5The Mouth AKA: oral cavity or buccal cavity Opening oral orifice Boundaries:Lips anteriorlyCheeks laterallyPalate superiorlyTongue inferiorlyContinuous with oropharynx posteriorly
6The Lips (Labia) and Cheeks Lips – orbicularis orisVery large! Extend from bottom of nose to bottom of chinRed margin – lipstick or kissesCheeks – buccinatorsBoth help to keep food between the teeth when we chewAlso play a role in speechLabial frenulum – median fold that joins the internal aspect of lips to the gum
7The Palate Roof of the mouth Hard palate Soft palate Palatine and maxillae bonesRigid surface against which the tongue forces food during chewingSoft palatePosterior – arch shapedMobile fold formed mostly of skeletal muscle
8PalateSoft PalateUvula – projects down from the free edge of the soft palateDuring swallowing both are drawn upwards closing off the nasopharynx and preventing foods/liquids from entering the nasal cavityTry and breathe and swallow at the same time
9Teeth Teeth break and rip apart food Increases surface area Smaller pieces increases the surface area enzymes in the saliva can get at the food easier chemical breakdown of food takes place quicker
10Teeth 2 sets of teeth Primary baby teeth (20) Permanent adult (32) First teeth appear ~6 moFall out b/t 6-12 yearsPermanent adult (32)Absorb roots of baby teeth causing them to fall outUsually all have erupted (except 3rd molars) by end of adolescenceWisdom teeth (3rd molars) erupt b/t years
11Teeth - Types Incisors Canines (cuspids/eyeteeth) Chisel-shapedCutting or nipping off pieces of foodCanines (cuspids/eyeteeth)Conical or fanglikeTear and piercePremolars (bicuspids)Broad crowns and rounded cuspsGrinding or crushingMolars
12Teeth - Regions Crown Root Exposed part of the tooth Covered in enamel a cellular, brittle material that bears the force of chewing. Hardest substance in the body. Can’t repair itself!RootPortion embedded in the jaw
13Teeth - CavitiesResult from a gradual demineralization of enamel and underlying dentin by bacteriaDental plaque (film of sugar, bacteria, etc.) adheres to teeth bacteria dissolve trapped sugars those produce acids, which dissolve the enamel.
14Salivary GlandsWe see food or think of food Mouth starts to water saliva is released from the salivary glands
15Salivary Glands Secrete saliva Cleanses mouthDissolves food chemicals for tastingMoistens food and aids in bolus formationContains enzymes that begin chemical breakdown of starchy foodsThree glands parotid, submandibular, sublingualLie outside oral cavity and empty saliva into it
16Composition of Saliva Water 97 – 99.5% Slightly acidic pH 6.75-7.0 Digestive enzyme salivary amylaseProteins Mucin – dissolved in water forms a thick mucus that lubricates the oral cavityLysozyme – inhibits bacterial growth in the mouthIgA – antibodies, protection against microorganismsMetabolic wastes urea and uric acid
17TongueOccupies most of the floor of the mouth and fills most of the oral cavity when mouth is closedComposed of interlacing bundles of skeletal muscle fibers during chewing grips and repositions food between the teeth
18Tongue Mixes food with saliva forms bolus (“lump”) Initiates swallowing pushes bolus posteriorlyHelps to form consonants when we speakHelps to keep food between the teeth by pushing the food against the hard palate
19TongueLingual frenulum – secures tongue to floor of mouth, limits posterior movementsAnkyloglossia (“fused tongue”) aka tongue-tied when lingual frenulum is too short limits movements of tongue so speech is distorted.
20Tongue Filiform papillae Smallest and most numerous Roughness that aids in licking foods and provides friction for manipulating foods in mouthAligned in parallel rowsWhitish appearance
21Tongue Fungiform papillae Circumvallate (vallate) papillae Mushroom-shapedScattered widely over the tongue surfaceHave a reddish hueHouse taste budsCircumvallate (vallate) papillae10-12, large, located in a V-shaped row at that back of the tongue
22Tongue Foliate papillae Sulcus terminalis Pleatlike, located on the lateral aspects of the posterior tongueHouse taste buds (only in infancy and early childhood)Sulcus terminalisPosterior to circumvallate papillaeGroove that distinguishes anterior and posterior tongue
23TasteFor a chemical to be tasted it must dissolve in saliva, diffuse into the taste pore, and contact the gustatory hair. This causes a reaction from the nervous system that allows us to “taste” our food
24Taste Taste buds – sensory receptors for taste Located mostly in the oral cavity ~10,000Most are on tongue. Few on soft palate, inner surface of cheeks, pharynx, and epiglottisMost are found in papillaeTops of fungiform papillae, sides of foliate papillae and circumvallate papillae
25TasteTaste qualities: sweet, sour, salty, bitter, and umami (“delicious”)Most taste buds respond to 2 or more taste qualities and many substances produce a mixture of the basic taste sensations
26TasteTaste maps, although common, are inaccurate (sweet tip, salty and sour sides, bitter back, umami pharynxIn reality, there are only slight differences in the localization of specific taste receptors in different regions of the tongue, all types of taste can be elicited from all areas that contain taste buds
27Taste Taste likes and dislikes have a homeostatic value Umami guides intakes of proteinsA liking for sugar and salt helps satisfy the body’s need for carbohydrates and minerals.Many sour, naturally acidic foods (lemons, tomatoes, oranges) are rich sources of vitamin C.Many natural poisons and spoiled foods are bitter, our dislike for bitterness is protective.
28TasteTaste is 80% smell. When olfactory receptors are blocked, food is bland.Mouth also contains thermoreceptors (temperature), mechanoreceptors (touch), and nociceptors (pain). The temperature and texture of foods can enhance or detract from their taste. Spicy or “hot” foods bring about their effects by activating the pain receptors in our mouth