What is the entrace to the GI tract?
What does the mouth serve to do?
- Disrupts foodstuffs
- Mix foodstuffs with saliva to form boluses
What can happen once food boluses have been formed?
They can be swallowed
What is the function of teeth?
- Mix food with saliva
Which type of teeth cut?
Which type of teeth crush?
What generates the force behind the teeth?
The powerul muscles of mastication, the Masseter
What innervates the Masseter?
A branch of the trigeminal nerve
What is the tongue?
A collection of 8 muscles
What does the tongue do?
- Works to manipulate food for mastication and form it into a bolus
- Aids swallowing by pushing bolus to back of mouth
Label this diagram
- A - Nasopharynx
- B - Oropharynx
- C - Hypopharynx
- D - Esophagus
- E - Sinus
- F - Nasal cavity
- G - Salivary glands
- H - Oral cavity
- I - Trachea
Where does the oropharynx lie?
Behind the oral cavity
What does the oropharynx form?
The portion of the pharynx below the nasopharynx but above the laryngopharynx
Where does the oropharynx extend?
From the uvula (the end of the palate), to the level of the hyoid bone
What closes over the glottis?
A flap of tissue called the epiglottis
Why is the epiglottis needed?
To prevent aspiration, as both food and air pass through the oropharynx
What is the oesophagus?
A muscular tube
What is the function of the oesophagus?
It passes food from the pharynx to the stomach
What is the oesophagus continuous with?
The lower part of the laryngopharynx
What are the layers of the oesophagus?
- Muscularis externa
What is the mucosa of the oesophagus composed of?
- Non-keratinised stratified squamous epithelium
- Lamina propria
- Layer of smooth muscle (Muscularis Mucosa)
What does the submucosa of the oesophagus contain?
The mucous secreting glands
What kind of muscle is in the muscularis externa of the oesophagus?
- Upper third is striated, skeletal muscle, under conscious control
- Lower two-thirds are smooth muscle, under autonomic control
What is the function of the skeletal muscle in the upper third of the oesophagus?
What is the function of the smooth muscle in the lower two thirds of the oesophagus?
How much saliva is produced each day?
What are the function of saliva?
- Lubricates and wets food
- Starts digestion of carbohydrates
- Protects oral environment
How does saliva start the digestion of carbohydrates?
Through the presence of amylase
How does saliva protect the oral environment?
- Keeps mucosa moist
- Washes teeth
- Maintains alkaline environment
- High Ca2+ environment
What is the purpose of the alkaline environment maintained by saliva?
Neutralises acid produced by bacteria