TOB S10 - Blood Cells and Haemopoiesis Flashcards Preview

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Flashcards in TOB S10 - Blood Cells and Haemopoiesis Deck (35):
1

What are the two stages of haemopoiesis?

Proliferation
Differentiation

2

Give a brief description of haemopoietic Proliferation

Starting with a stem cell the cell divides in two

One replaces the original stem cell

One will differentiate

3

Describe the process of haemopoietic differentiation

Haemopoietic progenitor cell will differentiate to either:

-A lymphoid blast which will go on to form immunoresponse cells

-A myeloid blast which will go on to form Erythrocytes, platelets or White blood cells

The progenitor will then differentiate into a certain cell type under the influence of particular cytokines

4

What cytokine will cause a myeloid blast to differentiate into an erythrocyte and which will cause it to differentiate into a platelet?

Erythrocyte = Erythropoietin

Platelet = Thrombopoietin

5

What controls rate of erythropoiesis?

Partial pressure of O2

Fall in pO2 will stimulate erythropoietin release from kidney

This stimulates maturation and release of red cells from the marrow

6

How many RBCs, granulocytes and platelets are produced per day?

RBCs = 2.5 billion/kg/day

Platelets = 2.5 billion/kg/day

Granulocytes = 1.0 billion/kg/day

7

Where are RBCs, WBCs and platelets produced in the body and how does this change as we age?

Produced in the bone marrow

Widespread throughout the bone marrow in infants

More limited distribution in adulthood:

Pelvis, Sternum, Skull, Ribs, Vertebrae

8

What are peripheral blood levels of:

Hb
RBCs
WBCs
Platelets

Hb = 130-160g/L

RBCs = 4.4-5.5x10^12/L

WBCs = 7-11x1^9/L

Platelets = 150-400x10^9/L

9

What are the main functions of a RBC?

To deliver oxygen to tissues and deliver carbon dioxide to the lungs

Carry haemoglobin

Maintain haemoglobin in its reduced state (ferrous)

Maintain osmotic equilibrium

Generate ATP

10

Describe the form of a RBC

How is this useful?

Biconcave flexible disk

8um in diameter

Facilitates passage through microvasculature which has a minimum diameter of 3.5um

11

How is Haemoglobin catabolised?

Broken down into constituent parts, Fe2+ is recycled

Haem is converted to bilirubin and conjugated in the liver

Liver releases conjugated bilirubin into the gall bladder/small intestine and it is changed into a variety of pigments, the most important of which are stercobilin and urobilinogen

Stercobilin is excreted in the faeces

Urobilinogen may be passed back into the blood and excreted by the kidneys.

12

How are the platelets produced?

Megakaryocytes produce platelets

Platelets bud off from the cytoplasm

13

Describe the features of platelet structure relevant to the clotting process

Phospholipid membrane w/glycoprotein receptors for clotting factors and platelet adhesion

alpha-granules in the cytoplasm produce the glycoproteins

Dense bodies in the cytoplasm produce 5-HT, ADP, catecholamines and calcium for platelet aggregation

14

How are platelets involved in a blood clot?

Platelets are activated leading to adhesion to the damaged section of membrane via Von Willebrand's factor

The then aggregate with other platelets

The Fibrin mesh of a blood clot traps platelets (as well as red cells)

Also involved in the clotting cascade, interact with various clotting factors via their phospholipid membrane (particularly factor III, which activates prothrombin into thrombin, resulting in fibrin production)

5-HT from the Dense granules constricts blood vessel

15

What are the effects of granulocyte - colony stimulating hormone on Neutrophils?

Increases production

Enhances chemotaxis - Attraction of the neutrophil to site of infection

Enhances phagocytosis and killing of pathogens

16

Give a basic outline of neutrophil function

What is the average survival time of a neutrophil?

Are inactive in the bloodstream

Migrate into infected tissues

Neutrophils phagocytose invader

Destroys the pathogen using hypochlorous acid

Gross accumulation visible as pus

Average survival time of 10 hours

17

What is the function of Monocytes?

Migrate to tissue and become active macrophages (inactive in bloodstream)

Respond to inflammation and antigenic stimuli

They phagocytose pathogens which are degraded with lysosomal enzymes

Can interact with T-cells

18

What is the Reticulo-endothelial system?

What is it's function?

What are the main organs of the RES?

Part of the immune system comprising of:

Monocytes
Macrophages
Kupfer Cells
Microglia
Tissue Histiocytes

Cells of the RES identify and mount an appropriate immune response to foreign antigens

Main organs are:

Spleen
Liver
Lymph Nodes

19

How long do Eosinophils remain in the circulation and what is their total lifespan?

3-8 hours in circulation

8-12 days total lifespan

20

What is the function of Eosinophils?

Phagocytosis of antibody-antigen complex

Mediate hypersensitivity reactions E.g. Asthma, skin inflammation

Can release cytotoxic enzymes to damage larger particles

21

What is the function of Basophils?

Active in allergic reactions using heparin and histamine

22

What s contained in the dense granules in the cytoplasm of Basophils?

Histamine
Heparin
Hyaluronic acid
5-HT

23

Where do Lymphocytes originate from and what are the 3 types?

Originate from bone marrow

B-cells
T-cells
Natural killer cells

24

What is the function of B-cells?

Express antigen specific Immunoglobulin (antibody)

Each B-cell only expresses a certain Ig

They interact with T-cells forming plasmablast or memory cells

25

What is the function of plasmablasts and memory cells?

Plasmablasts differentiate into plasma cells that express a large volume of an antibody when the cell is first exposed to the corresponding antigen

Memory cells retain antibodies for previously encountered antigens in order to mount a fast immune response in the case the antigen is re-introduced into the system

26

How are different forms of T-cells produced?

T-cells produced in the bone marrow will migrate to the thymus and differentiate

27

What are the two different forms of T-cells and what is their function?

CD4+ (Helper cells)
CD8+ (Suppressor cells)

CD4+ cells induce proliferation and differentiation of T&B cells and active macrophages

CD8+ cells have cytotoxic activity (destroy virally infected cells and cancer cells) and induce cell apoptosis

28

What is the function of natural killer cells?

Recognise the self
Kill non-self cells via the same mechanism as T-cells
Can however identify a stressed cell without the presentation of antibodies

29

What are the 5 types of white blood cell?

Monocytes
Neutrophils
Basophils
Eosinophils
Lymphocytes

30

How are white blood cells classified?

Polymorphonuclear granulocytes:

-Neutrophils
-Eosinophils
-Basophils

Agranulocytes:

-Monocytes
-Lymphocytes

31

What are the salient histological features of a neutrophil?

Pale cytoplasm with small granules

Multi-lobular nucleus

32

What are the salient histological features of a eosinophil?

Cytoplasm filled with large granules that stain deep red

Bi-lobular nucleus

33

What is the salient histological feature of a basophil?

Granules in cytoplasm stain intensely blue

34

What are the salient histological features of a monocyte?

Agranular cytoplasm

Cell cytoplasm abundant

Irregular kidney shaped nucleus

35

What are the salient histological features of a lymphocyte?

Agranular cytoplasm

Deep staining nucleus