heart anatomy and physiology Flashcards
what two systems is the heart innervated by?
- intrinsic conduction system
- extrinsic innervation
what is the purpose of the cardiovascular system?
to provide adequate blood flow to tissues/organs according to their needs
what type of cells are part of the intrinsic conduction system?
pacemaker cells
what are the five main parts of the intrinsic conduction system?
- sinoatrial node
- atrioventricular node
- atrioventricular bundle
- bundle branches
- purkinje fibres
what does the extrinsic innervation do?
ANS modifies the activity of the heart
what are the two cardiac centres of the extrinsic innervation in the medulla oblongata?
- cardioacceleratory centre
- cardioinhibitory centre
what does the cardioacceleratory centre do?
increases BOTH HR and force of contraction
is the cardioacceleratory centre parasympathetic or sympathetic?
sympathetic
what does the cardioinhibitory centre do?
decreases HR only
is the cardioinhibitory centre parasympathetic or sympathetic?
parasympathetic
what nodes does the cardioinhibitory centre innervate?
SA node
what nodes does the cardioacceleratory centre innervate?
SA and AV nodes
what are the ECG deflection?
- P wave
- QRS Complex
- T wave
what causes the P wave?
atrial depolarisation
where does the P wave begin?
SA node
where does ventricular depolarisation begin?
at apex
what wave does ventricular depolarisation cause?
ORS complex
what is masked by the QRS complex?
atrial repolarisation
where does ventricular repolarisation occur and what wave does it cause?
at apex, T wave
what is systole?
a period of contraction
what is diastole?
period of relaxation
what is the cardiac cycle?
one complete heartbeat
what are the three phases of the cardiac cycle?
- ventricular filling
- ventricular systole
- early diastole
are the AV valves open or closed in phase one ventricular filling?
open
are the SL valves open or closed in phase one ventricular filling?
closed
what happens during atrial systole?
both atria contract simultaneously completely filling relaxed ventricles with blood (EDV)
what happens in ventricular systole (isovolumetric)?
both ventricles contract, pushing blood upwards and increasing ventricular pressure
what does the upward movement of blood during ventricular systole (Isovolumetric contraction) do to the AV valves?
closes them
why is Phase 2a called isovolumetric contraction?
ventricular pressure is not great enough to open SL valves so there is no change in blood volume
what occurs during ventricular systole (ventricular ejection)?
increasing force of ventricular contraction above arterial pressure. blood ejected into aorta and pulmonary trunk
do the SL valves open or close in ventricular systole during ventricular ejection?
open
when do theAV vales close during ventricular systole- ventricular ejection?
as ventricular pressure is greater than arterial pressure
does ventricular diastole cause the SL valves to open or close?
close
what does heart sound 1 sound like?
lubb
what does heart sound 2 sound like?
dubb
what causes lubb heart sound?
closure of AV valves
what causes dubb heart sound?
closure of SL valves
what is a heart murmur?
swishing sounds as blood back flows through an incompetent valve
how does the P wave correlate electrical and mechanical events?
atrial depolarisation triggers atrial systole
how does the QRS complex correlate electrical and mechanical events?
ventricular depolarisation triggers ventricular systole
how does the T wave correlate electrical and mechanical events?
ventricular depolarisation results in ventricular diastole
what does EDV stand for?
end-diastolic volume
what does ESV stand for?
end-systolic volume
what is heart rate?
number of beats per min
what is stroke volume?
volume of blood ejected per beat (ml)
what is cardiac output?
volume of blood pumped into the systemic or pulmonary circuit per min (L/min)
what is the equation for SV?
SV= EDV - ESV
what is EDV?
the volume of blood in a ventricular at the end of relaxation period
what is ESV?
the volume of blood remaining in a ventricle after it has contracted
what is EDV determined by?
- venous return
- passive filling time
what is venous return?
amount of blood returning to the heart from the systemic or pulmonary circuits
what is passive filling time?
time both the atria and ventricle are in diastole
does passive filling time increase or decrease as HR increases?
decreases
what does venous return depend on?
- total blood volume
- patterns of blood flow determined by muscle/organ activity, sympathetic activity and body position
what does EDV determine?
preload
what is preload?
the degree the myocardium is stretched before it contracts
what does preload determine?
force of ventricular myocardial contraction therefore SV
what are factors affecting ESV?
-contractility
what is contractility?
amount of force produced by myocardial contraction
what is contractility increased by?
- sympathetic stimulation
- hormones
- high level of extracellular Ca2+
- exercise
what is contractility decreased by?
- acidosis
- increased extracellular K+
what is afterload?
the pressure that the ventricles must overcome to open SL valves to eject blood into arteries
what is the normal range of heartbeats per min?
60-100
what is the average rate of bpm?
75bpm (80bpm)
what is HR altered to do?
- meet needs of tissues/organs
- compensate for changes inSV
what does the cardiovascular centres in the medulla oblongata receive input from?
- proprioceptors
- chemoreceptors
- baroreceptors
does noradrenalin and adrenaline increase or decrease HR?
increases
does thyroxine (T4) increase or decrease HR?
increases
does increased body temp increase or decrease HR?
increases
does decreased body temp increase or decrease HR?
decreases
does increased extracellular NA+ or K+ increase or decrease HR?
decreases
does increased extracellular Ca2+ increase or decrease HR?
increases
whats the equation for cardiac output?
CO= SV x HR
what is heart rate determined by?
- ANS
- hormones
- plasma electrolytes
what are the three layers of the heart wall?
- epicardium
- myocardium
- endocardium
what are the three components that supply blood into the right atrium?
- superior and inferior vena cava
- coronary sinus
what are the names of the first valve that blood travels through as it enters right ventricle?
- right atrioventricular valve
- tricuspid valve
what is the name of the valve that blood moves through from the right ventricle into the pulmonary trunk?
pulmonary semilunar valve
what are the names of the valve that separates the left atrium and ventricle?
- left atrioventricular valve
- mitral valve or
- bicuspid valve
what valve separates the left ventricle and the aorta?
aortic semilunar valve