1. Mouth, Teeth, Salivary Glands, Pharynx & Esophagus

2. 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

3. 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

5. 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

7. 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?

8. 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

9. 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

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

12. 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

13. 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

15. 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.