lecture 6 Flashcards
what does RBC contain?
- Transport gases (O2 + CO2)
- Contains
○ Haemoglobin (allows O2 to bind to it)
○ Glycolytic enzymes (breakdown glucose- essential for metabolism cause RBC dont have mitochondria or nucleus)
Carbonic anhydrase- catalyses the conversion of CO2 + water to carbonic acid, which then dissociates into HCO3-, this transports CO2 and acts as a buffer
- Contains
define erythropoiesis + the process
- Is red blood production
- Starts from stem cell (hemocytoblast), to committed cell (proerthroblast) to early erythroblast, to late erythroblast, to normoblast, to reticulocyte, to erythrocyte
- Made from stem cells according to hormones
- RBC live only about 120 days
describe RBC generation time, where it is produced and found
- Red blood cells generate at a rate of 2-3 million/sec.
- Produced in red bone marrow, destroyed in spleen/liver
Found in long bones, vertebra, sternum, ribs, skull
- Produced in red bone marrow, destroyed in spleen/liver
describe the feedback loop when there isnt enough oxygen in the blood
*Reduced blood oxygen delievery (hypoxia) detected by kidney, cause kidney to release erythropoietin hormone
* Erythropoietin stimulates bone marrow to make more RBC- takes weeks
* Once blood oxygen delivered, erythropoietin secretion slowed
Can indicate erythropoietic activity seen by reticulocytes no. Greater then 1-2%
what is anaemia and how can we detect it and other illnesses?
- Anaemia- reduced oxygen carrying capacity of blood due to reduced Hb in blood
- Haematocrit can be used to detect anaemia/polycythaemia
○ 45% = normal
○ 30% = anaemia
○ 70% = polycythaemia
○ 70% =dehydration
- Haematocrit can be used to detect anaemia/polycythaemia
possuble causes of anaemia
○ Reduced haemoglobin levels (e.g. Iron deficiency)
○ Decreased erythropoiesis (RBC production)
Excessive RBC loss (e.g. Haemorrhage)
describe the 2 types of polycythaemia
- Primary- Due to overactive bone marrow
- Secondary- due to poor oxygen delivery (altitude, lung, or heart disease)
describe anaemias related to reduced haemoglobin levels
nutritional anaemia- Iron + folic acid deficiency
Pernicious anaemia- Lack of intrinsic factor, so cant absorb vitamin B12 (helps make iron)
describe anaemia related to decreased erythropoiesis
Aplastic anaemia- Toxins, radiation, cancer
Renal anaemia- Kidney disease reduces erythropoietin production
describe anaemia related to excessive RBC loss
Haemorrhagic anaemia- Accurate or chronic blood loss
Haemolytic anaemia- Caused by increased rate of RBC destruction, e.g. Sick-cell anaemia, malaria, toxins
describe sickle cell disease
- Genetic anaemia
- So oxygen carrying capacity of the blood is reduced
- When have this disease, RBC contain haemoglobin S (Hb-S), causes RBC to bend into a sickle shape, distorted shape leads to shorter life span (haemolysis)
Genetic advantage- provides resistance to malaria
describe platelets
- Responsible for thrombus formation
- Blood clots = reinforced platelet plugs
- Are cytoplasmic fragments of megakaryocytes
- Live for 5-9 days
Lack nuclei, but have energy, actin, and myosin
describe haemostasis
- Is the mechanism that stops bleeding
- Process involves
- Vascular spasm (vasoconstriction)
- Platelet plug formation
Blood clotting (coagulation)
- Process involves
describe platelet plug process
- Exposed collagen binds and activates platelets
2. Release of platelet factors
3. Attracts more platelets
4. Aggregate into platelet plug
describe blood coagulation cascade
- Process transforms blood from liquid to solid gel
- Plasma proteins are activated
- Thrombin is formed from prothrombin either in blood or extrinsically
- Thrombin acts on fibrinogen to form fibrin, an insoluble polymer
- Fibrin adheres to the damaged vessels and traps blood cells + platelets to form a clot
- The clot is stabilised by cross linkage
describe clot dissolution
- Used to re-open blood vessels
- The clot is dissolved + controlled by the enzyme plasmin (process called fibrinolysis)
Clot formation + dissolution are in constant action to prevent permanent clotting of tiny vessels that rupture daily
- The clot is dissolved + controlled by the enzyme plasmin (process called fibrinolysis)
describe heparin as an anticoagulants
- Heparin is a anticoagulant containing mast cells + basophils
- Used to prevent clots
- Long term anticoagulation is provided by warfarin or dicoumarol which inhibits synthesis of clotting factors
Use heparin or chelating agents to prevent coagulation, e.g. When getting blood transfusion, so doesnt clot
define embolism + stroke + pulmonary embolism
- Thrombosis
○ Is the formation of a clot that remains in a health blood vessel- Embolism
○ Occurs when a thrombosed blood clot lodges in a blood vessel, blocking it, causing damage and reducing O2 delievery
○ Stroke- blood flow to brain cut off
Pulmonary embolism- blood flow to lungs cut off
- Embolism
