Heart

• The Heart is a powerful muscular organ that can pump about 10,00 liters of blood daily.
• The heart works by contracting 70 to 72 times per minute daily.
• The heart is a four-chambered muscular structure.
• The upper thin-walled collecting chambers are the right and left atria.
• The right atrium collects deoxygenated blood from the body.
• The left atrium receives oxygenated blood from the lungs.
• The lower thick-walled pumping chambers are the ventricles.
• The right ventricle pumps oxygenated blood out of the heart and to the lungs for oxygenation.
• The left ventricle pumps oxygenated blood out of the heart to all parts of the body.
• The heart has valves that act as doors.
• An atrioventricular valve separates each atrium from the ventricle.
• A semilunar valve separates each ventricle from its artery.
• The tightening of heart muscles forces blood through the blood vessels. This produces the heart beat or cardiac cycle.
• The left and right sides of the heart are separated by a muscular wall called septum.
• The cardiac cycle consists of two parts: Systole (contraction of the heart muscle) and diastolic (relaxation of the heart muscle).
• The instrument used in measuring blood pressure is a sphygmomanometer.
• The highest pressure when the heart pumps blood into the arteries is called systolic pressure.
• The diastolic pressure is the lowest pressure when the heart is relaxed.
• The pulse is a wave of contraction transmitted along the arteries.
• Valves in the heart open and close during the cardiac cycle.
• Normal cardiac cycles (at rest) take 0.8 second.
• The blood flows throughout three kinds of blood vessels: arteries, capillaries, and veins.