Mitochondria are considered as the powerhouse of cell because they perform function cellular respiration process in a cell.
Cellular respiration is a process of converting the chemical energy present in nutrients into ATP which gives energy to organisms to carry out movement and physical actions.
Mitochondria performs cellular respiration process from which they can release energy present in food and nutrients.
Due to those reasons, mitochondria is called as powerhouse of cell.
Muscles can also receive messages from the brain when the body temperature decreases. They respond by shivering. Shivering causes the muscles to contract and relax quickly. This process generates heat.
