Stem cell therapies are not new. Doctors have been performing bone marrow stem cell transplants for decades. But when scientists learned how to remove stem cells from human embryos in 1998, both excitement and controversy ensued.
The excitement was due to the huge potential these cells have in curing human disease. The controversy centered on the moral implications of destroying human embryos. Political leaders began to debate over how to regulate and fund research involving human embryonic stem (hES) cells.
Newer breakthroughs may bring this debate to an end. In 2006 scientists learned how to stimulate a patient's own cells to behave like embryonic stem cells. These cells are reducing the need for human embryos in research and opening up exciting new possibilities for stem cell therapies.
<span>The answer is A. rock ages. B and C are common for topographic maps, and D is common on all maps. But only geologic maps show rock ages.
Hope this helped :)</span>
From mouth/nose, the air passes to the trachea (the wind pipe), there it enters (sequentially) the bronchi, bronchioles (small pipe-like structures), alveoli (widened empty sacs), the walls of which are in close contact with the blood vessels which contain the RBCs, which in turn contain the protein--hemoglobin, which binds to the oxygen present in the freshly inhaled air, and loses the carbondioide present DISSOLVED in the blood. This bound oxygen goes to the heart (of course along with the RBCs in the blood), from there to the smaller and smaller arteries, then to the capillaries, where again oxygen is lost to the surrounding tissue fluid, from where the cells collect oxygen by simple diffusion, and lose carbon dioxide, which gets dissolved in the water present in the blood.
From here the blood, with hemoglobin poorer in oxygen, and richer again in carbondioxide goes to the venules, and veins (capillaries continue as venules), which become successively larger to become superior and inferior vena cava and enter the right atrium, and then from there the blood again goes to the lungs and comes in contact with fresh air in the alveoli.
