In the human embryo, the first site of blood formation is the yolk sac. Later in embryonic life, the liver becomes the most important red blood cell-forming organ, but it is soon succeeded by the bone marrow, which in adult life is the only source of both red blood cells and the granulocytes. Their job is to transport oxygen to the body's tissues in exchange for carbon dioxide, which is carried to and eliminated by the lungs. Red blood cells are formed in the red bone marrow of bones. Stem cells in the red bone marrow called hemocytoblasts give rise to all of the formed elements in blood. Erythroid (red blood) cells are the first cell type to be specified in the postimplantation mammalian embryo and serve highly specialized, essential functions throughout gestation and postnatal life. The existence of 2 developmentally and morphologically distinct erythroid lineages, primitive (embryonic) and definitive (adult), was described for the mammalian embryo more than a century ago. Cells of the primitive erythroid lineage support the transition from rapidly growing embryo to fetus, whereas definitive erythrocytes function during the transition from fetal life to birth and continue to be crucial for a variety of normal physiologic processes. Over the past few years, it has become apparent that the ontogeny and maturation of these lineages are more complex than previously appreciated. In this review, we highlight some common and distinguishing features of the red blood cell lineages and summarize advances in our understanding of how these cells develop and differentiate throughout mammalian ontogeny.
Negative attitudes and feelings of helplessness and hopelessness can create chronic stress, which upsets the body's hormone balance, depletes the brain chemicals required for happiness, and damages the immune system. Chronic stress can actually decrease our lifespan.
<span><span>Rest</span><span>Ice</span><span>Compression</span><span>Elevation</span></span>
Answer:
Taking a class/ Online class
Explanation:
A short-term goal is something you want to accomplish soon. A short term goal is a goal you can achieve in 12 months or less.
Hope that helps!
Answer:
(B) Try to swim over to the tree.
Explanation:
Flash flood is defined as A flood in a brief period of time triggered by heavy or extreme rainfall, Flash flooding occurs within 6 hours of the rain event.
It is advisable to swim over to the tree as this would give you If a higher ground which is very neccesary. With the aid of the tree, you can hold tight to it also , so that the current of the flash flood wont carry or drown you.
