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The systematic circulation provides oxygen, nutrients and other substances to the tissues and

take C02 and other harmful substances away for removal.

Pulmonary Circulation

The flow of deoxygenated blood from the right ventricle to the lungs and the return of

oxygenated blood from the lung to the left atrium is called pulmonary circulation.

Two pulmonary veins from each lung transport the oxygenated blood to the left atrium.

Double circulation prevents the mixing of oxygenated and deoxygenated blood.

Regulation of Cardiac Activity

• Normal activities of heart are regulated by nodal tissue (SA and AV node), so the heart

is myogenic.

• A special neural centre in medulla oblongata moderates the cardiac function by ANS.

Sympathetic nerve can increase the rate of heart beat and parasympathetic nerve of

ANS decrease the rate of heart beat.

• Adrenal medullary hormone also increases the cardiac output.

Disorder of Circulatory System

1. Hypertension (high blood pressure) - Blood pressure higher than (120/80) . 120 mm Hg is

the systolic that is pumping pressure and 80 mm Hg is the diastole, resting pressure. It
leads to heart disease and affect vital organs like brain and kidney.

2. Coronary Artery Disease (CAD)- commonly called atherosclerosis that affects the blood

vessels that supply blood to heart muscles due to deposition of fat, calcium, cholesterol
that makes the arteries lumen narrower.

3. Angina- also called angina pectoris, acute chest pain due to less supply of oxygen to heart

muscles. It may occur in elderly male and female. It occurs due to restricted blood flow.

4. Heart failure- heart does not pump enough blood to meet the requirement of body. It is

also known as congestive heart failure because congestion of lung is one of its causes.
Heart failure is different from heart attack ( heart muscle is damaged by inadequate

blood supply) and cardiac arrest ( when heart stops beating).
5. Coronary Thrombosis- formation of clot in the coronary artery is coronary thrombosis.

It occurs most frequently in the left anterior descending coronary artery.

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