1. Summary

The type of nutrition in fungi is saprophytic.Parasites depend on host for their food Without killing them to meet basic needs is parasitic nutrition. The type of Nutrition in amoeba is holozoic.The type of Nutrition in paramecium is holozoic.The process  of breakdown of complex molecules into simple molecules is digestion. Mouth, buccal cavity, pharynx, oesophagus, stomach, intestine, rectum and anus are the parts of Digestive system.Glottis has a cartilaginous flap called Epiglottis.Wave like muscle contractions of alimentary canal that pass the food bolus is Peristalsis.

Partially digested food in the stomach is Chyme.Largest digestive gland  is Liver.Digestive juice secreted by liver is Bile Juice. An organ stores bile juice is gall bladder.Digestive juice secreted by pancreas is Pancreatic juicePosterior part of small intestine is IleumSmall finger like projections of  the wall of  ileum are Villi.Rectum is a part of large intestine which absorbs water from undigested food.Appendix is vestigial and an extended part of lower end of rectum of human.Anus is an opening of rectum which ejects excreta.Saliva protects tooth due to presence of amylase , lysozyme and minerals.

Animals that depend on plants or other animals for their nutrition are called heterotrophs. This type of nutrition is called heterotrophic nutrition.

Heterotrophs ,Heterotrophic nutrition

Nutrition in unicellular organisms like the amoeba and paramecium is of holozoic type. It involves the ingestion of liquid or solid organic material, digestion, absorption and assimilation to utilise it. The food in the food vacuoles of the amoeba and paramecium is digested by lytic enzymes.

Unicellular organisms , Holozoic typeUnicellular organisms , Holozoic type

The process of breaking down complex molecules into simple molecules is called digestion.

Digestive System, Alimentary Canal

In man, the digestive system consists of the alimentary canal and digestive glands. The mouth, buccal cavity, pharynx, oesophagus, stomach, intestine, rectum and anus are parts of the alimentary canal.

Digestive System, Alimentary Canal

Digestive System, Alimentary Canal

The digestive glands are the salivary glands, the gastric glands, the liver, the pancreas and the intestinal glands.

Digestive Glands

In man, three pairs of salivary glands open into the oral cavity, namely the submaxillary, sublingual and parotid glands.

Salivary Glands

Amylase, a digestive enzyme in saliva, breaks down the starch in food into simpler sugar.

Amylase, Saliva

Saliva also prevents tooth decay due to the presence of amylase, lysozyme and minerals.

Tooth decay

A series of muscular contractions in the oesophagus that pushes food forward to the stomach is called peristalsis.

Oesophagus, Peristalsis

The stomach is divided into cardiac, fundus or body, and pylorus. At the junction of the oesophagus and stomach, and of the stomach and duodenum are valves.

Stomach, Valves Stomach, Valves

In the stomach, food is mixed with the gastric juices secreted by the gastric glands, which contain chemicals like hydrochloric acid, and enzymes like pepsin, rennin and lipase. Partially digested food in the stomach is acidic, and is known as chyme.

Gastric Juice, Chyme

The liver is the largest gland in the body. It secretes bile juice, which helps in the emulsification of fats, and makes the medium alkaline for the action of pancreatic and intestinal enzymes in the duodenum and the small intestine.

Liver, Bile Juice

The pancreas secretes pancreatic juice, which includes trypsin and lipase that help break down proteins and fats.

Pancreas, Pancreatic Juice

In the small intestine, the intestinal enzymes such as invertase, maltase and lipase act upon partially digested proteins, carbohydrates and fats. They are simplified into amino acids, glucose, fatty acids and glycerolin a liquid medium known as chyle.

Small Intestine, Intestinal Enzymes, ChyleSmall Intestine, Intestinal Enzymes, Chyle

The villi in the small intestine increase its surface area to ensure efficient and rapid absorption of nutrients. Blood capillaries in the villi absorb nutrients and transport the food to all the cells in the body.

Villi, Nutrients

The large intestine absorbs water from undigested food and forms solid waste. The rectum stores the solid excreta until it is ready to be excreted from the digestive system through the anus.

Large Intestine, Rectum, Anus

The appendix is a small, hollow, finger-like pouch, which hangs at the end of the cecum. It does not have any function in the digestive system of humans. However, it is functional in herbivores such as cows.

Appendix , Cecum, Herbivores

2. Videos
  • LearnNext Video

  • Youtube - The Fundamentals of Digestion and Enzymes in The Human Body

  • Youtube - Human Digestive System animation work

  • Youtube - Liver Structure and the Flow of Blood and Bile

  • Youtube - The Role and Anatomy of the Pancreas

3. Activities & Simulations
4. Teacher Solved Exercises
5. Questions & Answers
1 . What is Dialysis
3 Answers
2 . Stomata
3 Answers
3 . Life processes
1 Answer

6. Related Concepts
8. Contributors