Digestive system / Bio160
Terms
undefined, object
copy deck
-
DIGESTIVE SYSTEM
Five Basic Processes -
Ingestion - eating
2. Movement of the food along the G.I. tract.
3. Digestion- chemical and mechanical breakdown of food.
4. Absorption of the breakdown products into the lymphatic and circulatory systems.
5. Defecation - elimination of undigested substances. - alimentary canal
-
The Gastrointestinal tract
- extends from the moth to the anus.
- 30 feet long (in the cadaver)
- accessory structures
- aid in digestion
- example: teeth, liver, pancreas -
Histology
- 4 basic layers with subdivisions - Mucosa, Submucosa, Muscularis, Serosa
- Epithelium
-
- in contact with the food
- varies from stratified squamous in esophagus and anal canal to simple columnar
in the small intestine - Mucosa
-
- mucous membrane
- lining of a tract
- has 3 sublayers
Epithelium, Lamina Propria, Muscularis mucosae - Lamina Propria
- - areolar connective tissue
- Muscularis mucosae
- smooth muscle
- Submucosa
-
- binds mucosa to underlining smooth muscle layer
- made of areolar connective tissue
- contains ANS supply to muscularis mucosae called Submucosal Plexus (Plexus
of Meissner) - Muscularis
-
- in mouth, pharynx and esophagus is skeletal muscle
- in the rest of the tract is smooth muscle.
- usually contains 2 sheets (stomach has 3)
- inner circular
- outer longitudinal
- contains the major nerve supply to the major nerve supply the Myenteric
Plexus (Plexus of auerbach) controls motility - Serosa
-
- serous membrane
- made of connective tissue and epithelium -
Mouth
- oral or buccal cavity
- anatomy - cheeks, labial frenulum, lingual frenulum, fauces, hard palate, soft palate
- cheeks
- help hold food in place between molars
- labial frenulum
-
- mucous membrane fold
- attaches lips to gums - lingual frenulum
- attaches tongue to base of oral cavity
- fauces
- opening between the oral cavity and the oropharynx (throat)
- hard palate - made from:
- palatine processes of the maxilla and horizontal plates of the palatine bones
- soft palate
- arch between oral pharynx and nasal pharynx
- Tongue
-
- holds food in place over molars (with cheeks) so food can be masticated
- moves food to back of mouth for swallowing and is involved in swallowing
- 2 sets of muscles
Extrinsic muscles, Intrinsic muscles - Extrinsic muscles
- the origin of the muscle is outside of the tongue. Functions; aids in chewing and swallowing and moves tongue in and out and from side to side.
- Intrinsic muscles
-
- origin and insertion of muscles is inside the tongue itself
- functions
- alters the shape of the tongue
- speech and swallowing - glands on the surface of the tongue secrete ________
-
Lingual Lipase
-digest triglycerides into fatty acids and monoglycerides -
Salivary Glands
- buccal glands secrete some_______
- 3 pairs of major salivary glands - saliva
-
Salivary Glands
- 3 pairs of major salivary glands - Parotid Salivary glands, Submandibular Salivary glands, Sublingual Salivary gland
- Parotid Salivary glands
-
- located anterior to the ears
- secrete through parotid duct into the oral cavity by upper second molar
- secrete a watery mucous with salivary amylase - Submandibular Salivary glands
-
- located under the mandible at sides of tongue
- secrete a thicker saliva with mucous and salivary amylase
- empty under the tongue - Sublingual Salivary gland
-
- located under the tongue
- secrete a thick mucous with little salivary amylase
- secrete into mouth under the tongue - saliva is composed of:
-
99.5% water, 0.5% solutes like: ions, gases, urea/uric aid, serum proteins,
lysozyme, salivary amylase - Secretion of Saliva
-
- 1000 to 1500 ml secreted daily from salivary glands
- under nervous system parasympathetic stimulation from the salivary nuclei in the brain stem - secretion of the saliva can be brought about by:
-
- food in the mouth
- thought, smell, sound, sight of food. - Teeth
-
- accessory structures
- aid in masticating food
- two dentitions:
Deciduous teeth, Permanent teeth