Mouth Structure and Function

Question 1

Anterior and lateral boundaries of oral cavity

Answer 1

labium (lips - keep food in), cheeks (hold food in + keep shape) and body of tounge (speech, swallowing)

Question 2

Oral cavity inferior boundary

Answer 2

geniohyoid and mylohyoid muscles. Make up mouth floor

Question 3

Oral cavity posterior boundary

Answer 3

uvula, palatine tonsil, tongue route and lingual tonsil

Question 4

Oral cavity superior boundary

Answer 4

soft and hard plate

Question 5

Cleft Def

Answer 5

Birth defect. Hard and soft plate incorrectly fused. Correceted via surgery

Question 6

Mastication mechanical outline

Answer 6

Increasing foods surface area for better exposure to lubricant and digestive enzymes

Question 7

Mastication Lubrication Outline

Answer 7

Mucus in saliva softens and acts as a glidant for food. Saliva engulfing food contains digestive enzymes

Question 8

Mastication and Secretion Relationship

Answer 8

Increased mastication = smaller particles = greater food binding to taste receptors. Taste receptor stimulation produces salivary and gastric secretion

Question 9

3 types of salivatory glands

Answer 9

parotid, submandibular and sublingual

Question 10

Parotid Gland Outline

Answer 10

Largest slaivary gland. Produce 20-25% net saliva vol. Saliva is serous and liquidy, contains main amylase component. Found anterior ear subcutanous tissue

Question 11

Submandibular Gland Outline

Answer 11

70-75% net saliva vol produced. Mix of serous and mucus (mainly mucus, 1:6)

Question 12

Sublingual Gland Outline

Answer 12

Smallest gland. 3-5% net saliva vol produced. Most mucus saliva (mainly mucin, very little amylase). Inferior to tongue on mouth floor

Question 13

Saliva components

Answer 13

99.5% H2O : 0.5% protein and electrolytes

Question 14

Saliva Protein Components

Answer 14

Salivary alpha-amylase, salivary alpha-lipase, mucins (glycoprotein lubricant), immunoglobin A and lysosome (both immune defense against opportunistic infections)

Question 15

Saliva Digestion and Lubrication Functions

Answer 15

Amylase and lipase begin breakdown, food molecules moistened, solubilized & lubricated and lips and tongue lubricated (enabling speech)

Question 16

Saliva Oral Hygiene

Answer 16

Lysosomes lyses certain bacteria, IgA monitors microbial environment ensuring homeostasis, saliva is a pH buffer (neutralises acids/bases that damage cells and teeth) and moves food particles away from teeth

Question 17

Simple (unconditioned) Salivary reflex

Answer 17

Stimulation of saliva production when food is in mouth due to chemo and baro receptors firing to salivary center (in medulla) in brain. parasympathetic NS stimulates vasodilation increasing saliva production and readying GI tract for food

Question 18

Acquired (conditioned) Salivary Reflex

Answer 18

Done without mouth receptors firing. Learned response based on presence/absence of stimulus (eg sound/smell)

Question 19

Where is the salivary center in the brain

Answer 19

Medulla

Question 20

Which part of autonomic NS is dominant in digestion

Answer 20

parasympathetic (acetylcholine binding to muscarinic receptors)

Question 21

Parasympathetic Action in GI tract

Answer 21

Vasodilation, large saliva volumes (watery, mucus and amylase containing). Inhibited by anticholinergic drugs, sustained by acetylcholinterase.

Question 22

Sympathetic Action in GIT

Answer 22

Vasoconstriction, small saliva volume (thick contains mucus and amylase).Stimulated by noradrenaline in adrenergic receptors

Question 23

What external stimuli stimulate sympathetic action in GIT

Answer 23

Sleep, fatigue and fear

Question 24

Pharynx Outline

Answer 24

Site of swallow reflex (both voluntary and involuntary). 3 parts: nasopharynx, oropharynx (entry point of food) and laryngopharynx

Question 25

Nasopharynx Outline

Answer 25

Nasal cavity continuation, brings air to larynx. adenoid tonsils (lymphatic) are on posterior wall. Located between base of skulland upper surface of soft palate

Question 26

Oropharynx Outline

Answer 26

Found behind mouth, entry point of food. Directs food from mouth to esophagus. Controls voluntary and involuntary swallowing reflexes. Palatine tonsils found on lateral wall

Question 27

Laryngopharynx Outline

Answer 27

Attached inferiorly to larynx, continuos with oesophagus. Controls involuntary swallowing

Question 28

Deglutition Outline

Answer 28

Process of swallowing from voluntary initiation to involuntary (reflex) continuation to stomach. 3 phases: oral/buccal, pharyngeal and esophageal

Question 29

Oral Swallowing

Answer 29

Voluntary. Mastication of food, bolus formed from food binding to water, tongue presses to hard pallete (using intrinsic muscles) forming trough, bolus is pushed from mouth to pharynx

Question 30

Pharyngeal Swallowing Outline

Answer 30

Involuntary (reflex). Bolus entering pharynx stimulates baroreceptors. Signal is sent to degullation center (medulla and pons) initiates muscular contractions

Question 31

Pharyngeal Phase Outline

Answer 31

Nasopharynx closes (soft palate moves up, closing nasal openings), larynx moves up, epiglottis closes over laryngeal opening (blocking trachea), opening of esophagus (upper esophageal sphincter stimulated by larynx movement) and pharynx begins fast contractions (medulla inhibits breathing)

Question 32

Oesophagial Pahse Outline

Answer 32

Upper oesophagial sphincter contracts, primary peristaltic wave (bolus forced from UES to lower eosphagial shincter), secondary peristalic wave (only when food is stuck due to inadequate lubrication)

Question 33

Esophageal Phase is stimulated by what

Answer 33

vagal (vagus) and intrinsic receptors. Primary peristalsis is stimulated by swallowing.

Question 34

Function of lower eosphageal sphincter

Answer 34

Contracts to prevent backflow of bolus and entery of stomach contents into oesophagus. Relaxes shortly before peristaltic contraction (bolus) reaches it due to release of vasoactive intestinal peptide and NO. Contracts once bolus hits stomach

Question 35

Oesophagus secretions

Answer 35

Mucus. Protects from stomach acid and enzymes and lubricating food

Question 36

Emesis Outline

Answer 36

Puking. When toxic substances enter body they signal emetic center in medulla to remove substances

Question 37

Causes of Emesis

Answer 37

Irritation of pharynx (=gag reflex), irritation/distention of stomach lining (mechanoreceptors and chemoreceptors), elevated intracranial pressure and psychogenic factors (fear)

Question 38

Drugs, toxins and chemotherapy pathway to emetic center

Answer 38

Chemoreceptor Trigger Zone

Question 39

Obstruction and distension pathway to emetic center

Answer 39

Afferent peripheral receptors (stomach, small intestine) to chemorecptor trigger zone

Question 40

Motion pathway to emetic center

Answer 40

Vestibular apparatus

Question 41

Sensory input and memory pathway to emetic center

Answer 41

Higher cortical center

Question 42

xerostomia outline

Answer 42

Dry mouth. Salivary gland malfunction (disease, hyposalavation). Caused by anticholiergic drugs, dehydration and anxiety. Results in difficulty in speech, gum disease, bad oral health and dysphagia (difficulty swallowing)