8.5 Flashcards
what is the heart made up of?
cardiac muscle
what provides the cardiac muscles with oxygen?
coronary arteries
what are the four chambers of the heart?
left atrium
left ventricle
right atrium
right ventricle
what are the semi-lunar valves?
valves found at the pulmonary artery and aorta which prevent blood from re-entering the ventricles
what are the atrioventricular valves?
valves found between the atrium and ventricles which prevents backflow of blood into the atrium
what is the septum?
inner dividing wall which prevents oxygenated and deoxygenated blood from mixing
why is the left side of the heart have a thicker muscular wall?
in order to sufficiently pump blood through the aorta at a high pressure to the rest of the body
what is diastole?
relaxing of the muscles
what is systole?
contracting of the muscles
what causes the lub sound?
closing of the atrioventricular valves
what causes dub sound?
closing of the semi-lunar valves
why is the cardiac muscle myogenic?
it has it’s own heart rythm
how is the heart stimulated?
the SAN send a wave of excitation to the atrial muscles causing atrial systole
this wave is picked up by the AVN which delays the wave before sending it down the bundle of His towards the apex
at the apex the wave is passed to the ventricular muscles which contract causing ventricular systole
what does the delay at the AVN ensure?
that the atria have stopped contracting before the ventricles start
what measures electrical excitation?
an electrocardiogram
ECG
what is the PQRST wave?
P wave
atrial systole
QRS wave
ventricular systole
T wave
ventricular diastole
what is tachycardia?
when the heartbeat is too rapid
what is bradychardia?
when the heartbeat is too slow
what is ectopic heartbeat?
extra heartbeats which are out of rhythm
what is atrial fibrillation?
abnormal rhythm of the heartbeat which results in short systole and blood not being pumped properly
the p wave is messed up
what is the order of events in one pump of the heart?
atrial systole
atrial diastole
ventricular systole
ventricular diastole
when do AV valves open?
when the pressure in atria is greater than ventricles
hen do AV valves close?
when the pressure in the ventricles is greater than the atria
when do the semi-lunar valves open?
when the pressure in the ventricles is greater than pressure in the aorta
when do the semi-lunar valves close?
when the pressure in the aorta is greater than pressure in the ventricles
atrial systole
walls of atria contract and force blood into the ventricles
the atrio-ventricular valves are opened
ventricular pressure begins to rise
ventricular systole
when ventricular pressure exceeds atrial pressure the atrio-ventricular valves close
semi-lunar valves open when ventricular pressure exceeds aortic pressure
ventricular muscles contract, forcing blood to be pushed into aorta
what is the cardiac output?
volume of blood pumped through the heart per minute
cardiac output equation
heart rate x stroke volume
what is the heart rate?
beats per minute
bpm
what is the stroke volume?
volume of blood pumped in each heartbeat
cm3
