The heart is a muscular organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to the lungs.
Motor neurons carry messages from the CNS to other parts of the body
<span>a. The model cell swells because it is in a hypotonic solution. The water enters the cell to move the glucose cells out into a solution to create equilibrium.</span>
So its acquired immunity and the cells responsible are the B lymphocytes that produces antibodies against the virus. Memory is keep since first encounter of the virus by the immune system by way of the antibodies that was initially produced. The antibodies are there already, which makes it fast to act upon when expose again.
The stress? Bad eating habits due to lack of money and time? There could be lots of reasons but that's what came to mind first.
