One primary function of the blood is to

transport oxygen to lungs, and any other respiratory organsto the body cells.

BLOOD COMPONENTSThe components of the blood consist

of:

Red Blood Cells (erythrocytes). Which carries oxygen throughout our entire body.

White Blood Cells (leucocytes). Which fight harmful bacteria.

Platelets (thrombocytes). Which is for clotting and sealing wounds.

Under the microscope, RBC appear as a tiny round or slightly oval disc-shape which are thinned out in the center. They are elastic:

therefore they can be squeezed out of shape but they can easily go back to their normal form.

Red Blood Cells

RBC are formed in bone marrow. They have a life span of about 120

days. The process of RBC distraction is called hemolysis.

RBC circulates throughout our entire body feeding supplying and even defending the cells or tissues that

make up our body.

RBC contains more than 200 million molecules of hemoglobin, a protein

pigment and efficient oxygen carrier. A hemoglobin carrying a full load of oxygen is called oxyhemoglobin.

A young RBC has a nucleus like any other cell. As it matures, its nucleus disappears. Although mature RBC do not contain a nucleus, they are still considered as living cells, because

they contains enzymes that enable to metabolized glucose.

RBC is not red in reality, it is a clear pale yellow liquid almost like water.

White Blood CellsWBC help to protect the body from

diseases.It serve to protect the body against

infection, for example when a boil develops on the neck the granulocytes move swiftly into the area collecting around the bacteria

and destroying them.They are much larger than RBC, but they

are far fewer in number(approximately 1:600)

About 2/3 of white blood cells are phagocytes which defend the body by eating up invading

germs that may have inter the body, while other WBC called lymphocytes, knock outs the germs by producing a disease-fighting chemicals called

antibodies. There are two types of phagocytes the neutrophil and the monocyte.

PlateletsHelp to stop the cuts from bleeding and quickly form a clot that plugs the wound which then becomes a scab and seals up the injury and damaged vessels.

Platelets have a very active metabolism, they are also important in blood clotting. When a blood vessel is cut they adhere to the rough surfaces and release substances that help from blood clot.

Platelets is the smallest blood cell and named for their plate like shape, and like red cells they have no nucleus , however, they contain a few granules which are collected mostly on the central part of the cell.They have a life span of about 9 days.

BLOOD VESSELS

There are three main parts of Blood Vessel:

Arteries

Veins

Capillaries

Arteries

•carry blood away from the heart and it

has a thick muscular walls to cope with high

pressure

Arteries are found deeper within our body. They have the same elastic, thick layers of wall that make them resistant to injury. However if an

artery is cut, blood is pumped out through the opening every time the heart beats. If not

stopped out through the opening every time the heart beats, if not stopped immediately, a person

may bleed to death in a few minutes.

Arteries become smaller and form the arterioles. As these arterioles become smaller and penetrate

our body tissues, the narrow down further become capillaries.

Veins

•carry blood back to the heart and it has a thinner muscular

walls and contains one valve to direct the blood back to the

heart.

Veins carry non-oxygenated blood to the heart.

Blood move slower in veins because our blood is under very low pressure.

Valves in the veins allow the blood to flow in one direction towards the

heart, if the blood starts to go backward, the valve closes.

They are so thin that a hair strand is even wider than ten of them is placed side by side. That is why only a single RBC can pass through the capillaries.

The word capillary is derived from Latin word capillus means “hair”.

Capillariesthey are tiny blood vessels that connect arteries with veins.

Blood circulates in the system that blood is pumped around the body by the heart. When the heart squeezes

blood is pushed out under high pressure into the arteries.

As the blood circulates around the body it gradually losses its pressure and flow more slowly through the

veins.

Blood Circulations

Questions:

1. Where does the Red Blood cells are formed?

2. It is a blood cell that protects our body from diseases.

3. It is known as the smallest blood cell.

4. What do you call to a blood vessel that carry blood away from the heart?

5. It is a tiny blood vessel that connects artery with veins