Digestive tract > from mouth to anus (alimentary tract), through head, neck, thorax, abdomen, pelvis
GI tract > stomach and intestines
Oral cavity > mouth, teeth, salivary glands, tonsils
Pharynx > throat
Small intestine > duodenum, jejunum, ileum, liver, gallbladder, pancreas *
Large intestine > cecum, colon, rectum, anal canal
Tongue forms food in bolus, pushes into oropharynx, contraction of pharyngeal constrictors moves
through laryngopharynx, esophagus, stomach.
Peristalsis > moves material through digestive tract, waves of smooth muscle contraction, relaxation of
muscles in front of bolus and contraction of muscles behind bolus to move it along controlled by vagus
3 physiological sphincters: cardiac sphincter prevents reflux of food back into esophagus.
Chewing, mix saliva w/ food (saliva has salivary amylase > breaks down amylose sugar or starches),
stomach muscles churn bolus into “chime”
Digestive enzymes, acids, bases secreted along GI tract.
Large organic molecules (macromolecules) digested into component parts before absorbed by digestive
tract. Minerals, water, vitamins NOT broken down before being absorbed.
Mainly in small intestine (increased SA), actively/passively absorbed, vitamins, fat = fatty
acids/cholesterol, Carbs = simple sugars, proteins = peptides/amino acids
Defacation Feces are formed in large intestine, absorbs water/salts to make it semi solid, stored in rectum,
regulated by contraction/relaxation of anal and rectal sphincters.
Attached posteriorly, free anteriorly, attached at bottom by LINGUAL FRENULUM.
Intrinsic muscles > within tongue, change shape during communication, elevating/flattening during
Extrinsic > outside tongue, but attached, protrude/retract tongue, change shape, move side to side
Terminal Sulcus > groove in the middle, divides in 2, anterior to this is covered by papillae* (some w/
taste buds). Posterior tongue has a few scattered taste buds, small glands, lymphatic tissue to form
Stratified Squamous ET covers tongue
Taste buds on fungiform: sweet, salty, sour, bitter, meaty
3 pairs of large, multicellular > parotid, submandibular, sublingual
Small, coiled, tubular salivary glands > deep to tongue epithelium (lingual), palate (palatine glands),
cheeks (buccal glands), lips (labial glands)
Acinar Glands >major large salivary glands, branching glands w/ clusters of acini, produce thin serous
secretions or thick mucous secretions.
Parotid > largest, serous, produce watery saliva, anterior to ear on each side of head. Parotid ducts exit
glands on anterior margin, crosses lateral masseter muscle, pierces bucinator muscle and enters oral
cavity by second upper molar. Mumps can inflame/swell parotid glands.
Submandibular > mixed glands w/ more serous than acini. Soft lump on inferior border of posterior half
of mandible. Submandibular duct exits each gland, passes anteriorly deep to mucosal membrane on the
oral cavity floor, opens into oral cavity beside frenulum of tongue.
Sublingual > smallest, mixed serous/mucous acini, lie on floor of oral cavity, opens onto floor of oral
cavity through 10-12 small ducts.
Saliva > keeps oral cavity moist, tastes food molecules/speech, begins digestion, prevents bacterial
infections, bicarbonate ions neutralize acids by oral bacteria, protects tooth enamel
Serous part of saliva > contains salivary amylase, breaks covalent bonds between glucose molecules in
starch/polysaccharides to produce dissacharides maltose and isomaltose (makes starch taste sweet)
Lysozome prevents bacterial infection Mucin > proteoglycan that lubricates secretions of salivary glands
Stimulated by parasympathetic nervous system mainly***, brainstem has salivary nuclei, sends AP’s
through facial and glossyopharyngeal nerves in response to tastes, tactile stimulation.
Epithelium > moist stratified squamous ET in mouth, oropharynx, esophagus, anal canal and simple
columnar ET in remainder of digestive tract, goblet cells, enzyme secreting cells, endocrine cells
Lamine Propria > loost CT, lymphoid tissue, capillary networks (in absorptive areas like small intestine)
Muscularis Mucosae > outer smooth muscle layer, increases SA for absorption, creates folds*
Epithelium extends deep into lamina propria to form intestinal glands/crypts.
Mechanoreceptors >peristaltic reflexes
Chemoreceptors > detect chemical composition of food
Beneath mucosa, thick CT la