S1) Purpose of the Gut Flashcards
Label the following components of the digestive system:
Identify the 8 functions of the gut
- Port of entry for food into the body
- Mechanically disrupt the food
- Temporarily store the food
- Chemically digest the food
- Kill pathogens in the food
- Move the food along the tract
- Absorb nutrients from the resultant solution
- Eliminate residual waste material
Which areas of the GI tract mechanically disrupt food?
- Mouth/teeth
- Stomach (vigorous contractions cause the food to be liquefied – chyme)
Describe how the upper and lower areas of the stomach mechanically disrupt food
- Upper area creates basal tone (slow/sustained contractions)
- Lower area has powerful peristaltic contractions that effectively grind food (thicker muscle layer distally)
Why must the GI tract temporarily store food?
We eat faster than we digest
How does the stomach act as a storage facility?
- Distension – accommodates entry of food
- Receptive relaxation – maintains intraluminal pressures
Explain how the colon also acts as a temporary store
Contents are only evacuated several times a day from the colon (mass movements)
In which areas does chemical digestion occur?
- Oral cavity (saliva)
- Stomach
- Duodenum/jejunum
Which substances are used for digestion by saliva?
- Amylase (starch)
- Lipase (fats)
Which substances are used for digestion by the stomach?
- Acid
- Pepsin (protein)
Which substances/structures are used for digestion by the duodenum/jejunum?
- Bile
- Exocrine pancreas secretions
What are the challenges to the GI’s ability to kill pathogens?
- Thin epithelia
- Large surface area
What are the defences of the GI tract to pathogens?
- Saliva
- HCl
- Liver (kupffer cells)
- Peyers patches (immune surveillance)
I. Lymphoid follicles
II. Submucosa/mucosa (terminal ileum)
Different regions in the GI tract used different types of movement to move food along.
Identify them
- Peristalsis
- Segmentation
- Haustral shuttling
- Mass movements
What type of muscle is found in the bowel?
- Small amounts of skeletal muscle
- Mainly smooth muscle