Mouth, Teeth, Salivary Glands, Pharynx & Esophagus

Mouth start of chemical and mechanical digestion structures chemical – mixing food with saliva mechanical – chewing food structures cheeks and lips aid in expression, chewing, and sensory input palate: hard and soft soft palate and uvula close off nasal cavity during swallowing

Tongue mixes food w/saliva, moves food toward pharynx, and positions food under teeth surface of tongue (papillae) provide friction and house taste buds attached to floor of mouth by sublingual frenulum anchored to hyoid bone

Teeth 2 sets begins mechanical digestion 2 main parts primary, deciduous, baby: 20 secondary, permanent, adult: 32 (w/wisdom) begins mechanical digestion chewing increases surface area of food so that chemical digestion is more efficient 2 main parts crown: above gum; covered in enamel (Ca2+ salts hardest sub in body) root: below gum; anchored to jaw by a periodontal ligament

Review Questions Where does digestion begin? How does the tongue function as part of the digestive system? What is the role of the soft palate during swallowing? Why do we chew food before swallowing?

Functions of Saliva moistens food helps bind food together begins chemical digestion of carbohydrates (salivary amylase) dissolves food so that it can be tasted helps cleanse mouth and teeth

Salivary Glands 2 types of cells 3 major glands serous: watery fluid w/enzymes (salivary amylase) mucous: mucus to aid in swallowing 3 major glands parotid: largest; located anterior and inferior to ear submandibular: located inside lower jaw sublingual: located inferior to tongue parasympathetic impulses stimulate the release of saliva when a person sees, smells, tastes, or thinks about food

Review Questions What are the functions of saliva? What stimulates salivary glands to secrete saliva? Where are the major salivary glands located?

Pharynx & Esophagus no digestion passageways for food and aid in swallowing esophagus straight, collapsible tube about 25 cm long connects pharynx to stomach lubricated w/mucus lower esophageal sphincter guards entrance to stomach usually contracted to keep stomach content from regurgitating into esophagus relaxed by peristaltic waves to allow food to enter stomach

Swallowing 3 stages food is chewed and mixed w/saliva, forms a bolus (mass) on tongue, forced into pharynx (voluntary) food stimulates receptors that trigger the swallowing reflex soft palate closes off nasal cavity epiglottis closes off larynx tongue closes off oral cavity peristalsis moves food from esophagus into stomach

Review Questions What is the function of the esophagus and pharynx? Describe the structure of the esophagus. List the major events that occur during swallowing.