Digestive system
The digestive system consists of organs that handle food intake, swallowing, chewing, digesting, absorbing, and eliminating digestive waste. This system includes an 8-10 meter canal, starting in the oral cavity and continuing to the pharynx, esophagus, stomach, and small and large intestines. Throughout our lives, our digestive system processes about 30 tons of food products and around 50,000 liters of fluids.
Functions of the Digestive System
- Food Intake and Mechanical Breakdown: Chewing and swallowing occur in the mouth.
- Secretory Function: Digestive glands secrete digestive juices that contain enzymes, minerals, and water.
- Motor Function: Smooth muscle contractions in the digestive tract break down food content, mix it with digestive juices, and transport it through the digestive tract.
- Food Material Breakdown: Digestive enzymes break down food material.
- Absorptive Function: The final products of food material hydrolysis, along with water, minerals, and vitamins, are absorbed and transported to the lymph and blood.
- Excretory Function: The system eliminates formed metabolites, heavy metal salts, drugs, and other substances.
- Endocrine Function: The digestive system secretes hormones that stimulate or inhibit its activity.
- Protective Function: The digestive system secretes substances with bactericidal, bacteriostatic, and detoxifying effects (notably in the liver) and involves a humoral immune response.
- Analytical Function: Food stimulates mechanical, chemical, and thermal receptors, which reflexively regulate digestion.
Appetite and Hunger
Appetite drives the desire to consume an appropriate amount of food each day. Hunger, a strong desire to eat, arises due to changes in blood levels of glucose, amino acids, and other food materials, as well as the volume of food in the stomach. Nervous impulses from chemoreceptors and mechanoreceptors reach the hunger center located in the lateral part of the hypothalamus.
Source | Glossary of Most Commonly Used Biomedical Terms and Concepts | Lithuanian University of Health Sciences | Academician Professor Antanas Praškevičius, Professor Laima Ivanovienė