Digestive System Flashcards
What are the 6 basic functions of the digestive system?
- Ingestion
- Secretion
- Propulsion & mixing (deglutition & peristalsis)
- Digestion (mechanical & chemical)
- Absorption
- Defecation
What are the 4 layers of the alimentary canal?
1) Mucosa
2) Submucosa
3) Muscularis
4) Serosa/ Adventitia
What are the main functions of the mucosa?
Inner layer lined with epithelial tissue
What does the mucosa do?
Lubricates the food to ease passage through the intestines
What is the submucosa?
Supports the mucosa. Made of connective tissue
What is the muscularis externa?
Provides movement
What is the serosa?
Outmost, protective layer
What does the mesentery and mesocolon do?
Binds the small intestines to the wall
What is the lesser omentum?
2 folds around stomach and duodenum suspending them from the liver
What is the greater omentum?
It folds itself twice and thus is 4 layered. Attaches itself along the stomach and duodenum, passes downward over the small intestines and upwards to the transverse colon.
What do the lips and cheeks do?
Help to keep food between teeth when chewing
What is the hard palate in the mouth?
Lies anterior, made of bone
What is the soft palate in the mouth?
Lies posterior, made of muscle
What does the tongue do?
Forms floor of the mouth, repositions and mixes food, initiates swallowing
What do the teeth do?
Tear and grind food
What is salivary amylase?
Converts starch to simple sugars
What is lingual lipase?
Starts the digestion of fat
What does deglutition mean?
Swallowing
What are the 3 stages of swallowing?
- Voluntary stage
- The pharyngeal stage
- The oesophageal stage
What happens in the voluntary stage of swallowing?
The tongue moves the bolus up and back into the oropharynx
What happens in the pharyngeal stage of swallowing?
The bolus stimulates the receptors in the oropharynx, messages travel via 2 cranial nerves to the medulla and lower pons in the brain stem. Then instructions from the motor branches cause the soft palate and uvula to move upwards closing the nasopharynx.
What happens once food passes from the oropharynx into the laryngopharynx?
The larynx is pulled forward and upward under the tongue which results in the epiglottis and vocal cords being moved thus sealing off the respiratory tract
What happens in the oesophageal stage of swallowing?
Movement through the oesophagus is almost instantaneous for fluids and 4-8 seconds for semi solid foods.