As you increase in altitude, there are fewer air molecules. Due to the lower amounts of air molecules, the atmospheric pressure decreases causing the air to be harder to breath in.
<span>The ischemic penumbra can maintain metabolic demand with marginal blood flow from collateral circulation for a maximum of 50% before increasing in size. A penumbra is the area where the flow of blood at about 25 - 50% can maintain normal metabolic demands for 6 - 8 hours only. When it continues to increase, the human cells will die and other neurological activity will be suspended causing the person to die slowly.</span>
What kinda cell, animal or plant?
The answer is Arteries
Arteries carry oxygen-rich blood from the heart to capillaries. On the contrary, veins carry blood without oxygen from the capillaries to the heart.
Arteries are very flexible and yet strong blood vessels so that efficient transport of oxygen-rich blood along the bloodstream through the organism is enabled.