Components of blood Flashcards
What is haemopoiesis?
The generation of new RBCs
What is haemostasis?
Stopping blood flow so we don’t bleed out.
What are the main components of plasma and what is its function?
More than 90% water, organic molecules (AA, lipids, glucose, proteins), vitamins, ions, gases.
Function is to transport molecules around the body (mostly water so some molecules can dissolve).
It has a high specific heat capacity so can transport metabolically-generated heat around the body to maintain body temperature.
Excess body heat can be brought to the surface by a convection current.
What proteins can be found in the plasma?
All mainly from the liver
Albumins - the most abundant. they contribute to the colloid osmotic pressure of plasma.
Globulins - clotting factors, enzymes, antibodies, carriers.
Immunoglobulins are synthesised and secreted by specialised blood cells.
Fibrinogen - forms fibrin, essential for blood clotting
Transferrin -globulins form typhoid tissue and other tissue provides transferrin. used in iron transport.
What are the cellular components of plasma?
RBC - erythrocytes - oxygen transfer
WBC - leukocytes - immune response - lymphocytes, monocytes, neutrophils, eosinophils, basophils
Platelets - thrombocytes - clotting response
How is a haematocrit taken and what does it show?
Blood is taken by a capillary tubing mechanism. Blood is allowed to settle and separate.
The red layer is the PCV (packed cell volume) containing all the RBC
The white layer is the Buffy coat made of WBC, if a DNA sample is needed then it should be taken from here.
The 3rd layer is the plasma.
What can decrease PCV?
The over production of WBC, this will increase the buffy coat layer, hence decreasing the % of PCV. Blood loss (if excessive blood loss occurs then pumped with only PCV). Anaemia will decrease PCV
What will increase PCV?
Dehydration will reduce the size of plasma hence increasing % of PCV. Lung/heart disease, less oxygen being transported so more RBC made. Polycythaemia vera - deprives of oxygen caused by smoking so more RBC made to accomodate.
How does blood doping effect PVC?
Purpose is to increase the oxygen carrying capacity of blood by increasing RBC (increasing PCV).
Blood transfusions (only PCV) or injection if erythropoietin (EPO will stimulate production of RBC)
Hematocrits are used as a screening test.
What is blood serum?
The clear liquid that can be separated from clotted blood. Plasma with the clotting factor, and cells.
It still contains, antibodies, hormones, drugs.
Why are the ionic components of plasma important?
Na+ and Cl- are important in determining the osmolarity. If too much water is drunk it will dilute the ionic composition of the plasma hence reducing the osmolarity, so water will move into the Brian and cause swelling and death.
K+ is involved with the initiation of action potentials. HCO3- is involved with buffering the blood.
How do plasma proteins effect oncotic pressure?
Osmotic pressure is determined by the solute content of a compartment, the main solute difference between the plasma and interstitial fluid is proteins (mainly albumin), so the osmotic pressure of plasma will always be higher than interstitial fluid, so water will always be drawn into plasma.
How does oedema cause swelling?
Immoblised limb causes swelling because the contraction of muscles usually pumps the lymph system so the lymph fluid collects. May be as a result the obstruction of lymph nodes.
Why is lymph essential after infection?
It reduced the interstitial protein count after infection. Lymph vessels lie close to capillaries, allowing fluid and proteins to drain into the lymph vessel. The fluid can then drain back into circulation with no proteins.
What are the factors disrupting the normal balance between capillary filtration and absorption?
Normally at the arterial end the hydrostatic pressure is higher than oncotic pressure drawing fluid out of the capillary, at the venous end the oncotic pressure is higher and fluid is drawn back in.
- If the capillary hydrostatic pressure increases the venous pressure will increase leading to heart failure, systemic build up of volume and increasing pressure in right atrium, so filtration will exceed absorption and swelling will occur.
- Decrease in plasma proteins as a result in severe malnutrition
- Increase in interstitial protein, leads to inflammation
