B9.4 Blood

What are the components of blood?

• Plasma

• Platelet cells

• Red blood cells

• White blood cells

What is the function of plasma?

• Watery fluid that transports blood cells, ions, soluble nutrients, hormones and carbon dioxide in the blood

What is the function of the platelets?

• Fragments of cells that are involved in clotting, for example if the skin is damaged and bleeding begins

What is the function of red blood cells?

• Transports oxygen from lungs to body tissue

• They contain haemoglobin, a protein that gives red blood cells their colour, and helps transport oxygen around the body

  • Haemoglobin binds with oxygen when oxygen levels are high (in the lungs) and releases oxygen when the levels are low (in respiring cells)

What are the adaptations of red blood cells?

1. Biconcave shape: larger surface area compared to volume

• Increases the rate at which oxygen diffuses out the cell

• Shape also helps them squeeze through capillaries

2. Thin: oxygen has to travel shorter distance to diffuse

3. Don’t have a nucleus: to make more space for haemoglobin

What are the functions of white blood cells?

• Part of the body’s immune system

• They do have a nucleus

  1. They can ingest and destroy pathogens with a process called phagocytosis

  2. They can also produce antibodies

What are the main types of white blood cells?

• Phagocytes: cells involved in phagocytosis

• Lymphocytes: cells involved in production of antibodies

What is blood clotting and what are the main roles?

• A cut or wound can cause bleeding, but platelets can form a plug to stop it from bleeding. Blood clotting as acts a barrier and prevents the entry of a pathogen.

  Roles:

• Prevent blood loss

• Prevent pathogen entry

Identify red blood cells and white blood cells in the photo