For today we would like to briefly share our knowledge on.. *drum rolls*
Hemopoesis
Wait, hemo what? What is it? What does it stands for? Clueless? Well,
Hematopoiesis also known as hemopoesis or hematogenesis is the production of all types of blood cells including formation, development, and differentiation of blood cells.
Do you know where this process occurs?? No??
Let us tell you..
In fetus (extramedularry hematopoiesis)
· 0-2 months in yolk sac (there is blood island where red blood
cells can be seen clearly)
· 2-7 months blood cells migrate to liver and spleen (it
continuous until two weeks after birth)
· 5-9 months bone marrows of most bones
Infants (medullary hematopoiesis)
· Occurs in red bone marrow
· In child red bone marrow is throughout skeletal system.
In adults
· Hematopoiesis specifically occurs at red bone marrow in
vertebrae, ribs, sternum, skull, pelvis and,proximal end of femur
Extramedullary hematopoiesis : production of
blood cells outside red bone marrow. For example, liver and spleen.
Medullary heamtopoiesis : production of blood
cells within the red bone marrow.
Before we move in deeper lets get to know few terms:
a)
Eryhropoiesis : Production of Red Blood cells
b)
Leukopoiesis :
Production of White Blood Cells
c)
Thrombopoiesis : Production of Platelets
Now, lets get deeper..
The process initially begins :
In 2 weeks old embryo, red blood cells precursors can already be recognized in the blood island which is in yolk sac.
Leucopoiesis and thrombopoiesis begins only after 6th
week old embryo when megakaryocytes and granulocytes can be seen in the yolk
sac.
In contrast to red blood cells, lymphocytes which are a type
of white blood cells are formed in lymph sacs which develops in 7th
week of an embryo.
At 2nd month of gestation, fetal blood cells
development will begin at the liver, hepatic hematopoiesis (where the liver is
the chief source of fetal blood cells until 30th week of pregnancy).
At the 10th week of pregnancy, spleen will begin
production of blood cells until 2nd trimester. Spleen is a secondary
important blood production organ.
About 20th week, bone cavities will start to form
and by 40th week of gestation, the bone marrow will become entirely
source of blood cells production in human.
HEMATOPOIESIS IN
CHILD AND ADULT
·
At birth until 3 years old , hematopoiesis
merely fills most of the red bone marrow space in almost every bone. Extramedullary
hematopoiesis will continue after 2 weeks of birth.
· At
4 years old, skeletal growth exceeds the demands of red blood cell production.
Thus hemapoietic activity moves to axial skeletal (vertebrae, ribs,
sternum, skull, pelvis and,proximal end of femur) completes at 18 years old.
·
Thus, as the child grows into adults, the
available bone marrow space expands and are eventually filled with inactive yellow
bone marrow.
·
Extramedullary hematopoiesis in adult only
occurs if:
I.
Bone marrow is not functional
II.
Bone marrow cannot keep up with demand for blood
cells.
Blood cells are produced by a stem cells which includes formation, development, and differentiation of blood
cells. Inclusive of red blood cell, white blood cells and platelets.
Image below shows a general description of
how our stem cells differentiate to become blood cells.
Hematopoiesis
process=)
Pheewwwwww! Too much information at once isn’t it??? There
are more but don’t worry.. watch the video below for a brief understanding of
how blood cells are produced.
Hematopoiesis Made easy !!
That’s all for today.. =) Hope our post was informative
enough. Feel free to drop your comments
on query or suggestions. Your feedback is our tool for improvisation.
Keep updated with our next post! Your support is our strength!Thank you. Good day
Love,
Precious blood team
