Cardiovascular System Flashcards
Define ‘systole’
Contraction of the heart
Define ‘diastole’
Relaxation of the heart
What is the pericardial sac?
The heart sits in the pericardial sac - the layer of tissue that protects the heart and allows it to move
How many steps are in the cardiac cycle?
6
State the Cardiac Cycle
Deoxygenated blood enters to right side of the heart through superior interior vena cava
Right Atrium contracts, blood flows from RA to RV, valves shuts to prevent back flow
Ventricle contracts, blood leaves through the pulmonary artery to lungs where it is oxygenated
Oxygenated blood return to the heart through pulmonary veins into left atrium
Left Atrium contract and blood goes to the left ventricle
Blood leaves through the aorta to the body
Define arteries
They carry blood away from the heart. Thick muscular walls to deal with higher blood pressure to pump blood to the body, with thin lumen (passageway)
Define veins
Carry blood to the heart. Thin walls, thick lumen (passageways), valves to prevent back flow of blood
How do you calculate Cardiac Output?
Stroke Volume x Heart Rate
What is stroke volume?
Amount of blood (mls) per beat
How is heart rate measured?
Beats per minute
What is Cardiac Output?
Amount of blood from the heart in 1 minute
What is the Conduction System?
A group of specialised cardiac muscles in the walls of the heart that send signal to the heart muscle causing it to contract
Name the 3 main components of the Conduction System?
- Sinoatrial node (SA Node)
- Atrioventricular Node (AV Node)
- Bundle of His
What’s the role of the Sinoatrial (SA) Node?
The main pacemaker of the heart situated near the vena cava
What’s the role of the Atrioventricular (AV) Node?
Serves as an electrical gateway to the ventricles and delays the electric impulses to the ventricles
Why does the AV Node delay electric impulses to the ventricles?
To ensure the atrium has projected all the blood into the ventricle before the ventricle contracts
How does the AV Node know when the delay of electric impulses is necessary?
AV Node receives signals from the SA Node to pass them onto the AV Bundle (of His)
What’s the role of Bundle of His?
It’s divided into left and right bundle branches which conduct impulses toward the apex of heart. The signals are then passed to the purkinje fibres, travelling upwards and spreading throughout the ventricle myocardium
What is an ECG?
Electrocardiogram. An ECG is a recording of all the action produced by the nodes and cells of the myocardium. Each wave of the ECG is a response to the cardiac electrical cycle.