What are the four stages of digestion?
Ingestion, digestion, absorption, elimination
What is digestion?
Process of breaking food down into molecules small enough to absorb
What type of digestion occurs in the mouth when food is mixed or crushed with your teeth?
Mechanical digestion
What is the chemical digestion that occurs in the mouth?
Digestive enzymes break down complex polymers into monomers
What is an enzyme?
Molecule that allows a substances to be converted into smaller molecules
- What is amylase?
2. What does it do?
- An enzyme produced by the salivary glands and found in saliva
- Breaks down starch into maltose
What does the tongue do to the food in the mouth?
Forms it into a bolus
- When is the swallowing reflex stimulated?
- What is the pharynx?
- What is an epiglottis?
- When food enters the pharynx
- Place in throat that opens up into trachea and esophagus
- A flap that flops down over the windpipe and allows food to enter esophagus
- How long is the esophagus and what does it connect to?
2. What is the sphincter valve?
- 25cm, connects to stomach
2. Food enters it but is prevented from going back up
What is peristalsis?
When food is pushed down the esophagus with help of involuntary muscle contractions
What are the stomach’s 3 functions?
- To store up to 2L of food and fluid
- To break down the food into liquid mixture
- To slowly empty liquid mixture into small intestine
What is churning?
When the smooth muscle in the stomach mixes the food
What is gastric juice made up of?
Hydrochloric acid, mucous, enzyme pepsin
- What does the hydrochloric acid in the gastric juice do?
- What is the role of pepsin?
- What does mucous do?
- Breaks down meat and plant material, kills bacteria in food
- Breaks down proteins into smaller amino acid chains
- Protects the lining of the stomach from the acid
- What does the bolus become?
2. This liquid is released from the stomach via what?
- Acid chyme
2. Pyloric sphincter
What can decrease the amount of mucous in the stomach?
Helicobacter pylori or chronic use of medication
If the inner linings of the stomach are exposed to acid, what does this cause?
- Irritation (gastritis)
2. Ulcers (sore/hole in stomach)
- Approx. how long is the small intestine?
- What is its main function?
- What are the names of the 3 parts of this organ?
- 6-7m long
- Transport nutrients into your bloodstream
- Duodenum, jejenum, ileum
- What are villi?
2. What does each villi contain?
- Folds on the small intestine that look like fingers and are made up of epithelial cells
- Microvilli
Why do villi and microvilli increase the surface area of the small intestine?
- Allows more nutrients to be absorbed into the bloodstream
2. Nutrients are absorbed into the blood faster
In the duodenum, the acid chyme mixes with digestive juices from which 3 other organs?
Pancreas, liver, gallbladder
- What enzymes does the pancreas produce and why?
2. What else does it produce and why?
- Lipase, to break down fats
2. Basic solution to neutralize the acid from chyme
- What does the liver produce?
- What is it?
- Where is it stored?
- Bile
- A liquid that allows fats to be absorbed into the bloodstream
- Gallbladder
What are the liver’s functions?
- To filter out harmful substances and turn some into more bile
- Determines the amount of nutrients that will be distributed to the body
