The Heart Flashcards
What is the cardiac muscle called?
Myocardium
How does the cardiac muscle of atria compare to that of the ventricles?
Ventricles of the heart have thicker muscular walls than the atria. Blood is pumped out the heart at greater pressure from these chambers compared to the atria
How does the cardiac muscle of the left and right ventricle compare?
Right - thinner - only pumps blood to the lungs
Left - thicker - pumps blood all around the body
What the function of heart valves?
To prevent the back flow of blood.
What is the function of the tensions cords?
To keep valves stable
What is the pericardium and what does it do?
It’s a double wall membrane enclosing the heart for protection.
It acts a friction barrier on the outside
What is the cardiac cycle
The sequence of events that occurs when the heart beats.
The heart is myogenic. What does mean?
It’s means the heart generates its own electrical impulse. It generates its own beating system.
What are the 3 stages of the cardiac cycle called?
The atria systole, Ventricular systole and the Diastole.
What is the atria systole?
The contraction of the atria pushing blood into the ventricles.
As the atria fills, pressure increases.
Atrioventricular valves open and blood flows into the ventricles.
Atria contracts, forcing blood into ventricles.
Ventricles are relaxed.
What is the ventricular systole?
= contraction of the ventricles pushing blood into the arteries
• ventricles contract from base of heart upwards
• pressure in ventricles increases closing the atrioventricular valves
(‘lub’ sound)
•Semi - lunar valves open and blood is pushed up and out into the arteries.
(• atria are relaxed)
What is the diastole?
= relaxation of atria and ventricles
- atria and ventricles relax lowering pressure in heart chambers
- higher pressure in arteries compared to ventricles pushes blood back, closing semi-lunar valves (‘ duh ‘ sound)
- blood from veins is drawn into low pressure atria starting the refill of the atria
(• coronary arteries fill)
What is an electrocardiogram?
A recording of the electrical activity of the heart over time.
What is the sino-atrial node (SAN) ?
= pace maker
•generates electrical impulse to trigger atrial systole
What is the Atrio-ventricular node (AVN) ?
• electrical impulse from SAN reaches AVN
(delayed to ensure atria are fully contracted and ventricles filled)
° AVN transmits impulse along bundle of His to purkyne fibre initiating ventricular systole from bottom of heart upwards
