the heart as a pump Flashcards
how can blood vessels regulate the amount of blood reaching each tissue
they are able to constrict and dilate changing the amount of blood reaching each tissue
explain the route blood takes around the body
deoxy enter right atria then right ventricle. pumped to lungs via pulmonary artery and then pumped back to left side of the heart via the pulmonary vein. pumped around body via aorta. systematic pressure= much higher than pulmonary pressure
what is systole
contraction and injection of blood from the ventricles
what is diastole
relaxation and filling of ventricles
how many tires of blood in the average man
5 L
what is stroke volume per beta of an average man
70ml
features of heart muscle
1 nuclei per cardiomyocyte, connected by intercalated discs which allows them to communicate for synchronised contraction. have longer length of contraction and use ca2+ for action potential. triggered by wave of excitation
valves found on the right side of the heart and their function
tricuspid and pulmonary valve - prevent back flow
valves found on the left side of the heart and their function
mitral (2 flaps instead of 3) and aortic valve - prevent blood back flow
what prevents the inversion of valves in the heart
papillary muscles attached to chordae teninae
explain the wave of excitation in the heart
starts at SAN, when reaches AVN a delay is imposed to allow the atria to finish contracting. it is then sent via the bundle of HIS to the apex of the heart where it flows up the side of the ventricles via the purkinje fibres allowing effective release of blood.
explain the wiggers diagram
it is a groan which shows the changing pressure in the aorta atria, ventricles and the volume in the ventricles. usually plotted just for the left side of the heart however right would be similar just at lower pressure because act in synchrony
stages of the wiggers diagram
1- atria contraction 2- isovolumetric contraction 3- rapid ejection 4- reduced ejection 5- isovoumteric relaxation 6- rapid filling 7- reduced filling
what happens during atria contraction
partial pressure rises because of atrial systole, this is called the A wave. ventricles finish filling
what is isovolumetric contraction
mitral valve closes causing a rapid increase in pressure in ventricles but there is no increase in the volume. atrial pressure shows C wave from small increase in pressure from mitral valve closing
what happens during rapid ejection
aortic valve opens when ventricle pressure exceeds that in the aorta. volume in the ventricles decreases although the pressure stays the sam as they are contracting. slight decrease in pressure in the atria due to atrial base being pulled down by ventricle contraction. this is called the x descent
what happens during reduced ejection
ventricle is depolarised meaning less ejection. atrial pressure starts increasing due to continued venous return - v wave
what happens during isovolmetric relaxation
ventricle pressure falls and there is back flow causing aortic valve to shut. volume is same however pressure has decreased a lot in ventricles
what happens during rapid filling
mitral valves opens causing drop in pressure in the atria (Y descent) and once valve is open the ventricle volume increases
what happens during reduced filling
rate of filling reduced as ventricles reach their relaxed volume
explain what is happening during the P wave in an ECG
onset of atrial depolarisation to allow atrial contraction. - heart is filling with blood- disatole
explain the QRS wave
ventricular depolarisation. start of systole as mitral valve has shut and contraction of the ventricles begings
explain the T wave
depolarisation- diastole begins and ventricles are relaxed and emptying
where is abnormal valve function usually found
on the left side due to much higher pressure here
what happens during aortic valve stenosis
its caused by congenial effects (bicuspid instead of tricuspid), degenerative effects or by rheumatic fever. it means that less blood gets through the valve increasing the pressure in the ventricles and therefore hypertrophy to pump blood harder and heart failure leading to syncope(fainting) and angina(not enough blood for coronary arteries meaning less energy for heart)
what happens during mitral valve stenosis
mainly caused by rheumatic fever and blood flows from atria to ventricles with much more difficulty leading to higher pressure in atria. causes atrial dilation which can cause fibrillation and thrombosis formation aswelll as oesophagus compression causing dysphagia. can also cause pulmonary oedema leading to left ventricle oedema due to blood build up in lungs which can cause right ventricle hypertrophy.
what happens during aortic valve regurgitation
caused by root dilation (look up if need to know) or valve damage by rheumatic fever. it means blood can flow back into ventricles meaning stroke volume and systolic pressure increase and diastolic pressure decrease. have greater PP = heading bobby and left ventricle hypertrophy to try and pump it out
explain mitral valve regurgitation
caused by degeneration/ weakness of the papillary muscles after a heart attack, rheumatic fever or left heart failure which can cause valve to stretch. it means there is more blood in the atria due to back flow meaning hypertrophy to maintain cardiac output.
