Circulatory System

Topics: Heart, Blood, Artery Pages: 4 (925 words) Published: August 18, 2014
Circulatory System

Composition of Blood

Red Cells
-These are tiny, disc-like cells which do not have nuclei.
-In their cytoplasm is the haemoglobin, a protein combined with iron. Haemoglobin combines with oxygen in places where there is a high concentration of oxygen, to form oxyhaemoglobin. -Oxyhagemoglobin is unstable compound. It breaks down and releases its oxygen in places where oxygen contentration is low.

White Cells
-They undergo a process of matruation and development in the thymus gland, lymph nodes or spleen. The two most numerous types of white cells are phagocytes and lymphocytes. Both of them take part in the protection of the body.

Platelets
-These are pieces of special blood cells budded off in the red bone marrow. They help to clot the blood at wounds and so stop the bleeding.

Plasma
-The liquid part of the blood is called plasma. It is water with a large number of substances dissolved in it. The ions of sodium, potassium, calcium, chloride and hydrogen carbonate are present. Proteins such as fibrinogen, albumin and globulins constitute and important part of the plasma. -The plasma will also contain varying amounts of food substances such as amino acids, glucose and lipids. There may also be hormones present, depending on the activities taking place in the body.

The heart

-Pumps blood through the circulatory system all around the body.

Atria (singular = atrium)

-Thin-walled chambers. Each of these open into a thick-walled chamber (ventricle).

Pulmonary Vein

-Large vein that brings oxygenated blood from the lungs into the left atrium.

Vena Cava

-Brings deoxygenated blood from the body tissues into the right atrium.

Aorta

-Artery that carries oxygenated blood to the body from the left ventricle Pulmonary Artery

-Carries deoxygenated blood from the right ventricle to the lungs

Semi-lunar Valves

-In the pulmonary artery and aorta. Each consist on three “pockets” which are pushed flat...
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