Liver:
The liver is responsible for various metabolic processes, including detoxification, protein synthesis, and the metabolism of carbohydrates, fats, and proteins. These processes require a significant amount of energy, which is why liver cells contain a large number of mitochondria to meet their high energy demands.
Muscle:
Muscle cells, especially those involved in rapid and forceful contractions, also have a high energy requirement. During muscle contraction, ATP (adenosine triphosphate) is rapidly broken down to provide energy. The mitochondria in muscle cells produce ATP through oxidative phosphorylation, which is a process that uses oxygen to generate energy from glucose or fatty acids. The more mitochondria a muscle cell has, the more ATP it can produce, allowing for sustained muscle activity.
