Lecture 8 - Haematology Flashcards
How much blood does the average adult have?
5 litres
What is the composition of blood?
Made up of:
Plasma
Red blood cells
White blood cells
Platelets
What is the function of blood?
Transport - gases, nutrients, excretory products
Defence using antibodies, WBC and clotting factors
What is haematopoiesis?
The production of blood cells and platelets
What is the process of haematopoiesis?
- Hemocytoblasts produce all blood cells
- They differentiate into either common myeloid or common lymphoid progenitors depending on body’s needs
- Then differentiate into different types
What is erythropoiesis?
The production of red blood cells
What are the stages of erythropoiesis?
- Stem cell
- Committed cell
- Developmental pathway
- Erythrocyte
What are the stages of the developmental pathway?
- Ribosome synthesis
- Haemoglobin accumulation
(haemoglobin produced by this point - Nucleic ejection
What are the requirements for erythropoiesis?
Erythropoietin
Iron
Vitamins B12 and folic acid
Intrinsic factor
Amino acid
Where does erythropoiesis occur in foetuses?
Early = in yolk sac then the liver and spleen
Later = Bone marrow
Where does erythropoiesis occur in infants?
In all bone marrow
Where does erythropoiesis occur in adults?
Only in red bone marrow
How much of the blood is made up of plasma?
55%
What is plasma made up of?
92% Water
7% Plasma proteins like albumins
1% Other solutes
What is the function of plasma?
Transport of inorganic and organic molecules
What is the structure of red blood cells?
Biconcave shape
No organelles
Only contains haemoglobin
What is the life cycle of red blood cells?
120 day life span
1. The cell is worn out and damaged
2. Passes through the spleen and liver
3. Macrophages recognise the RBC is worn and digest the cell
4. Iron from haemoglobin is recycled and used in new blood cells
5. Haem molecule is conjugated to bilirubin and removed from body
What is the process of erythrocyte homeostasis?
- Low oxygen level acts as a stimulus
- Kidneys increase production of erythropoietin
- Stem cells increase RBC production
- Oxygen levels in the blood return to normal
What is hypoxia?
Low oxygen levels of oxygen in the body’s tissues
What are some causes of hypoxia?
Increase in exercise
Smoking
High altitude
Bleeding
How many molecules of haemoglobin are in one RBC?
280 million molecules
What is the function of haemoglobin?
Transport of oxygen from lungs to tissues
Transport of carbon dioxide from tissues to lungs
What is the structure of haemoglobin?
4 subunits, 2 alpha and 2 beta
Each subunit has a haem bound to globin
In the centre of a haem group is a ferrous iron atom which reversibly binds to one molecule of oyxgen
What is a globin?
A long polypeptide chain
What is anaemia?
When the haemoglobin concentration in the whole blood is below the accepted normal range
What is a low level for blood haemoglobin?
Men: less than 13.5g/dL
Women: less 12.0g/dL
What is iron deficiency anaemia?
Most common
Hypochromic RBC
Microcytic RBC
Decreased cell volume
What are some causes of iron deficiency anaemia?
Pregnancy
Malabsorption
Menorrhagia
Malnutrition
What is megaloblastic anaemia?
Can be either Vitamin B12 deficiency or folate deficiency
Abnormal RBC
Increased cell volume
What are some causes of megaloblastic anaemia with vitamin b12 deficiency?
Chron’s
Coeliac disease
What is macrocytic anaemia? (folic acid)
Pregnancy
Old age
Diet
What is sickle cell anaemia?
Hereditary, common in Africa
Abnormal haemoglobin structure
Sickle shaped cells
