Exam 4: Digestive System Flashcards
(45 cards)
functions of the digestive system
5 primary, 2 associated
primary:
-ingestion, movement of food, digestion (mechanical and chemical), absorption, and excretion
associated:
-immune defense, endocrine secretions
composition of the digestive system
alimentary canal (digestive tract) - tube within a tube accessory organs: tongue, teeth, salivary glands, liver, gallbladder, pancreas
lumen of alimentary canal considered functionally external to the body
histology layers (4)
mucosal
submucosa
muscularis externa
serosa/adventitia
mucosal layer
-mainly epithelium - changes
depending on where you are
-basement membrane supporting it: lamina propria
-muscularis mucosa: muscle layer around, shape and secretions in layer
epithelium in stomach, esophagus, intestine, rectum
stomach: columnar cells
esophagus: non keratinized stratified squamous
intestine: villi in columnar
rectum: nonkeratinized stratified squamous
submucosa layer
dense, irregular connective tissue that supports the glands and blood vessels
muscularis externa layer
circular muscle and longitudinal muscle
work together to give peristalsis waves
-circular would constrict and longiudinal would push it along
serosa/adventitia layers
serosa: stomach and intestines, serous membranes that lubricate and protect, secretes fluid to avoid rubbing
adventitia: pharynx, esophagus, rectum
protective CT layer - no serous secretions, in places where no rubbing should occur
enteric plexus - autonomic nervous system
parasympathetic: inc muscle activity, tone, gland secretions
sympathetic: dec all activity - directs blood flow to skeletal muscle
stress can cause GI distress
enteric plexus is formed by 2 separate plexuses
submucosa and myenteric
submucosa plexus
contains stretch and chemical receptors
controls shape of mucosa ad degree of secretion
-closer to the lumen, sensitive to what moves through lumen
myenteric plexus
located between circular and longitudinal muscle layers
controls paristalsis
-faster if higher motility, slower if you want to process food slowly
oral cavity components and functions
components: tongue, teeth, gingiva, tonsils
receives secretions from salivary glands
site of mastication (chewing)
beginning of chemical digestion
dentition - adult
adult: 2,1,2,3/2,1,2,3 x2
2 incisors, 1 canine, 2 premolars, 3 molars
long roots
dentition-deciduous/baby teeth
2,1,2/2,1,2 x 2
short roots
only 3 types of teeth - no premolars
tooth anatomy - regions
root: embedded in bone
- well into alveolar process of mandible or maxilla
neck: protected by gum tissue
- sensitive to decay since not well protected by crown
crown: external surface
- strong and protective, enamel
root canal
contains pulp (blood vessels and nerve)
- of decay in this you can get abscess bacteria in bloodstream
- if infected may have to get a root canal - they remove the pulp
dentin
- secretory cells in channels
- cells secrete cementin to attach to socket
- produce periodontal ligaments
- matrix similar to bone by higher % of hydroxyapatite
- if lose a tooth you lose the stimulation to alveolar process area and can lose bone mass
enamel
hardest substance in body (97% hydroxyapatite)
cells degenerate after production
-important to keep enamel healthy, if it wears away you get access to dentin and can get cavities
why is saliva produced? (3)
chemical digestion
lubrication of food
defense of oral cavity
saliva composition
water electrolytes and buffer mucins- lubrication of food antibodies (IgA) enzymes
types of salivary enzymes (2)
salivary amylases: begins carbohydrate digestion
lingual lipase: begins lipid digestion
both inactived in stomach acid environment
functions of tongue and ulva
tongue: positions food, aids in forming bolus, contains taste buds
ulva: prevents food from entering nasopharynx
3 phases of deglutition
both voluntary and involuntary reflex
buccal phase, pharyngeal phase, esophageal phase
