Blood Cells

Question 1

what constitutes the cellular component of blood?

Answer 1

red blood cells, white blood cells, platelets

Question 2

what constitutes the fluid component of blood?

Answer 2

plasma

Question 3

what is normal haematocrit?

Answer 3

(volume of RBC in blood) 0.45

Question 4

what is the production of blood cells and platelets throughout life called?

Answer 4

haemopoiesis

Question 5

what are the lifespans of RBC, WBC and platelets?

Answer 5

RBC: 120 days
WBC: 6 hours
platelets: 7 - 10 days

Question 6

where is the bone marrow in adults, children and in utero?

Answer 6

adults: skull/ribs/spine/pelvis/long bones
children: all bones
in utero: yolk sac, liver, spleen

Question 7

what does it mean if precursor cells are found in blood?

Answer 7

the patient has leukaemia

Question 8

what are the hormonal growth factors that stimulate proliferation and differentiation of precursors into RBC, WBC and platelets?

Answer 8

RBC: epo (erythroprotein) [produced in kidneys]
WBC: GCSF (granulocyte colony stimulating factor)
platelets: TPO

Question 9

what is the effect of a decrease in pH on the oxygen dissociaiton curve?

Answer 9

fall in pH –> increase in concentration of H+ ions –> deoxyhaemoglobin is stabilised in T state –> less affinity for O2 –> increase in rate of O2 dissociation

Question 10

what is the effect of an increase in temperature on the oxygen dissociation curve?

Answer 10

increase in temperature –> bond between O2 and Fe2+ is denatured –> increase in rate of O2 dissociation

Question 11

what are the components of RBC?

Answer 11

1. haemoglobin
2. enzymes for glycolysis
3. membrane to enclose haemoglobin

Question 12

what does haemoglobin transfer O2 to when it reaches tissues?

Answer 12

myoglobin

Question 13

what is the dominance of A,B and O antigens?

Answer 13

A and B: co-dominant

O: recessive

Question 14

what does ‘Rhesus positive’ indicate?

Answer 14

D antigen is present

Question 15

what is anaemia?

Answer 15

a decrease in Hb level in blood

Question 16

what is the normal Hb level?

Answer 16

12.5 - 15.5 g/dl

Question 17

what is the condition when Hb levels are higher than normal?

Answer 17

polycythaemia

Question 18

what are causes of anaemia?

Answer 18

1. Fe deficiency
2. B12/folate deficiency
3. chronic disorder
4. haemolysis
5. bone marrow failure/infiltration

Question 19

how is RBC size measured and what is normal size?

Answer 19

MCV = mean cell volume

normal MCV = 82 - 96 fl

Question 20

what is RBC size and quantity in Fe deficiency anaemia?

Answer 20

MCV = < 80

quantity: low Hb levels

Question 21

what are the causes of Fe deficiency anaemia?

Answer 21

1. bleeding [occult gastrointestinal bleeding/menorrhagia]

2. dietary

Question 22

what happens to RBC in B12/folate deficiency anaemia?

Answer 22

MCV > 100 fl (macrocytic anaemia)

Question 23

how does B12 deficiency occur? how does it lead to anaemia?

Answer 23

cause 1: B12 absorption occurs at terminal ileum. For this to occur, the gastric parietal cells in the stomach must produce the intrinsic factor, as B12 must bind to intrinsic factor to be absorbed. Hence, stomach damage –> lower B12 absorption.

cause 2: autoimmune disease called pernicious anaemia –> causes antibodies to be made against gastric parietal cells (slow onset as liver has vast store of B12)

B12/folate are needed for DNA synthesis, so without B12, RBC cannot be produced

Question 24

how does folate deficiency occur?

Answer 24

• dietary (as folate is found in fruits/vegetables)
• malabsorption due to celiac disease
• increased ‘demand’ for folate (due to haemolysis/anything that leads to increased cell division)

Question 25

what is haemolysis?

Answer 25

normal or increased RBC production with decreased lifespan ( < 30 days)

Question 26

what are congenital causes of haemolysis?

Answer 26

1. membrane issues (spherocytosis)
2. enzyme issues (pyruvate kinase/G6Pd deficiency –> RBC not stabilised)
3. haemoglobin issues (sickle-cell disease/ thalassaemia)

Question 27

what are acquired causes of haemolysis?

Answer 27

1. autoimmune (can be triggered by blood transfusion)
2. mechanical (fragmentation of RBC by mechanical heart valve/intravascular thrombosis in disseminate vascular coagulation)
3. pregnancy (Rhesus disease which HDFN)

Question 28

what are the two main types of WBC?

Answer 28

neutrophils and lymphocytes

Question 29

what do neutrophils release?

Answer 29

chemotaxins and cytokines

Question 30

what are B cells named after? What do they do?

Answer 30

bone marrow

differentiate into plasma cells that produce immunoglobins and antigen-presenting cells (APCs)

Question 31

what are T cells named after? What do they do?

Answer 31

thymus

helper T cells: help B-cells in antibody generation, recruit more cytotoxic T cells

cytotoxic T cells: kill infected cells by releasing perforins and granzymes

Question 32

what are WBC conditions?

Answer 32

1. acute leukaemia: proliferation of precursor cells w/o differentiation –> replaces normal blood marrow cells –> anaemia, neutropenia and thrombocytopenia
2. acute myeloblastic leukaemia (AML): malignant proliferation of myeloblasts (adults)
3. acute lymphocytic leukaemia (ALL): malignant proliferation of the lymphoblast precursors (children)
4. high grade lymphoma: lymphocytes in lymph nodes –> malignant –> hodgkins/non-hodgkins lymphoma –> disease of the lymph nodes that spreads to liver, spleen, bone marrow, blood

Question 33

what do platelets determine?

Answer 33

bleeding time (PT: prothrombin time)

Question 34

what cells are platelets made from?

Answer 34

megakaryocytes

Question 35

normal number of platelets?

Answer 35

140 - 400 x 10^9 / L

Question 36

what is it called when there’s fewer platelets than normal + what are the risks?

Answer 36

thrombocytopenia

cranial bleeding (increased/spontaneous)

Question 37

what is it called when there’s more platelets than normal + what are the risks?

Answer 37

thrombocytosis

arterial/venous thrombosis –> increased risk of heart attack/stroke