haematopoiesis

Question 1

what is blood

Answer 1

special type of fluid connective tissue derived from the mesoderm (germ layer)

Question 2

what is the colour of blood in the arteries compared to the veins

Answer 2

blood is bright red in the arteries whereas in the veins its dark red

Question 3

what is the mass of blood

Answer 3

8% of the body mass

Question 4

what is the pH of blood

Answer 4

slightly alkaline (7.35-7.45)

Question 5

what is the taste of blood

Answer 5

salty

Question 6

what is the temperature of blood

Answer 6

38 degrees celcius

Question 7

what is the viscosity of blood

Answer 7

3-4 times more viscous than water

Question 8

what is the volume of blood

Answer 8

5-6 litres

Question 9

what is haematology

Answer 9

branch of science concerned with the study of blood, tissues that form blood and disorders associated with blood

Question 10

what are examples of blood disorders

Answer 10

• red blood cell disorder
• white blood cell disorder

Question 11

what is the composition of blood

Answer 11

• plasma (55%)
• buffy coat (4%)
• red blood cells (41%)

Question 12

describe plasma

Answer 12

• its the least dense component
• contains electrolytes (eg, Na+, K+), proteins (eg, immunoglobins) and small organic molecules (eg, glucose)

Question 13

describe the buffy coat

Answer 13

contains white blood cells (leukocytes) and platelets

Question 14

describe red blood cells

Answer 14

• most dense component
• haematocrit is the ratio of the volume of RBCs to the total volume of blood

Question 15

describe full blood count (FBC)

Answer 15

• most requested in haematology
• blood cell counting is used in differential diagnosis of anaemia, leukaemia and thrombocytopenia
• FBCs are performed by automated counting machines (eg, coulter analysers)

Question 16

what are the 10 parameters used

Answer 16

• Haemoglobin (Hb)
• Red blood cell count (RBC)
• white blood cell count (WBC)
• platelet count (PLT)
• mean corpuscular volume (MCV)- average RBC size
• mean corpuscular Hb (MCH)
• mean corpuscular Hb concentration (MCHC)
• packed cell volume (PCV)
• reticulocyte count
• differential white count

Question 17

what is haematopoiesis

Answer 17

blood cell production

Question 18

what type of cells do all blood cells originate from

Answer 18

haematopoietic stem cells from multipotent stem cells in the bone marrow

Question 19

what does erythropoiesis mean

Answer 19

production of RBCs

Question 20

what does thrombopoiesis mean

Answer 20

production of platelets

Question 21

what does myelopoiesis mean

Answer 21

production of WBCs

Question 22

what are stem cells

Answer 22

they are undifferentiated cells

Question 23

what are the two features of stem cells

Answer 23

• capable of self renewal
• can differentiate into any type of mature cell

Question 24

what is a mature cell

Answer 24

cell that is already differentiated

Question 25

what are haematopoietic stem cells

Answer 25

• very rare
• long term HSCs: able to repopulate the bone marrow
• short term HSCs: engraft transiently (over short time) for a few weeks

Question 26

what are the sites of haematopoiesis (from embryo to adult)

Answer 26

• foetus: 0-2 months occurs in yolk sac
  2-7 months occurs in the liver and spleen
  5-9 months occurs in the bone marrow
• infant: occurs in the bone marrow
• adults: occurs in the vertebrae, sternum, skull etc.

Question 27

where does haematopoiesis occur in adults

Answer 27

• major sites: sternum, femur, pelvis
• minor sites: ribs, skull, sacrum

Question 28

what is haematopoiesis occurring in the bone marrow called

Answer 28

intramedullary haematopoiesis

Question 29

what is haematopoiesis occurring in the liver and spleen called

Answer 29

extramedullary haematopoiesis

Question 30

what is the life span of erythrocytes

Answer 30

120 days