Heart Structure

—> the heart is made up of cardiac muscle
—> it’s a striated muscle similar to skeletal muscle, but the fibres are narrower.
—> muscle cells joined together at intercalated discs
—> allow fast transmission of the nerve impulses that cause the heart to contract.

—> is myogenic - can contract in a regular rhythm that it determines itself
—> doesn’t fatigue like skeletal muscle
—> to contract, the cardiac muscle needs oxygen and Ca2+ ions
—> provided by the blood in the coronary arteries that run on the surface of the heart

Heart consists of 4 chambers :
—> Atria : smaller with thinner walls

• found at the top of the heart

—> Ventricles : larger with thicker walls

• found at the bottom

—> the right and left side of the heart don’t mix
—> the sides are separated by the septum

—> surrounded by a connective tissue called the pericardium
—> going in and out of the heart are 4 major blood vessels

—> is a vein

—> function : carry deoxygenated blood from the tissues of the head and body to the right atrium of the heart

—> is an artery

—> function : carries deoxygenated blood from the right ventricle of the heart to the lungs to become oxygenated

—> is a vein

—> function : carries oxygenated blood from the lungs to the left atrium of the heart

—> is an artery

—> function : carried oxygenated blood from the left ventricle to the tissues of the head and body

—> valves stop the blood flowing backwards, ensuring unidirectional flow
—> whether calves are open or closed depends on pressure in front of and behind the valves

Atrioventricular Valves : prevent back flow of blood from ventricles back into atria.
(left is called bicuspid/ mitral valve
right is called tricuspid valve)

Semi-lunar Valves : prevent back flow of blood from arteries back into ventricles