 Stomach used in digestion and storage of food in most of vertebrates and some invertebrates.  Stomach consists of thick muscular wall in herbivores and carnivores.  There are gastric glands that secrete the pepsin enzyme and HCL acid.  Food is mixed with HCL in stomach and expose to the mechanical digestion by peristalsis (in arthropods and birds).  Pepsin enzyme involved in digestion of proteins.

1) It has differentiated parts that called the gastric glands that secrete the pepsin enzyme and HCL acid. 2) Food storage. 3) Destroy bacteria. 4) Digest the proteins.

 Intestines are long and bended in herbivores while shorter in carnivores.  Villi: - are finger like structure s (and microvilli on villi surface) in inner surface of intestine to increase the surface area for digestion and absorption.  Duodenum: - First part of small intestine it receives semi digested food through pyloric sphincter and the secretions from the liver and pancreas.  Chyme: - Food mass digestion complete in the duodenum.

Because the stomach consists of thick muscular wall in herbivores and carnivores.

Stomach has gastric glands that secrete the pepsin enzyme and HCL acid, and pepsin enzyme involved in digestion of proteins.

to increase the surface area for digestion and absorption.

irritation of the stomach and intestine caused by toxins.

Length of small intestine depend on nutrition type, ex: length of small intestine in frog larvae which is herbivore longer than small intestine of adult frog which is carnivore.

1- Complete the digestion of food absorbs the nutrients. 2- Carbohydrates are digested into glucose, galactose or fructose and pass to the blood. 3- Proteins are digested into amino acids and pass to the blood. 4- Fatty acids and glycerol is passing to the lymphatic system.

1- Trypsin and chemotrypsin are involved in digestion of proteins. 2- Lipase digests lipids into fatty acids and glycerol. 3- Nuclease digests the nucleic acids. 4- Amylase digests the starch molecules.

1- Detoxification of blood. 2- Stores the iron, vitamin A, B12, E and D. 3- Produces albumin and fibrinogen proteins. 4- Stores the excess amount of glucose as glycogen. 5- Convert ammonia to urea. 6- Produces bile from partition of old red blood cells. 7- Regulate the amount of cholesterol in blood.

the golden yellow color liquid is formed by partition of hemoglobin of old red blood cells and it involved in digestion of lipids in duodenum.

 Large intestine absorbs water and defecate the undigested food in form of a solid mass.  Water absorption is important for terrestrial organisms like insects, birds and reptiles.  There are many bacteria in human large intestine which convert some organic materials into vitamin K and little amount of vitamin B.

because the large intestine is absorbs water from remains digested food.

growth and for the repair of their damaged tissues from food.

-Carbohydrates - Lipids - Proteins - Vitamins - Minerals - Water

in regulation and activation of metabolic activities.

 Grains are main sources of carbohydrates.  They change into simple sugars gradually in digestive system and contain amount of fibers.  These fibers limit adhesion of carcinogenic material on wall of intestine and they prevent colon cancer by this way.  Dissolved fibers in oat prevent absorption of cholesterol and some harmful acids. But large amount of fibers prevent absorption of iron, zinc and calcium from food.

1- These fibers limit adhesion of carcinogenic material on wall of intestine and they prevent colon cancer by this way. 2- Dissolved fibers in oat prevent absorption of cholesterol and some harmful acids. 3- Large amount of fibers prevent absorption of iron, zinc and calcium from food.

Eskimos diet are contain large amount of fats and proteins but little amount of carbohydrates.

The development of an organism from a zygote and the formation of its organ systems are entirely depend on proteins.

structurally and functionally different subunits.

There are nine vital amino acids that cannot be synthesized in the body and they have role in development of children. The qualified proteins contain adequate amounts of vital amino acids and are easily digested. Generally, animal proteins are qualified but plant proteins are nonqualified.

 These giant molecules yield the most energy in comparison to other molecules.

There are two kinds of fats; saturated and unsaturated: 1- Saturated fats are generally obtained from animal products with exception of some plants like coconut oil. Consuming large amount of saturated fats causes arteriosclerosis. 2- Plant fats are unsaturated fats and necessary for human body for health. 3- Fish contain omega-3 fatty acids which have a role in prevention of heart attack.

Because the persons are consuming large amount of saturated fats.

is main source of necessary nutrients for babies. It contains all necessary materials for baby and contents change periodically according to growth of baby.

1- Colostrum secretion stage. 2- After fifth day of secretion colostrum secretion decreases and natural milk secretion start and continues until third or fourth week. 3- Mature milk secretion stage start after fourth week.

 Vitamins ingested in food and plays important role in regulation of body metabolism.  Most of them cannot be produced in the body.

Vitamins have two types according to their solubility; water soluble vitamins and lipid soluble vitamins.

 Inorganic molecules, or minerals, are as important for body functions as organic molecules.  They are required for health, continuity of metabolism and in the formation of bones and teeth.

1- They are required for health, continuity of metabolism and in the formation of bones and teeth. 2- They are divided into two main groups:-  Essential minerals (calcium, phosphorus, sodium, potassium).  Non-essential minerals (magnesium, iron, copper, zinc and other trace elements).