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Flashcards in Haemopoesis Deck (38):
0

What is the average lifespan of RBCs?

-approx. 120 days

1

What is the average size of a RBC?

-approx. 8um diameter

2

Where do RBCs originate?

-Bone marrow

3

By what system are RBCs removed?

-Reticulo-endothelial system (spleen)

4

What is the difference between the amount of bone marrow in infants and adults?

-Extensive throughout skeleton in infants
-Limited distribution in adults (pelvis, sternum, skull, ribs, vertrbrae)

5

What cell types are produced in bone marrow?

-RBCs, platelets and most WBCs

6

What is haemopoesis?

-The process of the production of blood cells and platelets which continues throughout life

7

Where does haemopoesis occur?

-Bone marrow

8

What do all RBCs originate from?

-Common myeloid progenitor cells

9

What drives haemopoesis?

-Cytokines

10

What cytokine drives haemopoesis of RBCs?

-Erythropoietin

11

What cells originate from the common myeloid progenitor?

-Megakaryocytes
-Erythrocyte
-Mast cell
-Myeloblasts

12

What cell type is derived from megakaryocytes?

-Platelets

13

What cell types are derived from myeloblasts?

-Basophils
-Neutrophils
-Eosinophils
-Monocytes

14

What cell type is derived from monocyte?

-Macrophage

15

What cell types originate from common lymphoid precursor?

-Lymphocytes
-Natural killer cells

16

Where do common myeloid progenitors and common lymphoid progenitors originate from?

-Multipotent haematopoeitic stem cells

17

What controls erythropoiesis?

-Reduced pO2 detected in interstitial peritubular kidney cells
-Increased production of erythropoietin
-Erythropoietin stimulates maturation of E-progenitor stem cells
-Release of mature RBCs from marrow
-Hb rises
-pO2 rises
-Erythropoietin production falls

18

What happens to Hb that is released from lysed RBCs?

-Broken down into bilirubin in liver
-Excreted through bile ducts into small intestine
-Excreted as urobiligen via kidneys when bilirubin is reabsorbed from small intestine

19

What is the consequence of blockage of the bile duct?

-Accumulation of bilirubin leading to jaundice

20

What controls haemapoiesis of platelets?

-Thrombopoietin

21

How do platelets form from megakaryocytes?

-Megakaryocyte increases in size and replicates DNA
-Platelets (which are cell fragments) bud from the cytoplasm

22

Which cells of the body can mobilise, divide and transform after to maturation?

-Lymphocytes
-Monocytes

23

Where does final lymphocyte maturation occur?

-T cells mature in the thymus
-B cells mature in the bone marrow

24

Describe the structure of erythrocytes

-Anucleate
-Bioconcave disc approx 8um in diameter
-Pale centre on blood smears due to shape
-Extremely flexible to allow passage through small BVs
-Contain Hb

25

What is the function of the glycoproteins attached to spectrins in RBCs membranes?

-Maintain elasticity

26

What is a reticulocyte?

-Newly formed RBC which have only just been released from BM

27

What is the structure of lymphocytes?

-Very large nucleus which almost fills the cell
-Thin rim of cytoplasm evident around the edge
-Small cytoplasmic projections visible with EM
-T cells expressing CD4+ on their surface are Thelper cells
-T cells expressing CD8+ on their surface are cytotoxic T cells

28

What are the functions of lymphocytes?

-Fundamental part of adaptive immune system
-Pass through endothelial lining of blood vessels into adjacent tissues in response to infection
-Thelper cells recognise foreign antigens when displayed on MHCII of APCs
-Once activated Th stimulate Tc
-Tc cells recognise and kill infected host cells
-B cells transform to plasma cells and secrete specific Ab

29

Describe the structure of monocytes

-Largest cell in peripheral blood
-Nucleus irregular in shape (kidney shaped)
-Abundant grey/blue cytoplasm
-Occasional lysozyme vacuoles

30

Describe the function of monocytes

-Highly motile
-Migrate into tissue in response to infection and differentiate into macrophages (have cytoplasmic projections)
-Both actively phagocytic
-Only remain in circulation 1-3 days
-Reserve in red pulp of spleen
-Macrphages capable of chemotaxis, involved in inflammation and interact with Thelper cells

31

Describe the structure of Eosinophils

-Bilobed nucleus
-Orange-staining granules

32

What is the function of an eosinophil?

-Capable of weak phagocytosis
-Release cytotoxic enzymes to damage large invading pathogens
-highly motile -> migrate to epithelial surfaces
-Associated with allergic reactions via ingestion of antigen:antibody complex and release of granules

33

What are the functions of basophils?

-Involved in inflammatory response
-Granules contain heparin and histamine which are released in response to local tissue damage
-Histamine causes vasodilation of BVs and leakage of fluid into tissues

34

What is the structure of a neutrophil?

-Multi-lobed nucleus
-Small granules in cytoplasm
-Pale cytoplasm

35

What are the functions of neutrophils?

-Phagocytic
-Granules are lysosomes which contain digestive enzymes
-Short lived
-Gross accumulation causes pus
-Capable of oxidative burst

36

Describe the structure and function of platelets

-Small cellular particles
-Contain granules containing fibrinogen and von willebrand's factor
-Phospholipid surface to provide binding sites for clotting factors during clotting cascade
-Rich in compounds which cause vasoconstriction eg serotonin
-Accumulate at sites of injury
-Responsible for forming a thrombus
-Rich in factor III starting extrinsic clotting cascade
-Adhere to connective tissue
-Aggregate with other platelets

37

What is von willebrand's factor?

-Factor needed to adhere to tissue