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