Physiology of the Mouth, Saliva and Oesophagus

Question 1

What is the functions of the mouth

Answer 1

Ingestion of food
Digestion: Mechanical and chemical
Formation of a bolus and the initiation of swallowing

Question 2

Whata re the functions of the tongue

Answer 2

• Facillitates ingestion
• Gripping and repositioning food during chewing
• Mixing food with saliva and forming the bolus
• Lingual lipase
• Sensation
• Initiation of swallowing
• Speech

Question 3

What are the functions of the different papillae of the tongue

Answer 3

Filiform: Gives the tongue roughness and provide friction

Fungiform: Scattered over the tongue and gives it a redish hue

Circumvallate: V-shaped row in the back of tongue

Follate: Only last 3 tastebuds

Question 4

Explain the process of taste perception

Answer 4

1. Ligands activate the taste cell
2. Ca2+ signal in cytoplasm triggers exocytosis or. ATP formation
3. ATP or neurotransmitter is released
4. Priamry sensory neuron fires and action potentials are sent to brain

Question 5

What is the function of saliva secreted by the salivary glands

Answer 5

Cleanses the mouth
Moistens and dissolves food chemicals
Aids in bolus formation
Contain enzymes that break down starch

Question 6

Name the different salivary glands

Answer 6

Extrinsic: Sub lingual, Sub mandibular, Parotid

Intrinsic: Buccal glands

Question 7

What is the composition of saliva

Answer 7

Mucus: Lubricant, bolus formation, facilitates swallowing
Salivary amylase: initiates digestion of complex carbs
Water and electrolytes: Moistening of food, solvent
Lysozyme: Kills bacteria

Question 8

What are the phases of swallowing

Answer 8

1. Buccal phase: Bolus forced into oropharynx
2. Pharyngeal-oesophageal phase: Controlled by medulla and lower pons
3. Oesophageal phase: Peristalsis moves food through the pharynx to the oesophagus

Question 9

Explain the process of peristalsis

Answer 9

Relex response is initiated when gut wall is stretched, this initiates a circular contraction behind the stimulus and an area of relaxation in front, the wave of contraction then moves in an oral-to-caudal direction

Question 10

Describe the effect of swallowing on the lower oesophageal sphincter and what increases and decreases pressure on it

Answer 10

Opens at the start of deglutition due to vagovagal reflex mediated by VIP and NO releasing neurons

Pressue in LES reduced by VIP, CCK, NO, GIP, Secretin and progesterone

Pressure in LES increased by Acetylcholine, gastrin and motilin