Human Body Presentation

THE CIRCULATORY SYSTEM

FABIANA CECCUCCI 4^CL

the structure

The human circulatory system (or cardiovascular system) consists of the heart, blood vessels and blood.

the heart

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pulmonary and systemic circulation

the systemic circulation

blood is transportated from the heart to the rest of the body.

the pulmonary circlulation

blood is transported to the lungs, where it is oxygenated, and then back to the heart.

THE CARDIAC CYCLE

The cardiac cycle refers to all of the events that occur from the beginning of one heartbeat to the beginning of the next

During a cardiac cycle, two phases alternate: -a relaxation phase (diastole); -a contraction phase (systole).

The heartbeat is controlled by electrical activity generated by the heart itself in the senatorial node (a natural pacemaker).

BLOOD

Blood contains cells that are suspended in plasma:

Red cells specialize in the transport of respiratory gases

White cells are dedicated to the defense of the organism and are the main component of the immune system.

Platelets are not real cells, but cell fragments. They allow blood clotting and repair damaged vessels.

blood vessels

Blood vessels include arteries, veins and capillaries – each have different structures and functions.

Veins transport blood back to the heart. They have thinner and less elastic walls.

Capillaries have very thin walls which allow the exchange of gases and nutrients. Capillaries control the blood flow to organs.

Arteries transport blood from the heart to the lungs and the rest of the body.

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left atrium

right atrium

The heart is a muscle organ, divided into two atria and two ventricles.

left ventricle

right ventricle

the walls of the heart