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Function of blood
Carry nutrient, fluids, hormones/enzymes to various area of body
Accountable for 7-8% of body weight (5-6L in person)
PH= 7.35-7.45 Temp= 38C
Transportation, defence, heat regulation, prevention of blood loss, creation of blood pressure
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Plasma
- account 55% of total blood volume
- 90% of plasma is body's solvent or water
- 1% consists of electrolytes, nutrients, waste product, respiratory gases
- 9% consists of 3 major plasma proteins
- Albumin- maintains osmotic pressure, a carrier for other protein, aid as blood buffer
- Fibrinogen- Blood clotting during inury to tissue
- Globulin- anitbodies
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Cellular compartment of blood
- Erythrocytes (red blood cell) 45% of blood
- Leukocytes (white blood cell) & platelets less than 1%
Removed by spleen onces cell dies
RBC has longest lifespan of 120days
Formation of blood cells is called hematopoiesis, occurs in red bone marrow
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Erthroytes (RBC)
Small flexible cells shaped, no nucleus, few organelles
unable to divide/grow
mature in days
Function is to carry O2 to cells in the body attached to haemoglobin molecules
anemia- decrease in the ability to transport O2
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Leukocytes
Cruicial to body's defense agains pathogens/disease
Transport in blood and lymph
Complete with nucleus and organelles.
Increased number of leukocytes indicated infection
- Formed into 2 major group
- Granulocytes and agranulocytes- (lymphocytes & monocytes)
Lymphocytes- 2nd most numerous leukocyte in blood and vital to immune response
monocytes are largest in size and change into macrophages to fight chronic infection
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Formation of RBC
- Takes 3 - 7 days
- >Produced in myeloid stem cells leading to production of haemoglobin
- >Fe is vital for haemoglobin
- >Fe is metabolised and stored in bone marrow attached to ferritin(special iron storage protein)
- >large amount of haemoglobin accumulates causing nucleus & organelles to be ejected out of cell
- >young RBC called reticulocytes leave marrow and enters bloodstream
- >reticulocytes mature within two days of being in blood stream
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Erthropoiesis - the process of erthrocyte production
- >Production is controlled by ability of erythrocyte to transport O2
- >controlled by hormones called erthropoietin which released via -ve feedback mechanism in response to decreased of O2 level ( hypoxia)
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Anaemia
- Sign of disease
- Not enough haemoglobin in blood resulting in lack of O2 being delivered o tissues
- Cause tiredness, confusion, risk of infection and short of breath.
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Formation of WBC
- production begins from lymphoid and myeloid stem cells
- formation is stimulated by cytokines
- overal formation is stimulated by CSF (coloy stimulating factors hormones) & interleukin-proteins released by cells of immune system, act as messagers to regulate immune function
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Platelets
- irregular shaped produced in bone marrow
- 2/3 found in body, 1/3 found in spleen
- 7-10 days lifespan
- required for blood clotting and preventing blood loss
- production is controlled by thrombopoiein hormone manufactured by liver.
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