lecture 6

Question 1

what does RBC contain?

Answer 1

• 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

Question 2

define erythropoiesis + the process

Answer 2

• 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

Question 3

describe RBC generation time, where it is produced and found

Answer 3

• 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

Question 4

describe the feedback loop when there isnt enough oxygen in the blood

Answer 4

*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%

Question 5

what is anaemia and how can we detect it and other illnesses?

Answer 5

• 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

Question 6

possuble causes of anaemia

Answer 6

○ Reduced haemoglobin levels (e.g. Iron deficiency)
○ Decreased erythropoiesis (RBC production)
Excessive RBC loss (e.g. Haemorrhage)

Question 7

describe the 2 types of polycythaemia

Answer 7

• Primary- Due to overactive bone marrow
• Secondary- due to poor oxygen delivery (altitude, lung, or heart disease)

Question 8

describe anaemias related to reduced haemoglobin levels

Answer 8

nutritional anaemia- Iron + folic acid deficiency
Pernicious anaemia- Lack of intrinsic factor, so cant absorb vitamin B12 (helps make iron)

Question 9

describe anaemia related to decreased erythropoiesis

Answer 9

Aplastic anaemia- Toxins, radiation, cancer
Renal anaemia- Kidney disease reduces erythropoietin production

Question 10

describe anaemia related to excessive RBC loss

Answer 10

Haemorrhagic anaemia- Accurate or chronic blood loss
Haemolytic anaemia- Caused by increased rate of RBC destruction, e.g. Sick-cell anaemia, malaria, toxins

Question 11

describe sickle cell disease

Answer 11

• 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

Question 12

describe platelets

Answer 12

• 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

Question 13

describe haemostasis

Answer 13

• Is the mechanism that stops bleeding
  
  • Process involves
    
    1. Vascular spasm (vasoconstriction)
    2. Platelet plug formation
       Blood clotting (coagulation)

Question 14

describe platelet plug process

Answer 14

1. Exposed collagen binds and activates platelets
   2. Release of platelet factors
   3. Attracts more platelets
   4. Aggregate into platelet plug

Question 15

describe blood coagulation cascade

Answer 15

• 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

Question 16

describe clot dissolution

Answer 16

• 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

Question 17

describe heparin as an anticoagulants

Answer 17

• 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

Question 18

define embolism + stroke + pulmonary embolism

Answer 18

• 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