Human digestive system Flashcards
Define nutrition
Nutrition is the process by which organisms obtain food and energy for growth, repair and maintenance of the body
Define digestion
Digestion is the process that breaks down complex food substances into simple, soluble molecules that are small enough to be absorbed into body cells
Where does food digestion take place
Alimentary canal
Define physical digestion
Physical digestion is the mechanical breakdown of food into smaller particles to increase surface area to volume ratio for faster rate of chemical digestion
Define chemical digestion
Chemical digestion is the breakdown of large food molecules into small soluble molecules catalysed by digestive enzymes through hydrolytic reactions
What is ingestion
The act of taking food into the mouth
What is the optimum pH in the mouth
6.5-7.5
What glands and enzymes are present in the mouth
Salivary gland
- Salivary amylase
What enzyme actions occur in the mouth
- Starch > Maltose (Amylase)
What is peristalsis
Rhythmic, wave-like, muscular contractions of the oesophagus
What does gastric juice contain
- HCl
- Pepsin
What is the purpose of HCl in the stomach
- Provides acidic medium suitable for stomach enzymes
- Kills bacteria in food
- Denatures salivary amylase
- Converts inactive forms of enzymes to active forms (pepsinogen > pepsin)
What glands and enzymes does the stomach contain
Gastric gland
- Pepsin
What enzyme actions occur in the stomach
Proteins > Polypeptides (Pepsin)
What are the glands and enzymes in the small intestine
Pancreas
- Pancreatic amylase
- Pancreatic lipase
- Trypsin
Intestinal gland
- Maltase
- Sucrase
- Lactase
- Intestinal lipase
- Peptidase