The Mouth and Swallowing

Question 1

What is the role of the hard palate in chewing?

Answer 1

Acts as an “anvil” to squash food

Question 2

What ensures the correct passage of food?

Answer 2

Soft palate and epiglottis

Question 3

What is the role of incisors?

Answer 3

Like blades, designed to cut off pieces of food

Question 4

What is the role of cuspids (canines)? Why are they called cuspids?

Answer 4

Pointed, spike into foods and tear them

They have a single root

Question 5

What is the role of premolars (bicuspids)?

Answer 5

Have three or four roots

Good at crushing and grinding food, especially as the jaw moves laterally

Question 6

What three types of mandibular movement does mastication involve?

Answer 6

Elevation and depression
Protraction and retraction
Medial and lateral movement

Question 7

What four muscles are involved in mastication?

Answer 7

Temporalis
Masseter
Lateral Pterygoid
Medial Pterygoid

Question 8

What is the temporomandibular joint?

Answer 8

Where the mandible and cranium articulate
Allows opening and closing and side to side movements of the jaw
(not just a simple rotation)

Question 9

How does the mandibular head move in the glenoid fossa when the mouth is opened?

Answer 9

Forward translation and rotation (doesn’t remain in the fossa)
Slides forward and backward as mouth opens and closes

Question 10

Which muscles open the mouth?

Answer 10

Lateral Pterygoid

Digastric

Question 11

Where do the two heads of the lateral pterygoid muscle attach?

Answer 11

The neck of the mandible and parts of the TMJ

Question 12

How does the lateral pterygoid muscle moves?

Answer 12

Fibres run anterior - posterior so contraction pulls the insertion site anteriorly, pulling the TMJ forward and protruding the mandible

Question 13

What muscles are involved in closing the mouth?

Answer 13

Temporalis
Masseter
Medial pterygoid

Question 14

Where is the temporalsis muscle?

Answer 14

Large muscle originating on lateral skull surface

Question 15

Which muscles elevate the mandible?

Answer 15

Temporalis

Masseter

Question 16

Which muscle retracts the mandible?

Answer 16

Temporalis

Question 17

What is the main function of the medial pterygoid muscle?

Answer 17

Side to side movement of the mandible

Question 18

Where do the muscles of mastication receive their motor and sensory supply?

Answer 18

C5

trigeminal nerve

Question 19

What are the 5 roles of saliva?

Answer 19

Lubrication
Cleaning
Taste - serous part dissolves molecules out of food and takes them to tastebuds
Protection - antibacterial enzymes, bicarbonate neutralises acid, calcium ions deposited on teeth to protect them
Digestion - salivary amylase and lingual lipase start the digestive process

Question 20

What is the composition of saliva?

Answer 20

Part serous fluid (watery) and part mucus (thick and slippery)

Question 21

How is saliva production regulated

Answer 21

Neural control (autonomic)
Parasympathetic (watery) and sympathetic (mucoid) activity both increase secretion

Question 22

Why does the mouth feel dry when you’re nervous/anxious?

Answer 22

Sympathetic drive is high and this stimulates mucoid activity so less serous fluid is in the saliva

Question 23

Where is the parasympathetic control of saliva and what 3 things is it driven by?

Answer 23

Salivatory centre in the brain stem

Local stimuli (touch, taste)
Central stimuli (smell, sight of food)
Learned reflex (like Pavlov's dogs)

Question 24

Where does primary salivary secretion occur?

Answer 24

In the acinus - specialised glandular cells for secretion

Question 25

How does primary salivary secretion occur?

Answer 25

Stimulation causes secretion of mucous/serious fluid, producing an isotonic fluid (NaCL, protein, mucus) which passes along the duct. This is secreted. Isotonic fluid is a similar salt once to interstitial fluid and plasma.

Question 26

What is the second stage of saliva secretion?

Answer 26

Isotonic fluid passes along the duct from the aicini toward the mouth, where the salt is reabsorbed and bicarbonate and K+ are secreted, and water follows. This creates a hypotonic fluid (less concentrated than the interstitial fluid) because salt is reabsorbed and water can't follow because of tight junctions.

Question 27

Why is the flow rate of saliva secretion important?

Answer 27

If flow rate is high, fluid will move quickly and be more isotonic in the mouth because there isn't enough time for reabsorption If flow rate is slow, more fluid will be processed and too much salt will be reabsorbed = small volume of dilute fluid

Question 28

What are the three main salivary glands and where are they?

Answer 28

Parotid - in cheek in front of ear Sublingual - underneath tongue Submandibular - inside corner of jaw

Question 29

How does parotid gland secrete into the mouth?

Answer 29

Duct passes through the cheek into the mouth (whereas sublingual and submandibular secrete via ducts into the floor of the mouth underneath the roof of the tongue)

Question 30

Which salivary gland is the largest?

Answer 30

Parotid | 25% of salivary volume

Question 31

What nerve supplies the parotid gland?

Answer 31

parasympathetic C9 | sympathetic - Glossophayngeal nerve

Question 32

What nerves suppliey the submandibular and sublingual glands?

Answer 32

parasympathetic CN7 | sympathetic - superior cervical ganglion

Question 33

What does the parotid gland produce?

Answer 33

``` Salivary amylase (break down polysaccharides) Proline-rich proteins (antibiotic activity) ```

Question 34

What does the submandibular gland produce?

Answer 34

Antibacterial enzymes | Lysozyme

Question 35

What does the sublingual gland produce?

Answer 35

Lingual lipase

Question 36

What is ptyalin a-amylase?

Answer 36

An alpha amylase | Cuts 1,4 linkages of polysaccharides for initiall digestion

Question 37

Which linkages in polysaccharides causes branches?

Answer 37

1,6

Question 38

Which linkages in polysaccharides can alpha-amylases cut?

Answer 38

1,4

Question 39

What is the role of lingual lipase?

Answer 39

Cleaves outer fatty acids off triglycerides | Optimum pH 4

Question 40

Why can't lingual lipase work in the stomach?

Answer 40

Denatured by pancreatic proteases

Question 41

Where are taste receptors located?

Answer 41

Inside taste buds across the bank of the tongue

Question 42

How do salt taste receptors work?

Answer 42

Sodium depolarises the membrane, opening calcium channels which further depolarises membrane. Molecules are released that interact with a neuron that takes a 'salt' signal to the brain BASICALLY SODIUM CHANNELS.

Question 43

What are the two types of taste receptors?

Answer 43

Salt and Sweet

Question 44

How do sweet taste receptors work?

Answer 44

Detect sweet and tigger cascade that causes calcium levels to rise. Depolarises membrane. Releases chemicals to neurone.

Question 45

What are odour receptors in the nose? How do they work?

Answer 45

Specialised nerve cells | Odour molecules bind and cause a release of cAMP, which initiates an action potential

Question 46

What type of epithelium is present in the oesophagus? Why is it folded?

Answer 46

Stratified squamous | It is folded so there is 'spare' incase anything large is swallowed

Question 47

What is the innervation of the oesophagus?

Answer 47

Oesophageal plexus

Question 48

What epithelium is the epithelium in the oesophagus similar to?

Answer 48

Skin - except there is no keratinisation

Question 49

What is secreted in the oesophagus by glands?

Answer 49

Mucus

Question 50

What nervous system mediates swallowing?

Answer 50

Parasympathetic system (other than salivary glands)

Question 51

What nervous system decreases GI activity?

Answer 51

Sympathetic

Question 52

which nerve controls GI motility and secretion?

Answer 52

Vagus (CNX, medulla)

Question 53

What does cephalic mean?

Answer 53

Head | So cephalic response - is oral part of GI tract