The Structure and Function of the Heart Flashcards
What is the Cardiac Ouput?
The volume of blood pumped out of each ventricle per minute
What is the formula for working out the cardiac output through stroke volume and heart rate?
CO=HRxSV
What does systole and diastole mean?
Systole - Contraction
Diastole - Relaxation
What causes the action of Atrio-Ventricular (AV) valves and Semi Lunar valves?
Pressure changes
What is responsible for making the heartbeat sound when listening to it through a stethoscope?
The opening and closing of the AV and SL valves
Where does the heartbeat originate?
Within itself
What sets the rate of the Cardiac Contraction and where is the location of it?
Sino-atrial Node (SAN) or Pacemaker by Autorhythmic cells and is located in the wall of the right atrium
What does the SAN do in relation to the Cardiac Conducting system?
It spreads electrical impulses across atria to AVN causing Atrial Systole
Where is the Atrio-ventricular Node (AVN) located and what does it do?
It is found at the base of the Atria and it sends impulses down the conducting fibres between ventricles and up across ventricles caused by ventricular systole
What do the electrical impulses do?
They generate currents in the heart which can be detected by an Electrocardiogram (ECG) - PQRST wave
What does the Medulla do?
This regulates rate of SAN through antagonistic action of the autonomic nervous system
What does the Sympathetic Accelerator Nerves do?
They realise nor-adrenaline to increase HR and slowing Parasympathetic nerves release Acetylcholine to decrease HR
What does blood pressure do during Ventricular Systole and Diastole?
Ventricular Systole - Increases
Ventricular Diastole - Decreases
Blood pressure is measured using what?
Sphygmomanometer
How does a Sphygmomanometer measure blood pressure?
An inflatable cuff stops blood flow in the artery and deflates gradually. After that bloods starts to flow again (this is detected as a pulse) - Systolic Pressure. Then the blood starts to flow freely (no pulse detected) - Diastolic Pressure. A typical reading is 120/80mmHg
