Lecture 8 - haemotology I Flashcards
Blood: what is it, how much space does it take, and what are its components of it?
The fluid of connective tissue
The average adult has 7% of their weight as blood and 5 litres of blood
Made of ~(55%) plasma, ~(45%) RBCs, and WBCs & platelets (<1%)
Erythropoiesis: what is it and what does it do, where does it occur?
The production of blood cells
Produces blood cells using Erythropoietin, Iron, Vitamins B12 & 9, intrinsic factor, amino acids
Different in each stage of life
Erythropoietin
Glycoprotein hormone, naturally produced by the peritubular cells of the kidney, that stimulates red blood cell production
Erythropoiesis: where does it occur in foetus, infants, and adults?
Foetus - Early in the yolk sac, then liver & spleen, later in bone marrow
Infants - just bone marrow
Adults - red bone marrow (ribs, ends of long bones, skull, vertebrae)
Erythropoietin: where is it synthesised, and how is the rate of production increased/decreased
Erythropoietin is synthesized in the kidney and liver
Low/high concentrations of oxygen in the kidney will increase/decrease erythropoietin synthesis for secretion into the blood
Haematocrit: what is it, what does it do, and why?
The technique of centrifuging blood to determine the red blood cell volume within the blood.
Used to determine if a person has a healthy ratio of RBC:WBC:platelets
Haemoglobin recycling: how does it happen, and what is lost?
Macrophages consume aged or damaged RBCs in the liver, spleen or lymph nodes
Hb is broken down into heme and globin. Globin is broken down into amino acids. Heme is broken down into bilirubin and iron. Iron is broken down into transferrin and ferritin. Iron (before being broken down) and transferrin are recycled.
Iron, transferrin, and globin are recycled.
Ferritin and bilirubin are removed from the body.
Hypoxia: what is it, what causes it, and how is it solved?
Decrease in oxygen levels in a part(s) of the body
It may be caused by an increase in exercise, high altitude, smoking, or bleeding.
The kidneys synthesize more erythropoietin which is then sent to the bone marrow where it is used to produce more RBCs.
Hypoxemia
Decrease in blood oxygen levels
It may be caused by an increase in exercise, high altitude, smoking, or bleeding.
The kidneys synthesize more erythropoietin which is then sent to the bone marrow where it is used to produce more RBCs.
Haemoglobin: what is it, how does it do its function, how much is in RBCs, and how much is made during erythropoiesis?
The protein in the body that carries oxygen and carbon dioxide in RBCs.
It has 2 alpha and 2 beta subunits. Each subunit has one haem bound to one globin chain. The centre is an iron (Fe²⁺) atom which can reversibly bind to oxygen atoms
~280 million haemoglobin per RBC
Synthesis begins at the proerythroblast (earliest) stage and by the reticulocyte (immature) stage, 35% of the cell’s Hb is produced and by the erythrocyte (mature) stage, the final 65% is produced.
RBC facts
- Average RBC size = 7.2-8.4 microns
- Take 20 seconds to circulate the body
- Circulate the body for ~120 days
- 25 trillion in an adult body
- 2-3 million made each second
- 280 million haemoglobin per RBC, 280 x 4 = 1120 million (1.12 billion)
Anaemia: what is it, how many people does it affect, and what is it caused by?
Blood haemoglobin concentration below the accepted minimum (13.5g/dl (M), 12 g/dl(F))
Affects 1/3 of the worldwide population
Caused by blood loss, decreased blood production, and increased blood destruction
Iron deficiency anaemia: what is it, what does it do, and what can it be caused by?
The most common form of anaemia and is caused by reduced iron meaning less haemoglobin is produced in the blood
Causes cells to be hypochromic (discoloured) and microcytic (undersized)
Can be caused by: pregnancy, bleeding from GI tract (ulcer, malignancy), malabsorption, menorrhagia (heavy period bleeding), malnutrition (dietary)
Megaloblastic anaemia (B9): what is it, what happens, and what are the causes?
A form of macrocytic anaemia (abnormally large red blood cells)
Blood is released as reticulocytes that have not undergone division to form smaller, mature RBCs
Vitamin deficiency anaemia - not enough vitamin B12 and/or vitamin B9, can be caused by pregnancy, elderly or diet.
Megaloblastic anaemia (B12): what is it, what happens, and what are the causes?
A form of macrocytic anaemia (abnormally large red blood cells)
Occurs as an intrinsic factor (IF) is not released adequately by the stomach so not enough B12 is absorbed
Can be caused by pernicious anaemia, Crohn’s, coeliac disease, or any other disease affecting the absorption of B12
