Cells Flashcards
Major components of the blood
- Erythrocytes (red blood cells)
- Leukocytes (white blood cells)
- Platelets
- Plasma
Define oxyhaemoglobin
When the haemoglobin molecule is bound to oxygen
Define deoxyhaemoglobin
When the haemoglobin molecule is not bound to oxygen
Essential features of the erythrocyte
- contain carbonic anhydrase (enzyme catalysing the conversion of carbon dioxide to carbonic acid)
- biconcave discs which maximise the surface area for diffusion
- flexible to squeeze through narrow capillaries
- lack organelles and a nuclei
- molecules on the surface of the erythrocyte confer the blood group of the patient
- erythrocyte production is regulated by negative feedback
Define anaemia
low blood haemoglobin concentration
Define microcytic anaemia
- size of the red blood cells are smaller than what is considered to be normal
- most common type of anaemia
- associated with gradual blood loss causing iron deficiency
- erythrocytes remain functional
- Small MCV
Causes of microcytic anaemia
- menstruation
- gastrointestinal tract lesions
- cancers
- parasitic infections
Define normocytic anaemia
- red blood cells are normal size but in insufficient quantities
- erythrocytes remain functional
- Normal MCV
Causes of normocytic anaemia
-acute blood loss (extreme, heavy and immediate loss of lots of blood)=internal or external bleeding
Define macrocytic anaemia
- red blood cells become larger than normal size
- DNA synthesis and cell division fail and there is reduced division of progenitor cells (early stem cell developments) so we have fewer larger erythrocytes
- erythrocytes remain functional
- large MCV
Causes of macrocytic anaemia
- Folic acid deficiency (required for thymine synthesis)
- Vitamin B12 deficiency (required for folic acid actions)
- Both molecules patients are deficient in are required for DNA synthesis
Cause of folic acid deficiency
-apparent in pregnancy because of high demands from the foetus
Causes of vitamin B12 deficiency
-autoimmune disease destroying B12 uptake in the gut
-pernicious anaemia
(anaemia from B12 deficiency=body produces an antibody attacking protein responsible for extracting B12 from food)
-Strict vegetarian or vegan diet
MCV
- Mean cell/corpuscular volume=average volume of a single red blood cell
- Diagnostic for certain types of anaemia from looking at the size of the erythrocytes
Define PMN granulocytes
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