Palate Hard palate anterior portion of mouths roof;

Palate  Hard palate  anterior portion of mouths roof;

Palate Hard palate anterior portion of mouths roof; formed by maxillae and palatine bones Soft palate posterior portion of mouth's roof; formed by two muscular arches:

Palatoglossal arch - extends from palate to tongue anterior to palatine tonsils Palatopharyngeal arch - extends from palate to pharyngeal wall posterior to palatine tonsil Figure 24.5 Structures of the mouth (oral cavity) Salivary Glands

General Saliva Functions: Keeps the oral and pharyngeal mucous membranes moist. Lubricates and dissolves food. Starts carbohydrate chemical digestion.

Most saliva is secreted by salivary glands. Some saliva comes from buccal glands in the mucous membrane that lines the mouth. Minor salivary glands include labial, buccal, lingual and palatal glands which make a small contribution to saliva. Salivary Glands

Outside the mouth ducts oral cavity 1. Parotid glands - below ear, over masseter; parotid ducts open into vestibule beside 2nd maxillary molar. 2. Submandibular glands - under mandible;

submandibular ducts open lateral to lingual frenulum 3. Sublingual glands - floor of mouth deep to tongue; lesser sublingual ducts open into floor of mouth Figure 24.6 The three major salivary glands parotid, sublingual, and submandibular Salivary Glands

Salivary gland cells are organized into acini. Acini: small saclike cavities (clusters) in a gland surrounded by secretory cells. Serous acini - secrete a watery fluid

Mucous acini - secrete a slimy, mucus secretion Parotid glands serous acini only Submandibular glands mostly serous acini and a few mucous acini Sublingual glands - mostly mucous acini and a few serous acini Figure 24.6b Histology of the submandibular gland Composition and Functions of Saliva Composition: 1.

2. 99.5% water 0.5% solutes (salts, gases, mucous, ions, enzymes, lysozyme, IgA) Functions: 3. 4. 5. 6. 7.

8. 9. Lubricate food for easier swallowing Dissolve food for tasting Moistens mucous membranes Bicarbonate ions buffer acidic foods Salivary amylase begins chemical digestion of starch (maltose) Lysozyme antibacterial IgA 1st line of defense

Salivation The secretion of saliva. Salivation is under ANS control Moistens mucous membranes Assists speech Almost all salivary components are reabsorbed Dehydration conserve water by not producing saliva Salivation

1. Increase salivation Sight, smell, sounds, thoughts/memory. Tongue stimulation taste buds Salivatory nuclei in brainstem increase salivation

Parasympathetic Facial 2. nerve impulses stimulate saliva (VII) and glossopharyngeal (IX) nerves. Stop salivation Sympathetic nerves inhibit salivation

Tongue Composed of skeletal muscle covered with mucous membrane. Forms oral cavitys floor. Participates in chewing, swallowing, and speech. Glands on tongues dorsum secrete lingual lipase

Tongue Lingual frenulum - attaches tongue to mouths floor Tongue-tied Ankyloglossia

Abnormally short frenulum Speech impediment Can be surgically repaired Tongue

Papillae cover upper surface (dorsum) and sides. Projections of lamina propria Some contain taste buds Figure 11.7 Muscles that Move the Tongue - FYI Teeth

Project into the mouth Alveolar processes of mandible and maxilla Covered by gingivae Teeth

Adapted for mechanical digestion. A typical tooth consists of crown, neck, and root. Composed primarily of dentin, which encloses the crowns pulp cavity the roots root canals. Roots dentin is covered by cementum Cementum attaches root to periodontal ligament Fibrous connective tissue Anchor Shock absorber Figure 24.7 A typical tooth and surrounding structures

Tooth Types 1. Incisors chisel shaped; cutting 2. Cuspids (canines) pointed; tearing 3.

Premolars bicuspid; crushing and grinding 4. Molars four cusps; crushing and grinding Dentition There are two sets of teeth in an individuals lifetime:

1. Deciduous (primary) teeth 20 teeth that start erupting at 6 months 2. Permanent (secondary) teeth 32 teeth that erupt between 6 and 12 years of age Figure 24.8 Deciduous (primary) dentition and times of

eruptions Figure 24.8b Permanent (secondary) dentition and times of eruptions Digestion in the Mouth Mechanical digestion (mastication or chewing) Breaks into pieces Mixes with saliva bolus

Chemical digestion Amylase Begins starch digestion at pH of 6.5 or 7.0 found in mouth When bolus & enzymes hit the pH of 2.5 (gastric juices), hydrolysis ceases Lingual lipase Secreted by glands in tongue Begins breakdown of triglycerides into fatty acids and glycerol once it reaches the acidic pH in the stomach PHARYNX

Pharynx Figures 23.2 / 24.10 Throat but dont call it that Funnel-shaped tube extending from internal nares to the esophagus and larynx Skeletal muscle lined by mucous membrane.

3 parts: Nasopharynx only respiratory fnc Oropharynx digestive and respiratory fnc Laryngopharynx digestive and respiratory fnc Figure 23.2 The pharynx

Pharynx Deglutition and mucus or swallowing is facilitated by saliva Starts when bolus is pushed into the oropharynx Sensory nerves send signals to deglutition center in

brainstem Soft palate is lifted, epiglottis is bent Ingested food mouth oropharynx laryngopharynx muscular contractions esophagus stomach ESOPHAGU S

Figure 24.1 Esophagus Secrete mucus and transport food to the stomach. Collapsible

muscular tube = flexible In front of vertebrae Posterior to trachea Posterior to the heart Connects pharynx to stomach Pierces diaphragm at hiatus

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