CGIER 3 - Blood cells, leucocytes, leukaemia; Erythrocytes; Blood coagulation, haemophilia

Question 1

What are the three types of blood cells that float in the plasma?

Answer 1

1. Leucocytes: white blood cells
2. Erythrocytes: red blood cells
3. Thrombocytes: platelets

Question 2

What is the function of leucocytes?

Answer 2

Leucocytes serve as the body’s defense system.

Question 3

What are the names of the groups of cells leucocytes are divided into?

Answer 3

Leucocytes can typically be divided into 2 groups:

1. Agranulocytes: Lymphocytes & Monocytes
2. Granulocytes: Neutrophils, Eosinophils, & Basophils

Question 4

Describe what a lymphocyte is and its function.

Answer 4

Lymphocytes are 8-10 micrometers in diameter and make up 30% of all white blood cells. They originate from lymphocytic stem cells in the bone marrow and are now produced in lymphoid tissue of lymph nodes, the spleen, thymus, and GIT. Their function is the production of antibodies.

Question 5

What are the major types of lymphocytes?

Answer 5

There are two major types of lymphocytes:

1. T-lymphocytes: responsible for cellular immunity.
2. B-lymphocytes: responsible for humoral immunity.

Question 6

Describe what a monocyte is and its function.

Answer 6

Monocytes are 15-20 micrometers in diameter and make up 5% of all white blood cells. They originate from red bone marrow and are now found in lymph nodes, the lungs, alveoli, liver, and spleen. Their function is to phagocytose invading organisms and leave circulation to produce macrophages.

Question 7

Describe what a neutrophil is and its function.

Answer 7

Neutrophils are 10-14 micrometers in diameter and make up 62% of all white blood cells. They originate from red bone marrow, have a lobed nucleus, and purplish lysosomes. Their function is to leave the capillaries and phagocytose damaged cells and invading organisms. Pus found in wounds is dead neutrophils.

Question 8

Describe what an eosinophil is and its function.

Answer 8

Eosinophils are 10-14 micrometers in diameter and make up 3% of all white blood cells. They originate from red bone marrow and are considered to be lysosomes. They are weakly phagocytic, but their function is fighting parasites.

Question 9

Describe what a basophil is and its function.

Answer 9

Basophils are 10-14 micrometers in diameter and make up 0.4% of all white blood cells. They originate from red bone marrow and contain heparin and histamine. They are similar to tissue mast cells involved in allergic reactions.

Question 10

What is the function of an erythrocyte?

Answer 10

The primary function of an erythrocyte is the transportation of oxygen to cells and the transport of carbon dioxide away from cells.

Question 11

How long do red blood cells survive, and what happens after they die?

Answer 11

Red blood cells survive for up to 120 days in the bloodstream until they are broken down by the liver and spleen at a rate of 2.5 million/second.

Question 12

What is bilirubin?

Answer 12

Bilirubin is the product of the breakdown of haemoglobin from the destruction of the erythrocytes by the liver. Bacteria in the colon convert bilirubin to stercobilin which gives faeces its characteristic brown colour.

Question 13

What is the shape of an erythrocyte and why is it so special?

Answer 13

Erythrocytes have a biconcave shape which gives it a large surface area to volume ration for oxygen exchange.

Question 14

What is haemopoiesis?

Answer 14

Haemopoiesis is the process that occurs to replace erythrocytes on a daily basis.

Question 15

Before birth, where does haemopoiesis take place in the body?

Answer 15

Before birth, haemopoiesis takes place in the lymph nodes, liver, and spleen. However, as bones develop during the fetal life, haemopoiesis begins in the red bone marrow cavities.

Question 16

After birth, where does haemopoiesis take place?

Answer 16

After birth, haemopoiesis takes place wherever red bone marrow is found in the body. Red bond marrow is found at the ends of long bones such as the femur and flatter bones such as the ribs, sternum, skull, and pelvis.

Question 17

What do all blood cells derive from and what are the names of the unipotent stem cells that are produced?

Answer 17

All blood cells derive from a pluripotent stem cell called a haemocytoblast. The five unipotent stem cells that form are:

1. Megakaryoblast
2. Proerythroblast
3. Lymphoblast
4. Myeloblast
5. Monoblast

Question 18

What is haemopoiesis of erythrocytes controlled by?

Answer 18

Haemopoiesis of erythrocytes is controlled by the hormone erythropoietin, which is released by the kidney when the oxygen levels are low. EPO can be released due to high altitudes, severe blood loss, or anemia. EPO lasts 1-2 days in circulation.

Question 19

What is the function of thrombocytes and how long do they last in the bloodstream?

Answer 19

Thrombocytes are involved in blood clotting and last about 8 days in the bloodstream.

Question 20

What two pathways does blood clotting involve?

Answer 20

The complex process of blood clotting involves the extrinsic and intrinsic pathways. The extrinsic pathway begins with trauma done to tissues outside the blood vessels, while the intrinsic pathway begins in the blood itself and involves platelets.

Question 21

How does blood clotting work?

Answer 21

Beta globulins (plasma proteins) are blood clotting factors that aid in activating the cascading sequence of reactions that take place during blood clotting:

1. Firstly, both the extrinsic and intrinsic pathways release calcium ions to activate the catalyst thrombokinase.
2. Thrombokinase then converts the protein prothrombin (formed in the liver) into thrombin with the help of calcium ions.
3. Thrombin then acts as an enzyme in converting soluble fibrinogen to insoluble fibrin.
4. Fibrin then attaches to the trauma site and creates a matrix of fibrin, platelets and trapped blood cells called a haemostatic plug or blood clot.
5. The fibrin then polymerizes into long threads, then contracts and after a few minutes a serum leaks from the clot.

Question 22

How can clotting be inhibited?

Answer 22

Clotting can be inhibited in two ways:

1. Heparin (from basophils)
2. Removal of calcium ions (used in blood banks to preserve blood by adding sodium citrate)

Question 23

What is haemophilia?

Answer 23

Haemophilia is an inherited disorder in which the levels of intrinsic blood clotting proteins are reduced. This leads to increased bleeding after trauma and sudden bleeding with no cause.

Question 24

What are the types of haemophilia?

Answer 24

There are two types of haemophilia:

1. Haemophilia A (most common 80%)
2. Haemophilia B (less common 20%)