C2 - Heart Function Flashcards
What is the function of the sinoatrial (SA) node?
It acts as the heart’s internal pacemaker by electrically stimulating both atria to contract and relax simultaneously.
What is the role of the atrioventricular (AV) node?
It transmits the electric signal through the Bundle of His and Purkinje fibers.
What are Purkinje fibers?
Specialized fibers that distribute the electrical signal to the ventricles, causing them to contract.
What does an electrocardiogram (ECG) measure?
The electrical activity of the heart through voltage changes.
What are the two phases of the heartbeat?
Systole (contraction, pumping blood out) and diastole (relaxation, refilling of blood).
What are the key waves in an ECG and what do they represent?
• P wave: Atria contract, blood moves into ventricles
• Q wave: Signal is delayed at the AV node
• R wave: Signal reaches Bundle of His and Purkinje fibers; ventricles contract, atria relax
• S wave: Ventricular excitation is complete
• T wave: Ventricles relax, semilunar valves close
What is blood pressure?
The pressure exerted by blood on vessel walls.
What do systolic and diastolic pressures represent?
• Systolic: Maximum pressure during ventricular contraction
• Diastolic: Minimum pressure during ventricular relaxation
How is cardiac output calculated?
Heart rate × Stroke volume (measured in mL/min).
What is stroke volume?
The amount of blood (mL) ejected from the heart per beat.
What effect does cardiovascular exercise have on the heart?
Increases stroke volume, strengthens ventricle walls, and enlarges ventricular chambers.
What is vasodilation?
The widening of blood vessels to increase heat loss.
What is vasoconstriction?
The narrowing of blood vessels to decrease heat loss.
What is hypertension?
Abnormally high blood pressure, often caused by lifestyle factors.
What is hypotension?
Abnormally low blood pressure, often due to dehydration, stress, or pain.
What is arteriosclerosis?
The thickening and loss of elasticity in artery walls, leading to increased blood pressure.
What is atherosclerosis?
The buildup of plaque inside artery walls, which can lead to blockages and heart attacks.
How does an aneurysm form?
Weakening of arterial walls leads to an enlargement, which can rupture.
What is an angioplasty?
A surgical procedure that opens blocked arteries.
What is a triple coronary bypass?
A surgery that creates three new pathways for blood to bypass blockages in coronary arteries.
