Haematology 1

Question 1

Where do blood cells originate from and what 2 things do they give rise to

Answer 1

Multipotent haemopoietic stem cells in the bone marrow

Myeloid stem cell/precursor
Lymphoid stem cell

Question 2

What can a lymphoid stem cell give rise to

Answer 2

NK cell
B cell
T cell

Question 3

What can a myeloid stem cell give rise to

Answer 3

Proerythroblast

Granulocyte
Erythroid
Megakaryocyte

Question 4

What feature are stem cells characterised by and how is it achieved

Answer 4

Ability to self renew and produce mature progeny
They can divide into two cells with different characteristics, one another stem cell and the other a cell capable of differentiating to mature progeny

Question 5

Describe the how a stem cell gives rise to a red cell

Answer 5

1. Multipotent haemopoietic stem cells
2. Myeloid stem cell precursor
3. Proerythroblast
4. Erythroblasts
5. erythrocytes

Question 6

What is erythropoiesis and what does it require

Answer 6

Production of red cells
Requires erythropoietin (synthesised by the kidney)

Question 7

Describe the red cell response to hypoxia

Answer 7

1. Hypoxia/anaemia
2. Erythropoietin synthesis
3. Increased bone marrow activity
4. Increased red cell production

Question 8

Where does erythropoietin synthesis occur (+proportion)

Answer 8

Liver hepatocytes and interstitial cells - 10%

Kidney juxtatubular interstitial cell - 90%

Question 9

Describe the red blood cell (lifespan, functions and excretion/removal)

Answer 9

Survives 120 days in the blood stream
Function is oxygen and CO2 transport
Destroyed phagocytic cells of the spleen

Question 10

Describe the physiology of white cells from stem cells

Answer 10

1. Multipotent haemopoietic stem cell
2. Myeloblast + monoblast
3. Granulocytes + monocytes

Question 11

Describe neutrophils

Answer 11

Defence against infections via phagocytosis

Neutrophil granulocytes survive 7-10 hours in the circulation before migrating to tissues

Question 12

Describe eosinophils (role+circulatory lifespan)

Answer 12

Defence against parasitic infection

Shorter duration in the circulation than the neutrophil

Question 13

What is the role of basophils

Answer 13

Allergic response

Question 14

Describe monocytes

Answer 14

Migrate to tissues where they develop into macrophages - phagocytic and scavenging function
Stores and releases iron
Stays in the circulation for several days

Question 15

Describe platelets

Answer 15

Primary haemostasis
Contribute phospholipid - promotes blood coagulation
Derived from megakaryocytic
Survive 10 days in circulation

Question 16

Describe lymphocytes

Answer 16

Lymphoid stem cells -> T, B, NK cells
Lymphocytes recirculate to lymph nodes and other tissues then back to the blood
Variable intravascular lifespan

Question 17

What is anisocytosis

Answer 17

Red cells show more variation in size than is normal

Question 18

What is poikilocytosis

Answer 18

Red cells show more variation in shape than is normal

Question 19

What is microcytosis

Answer 19

Red cells are smaller than normal

microcyte = cell that is smaller

Question 20

What is macrocytosis

Answer 20

Red cells are larger than normal

macrocyte = cell that is larger

Question 21

What are the types of macrocytes

Answer 21

Round macrocytes
Oval macrocytes
Polychromatic macrocytes

Question 22

Describe the colour differences in a normal red cell

Answer 22

1/3 of the diameter of red cells are pale

Due to the disk shape of the cell the centre has less haemoglobin

Question 23

What is hypochromia

Answer 23

Red cells have a larger area of central pallor than normal
Due to a lower haemoglobin content and conc. + flatter cell
Often associated with microcytosis

Question 24

What is hyperchromia

Answer 24

Cells lack central pallor
Due to greater thickness or abnormal shape
2 types: spherocytes and irregularly contracted cells

Question 25

Describe spherocytes

Answer 25

Cells that are approx. spherical Round, regular outline and lack central pallor Due to loss of cell membrane without the loss of an equivalent amount of cytoplasm -> round cell

Question 26

Describe irregularly contracted cells

Answer 26

Irregular outline but smaller than normal cells + no central pallor Due to oxidant damage to the cell membrane and to the haemoglobin

Question 27

What is polychromasia

Answer 27

Increased blue tinge to the cytoplasm of a red cell | Indicates that the red cell is young

Question 28

How can you tell which red cells are young

Answer 28

Look for polychromasia | Reticulocyte stain - exposes red cells to new methylene blue, precipitates as a network of reticulum

Question 29

What are the shapes that poikilocytes can come in

Answer 29

``` Spherocytes Irregularly contracted cells Sickle cells Target cells Elliptocytes q Fragments ```

Question 30

Describe target cells

Answer 30

Cells with an accumulation of haemoglobin in the centre of the area of central pallor Occurs in obstructive jaundice, liver disease, haemoglobinopathies and hyposplenism

Question 31

Describe elliptocytes

Answer 31

Elliptical in shape | Occurs in hereditary elliptocytosis and in iron deficiency

Question 32

Describe sickle cells

Answer 32

Sickle or crescent shaped | Results from the polymerisation of haemoglobin S when it is present in a high concentration

Question 33

Describe fragments

Answer 33

AKA schistocytes Small pieces of red cells Indicates that a red cell has fragmented

Question 34

Describe rouleaux

Answer 34

Stacks of red cells Resembles a pile of coins Results from alterations in plasma proteins

Question 35

What are agglutinates

Answer 35

Similar to rouleaux but are irregular clumps | Results from antibodies on the surface of the cells

Question 36

What is a Howell-Jolly body

Answer 36

Nuclear remnant in a red cell | Commonest cause is lack of splenic function

Question 37

``` Define: Leucocytosis Leucopenia Neutrophilia Neutropenia Lymphocytosis Eosniphilia ```

Answer 37

``` Leucocytosis - too many white cells Leucopenia - too few white cells Neutrophilia - too many neutrophils Neutropenia - too few neutrophils Lymphocytosis - too many lymphocytes Eosniphilia - too many eosinophils ```

Question 38

``` Define: Thrombocytosis Thrombocytopenia Erythrocytosis Reticulocytosis Lymphopenia ```

Answer 38

``` Thrombocytosis - too many Thrombocytopenia Erythrocytosis Reticulocytosis Lymphopenia ```

Question 39

What does atypical lymphocyte describe

Answer 39

Abnormal cells present in infectious mononucleosis (glandular fever)

Question 40

What is left shift

Answer 40

Increase in non-segmented neutrophils or neutrophil precursors present in the blood

Question 41

What is toxic granulation

Answer 41

Heavy granulation of neutrophils Results from infection, inflammation and tissue necrosis Normal feature of pregnancy

Question 42

Describe the hypersegmented neutrophil

Answer 42

Increase in the average number of neutrophil lobes or segments Results from a lack of vitamin B12 or folic acid Right shift

Question 43

What is required for differentiation of multipotent haemopoietic stem cells into granulocytes/monocytes

Answer 43

Cytokines (G-CSF, M-CSF, GM-CSF) | interleukins are required