GI A&P Flashcards
function of GI system
–provide nutrients for body with propulsive and mixing movements
–secretion of digestive juices
–absorption of nutrients
upper esophageal sphincter
prevents food and fluids from being aspirated into lungs
lower esophageal sphincter
–cardiac sphincter
–separates esophagus from stomach
–prevents acidic contents of stomach from entering back into esophagus
stomach capacity
1000-1500 mL
stomach cells
–lined with columnar epithelium containing millions of gastric glands
–glands contain special cells that secrete HCl, intrinsic factor, and gastrin
layers of the stomach
(1) mucosa layer: G-cells, parietal, chief, and epithelial
(2) two muscle layers: propel food from stomach to SI
(3) serosa: outer layer; acts as covering for inner layers
G-cells
produce gastrin
gastrin
hormone that facilitates production of HCl
parietal cells
–produce HCl to help break down food
–produce IF to protect mucosa
chief cells
secrete pepsin
epithelial cells
secrete bicarb-rich solution to coat and protect mucosa
small intestine components
–duodenum
–jejunum
–ileum
plicae circulares
circular fold mucous membrane that makes up entire inner wall of small intestines
intestinal villi
fingerlike projections situated on plicae circulares
microvilli
microscopic projections on each villus
crypts of Lieberkuhn
–intestinal glands that secrete about 2L of fluid/day into lumen of intestine
–fluid quickly reabsorbed by villi
Goblet cells and Brunner glands
secrete large amounts of mucus to protect small intestine from damage of acidic gastric juices
ileocecal sphincter
area where food passes from small into large intestine
sphincter of small intestine
–distention of terminal ileum causes relaxation to allow contents to enter large intestine
–distention of cecum prevents reflux back into ileum
components of large intestine
–appendix
–ascending colon
–transverse colon
–descending colon
–sigmoid colon
–rectum
cells of large intestine
–absorptive cells = absorb water and electrolytes
–goblet cells = produce mucous
–endocrine cells = present and produce hormones, but function is not really understood
how does motility work in the GI tract?
due to contraction of 2 layers of smooth muscle (longitudinal and circular)
2 types of GI motility
propulsive (peristalsis)
mixing (segmental)
what is GI motility regulated by?
enteric nervous system, autonomic nervous system, and hormones
function of esophagus
transports food
functions of stomach
–stores and churns food
–pepsin digests protein
–HCl activates enzymes, breaks up food, kills germs
–mucus protects stomach wall
–limited absorption
functions of small intestines
–completes digestion
–mucus protects gut wall
–absorbs nutrients, most water
–peptidase digests proteins
–sucrases digest sugars
–amylase digests polysaccharides
functions of large intestine
–reabsorbs some water and ions
–forms and stores feces
function of rectum
stores and expels feces