digestive system

• ingestion 


  eating
• propulsion

  segmentation, peristalsis and includes swallowing
• mechanical breakdown


  chewing and churning, segmentation and peristalsis
• digestion

  enzymatic breakdown
• absorption

  transport of nutrients from lumen to blood
• defecation

  elimination of feces
• most extensive serous membrane

  peritoneum
• connects the visceral and parietal layers, double serous, provides route for blood vessels, lymphatics and nerve

  mesentery
• organs behind the parietal layer

  retroperitoneal organs
• organs within the parietal layer

  intraperitoneal organs
• secretory and absorptive layer 


  mucosa
• layer composed of at least two muscle

  mucularis
• connective tissue layer, containing blood, lymph vessels, and nerves


  submucosa
• outermost layer of the wall; visceral peritoneum 


  serosa
• three stimuli that start a response from sensors in the wall of tract organs:

  mechanical and chemical stimuli

  smooth muscle movement

  nervous and hormonal control
• two primary nerve plexuses regulating digestive function:

  submucosal: glands and smooth muscle in mucosa

  myenteric: GI tract movement
• short reflexes 


  are stimulated inside GI tract and stimuli by gut brain
• long reflexes

  autonomic nervous system(parasympathetic and sympathetic)

  stimuli from outside tract
• functions of saliva


  cleanses mouth

  dissolves food chemicals

  moistens food

  breakdown of starch with enzyme amylase
• parotid opens

  oral vesicle
• submandibular opens in

  lingual frenulum
• subingua 


  10-12 inches into floor of mouth
• serous cells

  watery secretion: enzymes, ions, some mucin
• mucous cells


  produce mucus
• two digestive enzymes are found in salvia


  salivary amylase and lingual lipase
• this enzyme in saliva inhibits bacterial growth

  lysozyme
• salivation is controlled primarily by the...

  parasympathetic division of autonomic system
• chemoreceptors are strongly activated by 


  sour substances
• salivation induced by the sight or thought of food is a

  conditioned reflex
• the first set is called

  deciduous
• deciduous teeth start coming out at ages... and start being replaced at...

  6 to 24 months

  6 12 years old
• there is... in permanent teeth set and... in the first set

  32

  20
• In a permanent set of teeth you have

  2 incisors, 1 canine, two premolars, three molars and occasionally wisdom teeth
• material covering the tooth root

  cement
• hardest substance in the body; covers tooth crown

  enamel
• attaches the tooth to the bone and surrounding alveolar structures

  periodontal ligament
• forms bulk of tooth structure; similar to bone

  dentin
• collection of blood vessels, nerves, and lymphatics

  pulp cavity
• cells that produce this substance degenerate after tooth eruption

  enamel
• projections of intestinal mucosa that increase surface area

  villi