Haematology I - Lecture 8

Question 1

What is the average blood volume of an adult?

Answer 1

5L

Question 2

What are the main components of blood?

Answer 2

○ 55% = Plasma [normal range 46-63%]
○ 45% = Red blood cells
○ <1% = White blood cells and platelets

Question 3

What are the components of plasma?

Answer 3

○ Water = 92%
○ Plasma Proteins = 7% (Albumin, globulin, fibrinogen, regulatory proteins)
○ Other Solutes = 1% (Electrolytes, organic nutrients and waste)

Question 4

What are the main functions of blood?

Answer 4

Transport of:
○ O2 and CO2
○ Nutrients
○ Waste
○ Temperature
○ Hormones
Defenese:
○ Antibodies, WBCs
○ Clotting factors

Question 5

What is haematopoiesis?

Answer 5

Process by which blood cells are formed from hemocytoblast

Question 6

What happens during erythropoiesis?

Answer 6

○ Stem cell = hemocytoblast
○ Committed cell = proerythroblast
Phase 1: Ribsome synthesis (decreases)
○ Early erythroblast -> Late erythroblast
Phase 2: Haemoglobin accumulation (increases)
○ Late erythroblast -> Normoblast
Phase 3: Ejection of nucelus
○ Normoblast (ejected nucleus) -> Reticulocyte -> Erythrocyte

Question 7

What are the requirements for erythropoiesis?

Answer 7

○ Erythropoietin (EPO) = Growth factor
○ Iron
○ Vitamins B12 & folic acid (B9)
○ Intrinsic factor = Absorbs Vitamin B12
○ Amino acids = Used to make globin in haemaglobin

Question 8

Where does erythropoiesis occur?

Answer 8

○ Foetus: yolk sac, then liver & spleen, later in bone marrow
○ Infant: all bone marrow
○ Adult: red bone marrow (ribs, vertebrae, skull, upper ends of long bones)
Rate: 2-3 million red blood cells per second

Question 9

What is the structure of a red blood cell?

Answer 9

○ Biconcave disc
○ Highly flexible and readily deformed
○ Contains haemoglobin
○ Average size is 7.2-8.4 um
○ Lifespan ~ 120 days

Question 10

What cell breaks down aged or damaged RBCs?

Answer 10

○ Macrophage

Question 11

Which organs are macrophages found?

Answer 11

○ Liver
○ Spleen (main)
○ Lymph node

Question 12

What is haemaglobin broken down into?

Answer 12

Heme -> bilirubin and iron
Globin -> amino acids

Question 13

What happens to the broken down iron?

Answer 13

Transferrin (transport protein) stores it in the spleen or stores it as ferritin in the liver

Question 14

What happens to the broken down bilirubin?

Answer 14

○ Taken to the liver by serum albumin
○ Bilirubin is secreted into the bile
○ Excreted as urine or feces

Question 15

What happens in erythrocyte homeostasis?

Answer 15

○ Low O2 blood level detected
○ Kidneys increase production of erythropoietin
○ Stem cells increase RBC production
○ O2 blood levels return to normal

Question 16

What are the causes of hypoxia?

Answer 16

○ Increase in exercise
○ High altitude
○ Smoking
○ Bleeding

Question 17

How many haemoglobin molecules are there per red blood cell?

Answer 17

~280 million

Question 18

When does synthesis of haemoglobin begin?

Answer 18

Begins in proerythroblast
○ 65% at erythroblast stage
○ 35% at reticulocyte stage

Question 19

How much haemoglobin is there in males and females?

Answer 19

○ Females: 12-16g/dL
○ Males: 13.5-17.5g/dL

Question 20

What is the structure of Haemoglobin adult (HbA)?

Answer 20

○ 4 subunits: 2 alpha and 2 beta
○ Each subunit consists of: Haem bound to long polypeptide chain (globin)
○ Fe2+ in the centre

Question 21

What is anaemia?

Answer 21

○ Haemoglobin concentration in whole blood below the accepted normal range
○ Less than 13.5g/dL for men and less than 12.0g/dL for women
○ Common problem affecting 1/3 of the world population

Question 22

What are the causes of anaemia?

Answer 22

○ Decreased RBC production
○ Increased RBC destruction
○ Blood loss

Question 23

What are the characteristics of iron deficiency anaemia?

Answer 23

○ Most common anaemia
○ Hypochromic (pale RBCs)
○ Microcytic (small) RBCs
○ Decreased mean cell volume

Question 24

What are the causes of iron deficiency anaemia?

Answer 24

○ Pregnanacy
○ Bleeding from GI tract
○ Malabsorption
○ Menorrhagia
○ Malnutrition

Question 25

What are the characteristics of megaloblastic anaemia?

Answer 25

○ Abnormal RBC
○ Reduced Haemoglobin concentration
○ Macrocytic (large)
○ Increased mean cell volume

Question 26

What causes megaloblastic anaemia due to folate deficiency?

Answer 26

Get macrocytic anaemia
○ Pregnancy
○ Elderly
○ Dietary deficiency

Question 27

What causes megaloblastic anaemia due to Vitamin B12 deficiency?

Answer 27

Unable to absorb vitamin B12
○ Lack of Intrinsic Factor needed to absorb vitamin B12 (pernicious anaemia)
○ Chrohn’s, coeliac disease

Question 28

What are the characteristics of sickle cell anaemia?

Answer 28

○ Hereditary: African or West Indian descent
○ Abnormal haemoglobin structure
○ Sickle-shaped red blood cells, which can get stuck in blood vessels

Question 29

What are the characteristics of thalassaemias?

Answer 29

○ Hereditary: Mediterranean, Middle Eastern or Far Eastern descent
○ Abnormal haemoglobin production (alpha and beta thalassaemias)