Lecture 14 - Haemopoiesis

Question 1

What is haemopoeisis?

Answer 1

Differentiation of bone marrow cells to cells of the blood

Question 2

Structure linked to function of red blood cells

Answer 2

• biconcave shape to increase surface area fro diffusion of gases
• no nucleus/minimal organelles to maximalist oxygen holding capabilities
• no mitochondria to ensure oxygen is not used by erythrocytes
• haemoglobin (made from iron) to increase affinity of oxygen binding

Question 3

What is erythropoiesis?

Answer 3

The process in which red blood cells are formed from a myeloid progenitor

Question 4

Stages of erythropoiesis

Answer 4

• Erythroblasts start of with large nucleus , prominent nucleoli and large amounts of RNA
• gradually nucleus shrinks and is removed along with majority of RNA
• RBCs are formed

Question 5

What are reticulocytes ?

Answer 5

• final step before mature erythrocyte
• small RNA present to help make haemoglobin
• normally removed in 1-2 days

Question 6

What is high amount of reticulocytes in the blood be an indicator of?

Answer 6

A body recovering from blood loss

Question 7

How will the body stimulate more red blood cell production ?

Answer 7

• kidney senses tissue hypoxia (low levels of oxygen )
• low oxygen means low levels of red blood cells
• kidney increases secretion of erythropoietin

Question 8

What is erythropoietin ?

Answer 8

• glycoprotein(hormone) produced by kidney to increase levels of red blood cells
• produced by kidneys in response to tissue hypoxia
• acts yo stop programmed cell death of erythrocytes progenitors (myeloid)
• made in the liver during fetal and kidney by birth

Question 9

What are granulocytes?

Answer 9

• sub group of WBC’s that fight infections and inflammation
• act to mediate inflammatory reactions in the body
• act by releasing cytokines, interleukins, leukotrienes which recruit various other immune cells

Question 10

3 types of granulocytes

Answer 10

• neutrophils (12-15 micrometer )
• basophils (11-14 micrometer )
• eosinophil (10-12 micrometers )

Question 11

Key features of neutrophils

Answer 11

• multilobed nucleus
• 3 types of granules
• most abundant type of granulocytes

Question 12

Function of a neutrophil

Answer 12

• granules contains lysosomes, matrix metalloproteinases (MMPs)
• phagocytose
• antigen presents and signals
• Neutrophil extracellular traps (NET) ; capture multiple pathogens
• Respiratory burst; production of free radicals

Question 13

Role of G-CSF ?

Granulocyte - colony stimulating factor

Answer 13

• secreted by multiple immune cells and endothelial cells
• released in response to inflammation
• acts on the bone marrow to increase the number of circulating neutrophils
• increase the speed at which neutrophils mature as well as the numbers

Question 14

Structure of basophils

Answer 14

• bilobed nucleus
• purple granules (stained due to basic dye )
• granules contains histamine and heparin(blood thinner)

Question 15

Role of basophils

Answer 15

• Release histamine to trigger inflammation

- mediates hypersensitive reactions

Question 16

Structure of eosinophils

Answer 16

• 2 nuclear lobes

- spheric granules - acid loving granules

Question 17

Role of eosinophils

Answer 17

• phagocytose pathogens
• fight parasitic worms and have a role in inflammation

-granules contains
>(antihelminthic) anti parasite proteins such as major basic protein and eosinophilic cationic protein
>cell components destroying enzymes

Question 18

What does granulopoeisis entail ?

Answer 18

All 3 granulocytes go through the maturation process of nuclear condensation and lobulation and formation /increased number of granules

Question 19

Structure of macrophage (in tissues )/monocytes (in blood)

Answer 19

Largest of all mature blood cells

Unilobular horseshoe shaped nucleus

Question 20

Function of macrophages

Answer 20

• first line of defence
• phagocytose pathogens, cell debris and senescent cells
• presents foreign antigens

Question 21

What is thrombopoieis ?

Answer 21

Formation of platelets (thrombocytes)

Question 22

Structure of platelets (thrombocytes)

Answer 22

• 2 to 3 micro metre in size
• biconvex shape
• no nucleus , just cytoplasm
• contains vast amount of proteins and clotting factors
• have special receptors on surface which cause platelet aggregation

Question 23

Function of platelets ( thrombocytes)

Answer 23

To stop bleeding and ,editable haemostasis

Question 24

How is thrombopoesis regulated ?

Answer 24

Unregulated by thrombopoietin from the liver

Question 25

How are platelets(thrombocytes) eventually formed from thrombopoiesis ?

Answer 25

Megakaryocyte breaks down which eventually forms 2000-3000 platelets

Question 26

What is Lymphopoiesis ?

Answer 26

Formation of B lymphocyte, T lymphocyte and natural killer cell

Question 27

Function of B cells

Answer 27

• revolves around production of antibodies
• activates T cells
• play a part in humoral adaptive immunity

Question 28

Where does maturation occur for B lymphocytes ?

Answer 28

In the bone marrow

Intestines

Spleen

Lymph nodes

Question 29

Function of T lymphocytes

Answer 29

• kill virus infected cells , neoplastic cells and transplanted tissue
• carries out cell mediated immunity
• activates B cells to make antibodies using IL 4

Question 30

Structure of T lymphocytes

Answer 30

-large nucleus with small rim of cytoplasm

Microscopically indistinguishable from B cells

Question 31

Where to T cells mature ?

Answer 31

In the bone marrow or fetal liver then migrate to thymus to mature

Question 32

What is plasma ?

Answer 32

• supporting medium for all circulating blood cells
• made up of 92% water , 8%. Protein and ions

> proteins include albumin, clotting factors and hormones, cytokines, antibodies