Circulatory System – Notes
Cardiac cycle: The sequence of events that occurs in one complete beat of the heart.
Structure of the heart:
Superior vena cava – returns deoxygenated blood from the head and arms.
Right atrium – Pushes deoxygenated blood into the right ventricle.
Inferior vena cava – Returns deoxygenated blood from the legs, abdomen, liver and
kidneys.
Tricuspid atrioventricular valve – Prevents backflow of blood from the right ventricle
into the right atrium during ventricular systole.
Chordae tendineae – Prevents the atrioventricular valves from inverting (turning
inside out) during ventricular systole.
, Right ventricle – Pushes deoxygenated blood into the pulmonary artery towards the
lungs.
Left ventricle – Pushes oxygenated blood into the aorta towards all body tissue
(except lung tissue).
Papillary muscle – Contract to pull the chordae tendineae and open the
atrioventricular valves during atrial systole.
Semilunar valve – Prevents backflow of blood from an artery into the ventricle during
ventricular diastole.
Bicuspid atrioventricular valve – Prevents backflow of blood from the left ventricle
into the left atrium during ventricular systole.
Left atrium – Receives oxygenated blood from the lungs and pushes this blood into
the left ventricle.
Pulmonary vein – Carries oxygenated blood from the lungs to the left atrium.
Aorta – Carries oxygenated blood from the left ventricle to the body tissues (except
the lungs).
Pulmonary artery – Carries deoxygenated blood from the right ventricle to the lungs.
There are 2 phases of the cardiac cycle:
1. Pumping phase – Heart muscle contracts – called systole.
2. Filling phase – Heart muscle relaxes – called diastole.
For a short time, both atria and ventricles are in diastole – the atria fill with blood
and the ventricles also receive blood as the valves between them are open.
The atrioventricular valves regulate the blood flow between the atria and the
ventricles.
In the cardiac cycle, you always start off with diastole. When both the atria and the
ventricles are in diastole, blood flows in from the vena cava into the right atrium and
from the pulmonary veins into the left atrium.
Cardiac cycle: The sequence of events that occurs in one complete beat of the heart.
Structure of the heart:
Superior vena cava – returns deoxygenated blood from the head and arms.
Right atrium – Pushes deoxygenated blood into the right ventricle.
Inferior vena cava – Returns deoxygenated blood from the legs, abdomen, liver and
kidneys.
Tricuspid atrioventricular valve – Prevents backflow of blood from the right ventricle
into the right atrium during ventricular systole.
Chordae tendineae – Prevents the atrioventricular valves from inverting (turning
inside out) during ventricular systole.
, Right ventricle – Pushes deoxygenated blood into the pulmonary artery towards the
lungs.
Left ventricle – Pushes oxygenated blood into the aorta towards all body tissue
(except lung tissue).
Papillary muscle – Contract to pull the chordae tendineae and open the
atrioventricular valves during atrial systole.
Semilunar valve – Prevents backflow of blood from an artery into the ventricle during
ventricular diastole.
Bicuspid atrioventricular valve – Prevents backflow of blood from the left ventricle
into the left atrium during ventricular systole.
Left atrium – Receives oxygenated blood from the lungs and pushes this blood into
the left ventricle.
Pulmonary vein – Carries oxygenated blood from the lungs to the left atrium.
Aorta – Carries oxygenated blood from the left ventricle to the body tissues (except
the lungs).
Pulmonary artery – Carries deoxygenated blood from the right ventricle to the lungs.
There are 2 phases of the cardiac cycle:
1. Pumping phase – Heart muscle contracts – called systole.
2. Filling phase – Heart muscle relaxes – called diastole.
For a short time, both atria and ventricles are in diastole – the atria fill with blood
and the ventricles also receive blood as the valves between them are open.
The atrioventricular valves regulate the blood flow between the atria and the
ventricles.
In the cardiac cycle, you always start off with diastole. When both the atria and the
ventricles are in diastole, blood flows in from the vena cava into the right atrium and
from the pulmonary veins into the left atrium.
