Haematological System

Question 1

What are the 3 main functions of the blood?

Answer 1

• Transportation
• Regulation
• Protection

Question 2

How many litres of blood do men and women have?

Answer 2

Average male has 5 -6 litres of blood and the average female has 4 -5 litres of blood

Question 3

What are the components of plasma protein?

Answer 3

• Albumin
• Globulins
• Fibrinogen
• Other solutes are electrolytes, nutrients, gases, enzymes, hormones and water

Question 4

What are erythrocytes?

Answer 4

Whole red blood cells

Question 5

What are leucocytes?

Answer 5

Whole white blood cells

Question 6

What are thrombocytes?

Answer 6

Cell fragments - platelets

Question 7

What is haematocrit?

Answer 7

Total blood volume filled with red blood cells

Question 8

What is the haematocrit percentage for males and females?

Answer 8

Haematocrit adult females - approx 38% - 46%

Haematocrit adult males - approx 40% - 54%

Question 9

What is haemopoiesis?

Answer 9

The production of blood cells and platelets, which occur in the bone marrow

Question 10

What is the structure of haemoglobin?

Answer 10

Each RBC contains 280 million haemoglobin molecules. Each molecule consists of 4 polypeptide chains and haem is bound to each of the 4 chains. In the middle of the haem ring is a Fe ion which binds with 1 oxygen molecule therefore each haemoglobin molecule can carry 4 oxygen molecules around the body.

Question 11

What are granular leukocytes?

Answer 11

Include neutrophils, eosinophils and basophils. Develop from myeloid stem cells

Question 12

What are agranular leukocytes?

Answer 12

Include lymphocytes and monocytes. Develop from lymphoid stem cells. Contains cytoplasmic granule

Question 13

What are the functions of WBC’s?

Answer 13

Perform phagocytosis and produce antibodies

Question 14

What do monocytes do?

Answer 14

Migrate into infected tissue and develop into macrophages

Question 15

What do lymphocytes do?

Answer 15

Continually recirculate between blood, interstitial space and lymphatic fluid to provide immune responses

Question 16

What do eosinophils do?

Answer 16

Combat inflammation

Question 17

What do basophils do?

Answer 17

Are involved in inflammatory and allergic responses

Question 18

What do neutrophils do?

Answer 18

Release enzymes to destroy bacteria

Question 19

What is haemostasis?

Answer 19

Quick sequence of responses to stop bleeding from broken blood vessels

Question 20

What are the 3 mechanisms to reduce blood loss?

Answer 20

1) Vascular spasm
2) Platelet plug formation
3) Blood clotting (coagulation)

Question 21

What happens in vascular spasm?

Answer 21

• Blood vessel is damaged causing the smooth muscle in tis wall to contract. Pain receptors may also initiate this spasm
• Vascular spasm reduces blood loss for minutes to hours

Question 22

What happens in platelet plug formation?

Answer 22

1) Platelets stick to the damaged blood vessel. This is called platelet adhesion
2) Platelets become activated through adhesion. Extend their projections, connecting with one another, liberating the chemical in their vesicles. This is called platelet release reaction. Liberated chemicals activate platelets nearby and sustain the vascular spasm and decrease the blood flow
3) Platelet aggregation occurs a more platelets become activated and stick together. Accumulation of platelets - platelet plug. Fibrin threads reinforce the plug

Question 23

What happens in blood clotting?

Answer 23

Blood within a vessel is liquid, blood elsewhere becomes thick and forms a gel. This process is called clotting or coagulation. Eventually gel and liquid separate.

Question 24

What is it called when blood clots slowly?

Answer 24

Haemorrhage

Question 25

What is it called when blood clots quickly?

Answer 25

Thrombosis

Question 26

What is the extrinsic clotting pathway?

Answer 26

• Blood clotting occurs quickly
• Tissue factors leaks into the blood from damaged tissue cells extrinsic (outside) the blood vessel
• Tissue factor initiates reactions requiring calcium ions and other clotting factors to activate the enzyme prothrombinase

Question 27

What is the intrinsic clotting pathway?

Answer 27

• Slower and more complex pathway
• Activates if endothelial cells lining the blood vessels are damaged so that blood comes into direct contact with collagen fibre and connective tissue activating the clotting cascade
• Trauma to endothelial cells also activates platelets causing them to release phospholipids that also activate clotting factors
• Activation of clotting factors produces prothrombinase

Question 28

What is the common clotting pathway?

Answer 28

• Prothrombinase activates prothrombin by converting it to thrombin
• Thrombin converts soluble fibrinogen into soluble fibrin
• Fibrin forms the protein threads of a blood clot

Question 29

What is the life span of a RBC?

Answer 29

• RBC live for 120 days

- They are unable to reproduce as no nucleus or organelles.