CV2 Flashcards
what are the two determinants of flow
pressure gradient
resistance
why does resistance oppose flow
friction
______ is inversely proportional to resistance
flow (higher resistance, less flow)
___________ is directly proportional to flow
pressure gradient (higher flow, higher pressure gradient)
what is flow?
flow is the volume of fluid over a certain time. it is not how fast the liquid is flowing
larger radius = less _________
resistance
whats the primary determinant of resistance within the cardiovascular system
changes in radius (because of r^4)
resistance is proportional to what (that equation)
resistance is directly proportional to 1/radius^4
flow is proportional to what (that equation)
flow is directly proportional to 1/resistance
what is the resistance equation
R= 8nl/Pi(r^4)
a shorter length tube will have _____ resistance and _______ flow
less, more
what would happen to velocity is a vessel with a small constricted area
it would speed up velocity
at the same flow, would velocity be faster through a constricted vessel or a thicker vessel
it would be faster in a constricted vessel
what is considered the workhouse of the body
the heart
in one minute, the heart performs the equivalent work of lifting a ________ pound weight
5
where does the heart lay
the centre of the thorax
what is the top of the heart called
the base
what is the bottom of the heart called
the apex
what is the pericardium
a double walled sac filled with a thin layer of clear pericardial fluid
what does pericardial fluid do?
lubricates the hearts external surface as it beats within the sac
what is the heart mostly composed of
myocardium (cardiac muscle)
what do atrioventricular valves do
allow flow from the atria into the ventricles
what is one way flow through the heart ensured by
2 sets of valves
1. in heart
2. In veins
what side of the heart is the tricuspid valve on
right side
what side of the heart is the bicuspid (mitral) valve on
left side
why is it called the bicuspid valve
there are 2 flaps
what is the chordae tendinae
the tendon that attaches the AV valves to the papillary muscles on the walls of the ventricles
do the chordae tendinaes open to valve
no
what do papillary muscles do
they are structural muscles to supply stability to the valve
what are semilunar valves
one way valves that exist between the ventricle and outflow artery
how are semilunar valves composed
3 cup like leaflets
do semilunar valves require connective tendons
no because their shape prevents prolapse
what is the atrioventricular ring
it is the attachment point to muscle for the valves
what does the atrioventricular ring do
electrically isolates the atria from the ventricles
what is the cardia conduction system
a network of autorythmic cells in the heart
where does cardiac action potential originate
in a group of cells in the SA node
what else has slower pacemaker activity
AV node and Pukinje fibres
what passes through the atrioventricular ring
bundle of His
av bundle is also what
bundle of his
whats the order of the conduction system in the heart
SA node
internodal pathways
AV node
Av bundle = bundle of his
bundle branches
purkinje fibres
what would take over if SA node stopped working
AV node
the more HCN channels, the what
the faster the depolarization
what sets the heart rate
the autorythmic cells with the most rapid pacemaker activity
