KA.6 Structure & function of heart Flashcards
What is the pathway of blood
*blood from body
* Vena cava
* Right atrium
* Right ventricle
*Lungs
* Pulmonary vein
* Left atrium
* Left ventricle
* Aorta
* Blood to body
What is Atrio-ventricular valves
Prevents backflow of blood from ventricles into atria
What is semi-lunar valves
Prevents backflow of blood at the entrance of arteries leaving the heart (pulmonary artery, aorta) back down into ventricles
when happens when the SL valves open during Systole
allows blood into arteries and close when arterial pressure exceeds ventricular pressure, muscle relaxes (diastole)
what is heart rate
Number of heartbeats per minute
what is stroke volume
Volume of blood expelled by ventricles on contraction
What is cardiac output
Volume of blood pumped out of ventricle per minute
How is cardiac output calculated
Heart rate X Stroke volume
What is Cardiac cycle
Pattern of contraction (systole) (diastole) by heart during one heartbeat
What are the 3 stages of the Cardiac cycle
- Atrial and ventricular diastole (chambers relaxed and filling with blood)
- Atrial systole ( Atria contracts, remaining blood is pushed into ventricles)
- Ventricular systole ( ventricles contract, push out blood through aorta and pulmonary artery)
How long can cardiac cycle last
0.8 seconds, based on heart rate on 75 beats per minute
What is responsible for heart sounds
opening and closing of AV and SL valves, can be heard with a stethoscope
What is Sino-atrial node
contains auto-rhythmic cells
located in wall of right atrium and sets the rate at which cardiac muscle cell contract
what is a Cardiac conducting system (1)
The timing of cardiac cells contracting is controlled by impulses from Sino-atrial node (SAN) spreading through atria causing atrial systole
What is a cardiac conducting system (2)
then travel to Atrioventricular node (AVN) located in centre of heart