introduction to blood

Question 1

describe blood composition

Answer 1

• plasma (55%) and formed elements (45% - RBC, WBC, platelets)
• buffer coat (leucocytes and platelets <1%)

Question 2

what are the physical characteristic of blood

Answer 2

• sticky, opaque fluid, scarlet red to dark red (oxygen content)
• pH 7.35-7.45 (buffer)
  38˚C (higher than body temp)
• ~8% body weight, 5-6 L = males, 4-5 L = females

Question 3

what are the functions of blood

Answer 3

• distribution of: oxygen, nutrients (vitamins / AA), metabolic wastes and hormones
• regulation of: body temp (vasoconstriction / vasodilation), normal pH (buffer)
  protection against: blood loss (platelets) and infection (WBC)

Question 4

describe structure / function of plasma

Answer 4

• 90% water
• dissolved proteins: mainly produced by liver, 60% albumin = maintain osmotic pressure, 36% globulin = buffer / antibodies, 4% fibrinogen = clots with platelets
• nitrogenous byproducts, nutrients, electrolytes, respiratory gases and hormones

Question 5

summary of formed elements

Answer 5

• RBC survive 100-120 days
• others survive a few days
• BC originate in red bone marrow, do not divide
• BC formation = hematopoiesis
• WBC = real / complete, biggest
• RBC = no nuclei, most abundant
• platelets: cell fragments, smallest

Question 6

what are RBC

Answer 6

• erythrocytes (45% of blood)
• biconcave (increased SA)
• > 97% haemoglobin
• no mitochondria (ATP production = anaerobic)
• dense, elastic (compressible)
• F: 2 alpha + 2 beta chains = 4x iron / heme groups = 4x oxygen molecules, heme pigment (red),

Question 7

what is erythropoiesis, how is it regulated and what is hypoxia

Answer 7

• RBC production
• hemocytoblast (stem cells - ability to differentiate)
• transformed into pro-erythroblast and become reticulocyte (15 days)
• 2 days = erythrocyte once in blood
• regulation: hormonal control (erythropoietin - EPO) combined with adequate iron, AA and vit. B = stimulate growth
• little RBC = hypoxia (not enough O to maintain metabolism)
• too many = increase viscosity (stroke / heart attack)
• hypoxia: not enough EPO, haemorrhage, increased RBC destruction, insufficient haemoglobin (iron deficiency), high altitude (reduced availability of O)

Question 8

what is anaemia and the 3 different causes

Answer 8

• anaemia: abnormally low O2 carrying capacity, sign of underlying disease, cannot support metabolism
• fatigue, paleness, shortness of breath, chills
• insufficient RBC: hemorrhagic (escape of blood), haemolytic (destruction of RBC), aplastic (damaged bone marrow, doesn’t function normally)
• low haemoglobin: iron deficiency (follows hemorrhagic anaemia), pernicious anaemia (old people, lack vitamin B12; normal division of cells)
• abnormal haemoglobin: thalassemia (absent or faulty globin chain, thin RBC) and sickle cell (thin, fragile RBC, change in 1 of 146 AA)

Question 9

what are the 4 types of WBC

Answer 9

• granulocytes: granules in cytoplasm
• neutrophils: most numerus, fine granules, acidic and neutral, contain hydrolytic enzymes / defensins
• eosinophils: red / crimson, lysosome like granules, fight worms, important in allergic reaction
• basophils: rare, large purplish / black, contain histamine (inflammation / vasodilator), similar to mast cells

Question 10

what are lymphocytes

Answer 10

• present in lymphoid tissue
• few circulate in blood, crucial to immunity
• types: B (antibody), T (kill bacteria) and NK (natural killer cells, lack of MHC = invader, not phagocytic)

Question 11

what are monocytes

Answer 11

• abundant pale-blue cytoplasm, purple nucleus
• leave circulation enter tissues and differentiate into macrophages (phagocytic, immune response)
• actively phagocytic
• activate lymphocytes

Question 12

what are platelets

Answer 12

• small fragments of megakaryocytes, granules contain serotonin, Ca enzymes, ADP and PDGF (platelet derived GF)
• formation regulated by thrombopoietin
• involved in clotting (requires Ca and vitamin K)

Question 13

what are 2 types of blood disorders

Answer 13

• haemophilia: x linked, absence of factor VIII (coagulation factor), women usually carriers, external bleeding episodes, bruising / internal bleeding
• malaria: plasmodium (parasite) enters blood and affects RBC, female anopheles mosquito = vector, travel to liver destroying RBC, vomiting, fever, headaches, anaemia, joint pain