where does red blood cell production occur in adults
Red blood cell In humans, mature red blood cells are flexible and oval biconcave disks. They lack a cell nucleus and most organelles, in order to accommodate maximum space for hemoglobin; they can be viewed as sacks of hemoglobin, with a plasma membrane as the sack. Approximately 2.4 million new erythrocytes are produced per second in human adults.[2] The cells develop in the bone marrow and circulate for about 100â€“120 days in the body before their components are recycled by macrophages. Each circulation takes about 60 seconds (one minute).[3] Approximately a quarter of the cells in the human body are red blood cells.[4][5] Nearly half of the blood's volume (40% to 45%) is red blood cells.
Haematopoiesis In developing embryos, blood formation occurs in aggregates of blood cells in the yolk sac, called blood islands. As development progresses, blood formation occurs in the spleen, liver and lymph nodes. When bone marrow develops, it eventually assumes the task of forming most of the blood cells for the entire organism.[1] 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.[7]
Rate equation k is the first order rate constant, which has units of 1/s or sâˆ’1.
Cwm Rhondda Arglwydd, arwain trwy'r anialwch, Fi, bererin gwael ei wedd, Nad oes ynof nerth na bywyd Fel yn gorwedd yn y bedd: Hollalluog, Hollalluog, Ydyw'r Un a'm cwyd i'r lan. Ydyw'r Un a'm cwyd i'r lan Agor y ffynhonnau melus 'N tarddu i maes o'r Graig y sydd; Colofn dân rho'r nos i'm harwain, A rho golofn niwl y dydd; Rho i mi fanna, Rho i mi fanna, Fel na bwyf yn llwfwrhau. Fel na bwyf yn llwfwrhau. Pan yn troedio glan Iorddonen, Par i'm hofnau suddo i gyd; Dwg fi drwy y tonnau geirwon Draw i Ganaan – gartref clyd: Mawl diderfyn. Mawl diderfyn Fydd i'th enw byth am hyn. Fydd i'th enw byth am hyn.