The Digestive system Flashcards
Functions of the digestive system
1.Break down food into nutrients
2.Nutrients absorbed in the body
3. Transported through the circulatory system. Nutrients in the cell can be used as a source of energy or used for the synthesis of chemical compounds
The 4 stages of digestion
- Ingestion: taking in nutrients(eating/drinking)
- Digestion: breaking down complex molecules into smaller ones
- Absorption: Taking up of digestion molecules
- Egestion: removal of waste
Gastrointestinal tract(G1 tract)
the passageway or tube that extends from the mouth to the anus and in which the process of digestion takes place
Mechanical(physical) digestion
-large pieces of food become smaller pieces, increasing the surface area
-Chewing of the food in the mouth
-Churning and mixing of food that occurs in the stomach
Chemical digestion
-Parts of the digestive tract produce digestive enzymes
-Different enzymes break down macromolecules to small organic molecules that can be absorbed
Physical and chemical digestion in the mouth
-Digestion starts in the mouth
-Food is broken down physically by the teeth and tongue
-The salivary glands release a substance called saliva
-Saliva contains a mixtures of water, mucus, and enzymes
Amylase
enzyme found in saliva that breaks starch down to simple sugars
Bolus
Food that has been chewed and mixed with saliva becomes a bolus
How the body works with bolus
-As the bolus is pushed into the pharynx. the soft palate is raised to prevent food from entering the nasal passage
-A structure called the epiglottis also covers the entrance to the trachea so food does not enter our lungs but instead down the esophagus
The esophagus
-The esophagus is a muscular tube that passes food from the pharynx to the stomach.
- Wave like muscle contractions called peristalsis move it towards the stomach.
Stomach
-Mechanical and chemical digestion occur in the stomach
-The stomach is j-shaped, it stores food, and has a capacity of 2L
Sphincters
-Food enters and exits the stomach through sphincters
-Sphincters are muscles surrounding a tube-like structure
-The bulus enters the stomach when the esophageal sphincters relaxes
-When the esophageal sphincter contracts, it prevents food from moving back into the esophagus
Gastric juice
-The stomach releases gastrin which stimulates the release of gastric juice secreted by the cells in the stomach lining
Gastric juice contains a mixture of
-HCI (hydrochloric acid): breaks down food fibres & bacteria
-Enzymes (pepsin)
-Mucus: Protect stomach lining from HCI
*im stomach lining is destroyed—> ulcers will form
Cells of the stomach
-Parietal
-Cheif