Haemopoiesis

Question 1

What ability do haemopoietic stem cells have?

Answer 1

They have ability to self replicate and differentiate further

Question 2

What are progenitors limited by in terms of differentiation?

Answer 2

They are lineage bound so have a set number of cells they can become.

Question 3

What is the haemopoietic cell replication driven by?

Answer 3

Constant replication and differentiation driven by multiple hormones and chemical messengers.

Question 4

What does selection refer to in terms of haemopoietic replication?

Answer 4

Not all cells made in the marrow will enter the blood.
Some undergo programmed cell death (apoptosis)
Up to 40% survival rates in certain stages of rbc synth

Question 5

What is erythropoiesis?

Answer 5

The formation of red blood cells.

Question 6

What regulatory hormone is used in erythropoiesis?

Answer 6

Erythropoietin is the regulatory hormone to rbc’s

Question 7

How long is the life span of a red blood cell and what happens to them after this?

Answer 7

120 days then they are degraded by the liver/spleen.

Broken down earlier if damaged (ie sickle cell anemia)

Question 8

What structural specialisations do rbc’s have that improve their ability’s as oxygen transporters?

Answer 8

Biconcave shape-increase SA for gas diffusion

No nucleus + minimal organelles-maximise O2 holding

No mitochondria-ensure O2 isn’t used up by RBC (they respire anaerobically)

Heamoglobin-increases affinity of O2 binding

Question 9

What are the 3 main cell types n the process of erythropoiesis? Where are these cells found?

Answer 9

Erythroblast-bone marrow

Reticulocyte-peripheral blood

RBC-peripheral blood

Question 10

How does an erythroblast become a reticulocyte?

Answer 10

Erythroblast starts off with large nucleus, prominent nuclei and large amounts of RNA.

Gradually the nucleus shrinks and is removed with the majority of RNA

This forms a reticulocyte

Question 11

What is some key info regarding reticulocyte.

Answer 11

Final step before mature erythrocytes (RBC’s)

Only small amount of RNA-helps make heamoglobin

After 1/2 days the RNA is removed

Question 12

How can reticulocyte be used as a clinical marker?

Answer 12

If there is a high amount in the blood this means a lot of them have been produced quickly.

This shows attempted recovery from blood loss so can be useful clinically to establish blood loss has occurred in prev hours/days.

Question 13

How does the body stimulate an increase in RBC synthesis?

Answer 13

The kidney senses hypoxia in tissues. It then increases its secretion of erythropoietin hormones (this increases RBC synth)

Question 14

What is Erythropoietin?

Answer 14

A glycoproteins produced by the kidney to increase the level of RBC’s.

It’s produced in response to tissue hypoxia

Acts to stop apoptosis or erythrocyte progenitors meaning a higher % f them reach the blood

(During foetal life its made in the liver, taken over by kidney after birth)

Question 15

What is granulopoiesis?

Answer 15

The synthesis and release of granuloctyes into the blood

Question 16

What are granulocytes in general ?

Answer 16

A sub group of WBC’s they fight infection + Inflammation

Have granules in cytoplasm

Mediate inflammation in body

Release cytokines, interleukins, etc to recruit immune cells

Question 17

What 3 cells do granulocytes consist of?

Answer 17

Neutrophils
Basophils
Eosinophils

Question 18

Describe the make-up of a neutrophil.

Answer 18

A multilobule nucleus (stains blue)
3 types of granules in cytoplasm
Most abundant granulocyte

Question 19

What is the function of a neutrophil?

Answer 19

Kill bacteria in multiple ways

Granules contain lysosomes, MMPs and gelatinise

Perform phagocytosis

Signal and antigen presenting role

Form Neutrophil Extracellular traps (a DNA net catches pathogens, killing some bacteria and gathering others together for easier phagocytosis)

Respiratory burst (rapid release of oxidative free radicals to kill bacteria by damaging DNA)

Question 20

What is G-CSF (granulocyte-colony stimulating factor)?

Answer 20

Secreted by multiple immune cells and endothelial cells

Usually released in response to inflammation

Acts on bone marrow to increase number of circulating neutrophils

Increases speed at which neutrophils mature as well as heir numbers ( increase in 80% by 12 hours)

Question 21

What is a basophils?

Answer 21

They release histamine to trigger inflammation

Mediate hypersensitivity reactions (asthma)

Have a bilobule nucleus

Many purple granules (stain by basic dye)

Granules contain histamine and heparin

Question 22

What does histamine do?

Answer 22

Causes vasodilation of an area
Making it hot and swollen

It increases the number of immune cells ABLE to reach the site

Question 23

What does Heparin do?

Answer 23

It’s a blood thinner and is neede to reduce the risk of dangerous clots forming due to the vasodilation caused by histamine

Question 24

What are eosinophils?

Answer 24

They phagocytose pathogens.

Fight parasitic worms and have an inflammatory role

Have many granules

2 nuclear lobes

Granules are spherical and acid loving (stain red)

Question 25

What do the granules in eosinophils contain?

Answer 25

Antihelminthic proteins (major basic protein & eosinophils cationic protein)

Cell component destroying enzymes

Question 26

What occurs to cells in granulopoiesis.

Answer 26

The nucleus condenses and lobules form

The formation/increase of granules in the cytoplasm

Question 27

What are monocytes/macrophages?

Answer 27

Called a monocytes in the blood
Called a macrophage in the tissue

The first line of defence

Phagocytose pathogens, Cell debits and senescent cells

They present foreign antigens to lymphocytes

Unilobular nucleus in a horse shoe shape

Largest type of blood cell

Question 28

What is thrombopoiesis?

Answer 28

THe production of platelets (thrombocytes)

Uses thrombopoietin

Question 29

What are platelets?

Answer 29

They stop bleeding and mediate heamotasis

Biconvex in Shape

No nucleus, just cytoplasm

Contain large number of proteins and clotting factors

Have receptors on surface to cause platelet aggregation (plunging vessels)

Question 30

How do platelets form?

Answer 30

Thrombopoietin from the liver helps form a megakayocyte from cells.

The cytoplasm from this breaks off into small pieces that form the platelets.

Question 31

What is lymphopoiesis?

Answer 31

The formation of B lymphocytes, T lymphoctyes and natural killer cells using interleukins.

Question 32

What are B lymphocytes?

Answer 32

Produce antibodies

Specific to a specific antigen

Activate T cells

Humoral adaptive immunity (the circling liquids control it not cells)

Mature in bone marrow, then intestine Peyer’s patches, the spleen or lymph nodes.

Question 33

What are T lymphocytes?

Answer 33

Kill virus-infected cells, neoplastic (cancer) cells and transplanted tissue

Carry-out cell mediated immunity

Activate B cells to make antibodies using IL-4

Large nucleus with small cytoplasm rim

Proliferation + activation via IL 2

Indistinguishable from B cells under a microscope

Question 34

How/where do T cells migrate?

Answer 34

Start in the bone marrow or foetal liver, then migrate to the Thymus to mature.

After this they migrate to secondary lymphoid organs to wait for activation.

Question 35

List some secondary lymphoid organs

Answer 35

Tonsils
Spleen
Appendix
Lymph nodes

Question 36

What is plasma?

Answer 36

Maes up majority of circulating volume of blood

Is supporting medium for all blood cells

92% water, 8% proteins, + ions

Main protiens = albumin (liver) + clotting factor (liver) + hormones, cytokines, antibodies etc

Question 37

What is serum?

Answer 37

The plasma minus clotting factor (separates when blood is left to sit)

Question 38

What does a high clinical INR result mean?

Answer 38

Means clod is thinner than normal so bleeding can be dangerous as blood is lost quicker