Lecture 8

Question 1

What are the three types of blood cells?

Answer 1

Leucocytes, erythrocytes and thrombocytes

Question 2

Leucocytes?

Answer 2

• Part of body’s defence system
• Formed in the red bone marrow after birth through proliferates in lymphoid tissue
• Divided into two groups (agranulocytes and granulocytes)
• White blood cells

Question 3

Two types of agranulocytes?

Answer 3

Lymphocytes and monocytes

- Can’t observe granules under a microscope

Question 4

Lymphocytes?

Answer 4

• Smallest leucocyte
• Created from lymphocytic stem cells
• Two types (T-lymphocytes and B-lymphocytes)

Question 5

Role of T-lymphocytes?

Answer 5

Responsible for cellular immunity

Question 6

Role of B-lymphocytes?

Answer 6

Responsible for humoral immunity (antibodies)

Question 7

Monocytes?

Answer 7

• Largest leucocyte
• Have the ability to phagocytose invading organisms (eat)
• Once they leave circulation, they enlarge and transform in the tissue to macrophages

Question 8

Polymorphonuclear cells/granulocytes?

Answer 8

Have 3 types neutrophils, eosinophils and basophils

- Can observe granules under a microscope

Question 9

What is pus made of?

Answer 9

Mostly dead neutrophils

Question 10

Neutrophils?

Answer 10

• Most common leucocyte
• Have a lobed nucleus
• Contain lysosomes in cytoplasm
• Where tissue is damaged, granulocytes leave the capillaries, and start phagocytosis of damaged cells and invading pathogens

Question 11

Eosinophils?

Answer 11

• Acidiphilic granules are considered to be lysosomes

- Only weakly phagocytic but increase in parasitic infections

Question 12

Basophils?

Answer 12

• Rare
• Contain basophilic granules
• Don’t know function, but contain heparin and histamine
• May be involved with tissue mast cells in dealing with allergic reactions

Question 13

Macrophages?

Answer 13

More specialised cells in phagocytosis

Question 14

Erythrocytes?

Answer 14

• Made in red bone marrow
• Round “bags” of haemoglobin
• Function is the transport if O2 to body tissues, and the transport of CO2 away from the tissues
• Dumb-bell or biconcave shape

Question 15

Corpuscle?

Answer 15

A term that refers to any cell floating freely in a liquid

Question 16

What is the purpose of the dumb-bell or biconcave shape of erythrocytes?

Answer 16

A large surface area to volume ratio for the exchange of O2

Question 17

How long do erythrocytes live?

Answer 17

120 days in the blood stream before getting broken down and removed by the liver and spleen

Question 18

What is the product of the breaking down of erythrocytes? How is it eliminated?

Answer 18

Bilirubin and it is eliminated through the bile duct, which causes the brown colouration of faeces

Question 19

What is the process called that replaces erythrocytes?

Answer 19

Haemopoiesis

Question 20

Haemophilia?

Answer 20

Abnormal bleeding caused by inherited disorders where the levels of certain protein components of the blood clotting cascade are reduced. Two types:

1. Haemophilia A - Most common, deficiency in clotting factor VIII
2. Haemophilia B - Less common, deficiency in clotting factor IX

Question 21

What are early sites of haemopoiesis?

Answer 21

Liver, spleen, lymph nodes

Question 22

What is the cell that is the exception, and doesn’t get produced after birth in the red bone marrow?

Answer 22

Lymphocytes, which proliferate after birth in various lymphoid tissues

Question 23

Where is red bone marrow found?

Answer 23

In the ends of the ling bones (femur0 and in flatter bones (ribs, sternum, skull and pelvis)

Question 24

What are all blood cells derived from?

Answer 24

A multipotent stem cell called a haemocytoblast

Question 25

What do haemocytoblast do?

Answer 25

Replicate at a slow rate, producing 5 types of unipotent cells (magakaryoblasts, proerythroblasts, lymphoblasts, myeloblasts, and monoblasts), which then begin to divide rapidly

Question 26

Haemopoisesis of erythrocytes?

Answer 26

- Production of erythrocytes - Low O2 levels (hypoxia) triggers the release of the hormone erythroprotein from the kidney, which controls the haemopoisesis (production) of erythrocytes

Question 27

Hypoxia?

Answer 27

Low O2 levels

Question 28

Thrombocytes?

Answer 28

- Come from big cells in the red bone marrow called megakaryocytes - Involved in the haemostasis (control of bleeding) by forming clots

Question 29

What are the two processes that bring about blood clotting?

Answer 29

Intrinsic and extrinsic pathways

Question 30

What protein causes most clotting?

Answer 30

Fibrinogen

Question 31

Where does the intrinsic pathway begin?

Answer 31

Begins in the blood itself and involves platelets

Question 32

Where does the extrinsic pathway begin?

Answer 32

Begins with trauma or damage to tissues outside the blood vessels

Question 33

Steps to blood clotting?

Answer 33

1. Tissue damage/trauma occurs 2. Plasma proteins (B-globulins) aka blood clotting factors are triggered in a cascade sequence (one activation triggers another, and so on) 3. In the presence of Ca^2+ ions, both pathways produce an active catalyst called thrombokinase 4. This enzyme converts another protein (prothrombin) to thrombin 5. Thrombin then acts as an enzyme to convert the soluble fibrinogen to the insoluble fibrin 6. Fibrin then attaches to the damage site and creates a growing matrix of fibrin, platelets and trapped blood cells. This creates a haemostatic plug, or blood clot 7. The fibrin then polymerises into long threads and then contracts after a few minutes, which releases a clear fluid from the clot (the serum)

Question 34

How long does extrinsic vs intrinsic clotting take?

Answer 34

``` Extrinsic = 15 seconds Intrinsic = 1-3 minutes ```

Question 35

What inhibits clotting?

Answer 35

- Heparin | - Removal of free Ca^2+