Humans and animals eat the plants which are full of glucose and oxygen which we get the energy from we also eat the animals that ate the plants so we get the energy from them. This makes us heterotrophs.
There are 3 or 4 macronutrients that break down the food in your mouth. These macronutrients are all located in saliva they are amylase, pepsin/trypsin, and lipase. The amylase breaks down the carbs in your food, the pepsin and trypsin break down proteins, and lipase breaks down lipids. All these macronutrients make the food you eat into a mushy mash that you then swallow.
Food is chewed up in the mouth and partially broken down by the amylase in your saliva.
It goes through the pharynx and larynx, and then to the esophagus. It is deposited in the stomach, where it is digested in a chemical bath.
The result of this flows into the small intestine, where small protrusions called villi absorb nutrients, a key one being glucose. The mesentery is the thing that holds the intestines to the body.
The extracted material is filtered by the liver. Waste is converted into uric acid and removed by the kidneys and urinary system.
The rest of the material flows into the large intestine, where water is removed.
The remainder is stored in the rectum until it is ejected through the anus.