Haematological System Flashcards
What are the 3 main functions of the blood?
- Transportation
- Regulation
- Protection
How many litres of blood do men and women have?
Average male has 5 -6 litres of blood and the average female has 4 -5 litres of blood
What are the components of plasma protein?
- Albumin
- Globulins
- Fibrinogen
- Other solutes are electrolytes, nutrients, gases, enzymes, hormones and water
What are erythrocytes?
Whole red blood cells
What are leucocytes?
Whole white blood cells
What are thrombocytes?
Cell fragments - platelets
What is haematocrit?
Total blood volume filled with red blood cells
What is the haematocrit percentage for males and females?
Haematocrit adult females - approx 38% - 46%
Haematocrit adult males - approx 40% - 54%
What is haemopoiesis?
The production of blood cells and platelets, which occur in the bone marrow
What is the structure of haemoglobin?
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.
What are granular leukocytes?
Include neutrophils, eosinophils and basophils. Develop from myeloid stem cells
What are agranular leukocytes?
Include lymphocytes and monocytes. Develop from lymphoid stem cells. Contains cytoplasmic granule
What are the functions of WBC’s?
Perform phagocytosis and produce antibodies
What do monocytes do?
Migrate into infected tissue and develop into macrophages
What do lymphocytes do?
Continually recirculate between blood, interstitial space and lymphatic fluid to provide immune responses
What do eosinophils do?
Combat inflammation
What do basophils do?
Are involved in inflammatory and allergic responses
What do neutrophils do?
Release enzymes to destroy bacteria
What is haemostasis?
Quick sequence of responses to stop bleeding from broken blood vessels
What are the 3 mechanisms to reduce blood loss?
1) Vascular spasm
2) Platelet plug formation
3) Blood clotting (coagulation)
What happens in vascular spasm?
- 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
What happens in platelet plug formation?
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
What happens in blood clotting?
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.
What is it called when blood clots slowly?
Haemorrhage
What is it called when blood clots quickly?
Thrombosis
What is the extrinsic clotting pathway?
- 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
What is the intrinsic clotting pathway?
- 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
What is the common clotting pathway?
- Prothrombinase activates prothrombin by converting it to thrombin
- Thrombin converts soluble fibrinogen into soluble fibrin
- Fibrin forms the protein threads of a blood clot
What is the life span of a RBC?
- RBC live for 120 days
- They are unable to reproduce as no nucleus or organelles.
