Answer:
As the heart pumps, glucose is carried in the bloodstream to cells all over the animal’s body. Oxygen which enters the animal’s body through its respiratory system (lungs, gills, skin, or exoskeleton) is carried by its transport system (blood for many animals to every animal cell. Once the glucose and oxygen arrive in the cell they can go through a chemical reaction. Glucose reacts with oxygen to produce carbon dioxide and water. Cells transform the chemical energy in the glucose molecules into energy for cell functions, motion energy, and heat. Because of cellular respiration, muscle cells have access to the energy necessary to contract or relax in response to a signal from the brain sent through nerve cells, so muscles can contract or relax enabling the animal to move. During cellular respiration, energy is released in the cell to enable the work of the cell to occur. The atoms found in glucose are rearranged into carbon dioxide and water and are no longer needed by the cell so they are considered waste products. Cells have to get rid of unwanted waste products. Carbon dioxide and water move out of cells and into the blood. The blood carries the carbon dioxide and water to different places in different animals (the lungs, gills, skin, kidneys, or exoskeleton) where they are released into the environment. Animal movement we observe at the macroscopic scale is possible because cellular respiration is happening at the atomic-molecular scale.
