Red Blood Cells
Blood as a transport system
- The role of blood in the body is to act as a transport system carrying useful substances to every cell of the body, and carrying harmful waste substances to other organs for processing and/or excretion
- It also plays a vital role in transferring heat from “active” organs to cooler parts of the body (such as the extremities – hands and feet)
- Blood consists predominantly of red blood cells and plasma
- Over half of the volume of the blood is made up of plasma
- The majority of the other half is made up of red blood cells
- Less than 1% of blood contains white blood cells and platelets
- Blood consists predominantly of red blood cells and plasma
- It also plays a vital role in transferring heat from “active” organs to cooler parts of the body (such as the extremities – hands and feet)
Blood micrograph
Composition of human blood
Red blood cells carry oxygen
- Red blood cells are specialised cells that carry oxygen from the lungs to cells throughout the body
- The structure of red blood cells are adapted for this function in 3 key ways
- Red blood cells are small with a 'biconcave disk' shape which gives them a large surface area to volume ratio to maximise diffusion of oxygen in and out
- They are full of haemoglobin, a protein that binds to oxygen to form oxyhaemoglobin
- They have no nucleus which allows more space for haemoglobin to be packed in
- Their small size and flexibility allows them to pass through capillaries
Red blood cells
