a unit of energy that indicates the amount of energy contained in food.

Nutritional Requirements of Animals

It is the major source of energy and can be obtained from rice and wheat.

– can also be used as an energy source but the body mainly uses these as building materials for cell structures and as enzymes, hormones, parts of muscles, and bones.

- come from dairy products, poultry, fish, meat, and grains.

- It contains higher amount of energy per gram than carbohydrates or proteins, about 9 calories per gram.

- used to build cell membranes, steroid hormones, and other cellular structures; also used to insulate nervous tissue, and also serve as an energy source.

substances that animals can only get from the foods they eat because they could not be synthesized inside the body.

Essential Nutrients are divided into three: 

These are organic molecules required in small amounts for normal metabolism and usually divided into two groups: fat-soluble and water-soluble.

Vitamins A, D, E, K

Vitamins B, B2, B3, B12, C

needed for synthesis of proteins and enzymes

used for making special membrane lipids; an example is linoleic acid in humans

where food is initially chewed into shreds by the teeth, and mixed with saliva by the tongue.

- serves as airway to the lungs

- serves as the entrance to the esophagus that connects to the stomach and trachea (windpipe)

– connects the pharynx with the stomach

-  about 25 cm (10 in.) long.

-  the contractions within its muscular wall propel the food past a sphincter, into the stomach

a muscular, stretchable sac located just below the diaphragm.

a combination of HCl and acid-stable proteases.

The churning action of the stomach together with the potent acidity of the gastric juice convert food into a thick, liquid mixture called ______

- approximately 6 meters long

- composed of three regions: the duodenum, jejunum, and ileum.

- where most enzymatic hydrolysis of the macromolecules from food occurs.

Absorption of the end products of digestion takes place in the ileum, the surface area of which is increased by _____ and ______

- shorter than the small intestine, about 1 meter.

- It concentrates and stores undigested matter by absorbing mineral ions and water.

- a short extension of the large intestine and is the final segment of the digestive tract.

- the terminal opening of the digestive system through which feces are expelled.

The Main Stages Of Food Processing

expulsion of the undigested and unabsorbed materials from the end of the gut.

- passage of digested nutrients and fluid across the tube wall and into the body fluids

- the cells take up small molecules such as amino acids and simple sugars

the act of eating or feeding; this is coupled with the mechanical breakdown of food into smaller pieces allowing for a greater surface area for chemical digestion.

breakdown of food into particles