- A glycoprotein - Stops programmed cell death (apoptosis) of erythrocyte progenitors - Made in liver during fetal life

L14- Haemopoiesis Flashcards by Saskia Chapman

haemopoiesis describes

The production of all types of blood cells including formation, development, and differentiation of blood cells.

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what do all of the cells in the blood come from

bone marrow haemopoetic stem cells

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where does prenatal haemopoiesis occur

Occurs in the yolk sack then the liver and lastly the bone marrow

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stem cells all originate

in bone marrow and have the ability to differentiate into many cell types

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two main types of progenitor cells that come from multipotent haemtopoietic stem cells

o Myeloid and lymphoid progenitors

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myeloid cell examples

thrombocytes (platelets)
erythrocytes
mast cells
basophils
neutrophils
eosinophils
monocytes (macrophages)

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lymphoid cell examples

T and B cells

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not all cells found in the bone marrow

will end up int he blood

- apoptose (40% survival in certain stages)

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Hemocytoblasts

Multipotential hematopoietic stem cells

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lifespan of RBC

120 days

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where are RBC degraded

liver/spleen

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how many molecules of oxygen can one RBC carry

one billion

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how many seconds for an RBC to circulate around the whole body

20 seconds

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width of RBC

7um

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shape of RBC

biconcave

- increase surface area for gas exchange

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why do RBC have no nucleus

to maximize ability to hold onto oxygen

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why do RBC have no mitochondria

otherwise cell would be using up oxygen that’s meant to be delivered to tissues

Anaerobic respiration - Glucose —> pyruvate

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RBC utilise

lactate dehydrogenase to regenerate NAD so that the glycolysis can continue (only source of ATP)

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what reaction does lactate dehydrogenase catalyse

NADH + H+ + pyruvate —> NAD+ + lactate

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how does the body stimulate RBC production after blood loss

The kidney senses tissue hypoxia and response by increasing secretion of Erythropoietin.

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erythropoietin

A glycoprotein
Stops programmed cell death (apoptosis) of erythrocyte progenitors
Made in liver during fetal life

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erythropoiesis

‘The process which produces red blood cells (erythrocytes), which is the development from erythropoietic stem cell to mature red blood cell.’

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outline erythropoiesis

Erythroblasts start with large nucleus, prominent nucleoli and large amounts of RNA
Nucleus gradual shrinks and is removed along with most RNA
Becomes reticulocyte before becoming a mature RBC
o Final step before mature erythrocyte
o Only small amount of RNA remains to make haem
o Removed within 1-2 days
o Clinical use: presents in the blood when the body is recovering from blood loss

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granulocytes

Sub group of WBC- fight infection and inflammation

- Named due to presence of granules within cytoplasm

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granulocytes work by

Act by releasing cytokine, interleukins, leukotrienes | o Recruitment of other immune cells

name the granulocytes

neutrophils (60%) basophils eosinophils

Neutrophils function

First responder and first one of defence against bacteria * Phagocytosis * Signal to other immune cells e.g. antigen presenting * Neutrophil Extracellular traps (NETs) * DNA nets that the neutrophil sends out to trap bacteria • * Intrinsic ability to kill * Respiratory burst * Makes free radicals which damages the DNA of certain pathogens causing cell death

structure of neutrophil

• Multilobed nucleus

which granules do neutrophils produce

lysosomes, matrix metalloproteinases (MMP) and gelatinise

basophils release

histamine and heparin

histamine causes

vasodilation of vessels • Increasing blood and cells the area • Hot and swollen

structure of basophils

bilobed | many purple granules (acid loving)

heparin

blood thinner- decreases clotting risk that histamine presents

eosinophils main functions

- Phagocytosis pathogens | - Fight parasitic worms and have a role in inflammation/ allergy

granules in eosinophils contain

- antihelminth proteins | - acid hydrolases

structure of eosinophils

2 nuclear lobes

name some antihelminth proteins eosinophils secrete

major basic proteins eosinophilic cationic protein

granulopoiesis general

All 3 lineages go through the process of: 1) Nuclear condensation and lobulation 2) Formation/ increased no. of granules

when monocytes in the blood enter tissue they mature into

macrophages

function of macrophages

* Phagocytosis pathogens, cell debris and senescent cells | * Present foreign antigens i.e. raise the alarm to lymphocytes

macrophages are the ...... of all mature blood cells

largest

structure of macrophage

unilocular (horseshoe) shaped nucleus

thrombopoiesis

Is the process of thrombocyte generation.

Thromobocytes are

ligations of the cytoplasm from megakaryocytes.

A single megakaryocyte can give rise

to thousands of thrombocytes.

thrombocytes (platelet) function

• Stop bleeding and mediate haemostasis

Haemostasis

the prevention of blood loss following damage to a blood vessel,

shape of platelets

biconvex contain lots of proteins and clotting factors

platelets do not have

NUCLEUS' --> not really classes as a cell

what do platelets have on their surface

Have specialised receptors on surface which causes platelet aggregation (gpIIb/ gbIIIa)

what up regulates thrombopoiesis

thrombopoietin from the liver

cytoplasm of megakaryocytic =

platelets

1 megakaryocytic =

2000-3000 platelets

what upregulates lymphopoiesis (production of lymphoid cells)

interluekins

3 main types of lymphoid cells

T cells B cells NK cells

T lymphocytes make up ...... of the lymphoid cells

80%

B lymphocytes make up.... of the lymphoid cells

20%

where do T cells mature

thymus | - T cell education

T cells kill

cancer cell (neoplastic) virally infected cells transplanted tissue

T cells activate

B cells to produce antibodies using IL-4

T cells proliferation and activation by which interleukin

IL-2

B and T cells are microscopically

indistinguishable

structure of T and B cell

• Large nucleus with small rim of cytoplasm

journey of a T cell

1) T cells start off in the bone marrow or fetal liver and migrate to the thymus to mature 2) After this they migrate to secondary lymphoid organs where they wait to be activated

B cells basis of

humoral adaptive immunity

B cells become ..... and produce.....

plasma cells antibodies

B cells produce

specific antibodies

journey of a B cell

* Maturation occurs in bone marrow and then: * Intestines (Peters batches) * Spleen * Lymph nodes (secondary lymphoid organs)

where does haemopoeisis start at the beginning ion the foetal period

yolk sac

during most of the fatal months haemopoeisis occurs in

the liver (mainly) and spleen

near the end of the foetal period haemopoeisis occurs sole in the

bone marrow

plasma is...

blood without RBC

plasma acts as

supporting medium for all circulating blood cells

composition of plasma

* Mostly composed of : * Water (92%) * 8% protein * Ions Proteins: • Albumin • Clotting factors • Hormones, cytokines, antibodies

serum is

plasma without clotting factor

Patient presents with - Yellow skin - Ascites- oedema in the abdomen - Bruises easily Consultant says ‘get bags of blood ready in case- we will be in trouble if he starts bleeding’. Clinical findings - Platelets low- 30 (140-400 10^9) - INR high- 1.6 (0.9-1.1) o Very thin blood Doctor says ‘he’s just vomited blood’ WHAT HAS HAPPENED?

* Damaged liver not producing thrombopoietin (Low platelets- thrombocytopenia) * Damaged liver not producing clotting factors (blood is not clotting as well i.e. INR raised) * Alcohol causes gastritis- greater risk of ulcers * Oesophageal varices associated with ALD