cardiovascular system: cardiac structure and function- week 5 Flashcards
how does the heart get its blood supply ?
the coronary arteries
what is myocardial infarction?
blockage in the coronary blood flow which causes cell damage
exercise training protects against heart damage during MI
what is the epicardium ? (3)
the outer layer of the heart
function:lubricative outer covering
membrane containing capillaries and nerve fibres
what is the myocardium? (3)
middle layer of the heart
function: provides muscular contractions ejecting blood from chambers
connective tissues with capillaries and nerve fibres
what is the endocardium ? (3)
inner layer of the heart
function: protective lining of chambers and valves
thick subendothelial layer of elastic and collagenous fibres
how does branching of muscle fibres in the heart benefit it ?
allows simultaneous contraction
what is the SA node?(3)
sinoatrial node
pacemaker
imitates depolarisation - generates AP
what is the AV node? (3)
atrioventricular node
passes depolarisation to ventricles
causes brief delay of Ap to allow ventricle filling
what are bundle fibres ?
connect atria to left and right ventricle
what are purkinje fibres ?
spread depolarisation through ventricles
what is meant by automaticity ?
heart can generate its own AP
what is an ECG and what does it do?
electrocardiogram
records heart electrical activity
what is the P wave in an ECG?
shows atrial depolarisation
what is the QRS complex in an ECG?
shows ventricular depolarisation and atrial repolarisation
what is the T wave in an ECG?
shows ventricular repolarisation
what is meant by EDV?
end diastolic volume
max volume of blood in the ventricle
what is systolic volume ?
blood left in the heart post contraction
what is stroke volume ?
amount of blood ejected from the left ventricle per beat
what is atherosclerosis ?(3)
can be found through ECG
plaque narrows coronary arteries
reduces blood flow to myocardium
how is regular exercise cardioprotective ?
more pathways for coronary arteries which can increase O2 supply to myocardium
increased survival from heart attack
how does exercise reduce the amount of myocardial damage from heart attack ?
improves heart antioxidant capacity - fights free radicals
improved function of ATP sensitive potassium channels
how does the parasympathetic nervous system affect HR?
release of acetylcholine
- increasing K+ , decreasing AP + HR
slows HR by inhibiting the SA and Av node
how does the sympathetic NS affect HR?
release of norepinephrine
- increases Ca+ and increases HR
increases hR by stimulating the SA and AV node
what do exercise stress tests examine ?
can detect restricted coronary flow due to coronary artery disease
if they get blocked there’s no coming back due to no blood supply to the heart
what is meant by chronotropic ?
HR increases
what is meant by inotropic ?
contractility increases
what is the main metabolic vasodilator? (by product. of atp)
adenosine
by product of ATP
where/when does more coronary flow take place?
diastole 80%
