conduction system Flashcards
what kind of system in the heart
double pump
what is the path of the blood on the left side of the heart
Blood is oxygenated at the lungs and brought back to the heart via the pulmonary vein
Oxygenated blood moves from the left atrium through the left AV (bicuspid) valve into the left ventricle
From here it is forced out of the left side of the heart into the aorta
The aorta carries the oxygenated blood to the muscles and organs
what is the path of the blood on the right side
Deoxygenated blood from the muscles and organs enters the right atrium through the vena cava
It moves from the right atrium, through the right AV valve (tricuspid) into the right ventricle
Here it is forced out of the right side of the heart into the pulmonary artery
The pulmonary artery carries blood into the lungs, for re-oxygenation.
what is the cardiac cycle
The process of cardiac muscle contraction and blood moving through the chambers.
how long does one cardiac cycle take
It takes approx 0.8s.
how long does Diastole (relaxation and filling) Atria then Ventricles take
0.4s
how long does Atrial systole (contraction and emptying) take
0.1s
how long does Ventricular systole (contraction and emptying) take
0.3s
what is diastole
the phase of the cardiac cycle that sees the heart relax and fill with blood.
what does the pressure in the atria increasing cause
the AV valves to open
how does the blood get into the ventricle
passively
what happens after the blood is in
The SL valves then close to present blood leaving the heart
what are the 2 valves
Rising pressure is Atria against AV valves forces blood into ventricles passively
- right = tricuspid valve
- left = bicuspid valve
what is the Volume of blood after filling stage
END DIASTOLIC VOLUME (EDV)
what is systole
is when the atria contracts, forcing blood into the ventricles.
where does systole occur
Contraction of left and right atria
what happens in ventricular systole
The ventricles contract, increasing pressure closing the AV valves to prevent backflow into the atria
Contraction of left and right ventricles takes 0.3 secs
Increased blood pressure through ventricular contraction forces blood out of both ventricles (STROKE VOLUME)
Right ventricle forces blood through pulmonary valve into pulmonary artery (to lungs)
Left ventricle forces blood through aortic valve into aorta (to body)
what do the valves do after ventricular systole
Tri and bicuspid valves remain shut, and the aortic and pulmonary valves shut to prevent backflow
what does myogenic mean
this means it generates its own impulse.
once the impulses is generated what happens to it
The impulse is generated and passes through the muscular walls, causing them to contract
what is a cardiac impulse
The electrical impulse responsible for stimulating the heart
what Is the the Sino-atrial Node (SA node) and what’s its job
A mass of cardiac cells located in the right atrium wall, emits an impulse and fires it through the atria walls, causing an impulse. This creates heart rate (depolarization)
what happens to the impulse after its been created by the SA node
The impulse spreads to the adjacent interconnecting fibres of the left atrium
- This impulse then moves to the specialised cells called atria-ventricular nodes (AV nodes)
what happens after the impasse has reached the AV node
The AV Node acts as a distributor and passes the
action potential (impulse) to the Bundle of His
There is a delay of 0.1 secs from the AV node to BoH. This is called a relay signal
This is crucial, as it allows full atrial contraction
The impulse then moves DOWN the Bundle of His to the Apex of the heart
The impulse then spreads up the Purkinje Fibres (in the ventricle walls), causing excitation and ventricular systole (contraction)
