Composition Of Blood

Question 1

What is the description and function of red blood cells?

Answer 1

• Their role is to carry oxygen in the blood.

• They don’t contain a nucleus so there’s more space inside to carry oxygen.

• They have a biconcave shape to increase their surface area, this helps carry more oxygen.

• They contain haemoglobin to help absorb oxygen.

Question 2

What is the description and function of white blood cells?

Answer 2

• White blood cells defend the body against infection from pathogens. They originate in bone marrow and are stored in the blood. There are two different types of white blood cells.

• Phagocytes kill pathogens. They do this by engulfing the pathogen. Phagocytes contain enzymes that digest pathogens.

• Lymphocytes produce antibodies that stick to pathogens which either kills it or causes them to clump together, making it easier for the phagocytes to engulf or destroy them.

Question 3

What is the description and function of platelets?

Answer 3

• Platelets are small fragments of cells and they have no nucleus.

• When the wall of a blood vessel is damaged, platelets attach together to form a plug (blood clot). The platelets then release fibrin and seal the wound/stop any further bleeding. The fibrin traps all of the RBC, WBC and plasma and hardens enabling the wound to seal and repair.

• This prevents blood cells from being lost from the blood and also stops pathogens entering the blood through the wound.

Question 4

What is the description and function of plasma?

Answer 4

• It’s a straw coloured liquid.

• It is made up of approximately 90% water as well as electrolytes.

• Plasma carries all of the different types of cell contained in the blood.

• Its role is to transport nutrients / RBC / WBC around the body, maintaining homeostasis / normal blood pressure.

• Since the blood plasma is a liquid some substances are carried by being dissolved directly in the blood plasma.