Cardiac Flashcards
define blood pressure
force on the blood vessel walls
periods of relaxation in the heart are called …
diastole
periods of contraction are called …
systole
what are the 2 AV valves called
bicuspid
tricuspid
location of the bicuspid valve
left side
location of tricuspid valve
right side
how do AV valves work to prevent back flow of blood
as ventricles contract, blood tries to move back to the atria.
the blood gets caught in the pockets of the valves and pushes them shut
what muscles contract preventing valves folding back into the atria under high pressure
papillary muscles and they pull on heart strings
two semilunar valves are called
aortic valve
pulmnary valve
how do the semilunar valves work to prevent back flow of blood
as pressure falls in ventricles, blood tries to flow back from aorta and pulmonary artery into the ventricles
the semilunar valves fill with blood and the bulge prevents back flow
what is the function of papillary muscles
to contract and pull on the heart strings which resists pressure of blood forcing valves to turn inside out when ventricles contract
describe blood flow on the right side
vena cavae
right atrium
tricuspid valve
right ventricle
pulmonary semi lunar valve
pulmonary artery
describe blood flow on the left side
pulmonary vein
left atrium
bicuspid valve
left ventricle
aortic semilunar valve
aortic artery
describe the pulmonary circuit
right ventricle
pulmonary artery
capillary beds of lung
pulmonary vein
left atria
describe the systematic circuit
left ventricle
aorta
capillary beds of body tissues
vena cava
right atrium
what is the function of the coronary circulation
to supply blood to the heart as the heart muscle is too thick to allow diffusion
where does the coronary circulation originate
oxygenated blood from the aorta
where does the coronary circulation terminate
right atrium as the blood will be deoxygenated and ready to go back to the lungs
what is meant by intrinsic conduction system
internal conduction system
basic rythym of intrinsic conduction system
100 beats per minute
how is heart rate modified by neural innervation
the SA and AV nodes are connected by parasympathetic and sympathetic nerves, they slow down and speed up the nerves
how is the heart rate modified by hormonal influences
adrenaline and thyroxine are released into the blood and circulate to stimulate the heart directly
what are the 3 major events of the cardiac cycle
atrial and ventricle diastole
atrial systole and ventricle diastole
atrial diastole and ventricular systole
define stroke volume
volume of blood ejected from the heart per beat
define cardiac output
volume of blood pumped out the heart per minute
define preload
degree of stretch on the ventricle walls by blood return
what effect does an increase in preload cause
actin and myosin are in a better position to form cross bridges generating greater force
what effect does generating more force through preload cause
increases stroke volume and therefore cardiac output
define afterload
degree of stretch on the ventricle walls caused by pressure within the blood vessels leaving the heart
what effect does an increase in afterload cause
sarcomeres can become overstretched which reduces the ability to form cross bridges
what effect does reducing the force cause
decreases stroke volume and therefore cardiac output
define contractility
force of contraction at a given length of muscle
what effect does calcium cause on contractility
exposes more actin binding sites allowing more cross bridge formation
what 2 things increase cardiac output
increase in preload
increase in contractility
what decreases cardiac output
increasing afterload
what does the p wave show
atrial systole
what does the QRS wave show
venricular systole and atrial diastole
what does the T wave show
ventricle diastole
