Cardiac Cycle & Conduction System Flashcards
Path of blood through the heart - left Side
Blood is oxygenated at the lungs and brought back to the heart via the pulmonary vein - oxygenated blood moves from the left atrium to the left AV (bicuspid) valve into the left ventricle - it is then forced out of the left side of the heart into the aorta - the aorta carries the oxygenated blood to the muscles and organs
Path of blood through the heart - Right Side
Deoxygenated blood from the muscles and organs enter right atrium through the vena cava - from right atrium to the right AV valve (tricuspid) into right ventricle - here it is forced out of the right side of the heart into the pulmonary artery - this carries blood into the lungs for re-oxygenation
State what is the cardiac cycle
A process of cardiac muscle contraction and blood moving through the chambers - one complete cardiac cycle represents one full heartbeat
How long does one cardiac cycle take ?
0.8 seconds (approx)
What are the cardiac cycle stages and how long do they take ?
Diastole - relaxing and filling (0.4 seconds)
Atrial systole - contraction and emptying (0.1 seconds)
Ventricular systole - contraction and emptying (0.3 seconds)
Diastole Phase
Relax and fill with blood
How does the diastole phase work ?
-Pressure in the atria increases causing the AV valves to open
-Blood passively enters the ventricles
-The SL valves then close to prevent blood leaving the heart
-oxygenated blood enters the left atrium from the pulmonary veins
Volume of blood after filling stage is called What ?
End diastolic volume (EDV)
Atrial Systole
When the atria contracts, forcing blood into the ventricles - contraction of left and right atria
Ventricular Systole
The ventricles contract, increasing pressure closing the AV valves prevent backflow into the atria - increased blood pressure through ventricular contraction forces blood out of both ventricles
In the ventricular systole phase where does the right ventricle force blood to ?
Through the pulmonary valve into the pulmonary artery - to the lungs
In the ventricular systole phase where does the left ventricle force blood to ?
Through the aortic valve into the aorta - to the body
What is the conduction system ?
Heart is myogenic - the impulse is generated and passes through the muscular walls = contracting
The electrical impulse is responsible for stimulating the heart is called the cardiac impulse
What does the heart is myogenic mean ?
It generates its own impulse
The electrical impulse is responsible for stimulating the heart is called what ?
Cardiac Impulse
Steps of the conduction system !
SA node emits an impulse and fires it through the atria walls, causing an impulse - this creates heart rate - the impulse spreads to the adjacent interconnecting fibres of the left atrium - the impulse moves to the specialised cells called the AV nodes (they act as a distributor and passes the AP impulse to the BOH - BOH happens then the impulse then moves down the BOH to the Apex of the heart - yeh impulse then spreads up the Purkinje fibres causing excitation and ventricular systole.
What does the SA node stand for ?
Sino-atrial node
Where is the SA node located ?
Right atria wall
What does the AV node stand for ?
Atria - ventricular node
What does BOH stand for
Bundle Of His
What is the bundle of his
Delay of 0.1 seconds from the AV node - relay signal which allows full atrial contraction
