MASS TRANSPORT : HEART Flashcards
Atrioventricular valves
between atria and ventricles
- tricuspid = right
- bicuspid = left
semi lunar valves
between aorta and left ventricle
between pulmoary artery and right ventricle
myogenic
the muscles cam contract rhythmatically without any nervous stimulation
coronary arties
coronary arteries supplies oxygenated blood to the cardiac muscles.
how is a heart attack caused
if the coronary arteries does not supply oxygen to the cardiac muscles then the cells will not be able to respire and die resulting in heart attack.
valves in heart
tricuspid in right side
bicuspid or mitral valve
semi lunar valves - aortic and pulmonic.
systole and diastole
the period of contraction is called systole and the ;eriod of relaxation is called diastole.
one cardiac cycle
each heartbeat is known as one cardiac cycle.
3 main stages of cardiac cycle
atrial systole, ventricular systole and diastole.
diastole
it is when the muscles in atria and ventricles are relaxed. blood enters into the atria through venacava and pulmonary vein. the blood entering the atria increases the pressure in the atria.
- volume is increased a sthe blood flows into
atrial systole
muscular walls in atria contract which increases the pressure and decreases the volume. this causes the atrio ventricular valves to open and blood to flow into ventricles. the ventricular muscular walls are relaxed.
ventricular systole
it is when the ventricles muscles contract and the pressure is higher in ventricles than in the atria . so it causes the atrio ventricular valves to shut down and open the semi lunar va;lves and blood is pushed out to arteries ( pulmonary artery and aorta)
formula of cardiac output
heart rate * stroke volume.
- stroke volume = volume of blood that leaves heart in dm3
when does the valve open
when the pressure is higher behind the valves.
when does atrio ventricular valves open
atrioventricular valves open when the pressure is higher in atria than in the ventricles.#
it closes when the pressure is higher in ventricles than in the atria.
when does the semi lunar valves open
the semi lunar valves open when the pressure is higher in ventricles than in the atria.
san and avn
sino atrial node and atrio ventricular node
where is san and avn located
san is located ij the right atrium also known as pacemaker and avn is located between walls of atria and ventricles.
bundle of his and purkyne fibers
bundle of his runs through septum and purkyne fibres are in walls of ventricles.
mechanism for control of heart
the SAN releases the first wave of depolarisation which causes the atria to contract( atrial systole). the avn also releases a second wave of depolarisation after the first wave hits it. there is a muscular layer between atria and ventricles which prevents the conductivity of wave of depolarisation. however the bundle of his running through the septum can conduct the wave of depolarisation into purkyne fibres in the wall of vemtricles . the apex and walls of ventricles contract . there is a short delay when this happens so that the atria can contract fully and pump blood to the ventricles. the avn transmits second wave of depolarisation.
parasympathetic nervous system
the heart rate is controlled by the medulla oblongata in the brain via the autonomic nervous system which is of two parts paraysympathetic and sympathetic
symathetic ns
increases heart rate
parasympathetic ns
decreases heart rate.
stimulus - increased pressure
the pressure receptors present in the cartoid artery and aorta sare stretched and they send more electrical impulses to the medulla oblongata and the impulses is sent via parasympathetic nervous system to the SAN to decrease the frequemce of electrical impulses which then lowers the heart rate.
