Physiology of Blood Cells and Haematological Terminology

Question 1

What are all blood cells ultimate derived from?

Answer 1

multipotent haematopoietic stem cells

Question 2

What two lineages can this give rise to?

Answer 2

Lymphoid

Myeloid

Question 3

What cells are derived from the multipotent myeloid precursor?

Answer 3

Megakaryocytes
Granulocyte-Monocyte
Erythroid

Question 4

What cells are derived from the multipotent lymphoid precursor?

Answer 4

T cells
B cells
NK cells

Question 5

What are some common features of blasts?

Answer 5

They have a large nucleus and a small amount of cytoplasm

Multipotent haematopoietic stem cells give rise to blasts eg myeloblast

Question 6

How does the colour of red cells change as they mature?

Answer 6

When they are immature they are more blue/purple

As they mature they become pinker

Question 7

Which cells produce EPO? What can trigger the production of EPO?

Answer 7

EPO is mainly produced in the kidneys by the juxtatubular interstitial cells (90%)
It is also produced to a lesser extent by the liver (10%)
EPO production is stimulated by hypoxia

Question 8

What is the life span of a red blood cell?

Answer 8

120 days

Question 9

What feature allows red blood cells to wriggle through small holes in the capillaries in the spleen?

Answer 9

As they lack a nucleus, red blood cells have an extensive cytoskeleton meaning that it is very flexible and can fit through small gaps.
As the cells get older, they becomes less flexible and less able to pass through the capillaries into the sinuses in the spleen
This means that they are more likely to be retained in the spleen and phagocytosed
Normally, they dont get stuck and so can carry on in the circulation without being phagocytosed

Question 10

Define anisocytosis and poikilocytosis

Answer 10

Anisocytosis = red cells show more variation in SIZE than is normal (latin for aniso= uneven)
Poikilocytosis = red cells show more variation in SHAPE than is normal (poikilo=variation/uneven)

Question 11

What can be used as a reference in a blood film to determine whether the red blood cells are microcytic or macrocytic?

Answer 11

Lymphocytes are generally all the same size and are used as a reference.

Normally RBCs are a bit smaller than lymphocytes

Question 12

Define hypochromia.

Answer 12

The red cells have a larger area of central pallor than normal
NOTE: normal red cells have a central pallor that covers around 1/3 of the red cell diameter
NOTE: hypochromia and microcytosis tend to go together as they are both caused by reduced Hb synthesis

Question 13

Define hyperchromia.

Answer 13

The red cells lack a central pallor

Question 14

State two important types(causes) of hyperchromatic cells.

Answer 14

Spherocytes

Irregularly Contracted Cells

Question 15

What is responsible for the round shape of the spherocytes in spherocytosis?

Answer 15

It is caused by a loss of cell membrane that is not accompanied by an equivalent loss of cytoplasm (inadequate attachment between cytoskeleton and membrane)

Question 16

State a cause of spherocytosis.

Answer 16

Hereditary spherocytosis

Question 17

What usually causes the formation of irregularly contracted cells?

Answer 17

Oxidant damage

Question 18

Define polychromasia.

Answer 18

An increased blue tinge to the cytoplasm of a cell

Question 19

What can reticulocytes be stained with?

Answer 19

Methylene blue

Question 20

State six different types of poikilocytosis.

Answer 20

Spherocytes  
Elliptocytes 
Fragments 
Irregularly contracted cells  
Target cells  
Sickle cells

Question 21

What are target cells? State some causes of target cells in the blood film.

Answer 21

Target cells have an accumulation of haemoglobin in the middle of the central pallor
It is caused by obstructive jaundice, hyposplenism, liver disease, haemoglobinopathies

Question 22

State two causes of eliptocytosis.

Answer 22

Hereditary eliptocytosis  
Iron deficiency (also hypochromic)

Question 23

What biochemical phenomenon causes the sickling of red blood cells?

Answer 23

Polymerisation of haemoglobin S when present in a high concentration

Question 24

What is another name for fragments?

Answer 24

Schistocytes

Question 25

State two different ways in which red blood cells can clump together and describe why they happen.

Answer 25

Rouleaux – like a stack of coins – it is caused by a change in plasma proteins pushing the red cells together
Agglutinates – irregular clumps – caused by antibodies on the cell surface making the cells stick together

Question 26

What is a Howell-Jolly Body and what is it usually caused by?

Answer 26

This is a nuclear remnant in the red cells
This is most commonly caused by a lack of splenic function (the spleen should remove these tiny bits of nuclear material)

Question 27

Which cytokines are important in the differentiation of myeloblasts to granulocytes and monocytes?

Answer 27

G-CSF granulocyte colony stimulating factor
M-CSF macrophage CSF
GM-CSF granulocyt-macrophage csf
Interleukins

Question 28

How long do neutrophils survive for in the circulation?

Answer 28

7-10 hours

Question 29

What is the main role of eosinophils?

Answer 29

Parasitic infections. But also involved in allergic reactions

Question 30

Describe the shape of the nucleus of an eosinophil.

Answer 30

Eosinophils have a bilobed nucleus

Question 31

What is the main role of basophils?

Answer 31

They are involve in the allergic response, histamine release etc

Question 32

Describe the appearance of basophils.

Answer 32

They have lots of dark blue dots in the cytoplasm (granules)
Often there are so many blue dots that you can’t even see the nucleus

Question 33

Describe the appearance of monocytes.

Answer 33

They have a kidney bean shaped nucleus

They are large

Question 34

Other than phagocytosis, what is another role of macrophages?

Answer 34

They store and release iron

Question 35

How long do platelets survive for in the circulation?

Answer 35

10 days

Question 36

What term is used to describe having too many white blood cells?

Answer 36

Leucocytosis

Question 37

What term is used to describe having too many platelets?

Answer 37

Thrombocytosis

Question 38

Describe the appearance of an atypical lymphocyte. What can cause these to appear in a blood film?

Answer 38

An atypical lymphocyte will have a large nucleus and a large amount of faint cytoplasm
This is typical of having a viral infection and is seen in glandular fever (infectious mononucleosis)

Question 39

What is ‘left shift’?

Answer 39

An increase in the number of non-segmented neutrophils or that there are a lot of neutrophil precursors in the blood
One of the first steps in segmenting is that it becomes a slightly more squashed looking nucleus that has more of a band shape (these precursors are called band forms)
If someone’s blood film has a lot of these band form nuclei then there has been a left shift see slide 14 and 65

Question 40

What is toxic granulation? What can cause it?

Answer 40

This is the heavy granulation of neutrophils
It results from infection, inflammation and tissue necrosis
It is also a feature of normal pregnancy

Question 41

What is hypersegmentation of neutrophils? What can cause it?

Answer 41

Neutrophil hypersegmentation means that there is an increase in the average number of neutrophil lobes or segments (normal= 3 or 4 lobes)
It usually results from a lack of vitamin B12 or folic acid