Digestive system
- Mouth (and tongue): Digestion begins here whereby mechanical digestion takes place when the teeth grind the food and break it down into smaller pieces for easier digestion. The salivary enzymes help to digest carbohydrates (starch) and also soften the food. This is chemical digestion. Then, the tongue rolls the food into a ball called bolus and pushes it down to the esophagus.

- Esophagus: The muscles in the esophagus push the bolus of food down to the stomach. This process is called peristalsis.

- Stomach: The food is broken down into even simpler substances whereby mechanical digestion takes place when the stomach churns the food. Protein is digested in the stomach through chemical digestion.

- Small Intestine: The first part of the small intestine is called the duodenum. In the duodenum, bile from the liver and gall bladder, and pancreatic juice from the pancreas work together to digest everything -- carbohydrates, proteins and fats. The small intestine is designed specifically to maximize digestion and absorption. Firstly, to increase its surface area, the small intestine is very very long and has folds, villus and microvilli. Second, to increase the rate of diffusion, it has thin walls and a network of capillaries (concentration gradient). In the small intestine, carbohydrates, proteins and fats are broken down into their simplest forms namely monosaccharide, amino acids and fatty acids + glycerol respectively. Digestion ends in the small intestine.

- Large Intestine: The large intestine absorbs water from undigested food. It also manufactures vitamins, produces mucous and forms and expels feces.

- Rectum: This is where the feces end up before egestion takes place.

Watch this video to help you understand the digestive system better :)