What are the broad category of disorders of blood cells?
Too many, not enough, not working properly
What is anaemia?
Not enough red blood cells, but defined as low haemaglobin levels
What factors affect tissue oxygen delivery?
CO (HR, SV), Hb, % saturation of blood
What are some signs of anaemia?
Low Hb:
pale
Low Hb->Low O2:
Hypoxic
Ischaemic
Low Hb->Low O2->Low energy:
Lethargic
Failure to thrive
Tachycardia (compensatory response to increase CO and thus O2 delivery)
What are the classes of causes of anaemia?
Decreased production, Increased destruction/loss, Inappropriate production
Where does haemopoesis occur?
In adults, within the stroma of bone marrow. Individual cells migrate as they mature, and this migration is mediated by the differing expression of adhesion molecules
What are some examples of haemotinics and how does the lack affect blood?
Haemotinics such as iron, vitamin B12 and folate are essential for the production of RBCs. Deficiencies will lead to decreased production of RBCs
What are some examples of haemotinics and how does the lack affect blood?
Haemotinics such as iron, vitamin B12 and folate are essential for the production of RBCs. Deficiencies will lead to decreased production of RBCs
What is involved in primary haemostasis?
Vasoconstriction, platelet adhesion, platelet aggregation
What is involved in secondary haemostasis?
Activation of coagulation factors, fibrin formation
What is fibrinolysis?
Lysis of a fibrin clot
What is the function of thrombin?
Described as a key enzyme for haemostasis, thrombin has many actions. One of its key actions is to cleave fibrinogen to form fibrin, leading to the formation of a clot.
Depending on the microenvironment, there can be either negative or positive feedback regulating the production of thrombin.
What abnormalities increase the risk of thrombosis?
Abnormal blood flow, abnormal endothelium, abnormal blood contents
What abnormalities increase the risk of thrombosis?
Abnormal blood flow, abnormal endothelium, abnormal blood contents
What characteristics make Hb a good O2 carrier
Differing conformational states allow Hb to bind O2 well at high concentrations, and give up O2 to tissues in need
What conformational change occurs in Hb when O2 binds to heme?
Deoxygenated heme is domed. When an oxygen molecule attaches to the heme, the Fe(II) molecule is pulled into the plane of the heme, leading to a conformational change int he entire subunit. This leads to cooperative conformational changes in the other 3 subunits of Hb such that they are all more likely to pick O2 molecules
What is the function of myoglobin, and how does it achieve this?
It stores O2 in peripheral tissues, such as muscles. In times of great O2 demand, they are able to release the stored O2 until blood supply is restored to sufficient levels.
They have a much higher affinity for O2, and so are able to take O2 from Hb molecules. They also do not release O2 until the oxygen saturation has been sufficiently lowered
What ways can Hb affinity for O2 be modified, and how are they used for efficient O2 transport?
Affinity of O2 is decreased by high CO2, low pH, and by 2,3-BPG
These CO2 and pH changes are present in working tissues, and absent from the lungs, allowing O2 to be more easily released into tissues in need. 2,3-BPG stabilises deoxy-Hb, allowing it to more efficiently release O2, except at high altitudes, where is can impair O2 loading by decreasing O2 affinity in an environment of low atmospheric O2
How does foetal Hb function?
By having a higher affinity of O2 than adult Hb, the foetus is able to take O2 from maternal Hb and thus supply the foetus with sufficient O2