Starfish larvae lose substantial energy to maintain digestion under ocean acidification conditions

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...

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.

Chemical reactions, such as those that occur when you light a match, involve changes in energy as well as matter.

The total of all possible kinds of energy present in a substance is called the internal energy (U), sometimes symbolized as E. Suppose a system with initial internal energy, Uinitial, undergoes a change in energy (transfer of work or heat), and the final internal energy of the system is Ufinal. Change in internal energy equals the difference between Ufinal and Uinitial.

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.

The universe is composed of matter in different forms, and all forms of matter contain energy.  The different forms of energy on Earth originate from the Sun — the ultimate energy source. Plants capture light energy from the Sun, and, via the process of photosynthesis, convert it into chemical energy. This stored energy from plants can be harnessed in many ways. For example, eating plant products as food provides energy for our body to function, and burning wood or coal (fossilized...