Haemopoiesis Flashcards
Where does haemopoiesis predominantly occur in adult life
Bone marrow
Where does haemopoiesis occur in certain pathological conditions
- Liver
- Lymph nodes
- Spleen
Where does haemopoiesis occur in the foetus
- Bone marrow
aswell as: - liver
- spleen
- lymph nodes
Where does haemopoiesis occur in the embryo
In the yolk sac
What is it called when haemopoiesis occurs in the bone marrow
Intramedullary
What is it called when haemopoiesis occurs o/s the bone marrow - in liver & spleen
Extramedullary
What area in the yolk sac has to form for there to be blood cell formation
A specialised zone - the area vasculosa
When does the mesoblastic/embryonic phase of blood formation commence
As early as week 2 - 3 of gestation
3 phases of haemopoiesis
- Mesoblastic/embryonic phase
- Hepatosplenic phase
- Myeloid/ bone marow phase
What happens during the Mesoblastic/Embryonic Phase
- First few weeks of gestation until around 2 months, the yolk sac is the area of haemopoiesis
- Primitive haemopoiesis occurs
- Primitive Hb forms (Gower & Portland)
What happens during the Hepatosplenic Phase
- Maximal at 4 months gestation
- Major organs are being produced
- Liver, spleen, thymus capable of producing rbcs at this stage
- Hb F produced in the red cells
- Rapid development = increased need for blood
What happens during the myeloid (bone marrow) phase
- Occurs 5-9 months of gestation, continues through life
- Bone marrow takes over & produces Hb A
- Bone marrow the production site of rbcs for rest of life
- Main Hb in adults is Hb A (little Hb A2 & Hb F)
What can happen if bone marrow collapses / is in diseased state
Haemopoiesis can revert to taking place in liver & spleen
The red bone marrow of what bones is where haemopoiesis occurs in adult life
- Sternum
- Hip bones
- Pelvis
- Ribs
- Vertebrae
- Femur
- Cranium
What is yellow marrow for
Fat storage
What does haemopoiesis rely upon
- Growth factors
- Cytokines
- Environmental factors
- Amount of O2 in body
Lifespan of mature granulocytes in bloodstream
Hours
Lifespan of mature red cells in bloodstream
Weeks - months (120 days)
What would increased blood cell production be as a result of
Increased number of cells required in response to increased demands - infection & blood loss
What stem cell are all precursor cells derived from
The Haemopoietic Pluripotent stem cell
What % of bone marrow population are stem cells
0.01% - 0.05%
2 characteristic features of stem cells
- Ability to proliferate & to self renew
- Haemopoietic stem cell will proliferate & differentiate (develop into separate lineages), produce highly specialised cells which mature into mature blood cells
