Week 5 - Haemotology Flashcards
What are the 4 components of ‘blood’ in general
- red blood cells
- white blood cells
- plasma
- platelets
What is the function of blood?
- transport - inorganic / organic molecules, gases, nutrients, excretory products
- temperature regulation
What is erythropoiesis?
Formation of red blood cells
What are the requirements for erythropoiesis to occur?
- erythropoietin (EPO)
- iron
- vitamins B12 + folic acid
- amino acids
- intrinsic factor
Where does erythropoiesis occur ?
Foetus
- early foetus - yolk sac, spleen, liver
- late foetus - bone marrow
Infant - all bone marrow
Adult - only red bone marrow - ribs, vertebrae, skull, upper ends of long bones
Where is erythropoietin produced?
Kidneys
What is the function of haemoglobin?
- transport O2 from lungs to tissues
- transport CO2 from tissues to lungs
Describe the structure of haemoglobin
- 4 subunits - 2 alpha + 2 beta
- surround a central haem group (Fe2+ ion) - can bind reversibly w/ oxygen molecule
What is anaemia?
When haemoglobin conc. in whole blood is below the accepted range
( less than 13.5 g/dl for men)
( less than 12 g/dl for women)
What are some causes of hypoxia? (Low O2 levels)
- increase in exercise
- high altitude
- smoking
- bleeding
What are some features of iron deficiency anaemia? (5)
- most common form of anaemia
- hypochromic
- microcytic RBC’s
- decreased mean cell volume (MCV)
- causes - pregnancy, malnutrition, menorrhagia
What are some features of megaloblastic anaemia? (5)
- vitamin B12 / folate deficiency
- abnormal RBC’s
- reduced Hb concentration
- macrocytic
- increase mean cell volume (MCV)
What are some features of sickle cell anaemia?
- hereditary
- abnormal Hb structure
- sickle shape cell - RBC’s get stuck in blood vessels
What are the first 3 things to occur when a vessel injury occurs?
- platelet adhesion (due to collagen exposure)
- vasoconstriction
- blood coagulation cascade
What is the purpose of the coagulation phase?
To convert soluble plasma proteins to insoluble rigid polymer fibrin
Outline the extrinsic pathway of the coagulation phase
- tissue damage occurs
- Tissue factor III binds Ca2+ and clotting factor VII
- forms factor VII-tissue factor complex
- binds to factor X to form FXa
Outline the intrinsic pathway in the coagulation phase
Factor XIII binds with PF-3, Ca2+, co-factor VIII, and factor IX
- forms factor X activator complex
- activates factor X to become FXa
Outline the common pathway in the coagulation phase
- starts with prothrombinase (consists of FXa and FVa as a cofactor)
- prothrombinase activates prothrombin to form thrombin
- thrombin converts fibrinogen to fibrin
What is the importance of calcium and vitamin K to the clotting process?
- affect almost every aspect of clotting process
- any disorder that decreases Ca2+ conc. will impair blood clotting
- vitamin K necessary from production of clotting factors in liver e.g. prothrombin
Outline the clotting process
- injury occurs
- activates tissue factors, platelet adhesion, and vasoconstriction
- as a result of the tissue factors, the coagulation phase occurs, resulting in fibrin production
- as a result of platelet adhesion and vasoconstriction, platelet aggregation can occur, leading to the formation of a primary haemostatic plug
- when primary haemostatic plug is combined with fibrin, it forms stable haemostatic plug (i.e. a clot)
How is clotting controlled?
- Antithrombin - inhibits thrombin + other factors
- heparin - co-factor that accelerates actions of antithrombin
Antithrombin is main bully and heparin is a goon
What is fibrinolysis?
- fibrin clot being broken down
- occurs via plasmin - enzyme that produces fibrin degradation products
Which of A, B, or O genes are recessive or dominant?
- A + B genes are dominant (and if inherited together express codominance)
- O gene is recessive
How is the Rhesus blood group dictated as a positive or negative?
- ## presence or absence of D antigen
