & total peripheral resistance → autonomic nervous system
Regulating blood pressure
Long term (minutes to days)
Adjusting the volume of blood → restoring salt & water balance → impact on urine output and thirst
Short term responses are stimulated by
Baroreceptors
Carotid sinus
Aortic arch
Respond to mean
and pulse pressure
Arterioles have major resistance, why?
Small radius
Arterioles regulate resistance, how?
Smooth muscle cells run circulatory around the vessel- constrict = higher pressure = higher resistance
Venus return
Volume of blood entering each atrium per minute
Veins stretch but don’t
recoil like arteries
Veins act as a
Blood reservoir (at rest contain more than 60% of blood)
Smooth muscle of veins
Vasoconstriction
– Increases resistance but large radius of veins means
extra resistance has little effect
– Moderately increases venous pressure
Vein valves
Constricting veins – one way blood flow
What happens if a person stands still for a very long time with no movement?
Valves help keep the person upright
Vasoconstriction keeps the person upright
The person doesn’t stay upright
Two of these option
Gravity on venous pressure
AV valves open and close together
Semilunar valves open and close together
What happens to the valves when the papillary muscle contracts?
The papillary muscles are “nipple” like projections of the myocardia and contract when the myocardia contracts. As a result, they pull on the chordae tendinae and help to prevent prolapsing of the AV valves.
