lecture 1 - the blood count

Question 1

What is the morphology of RBCs in a normal blood film?

Answer 1

Uniform size, central pale zone occupies 1/3 red cell diameter.

Question 2

What stain is typically used in a blood film?

Answer 2

Romanowsky stain

Question 3

What is the morphology of platelets in a stained normal blood film?

Answer 3

Pale purple cytoplasm, central granules

Question 4

What RBC values are measured in a blood count?

Answer 4

Haemoglobin, mean cell volume, mean cell Hb, Haematocrit, Red cell count, mean cell Hb conc.

Question 5

What are the 2 most important RBC parameters in a blood count?

Answer 5

Haemoglobin (g/L), mean cell volume (fL)

Question 6

What does the mean cell volume show about RBCs?

Answer 6

Their size, and therefore how much Hb they are carrying.

Question 7

What 3 values regarding RBCs are measured in a blood count, and are then used to calculate other parameters?

Answer 7

Hb concentration, mean cell volume, red cell count

Question 8

What is the normal range for MCV (mean cell volume in fL) for adult females?

Answer 8

80-99 (same as males)

Question 9

What is the normal range for MCV (mean cell volume in fL) for adult males?

Answer 9

80-90 (same as females)

Question 10

What is the biomedical definition of Anaemia?

Answer 10

Low haemoglobin levels - and thus a reduced ability to transport oxygen in blood

Question 11

What is the WHO definition of anaemia for males, in terms of Hb concentration (g/L)?

Answer 11

Hb < 130g/L

Question 12

What are the 3 types of anaemia, based on morphological pattern/cell size?

Answer 12

microcytic (small cells), normocytic (normal cells), macrocytic (large cells)

Question 13

What terms are used to describe low, normal and high levels of Hb in a RBC?

Answer 13

hypochromic (low Hb), normochromic (normal Hb), hyperchromic (high Hb)

Question 14

What is observed in a blood film displaying normocytic anaemia?

Answer 14

Normal red cells, but fewer of them

Question 15

What is observed in a blood film displaying microcytic anaemia?

Answer 15

Small under-filled pale red cells containing less Hb

Question 16

What is observed in a blood film displaying macrocytic anaemia?

Answer 16

Large red cells

Question 17

What type of anaemia is caused by iron deficiency?

Answer 17

microcytic anaemia

Question 18

What are the features of microcytic anaemia in a blood count?

Answer 18

Low Hb, low MCV (mean cell volume)

Question 19

What are the causes of normocytic anaemia?

Answer 19

haemodilution, renal failure, bone marrow failure, anaemia of inflammation

Question 20

What type of anaemia does haemodilution cause, and why?

Answer 20

Normocytic - after acute blood loss the blood can be diluted before RBCs can be generated.

Question 21

What type of anaemia does renal failure often cause, and why?

Answer 21

Normocytic anaemia - insufficient erythropoietin (EPO) production leads to lower RBC production

Question 22

What type of anaemia does inflammation cause, and why?

Answer 22

Normocytic, though microcytic when severe - reduced RBC production due to reduced availability of iron to prevent bacterial colonisation.

Question 23

What are the features of normocytic anaemia in a blood count?

Answer 23

Low Hb concentration, but normal mean cell volume

Question 24

What is the most common cause of macrocytic anaemias?

Answer 24

Liver disease,folic acid & vitamin B12 deficiency

Question 25

What specific type of anaemia does folic acid or Vitamin B12 deficiency cause?

Answer 25

Megaloblastic anaemia

Question 26

What is megaloblastic anaemia?

Answer 26

When the bone marrow produces large, irregular, immature red blood cells (megaloblasts)

Question 27

What are the features across a blood count, of macrocytic anaemia?

Answer 27

Pancytopenia - reduction in Hb, platelets and neutrophils, high mean cell volume, and mean cell haemoglobin

Question 28

What is the name of the process in which blood cells are made?

Answer 28

Haematopoiesis

Question 29

Where does haematopoiesis occur?

Answer 29

Bone marrow

Question 30

Where is the bone marrow in which haematopoiesis occurs in adults?

Answer 30

mainly the axial skeleton - skull, vertebrae, ribs, sternum, pelvis

Question 31

Where is the bone marrow in which haematopoiesis occurs in children?

Answer 31

axial skeleton and long bones

Question 32

Where does haematopoiesis occur in fetuses?

Answer 32

The liver and spleen, minimal in the bone marrow

Question 33

What is the difference between totipotent and pluripotent stem cells?

Answer 33

Totipotent can develop into embryonic or placental tissues, while pluripotent can develop into all embryonic lineages

Question 34

What is the name for blood stem cells in the marrow that can develop into all types of blood cell?

Answer 34

Haematopoietic stem cells

Question 35

What are the 2 committed stem cells that haematopoietic stem cells can directly differentiate into, and what lineages do they begin?

Answer 35

Myeloid stem cells (meyloid lineage), lymphoid stem cells (lymphoid lineage)

Question 36

What cells are in the myeloid lineage?

Answer 36

erythrocytes (RBCs), platelets, some white blood cells (granulocytes, monocytes/macrophages),

Question 37

What cells are the lymphoid lineage?

Answer 37

B-cells, T-cells, Natural Killer Cells

Question 38

What is the role of cytokine signals in haematopoiesis?

Answer 38

Regulation - induce growth & differentiation

Question 39

Where are cytokine signals that regulate haematopoiesis produced?

Answer 39

Peripheral tissues and cells of bone marrow

Question 40

What is the role of marrow stromal cells in haematopoiesis regulation?

Answer 40

regulatory signals act on marrow stromal cells.

Question 41

What is erythropoiesis?

Answer 41

Red blood cell (erythrocyte) production