Mouth Structure and Function Flashcards
Anterior and lateral boundaries of oral cavity
labium (lips - keep food in), cheeks (hold food in + keep shape) and body of tounge (speech, swallowing)
Oral cavity inferior boundary
geniohyoid and mylohyoid muscles. Make up mouth floor
Oral cavity posterior boundary
uvula, palatine tonsil, tongue route and lingual tonsil
Oral cavity superior boundary
soft and hard plate
Cleft Def
Birth defect. Hard and soft plate incorrectly fused. Correceted via surgery
Mastication mechanical outline
Increasing foods surface area for better exposure to lubricant and digestive enzymes
Mastication Lubrication Outline
Mucus in saliva softens and acts as a glidant for food. Saliva engulfing food contains digestive enzymes
Mastication and Secretion Relationship
Increased mastication = smaller particles = greater food binding to taste receptors. Taste receptor stimulation produces salivary and gastric secretion
3 types of salivatory glands
parotid, submandibular and sublingual
Parotid Gland Outline
Largest slaivary gland. Produce 20-25% net saliva vol. Saliva is serous and liquidy, contains main amylase component. Found anterior ear subcutanous tissue
Submandibular Gland Outline
70-75% net saliva vol produced. Mix of serous and mucus (mainly mucus, 1:6)
Sublingual Gland Outline
Smallest gland. 3-5% net saliva vol produced. Most mucus saliva (mainly mucin, very little amylase). Inferior to tongue on mouth floor
Saliva components
99.5% H2O : 0.5% protein and electrolytes
Saliva Protein Components
Salivary alpha-amylase, salivary alpha-lipase, mucins (glycoprotein lubricant), immunoglobin A and lysosome (both immune defense against opportunistic infections)
Saliva Digestion and Lubrication Functions
Amylase and lipase begin breakdown, food molecules moistened, solubilized & lubricated and lips and tongue lubricated (enabling speech)
Saliva Oral Hygiene
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
Simple (unconditioned) Salivary reflex
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
Acquired (conditioned) Salivary Reflex
Done without mouth receptors firing. Learned response based on presence/absence of stimulus (eg sound/smell)
Where is the salivary center in the brain
Medulla
Which part of autonomic NS is dominant in digestion
parasympathetic (acetylcholine binding to muscarinic receptors)
Parasympathetic Action in GI tract
Vasodilation, large saliva volumes (watery, mucus and amylase containing). Inhibited by anticholinergic drugs, sustained by acetylcholinterase.
Sympathetic Action in GIT
Vasoconstriction, small saliva volume (thick contains mucus and amylase).Stimulated by noradrenaline in adrenergic receptors
What external stimuli stimulate sympathetic action in GIT
Sleep, fatigue and fear
Pharynx Outline
Site of swallow reflex (both voluntary and involuntary). 3 parts: nasopharynx, oropharynx (entry point of food) and laryngopharynx
Nasopharynx Outline
Nasal cavity continuation, brings air to larynx. adenoid tonsils (lymphatic) are on posterior wall. Located between base of skulland upper surface of soft palate
Oropharynx Outline
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
Laryngopharynx Outline
Attached inferiorly to larynx, continuos with oesophagus. Controls involuntary swallowing
Deglutition Outline
Process of swallowing from voluntary initiation to involuntary (reflex) continuation to stomach. 3 phases: oral/buccal, pharyngeal and esophageal
Oral Swallowing
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
Pharyngeal Swallowing Outline
Involuntary (reflex). Bolus entering pharynx stimulates baroreceptors. Signal is sent to degullation center (medulla and pons) initiates muscular contractions
Pharyngeal Phase Outline
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)
Oesophagial Pahse Outline
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)
Esophageal Phase is stimulated by what
vagal (vagus) and intrinsic receptors. Primary peristalsis is stimulated by swallowing.
Function of lower eosphageal sphincter
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
Oesophagus secretions
Mucus. Protects from stomach acid and enzymes and lubricating food
Emesis Outline
Puking. When toxic substances enter body they signal emetic center in medulla to remove substances
Causes of Emesis
Irritation of pharynx (=gag reflex), irritation/distention of stomach lining (mechanoreceptors and chemoreceptors), elevated intracranial pressure and psychogenic factors (fear)
Drugs, toxins and chemotherapy pathway to emetic center
Chemoreceptor Trigger Zone
Obstruction and distension pathway to emetic center
Afferent peripheral receptors (stomach, small intestine) to chemorecptor trigger zone
Motion pathway to emetic center
Vestibular apparatus
Sensory input and memory pathway to emetic center
Higher cortical center
xerostomia outline
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)
Candiadias Outline
Replacement of saliva. eg chewing gum
