*Blood flow is regulated in all three types of blood vessels through constriction and dilation.
*Contraction of blood vessels slows blood flow, while relaxation of blood vessels, or dilation, allows free flow of blood.
*Muscle fibers control the constriction and dilation of vessels. In the capillaries, rings of muscle called capillary sphincters control blood flow.
*The directional flow of blood in the veins is controlled with valves , which prevent backward blood flow when closed, and allow blood to flow only toward the heart when open.
Vasoconstriction and vasodilatation allow blood vessels (arteries and veins) to control blood flow and thus control the blood pressure. This is possible because of the smooth muscle cells that surround the vessels. The contraction and dilatation of those muscles is controlled by chemical signals (e.g. norepinephrine constricts the vessels, while NO dilates them).
Answer:
by mimicking disease agents and stimulating the immune system to build up defenses against them.
Explanation:
The chloroplast contains chlorophyll<span> within its thylakoids, which absorbs light energy and gives chloroplasts its green color. Stacks of thylakoids are known as grana, which exist in the open space of the chloroplast known as the stroma.</span>
Answer:
recycle, use less nonrenewable resources, dont do pollution, dont litter. Take care of our Earth <3 there is no backup planet..
Explanation:
Is chemistry for reactions to take place energy must be provided. As heat is a form of energy, the more the heat, the more the energy, the faster the reaction occurs
