L14- Haemopoiesis Flashcards
haemopoiesis describes
The production of all types of blood cells including formation, development, and differentiation of blood cells.
what do all of the cells in the blood come from
bone marrow haemopoetic stem cells
where does prenatal haemopoiesis occur
Occurs in the yolk sack then the liver and lastly the bone marrow
stem cells all originate
in bone marrow and have the ability to differentiate into many cell types
two main types of progenitor cells that come from multipotent haemtopoietic stem cells
o Myeloid and lymphoid progenitors
myeloid cell examples
- thrombocytes (platelets)
- erythrocytes
- mast cells
- basophils
- neutrophils
- eosinophils
- monocytes (macrophages)
lymphoid cell examples
T and B cells
not all cells found in the bone marrow
will end up int he blood
- apoptose (40% survival in certain stages)
Hemocytoblasts
Multipotential hematopoietic stem cells
lifespan of RBC
120 days
where are RBC degraded
liver/spleen
how many molecules of oxygen can one RBC carry
one billion
how many seconds for an RBC to circulate around the whole body
20 seconds
width of RBC
7um
shape of RBC
biconcave
- increase surface area for gas exchange
why do RBC have no nucleus
to maximize ability to hold onto oxygen
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
RBC utilise
lactate dehydrogenase to regenerate NAD so that the glycolysis can continue (only source of ATP)
what reaction does lactate dehydrogenase catalyse
NADH + H+ + pyruvate —> NAD+ + lactate
how does the body stimulate RBC production after blood loss
The kidney senses tissue hypoxia and response by increasing secretion of Erythropoietin.
erythropoietin
- A glycoprotein
- Stops programmed cell death (apoptosis) of erythrocyte progenitors
- Made in liver during fetal life
erythropoiesis
‘The process which produces red blood cells (erythrocytes), which is the development from erythropoietic stem cell to mature red blood cell.’
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
granulocytes
Sub group of WBC- fight infection and inflammation
- Named due to presence of granules within cytoplasm
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
