Blood physiology - Blood life cycle Flashcards
Describe blood composition.
Red blood cells
Plasma
Buffy coat - white blood cells, platelets
Haematocrit - the ratio of red blood cells to total blood volume
Complete blood count calculates the cellular or formed elements of the blood
What are erythrocytes ?
Biconcave discs
Develop in bone marrow
No DNA or major organelles to allow more space to carry haemoglobin
Produce ATP through glycolysis
Squeeze through micro vessels by changing shape
Broken down by reticuloendothelial system after 120 days
What are the functions of erythrocytes?
95% haemoglobin - oxygen carrying protein
Contains 4 polypeptide chains, each linked to an iron carrying a haem
1 haemoglobin molecule can carry 4 oxygen molecules
Facilitation of carbon dioxide transport
Control of acid-base equilibrium in the blood
What is Erythropoiesis ?
Process of erythrocyte production from pluripotental haemotopoietic stem cells
Pluripotential cells differentiate into erythroid cells then normoblasts
Nuclear material reabsorbed forming reticulocyte
Matures within 1 day forming erythrocyte
Formed in bone marrow
Vitamin B12 and folate essential for maturation
How is erythropoiesis controlled?
Stimulus - hypoxia
Detector - kidney
Effector - EPO
What is anaemia?
Deficiency of haemoglobin in the blood because of too few red blood cells or not enough haemoglobin reducing oxygen carrying capacity of blood
Possible causes of anaemia:
Abnormalities of erythropoiesis
Deficiencies of erythrocytes
Describe microcytic anaemia.
Caused by iron deficiency
Decreased MCH
Erythrocytes will contain less haemoglobin
Erythrocytes produced are much smaller than normal
Describe macrocytic anaemia .
Erythrocytes abnormally large
Rupture easily causing jaundice
Occurs when
Reduction in Vitamin B12 or folate
pernicious anaemia - reduced secretion of intrinsic factor
Describe sickle cell anaemia.
Genetic condition
Abnormal haemoglobin synthesised
Long crystals cause cells to elongate
Cells rupture easily and cause blood flow to back up
