B2 - Blood

Blood = liquid tissue

The function is to transport dissolved substances, i.e hormones, around the body. It supplies all organs and tissues. 

There is a network of arteries, veins and capillaries keep the blood circulating.

It is made of four components.

1. Plasma

2. Red blood cells

3. White blood cells

4. Platelets

Each of the four has a specific job.

Plasma and red blood cells are involved in the transport and white blood cells and platelets are a part of the immune system.

Plasma

55% of the blood. Straw coloured.

It is the liquid part and carries the blood cells through the blood vessels and has dissolved substances such as hormones, nutrients (water, glucose, amino acids, vitamins and minerals), and waste stubstances (urea and carbon dioxide).

White blood cells

• Are larger than red blood cells
• Have a nucleus
• Some WBCs surround and destroy pathogens
• Some WBCs produce antibodies that destroy pathogens

Platelets

= fragments of larger cells

No nucleus

Their job is to cause blood clotting when a blood vessel has been damaged - the clot blocks the wound and prevents pathogens getting into the blood

Red Blood Cells

45% of the blood.

The bioconcave shape allows oxygen to be able to diffuse in and out of the cell easier because there is a larger surface area.

The RBC has no nucleus, meaning that there is more room on the cell for the haemoglobin to carry more oxygen

Haemoglobin = a red protein that is found in red blood cells. It binds to oxgen and transports it around the body, allowing it to be taken to the circulatory system.