6 Principles of Physiological Process of Digestive Organ
Human digestive system consists of GI tract (gastrointestinal tract) and the accessory organs of digestion.
The principles of physiological process of digestive organ are-
1. Ingestion
2. Digestion
3. Mixing and Propulsion
4. Absorption
5. Assimilation
6. Elimination (Defecation or Egestion)
1. Ingestion
Ingestion is taking food into the alimentary track.
Ingestion is process, food enters the digestive system through the mouth.
Once food in the mouth is chewed to form a ball of food called a bolus.
Swallowing starts with the oral phase, at star act of swallowing food or liquid is voluntary. But once it begins, process becomes involuntary and continues under the control of nerves.
2. Digestion
Digestion involve physical or mechanical and chemical breakdown of food.
Digestion process begins in the mouth, when chew and swallow of food and till completed in the small intestine.
3. Mixing and Propulsion
(Mix food and propel them)
In stomach, peristalsis churns the swallowed food, mix the food with gastric juices. Mechanical and chemical actions break down food into a substance called chyme. Chyme is semi-fluid mass of partly digested food that is expelled by stomach into the duodenum.
The muscles of the small intestine propel the mixture of chyme (mix with digestive juices from the pancreas, liver, and intestine) for further digestion.
Propulsion refers movement of food through the digestive tract. It includes voluntary process of swallowing and involuntary process of peristalsis.
Peristalsis is movements that propel the food particles through digestive tract.
4. Absorption
(Making absorption of nutrients)
Nutrients are absorbed by epithelial cell of intestinal villi. The absorption of nutrients takes place by diffusion through the wall of the small intestine. Absorption of ion, minerals, vitamin, fat , glucose, fructose, amino acid , peptides occurs.
Entire small intestine involve in absorption of water and lipid. Most absorption of carbohydrates and protein occurs in Jejunum.
5. Assimilation
Movement of absorbed food into the cells of the body where they are used. Absorbed nutrient reaches the cell via liver.
For example,
1. Glucose used in respiration to provide energy
2. Energy for growth and respiration
3. Cellular metabolism
4. Amino acids; used to build new proteins.
6. Elimination
(Defecation or Egestion, Excretion)
Elimination of indigestible substance (such as fibers, bile, salts, bile pigment, etc) and unabsorbed water and electrolytes.
Peristalsis
Move food through digestive track with alternative waves of muscle contraction and relaxation.Peristalsis, involuntary movement; sequental smooth muscle contraction and move ingested nutrient to digestive track.
Organs of Digestive System
1. Digestive System (Gastrointestinal tract or Alimentary tract)
The gastrointestinal tract is the passageway of the digestive system that tube directly run from mouth to the anus.
Organ of gastrointestinal tract-
1. Mouth
2. Pharynx
3. Oesophagus
4. Stomach
5. Small Intestine
6. Large intestine
7. Rectum
8. Anal canal and
9. Anus
2. Accessory Organs
Accessory digestive organs or structures that aid digestion physically and produce secretions. Accessory organs are Indirectly aids in digestion.
Accessory digestive organs are-
1. Lips
2. Teeth
3. Tongue
4. Salivary glands
5. Palate
6. Pancreas
7. Liver
8. Gall bladder
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