Exam 4: Digestive System Flashcards
Gastrointestinal (GI) Tract
- tube that extends from mouth to anus
- mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus
Functions of GI Tract
- digestion
- absorption
- elimination of wastes
Digestion
- process of breaking down food into small fragments
- 2 types mechanical and chemical
Mechanical Digestion
- using forces/physically breaking down food
- Ex: stomach mechanically digests by muscle contraction
Chemical Digestion
- uses enzymes (proteins) that speed up a chemical reaction
- Ex: stomach chemically digests with gastric juices
Absorption
- water and food molecules pass through to GI lymphatics and blood vessels
- most nutrients absorbed in blood vessels
Lacteals
-absorb lipids and lipid soluble vitamins in small intestine (A, D, E, K)
Accessory Digestive Organs
- not part of GI tract but assist with digestion
- tongue, teeth, salivary glans, liver, gallbladder, pancreas
Peritoneum
- serous membrane that lines the abdominal cavity
- parietal lines abdominal wall
- visceral covers abdominal organs
- peritoneal cavity is the space between the two, serous fluid secreted here
Parasympathetic Innervation
-in general, it stimulates or increases activity of GI tract
Sympathetic Innervation
-in general, it inhibits or decreases activity of GI tract
Oral Cavity
- continuous posteriorly with oropharynx
- nonkeratinized stratified squamous epithelium
- upper part of the oral cavity: palate
Hard Palate
-anterior 2/3 of palate, bony
Soft Palate
-posterior 1/3 of palate, formed from skeletal muscle
Uvula
-dangling muscle off soft palate
Extra Credit Names
-Osmosis Jones and Drix
Function of Soft Palate and Uvula
- close off opening to nasopharynx when you swallow
- these muscles move and that’s why milk goes up your nose
Teeth
-20 deciduous (baby) teeth replaced by 32 permanent teeth
Tongue
- big skeletal muscle
- covered with stratified squamous epithelium
- function: perceives taste and mechanical digestion
Salivary Glands
- 3 pairs
- secrete saliva composed of water, mucus, amylase (digests carbs), lysozyme (antibacterial agent) and antibodies
- functions: dissolves food molecules so they can be tasted, moistens food and turns it into bolus, chemically digests carbs, cleanses mouth, lysozyme and antibodies inhibit bacterial growth
Pharynx
- throat
- muscular tube that connects nasal cavity and mouth, to larynx and esophagus
- function: propel food and drink to esophagus and air to larynx
- only the oropharynx and laryngopharynx conduct both food and air
GI Tract Layers
- 4 layers, tunics
- mucosa, submucosa, muscularis, adventita/serosa
Mucuosa
- innermost tunic
- esophagus has nonkeratinized stratified squamous epithelium
- stomach to anal canal has simple columnar epithelium
- areolar CT