The human body contains a monogastric digestive system. In a monogastric digestive system, the stomach only contains one chamber in which it digests food. Several other animal species also have monogastric digestive systems, including pigs, horses, dogs, and birds. This chapter, however, focuses on the human digestive system.

Digestive SystemThe digestive system is how our body turns food into energy and nutrients. It’s made up of a series of connected organs that each have a specific role in the process of digestion. This includes breaking food into smaller parts, absorbing nutrients into the bloodstream, and removing waste. Starting in the mouth and ending in the anus, the system also includes key helper organs like the liver and pancreas. Learning how the digestive system works helps us understand how our...

Protein digestion begins in the stomach, where the highly acidic environment can easily disrupt protein structure by exposing the peptide bonds of polypeptide chains. After polypeptide chains are broken into individual amino acids by a series of digestive enzymes, the amino acids are transported to the liver via the bloodstream to produce energy.

Digestive System OrgansThe digestive system is a group of organs that work together to break down the food we eat into nutrients our body can use. It starts at the mouth and ends at the anus. Along the way, food travels through the esophagus, stomach, small intestine, and large intestine. Other important organs like the liver, pancreas, and gallbladder help with digestion by producing special chemicals and enzymes. Each organ has a specific role, and together, they make sure our body gets the...

Lipids are large molecules that are generally not water-soluble. Since most of the digestive enzymes in the human body are water-based, there are specific steps the body must take to break down lipids and make them available for use.

Carbohydrate digestion and metabolism break down simple and complex carbohydrates from food into saccharides (i.e., sugars) for the body to use as energy. Carbohydrate digestion starts in the mouth during mastication, or chewing. The masticated carbohydrates remain intact in the stomach. Digestion resumes in the duodenum of the small intestine, where pancreatic alpha-amylase and brush border enzymes of the microvilli convert complex carbohydrates to monosaccharides. Finally, the monosaccharides...