Blood Flashcards
How is the blood distributed in the body?
One litre in the lungs, one litre in the heart/arterial system and three litres in the systemic veneous circulation.
What are the six functions of blood?
Carriage of physiologically active molecules and compounds Clotting Defence Carriage of gas (O2 and CO2) Thermoregulation Maintain ECF pH
What are the four elements of the blood?
Plasma, red blood cells, white blood cells and platelets
What are the three categories of plasma proteins and what do they do?
Albumin is the most abundant plasma protein (60%). It generates colloid oncotic pressure, acts as a transport protein and helps buffer the blood.
Globulin (38%) can be alpha, beta or gamma. Alpha and beta do the same as albumin but Gamma Globulins (immunoglobulins) help with defence against pathogens.
Fibrinogen and clotting factors (2%) help to clot the blood.
What is colloid oncotic pressure?
Plasma Proteins don’t cross the capillary wall so this draws in water and other molecules permeable to the wall. This generates a pressure of around 25mmHg.
The concentration of the fluid is unchanged but the volume of the plasma and IS is changed.
Interstitial fluid acts as a resovoir.
What is capillary hydrostatic pressure?
This exceeds the interstitial hydrostatic pressure.
It favours the movement of fluid out of capillary.
The balance of colloid and hydrostatic pressure keeps the plasma protein concentration high.
What is hypoproteinaemia and what are some causes?
It is a lack of plasma proteins or abnormally low levels.
It can be caused by starvation, liver disease, intestinal disease and nephrosis. This leads to oedema of the limbs due to loss of oncotic pressure so fluid is lost to the IS and can’t get back.
What is the difference between myeloid and lymphoid cells?
Myeloid cells come from uncommitted cells and lymphoid cells come from lymphotic stem cells. Hormones determine which ones the stem cells become.
Describe the structure and function of erythrocytes
They have a 120 day lifespan, are highly flexible, biconcave and non nucleate. They are packed with haemoglobin and transport it round the body. Arterial blood is bright red (oxyhaemoglobin) and venous blood is blue/purple (deoxyhaemoglobin). This is due to the haemoglobin changing colour.
What is erythropoiesis and what regulates it?
It is the formation of red blood cells. It is controlled by erythropoietin, of which 85% is secreted by peritubular capillary cells and 15% by hepatocytes.
Secretion of this hormone is increased when the kidneys become hypoxic which can be caused by haemorrhage, anaemia, cardiac or lung dysfunction.
What are leukocytes and how are they organised?
They are nucleated and larger than red blood cells and are involved in the body’s defence against pathogens.
They are organised into granulocytes and agranulocytes (which also include lymphocytes).
What is leukopoiesis and how does it happen?
This is the formation of white blood cells. It is controlled by cytokines (proteins/peptides) and colony stimulating factors.
Cytokines are released from the endothelial cells, fibroblasts and mature white blood cells. These stimulate mitosis and maturation. There are different stimulations of leukopoeisis in response to different pathogens.
What are platelets and what role do they play?
These are membrane bound fragments of cells from megakaryocytes. They are rarely nucleated due to merely being a section of cytoplasm.
They adhere to damaged vessel walls and exposed connective tissue (platelet plug, scaffold) to mediate clotting.
What is haemotocrit and what are the normal reference values? What can affect these values?
This is the ratio of red blood cells to the total volume of blood.
Male- 40-54%
Female- 37-47%
This can be affected by heart or lung disease or if people are acclimated at altitude (high).
What plasma protein is associated with jaundice?
Bilirubin is a plasma protein found in high concentrations when the liver is dysfunctional.
Plasma is yellow due to this bilirubin.
