Answer:
Explanation:
1) Excitation brings about contraction.
2) Contraction leads to an increase in blood pressure.
3) Changes in blood pressure results in the opening and closing of the heart valves.
4) The opening and closing of heart valves then regulates the flow of blood and it's volume.
Answer:
The loss of trees and other vegetation can cause climate change, desertification, soil erosion, fewer crops, flooding, increased greenhouse gases in the atmosphere, and a host of problems for indigenous people.
Explanation:
The things that birds have attached to their bodies called their wings, a left one and a right one, cause them to have the ability to fly.
The immune system and the nervous system maintain extensive communication, including 'hardwiring' of sympathetic and parasympathetic nerves to lymphoid organs. Neurotransmitters such as acetylcholine, norepinephrine, vasoactive intestinal peptide, substance P and histamine modulate immune activity.
