Blood

Question 0

What are the functions of the blood?

Answer 0

1. Transports gases, nutrients, hormones and metabolic wastes.
2. Regulates pH and electrolyte composition of interstitial fluids throughout the body.
3. Restriction of fluid losses (haemostasis)
4. Defence against toxins and pathogens.
5. Stabilisation of body temperature.

Question 1

What are the main components of the blood?

Answer 1

1. Plasma (which contain water, ions, organic molecules (amino acids, proteins, glucose, lipids and nitrogenous waste), trace elements, vitamins and gases). The proteins include albumins, globulins and fibrinogen.
2. Red blood cells
3. White blood cells
4. Platelets

Question 2

What are the different functions of the proteins in the blood?

Answer 2

Fibrinogen is involved in blood coagulation. It is converted into fibrin by thrombin and fibrin stabilises blood clots.

Globulins are involved in ion transport and the immune system.

Albumins are responsible for the osmotic pressure if the blood and are also involved in the transport of hormones.

Question 3

What are the properties of red blood cells that allow them to transport oxygen?

Answer 3

They contain a red pigment/protein called haemoglobin which has 2 alpha and 2 beta chains. Each chain contains a heme/haem (iron) group and each heme group can reversibly bind to a molecule of oxygen in the lungs.

Question 4

What is the function of white blood cells/leukocytes? Name all the types of white blood cells.

Answer 4

They are involved in defending the body against pathogens. Lymphocytes (B and T cells), monocytes, neutrophils (phagocytes), eosinophils and basophils.

Question 5

What is the other name for red blood cells?

Answer 5

Erythrocytes

Question 6

Where are blood cells produced?

Answer 6

Both red and white blood cells are produced in the bone marrow.

Question 7

What triggers red blood cell production in the bone marrow?

Answer 7

When oxygen levels are low, erythropoietin is produced from the kidney which acts on the bone marrow to stimulate red blood cell production. Red blood cell production is called erythropoiesis.

Question 8

What is the main difference between lymphocytes and neutrophils?

Answer 8

Neutrophils are phagocytic, they engulf and digest bacteria. A high neutrophil count suggests a bacterial infection. Neutrophils are the body’s first line of defence and they have a life span of a few days.

Lymphocytes secrete antibodies and they have a life span of a few years.

Question 9

What is the name given to the process of blood cell formation?

Answer 9

Haematopoiesis.

Question 10

What is the name given to the process of RED blood cell formation?

Answer 10

Erythropoiesis.

Question 11

Give 3 examples where an individual may have a high red blood cell count.

Answer 11

Polycythemia - this is where the proportion of blood volume occupied by red blood cells increases (haemotocrit level increases).

Bronchitis and emphysema - this is where the level of oxygen transported to tissues is decreased due to a decline in lung function. Therefore the red blood count is high to ensure that enough oxygen is delivered to tissues.

Question 12

What is a haemotocrit?

Answer 12

It is the proportion of plasma to blood (blood cells). It is used to measure the proportion of blood cells. About 60% of blood is plasma and 40% is cellular (blood cells).

Question 13

What is the main condition associated with anaemia?

Answer 13

It is where the blood cannot transport enough oxygen to the tissues because there is a reduction in the number of red blood cells.

Question 14

Why does malaria cause anaemia?

Answer 14

The Plasmodium parasite destroys red blood cells, therefore there are fewer red blood cells in the blood and less oxygen is delivered to tissues.

Question 15

What is haemostasis?

Answer 15

It is keeping blood from being lost from the vascular system by blood clotting.

Question 16

Describe the process of blood coagulation (clotting) and clot stabilisation.

Answer 16

When there is a cut/skin is broken, the endothelial cells at that area of the skin are destroyed exposed collagen binds and activates platelets. Platelet factors are released and these platelet factors attract more platelets. The platelets aggregate into a platelet plug.

Question 17

What is the main role of collagen in blood coagulation?

Answer 17

Collagen exposure initiates a process where activated blood factors activate other factors in a cascade.

Zymogens (inactive forms/precursors of enzymes) are activated and in turn activate other factors.

Question 18

How does fibrin stabilise a blood clot?

Answer 18

Thrombin (which is produced at the last stage of the cascade) catalysers the production of fibrin from fibrinogen. Fibrin then forms a ‘net’ that covers the wounded surface.

Question 19

What are the two main stages involved in blood clotting?

Answer 19

1. Platelet activation

2. Fibrin stabilisation

Question 20

Give two examples where clotting can ‘go wrong.’

Answer 20

Insufficient clotting - haemophilia - where an individual does not stop bleeding or bleeds for a longer time at the wounded area.

Inappropriate clotting - thrombosis - where a blood clot forms and blocks the flow of blood through the blood vessel.

Question 21

What is the function of the lymphatic system?

Answer 21

It is made up of vessels called lymph nodes which allow one way movement of excess interstitial fluid (called lymph) from the tissues into circulation. It also removes waste and destroys pathogens.

Question 22

What is causes edema of the lymph nodes?

Answer 22

Edema is swelling. In the lymph nodes, edema occurs when the normal exchange between the circulatory system and the lymphatics has been disrupted due to inadequate drainage or the blood capillary filtration greatly exceeding capillary absorption.

Question 23

How does fluid travel through the lymphatic system?

Answer 23

Via capillaries through valves which ensures the one way movement of fluid.

Question 24

What does a high neutrophil and high lymphocyte count suggest?

Answer 24

High neutrophil count suggests a bacterial infection.

High lymphocyte count suggests that the individual has glandular fever which is caused by Epstein-Barr virus.