THE CIRCULATORY SYSTEMLesson 03

PRINCIPAL ORGANS

Heart Lungs Veins Arteries Blood Capillaries Blood

FUNCTIONS OF THE CIRCULATORY SYSTEM

Supply each body part with oxygenated blood

Remove the toxic carbon dioxide Transport medium for nutrients,

wastes, electrolytes, and hormones Maintain body temperature. Convert inactive materials into active

ones Carry immune substances that

contribute to the body’s defence.

FUNCTIONS OF CIRCULATORY SYSTEM

• Bulk Transport of materials such as nutrients, respiratory gases, waste materials etc.

• Communication channel for transporting chemical messengers such as hormones.

• Transporting protective molecules such as those involved in immune response

THREE DIVISIONS OF BLOOD CIRCULATION

Coronary Circulation (Circulation in the heart)

Pulmonary Circulation (Circulation in the lungs)

Systemic Circulation (Circulation in the whole body)

CORONARY AND PULMONARY CIRCULATION Blood circulates in the heart Right Atrium – Right Ventricle –

Pulmonary Artery – Lungs – Pulmonary Vein – Left Atrium – Left Ventricle

The lungs oxygnate the blood and remove the carbon dioxide

Coronary and pulmonary circulations go hand in hand

ESSENTIAL COMPONENTS OF A CIRCULATORY SYSTEM

• Fluid to be circulated: Blood and hemolymph in the present context. Blood consists of

plasma, cells, and dissolved solutes and macromolecules.

• A pump to generate propulsion of flow: Heart and contractions of skeletal muscles.

• A system of tubes or channels for circulation and distribution of materials and to maintain

pressure: Blood vessels, arteries, arterioles, capillaries, veins and venules.

Open and closed circulatory systems:

In open system, blood is pumped by heart to various parts of the body and then drains into sinuses or pools. From there, it percolates back into the heart (s).

In a closed system, heart pumps blood into tube-like vessels which go to every part of the body and returns to heart. It never leaves the vessels.

Vertebrates have closed system and may have single-, double- or triple-circuit circulation system.

Most fishes have single-circuit system but some have an accessory caudal heart in addition to the main one.

Frogs have triple-circuit system.

All mammals have double-circuit system.

Double-circuit Circulatory system in mammals

In mammals, oxygenated and deoxygenated blood is completely separated in the heart. However, congenital defects occur where there is a hole in the septum and oxygenated and deoxygenated blood mixes and gives rise to the phenomenon of “blue baby”. This defect can be corrected surgically.

HUMAN CIRCULATORY SYSTEM + HEART

CORONARY CIRCULATION

PULMONARY CIRCULATION

SYSTEMIC CIRCULATION

Carries the blood from the heart to the rest of the body.

Carried out by the blood vessels. Arteries transport the blood away from the heart to

the different body parts. Veins bring the blood back to the heart. Blood is filled with oxygen – left ventricle – aorta –

branches into smaller arteries –subdivide into arterioles – subdivided into systemic capillaries – oxygen is taken up by the body tissues –back to the heart by the veins – the vena cava (inferior for the lower body parts, superior for the upper ones) – right atrium

Result: coronary and pulmonary circulation can occur

SYSTEMIC CIRCULATION

VEINS AND ARTERIES

Usually, the venal blood is deoxygenated while the arterial blood is oxygen-rich.

Exception: pulmonary arteries leaving the right ventricle for the lungs carry deoxygenated blood, while the pulmonary veins carry oxygenated blood.

THE BLOOD Special connective tissue travelling through the

whole body It is made up of Blood plasma: extracellular fluid essentially

made up of proteins responsible for clotting, defence, and transport;

Red blood cells, or erythrocytes, are oxygen and carbon dioxide carriers;

White blood cells, or leukocytes, defend the body by destroying invaders;

Platelets, or thrombocytes, are parts of bone marrow and principally function in blood clotting.

THE BLOOD

You are required to know ANY 10 of the major veins and arteries listed on this picture for the exam! This exact picture will be on the test.