Haemopoiesis ? :)
WHAT IS HAEMOPOIESIS?
Uuuu what is that? A handbag? Lipstick brand like Kylie? Hm ok I'm done with the suggestions. Women are inseparatable with make ups aren't we? Obviously we as a human being don't realise about one thing that is crucial in life ; like seriously we will die without it! à BLOOD ! OUR BLOOD ! YOUR BLOOD ! MY BLOOD ! no one can take my blood or else you must be the new era’s vampire hihi. Whilst we are actually busy living our life to the fullest, socialize with your loved ones, we don't realise that our blood is functioning, working, circulating here and there. Blood is one of the most important thing or I can say CRUCIAL to us as they transport oxygen to all parts of our body ; like giving food to the cells. No food, cells die. You hungry, you die.
Okay back to the topic, what is haemopoiesis ?
HAEMOPOIESES / HAEMATOPOIESES ( urgh i have difficulty to spell it ) – Is about formation of the blood cell.
WHERE DOES IT OCCURS IN OUR BODY ?
Prior to birth, haemapoieses occurs in the yolk sac ( not the typical egg yolk that you know ) then in the fetal liver before taking place in the bone marrow and lymphatic system of normal adults. Haemopoieses is the process of generating mature blood cells from pluripotent hematopoietic cells, otherwise known as stem cells.
Hematopoietic stem cell (HSCs) reside in the medulla of the bone (bone marrow) and have the unique ability to give rise to all of the different mature blood cell types and tissues. HSCs are self-renewing cells : when they proliferate, at least some of their daughter cells remain as HSCs, so the pool of stem cells is not depleted.This phenomenon is called asymmetric division. The other daughters of HSCs (myeloid and lymphoid progenitor cells) can follow any of the other differentiation pathways that lead to the production of one or more specific types of blood cell, but cannot renew themselves. The pool of progenitors is heterogeneous and can be divided into two groups; long-term self-renewing HSC and only transiently self-renewing HSC, also called short-terms. This is one of the main vital processes in the body.
All blood cells are divided into three lineages.
Erythroid cells are the oxygen carrying red blood cells. Both reticulocytes and erythrocytes are functional and are released into the blood. In fact, a reticulocyte count estimates the rate of erythropoiesis.
Lymphocytes are the cornerstone of the adaptive immune system. They are derived from common lymphoid progenitors. The lymphoid lineage is primarily composed of T-cells and B-cells (types of white blood cells). This is lymphopoiesis.
Myelocytes, which include granulocytes, megakaryocytes and machropages and are derived from common myeloid progenitors, are involved in such diverse roles as innate immunity, adaptive immunity and blood clotting. This is myelopoiesis.
At this moment, you will get bored as I will give you so much facts but DO READ IT & DONT STOP!
As development progresses, blood formation occurs in the lymph nodes, spleen and liver. When bone marrow develops, it eventually assumes the task of forming most of the blood cells for the entire organism. However, maturation, activation, and some proliferation of lymphoid cells occurs in the spleen, thymus and lymph nodes. In children, haematopoiesis occurs in the marrow of the long bones such as the femur and tibia. In adults, it occurs mainly in the pelvis, cranium, vertebrae, and sternum.
Extramedullary
In some cases, the liver, thymus, and spleen may resume their haematopoietic function, if necessary. This is called extramedullary haematopoiesis. It may cause these organs to increase in size substantially. During fetal development, since bones and thus the bone marrow develop later, the liver functions as the main haematopoetic organ. Therefore, the liver is enlarged during development.
Other vertebrates
In some vertebrates, haematopoiesis can occur wherever there is a looses stroma of connective tissue and slow blood supply, such as the gut, spleen or kidney.
Red and white blood cell production is regulated with great precision in healthy humans, and the production of leukocytes is rapidly increased during infection. The proliferation and self-renewal of these cells depend on growth factors. One of the key players in self-renewal and development of haematopoietic cells is stem cell factor (SCF),which binds to the c-kit receptor on the HSC. Absence of SCF is lethal.
There are other important glycoprotein growth factors which regulate the proliferation and maturation, such as interleukins IL-2, IL-3, IL-6, IL-7. Other factors, termed colony-stimulating factors (CSFs), specifically stimulate the production of committed cells. Three CSFs are granulocyte-macrophage CSF (GM-CSF), granulocyte CSF (G-CSF) and macrophage CSF (M-CSF).These stimulate granulocyte formation and are active on either progenitor cells or end product cells.
Erythropoietin is required for a myeloid progenitor cell to become an erythrocyte. On the other hand, thrombopoietin makes myeloid progenitor cells differentiate to megakaryocytes (thrombocyte-forming cells).The diagram to the right provides examples of cytokines and the differentiated blood cells they give rise to.
REFERENCES LINK
1. http://medicine.academic.ru/3793/Hematopoiesis
2. https://instruction.cvhs.okstate.edu/Histology/HistologyReference/hrhemac.htm
3. http://www.bloodjournal.org/content/90/4/1345?sso-checked=true
p/s : Fuhh i took more time than I expected to elaborate about this specific topic. Afterall, it is all about how the blood cell is produced, where it is produced and when. Please, get rid of the wrinkles on your forehead, this is only the surface of it :D