Digestion is the complex process through which the food that we eat is broken down into nutrients and those nutrients are used by our body for cell growth, energy, cell repair and in order to survive. Digestion also involves removal of waste from our body.
The digestive system is the group of organs that work together for conversion of food into energy and the basic nutrients for feeding the entire body. The food passes through a long tube which is present inside the body known as the alimentary canal or also as the gastrointestinal tract. The gastrointestinal tract is composed of oral cavity, pharynx, stomach, esophagus, small intestines and the large intestines.
The accessory organs of digestive system which help the body in digesting food without the food passing through them include teeth, tongue, the salivary glands, gallbladder, liver, and also pancreas. Hormone and nerve regulators control digestive process.
HOW DOES DIGESTION WORK
Food enters the mouth> passes through alimentary canal> mixes with digestive juices causing breakdown of large molecules> body absorbs small molecules through small intestine into blood> waste products travel through large intestine> out of the body.
PROCESSES OF DIGESTIVE SYSTEM
Six major processes take place in the digestive system for the absorption of food, and gaining energy and nutrients. They are-
- Ingestion- intake of food. Mouth and stomach stores the food while it gets digested.
- Secretion- digestive system secretes around 7 liters of fluids including saliva (moistens dry food and salivary amylase present in saliva digests carbohydrates), mucus (protective barrier and the lubricant of alimentary canal), hydrochloric acid (digests food chemically and protection of body by killing bacteria from our food), enzymes (tiny biochemical machine used for disassembling large macromolecules of proteins, lipids, carbohydrates into small components) and bile (emulsifies lipids into tiny globules).
- Mixing and movement- involves swallowing (food is passed out of the mouth, via pharynx into esophagus), peristalsis (muscular wave hat moves partially digested food down the alimentary canal- from esophagus through stomach and intestines and reach the end of alimentary canal) and segmentation (occurs in small intestines to increase absorption of nutrients).
- Digestion- large pieces of food breakdown into its component chemicals.
- Absorption- begins in stomach when water and alcohol goes directly into bloodstream. Majority of it takes place in walls of small intestine from where smaller blood and lymphatic vessels pick up the molecules, carrying them to the rest of the body. Large intestine helps in absorption of water, Vitamin B and K.
Excretion- defecation takes place which removes indigestible substances out of the body and must be done to avoid accumulation of food inside the guts.