Physiology Lecture 17- Digestive System I
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anatomy of the digestive system - Answer 2 parts: gastrointestinal tract (mouth to anus)
and accessory glands
mucosa - Answer innermost; the principal portion of it is the mucous membrane (the
epithelium), which is next to the cavity (lumen); the epithelial cells can be secreting
(mucus; enzymes; hormones) or absorptive
submucosa - Answer primarily connective tissue containing the submucosal nerve
plexus (controls mucous secreting glands)
submucosal nerve plexus - Answer controls mucous secreting glands
muscularis (externa) - Answer primarily composed of smooth muscle, which contracts in
a wave like pattern (peristalsis=keeps food moving in one direction)
peristalsis - Answer keeps food moving in one direction; a wave life pattern
serosa - Answer outermost layer; secretes a watery fluid to allow for organs to slide
over one another=peritoneum
mouth - Answer food is masticated here (mechanical digestion) and saliva is added;
saliva contains salivary amylase (chemical digestion) which initiates the breakdown of
carbohydrates
salivary amylase - Answer found in the mouth; chemical digestion; enzyme which
initiates the breakdown of carbohydrates
pharynx - Answer throat; has skeletal muscle in muscularis externa, thus is voluntarily
propels food to the esophagus
esophagus - Answer has skeletal muscle in the upper half and smooth muscle in the
lower half; function: voluntary and involuntary movement of food to the stomach
stomach - Answer a sac-like portion of the GI tract with a thick muscular wall for
churning food into chyme; it contains gastric gland, which contains cells that secrete
gastric juices; gastric juices contains: pariental cells, chief cells, neck mucous cells,
surface epithelial cells, G-cells, and some make gastric lipase
parietal cells - Answer secrete hydrochloric acid (HCl) and intrinsic factor (IF; needed
for vitamin B 12 absorption)
chief cells - Answer secrete pepsinogen (an inactive enzyme) which is needed to
activate pepsinogen to pepsin (an enzyme which breaks down proteins)
pepsin - Answer found in the stomach; an enzyme which breaks down protein
