Ch14: GI tract Flashcards
digestive tract/GI system
oropharynx, alimentary tract and pancreatic tract
oropharynx
mouth
salivary glands
pharynx
alimentary tract
esophagus stomach small & large intestine vermiform appendix anus
pancreatic tract
liver
gallbladder
bile ducts
pancreas
digestion
mechanical, chemical and enzymatic processes by which ingested food is converted into simple soluble suitable for assimilation into cells of the body for production of energy and synthesis of tissues
esophagus
straight muscular tube that conveys food from the pharynx to stomach
stomach
distensible organ whose epithelial components vary in different locations
fundus
antrum
pyloris
fundus
body of stomach
mucosal cells secrete HYDROCHLORIC ACID and PROTEOLYTIC ENZYMES which aid in digestion
antrum
lower part of stomach
lined by mucous cells that produce thick, basic mucus that protects the epithelial cells from the high acidic content of the gastric juice
pylorus
extreme distal end of stomach
muscular sphicter that controls the rate of emptying of the stomach into the small intestine
small intestine
major function= absorption
divided into: duodenum, jejunum, ileum
different nutrients are absorbed into different parts
(iron-duodenum, vit B-jej)
large intestine
“colon”
storage reservoir for the wastes left over from digestion and also is the main site of water absorption
cecum ascending colon transverse colon descending colon sigmoid colon rectum
appendix
nonfunctional vestigial structure attached to the cecum
anus
muscle sphincter
allows for controlled evacuation of rectal contents at social appropriate times and locations
layers of the GI tract
all segments of GI tract are made of the same 4 layers which are continuous with each other:
1: mucosal layer
2: submucosa
3: muscularis propria
4: serosa
mucosal layer (mucosa)
3 components:
EPITHELIUM line surface and form glands that are supported by LAMINA PROPRIA (loose CT) and a unique thin muscular layer called MUSCULARIS MUCOSA.
cells varied in accordance with their specialized function at each level of the tract
(esophagus-stratified squamous epithelium for masticated food, stomach-thick glandular mucosa-acid enzymes to break up food, small intestine-villous structures-active absorption, large intestine-mucus secreting cells for storage/evacuation of feces)
submucosa
deep to mucosa and provides structural support
contacts lymphatic and vascular channels- pick up absorbed nutrients and carry them to the liver for further processing
muscularis propria
contracts rhythmically to move materials through the alimentary tract
serosa
thin, smooth membrane present on the outer surface of the alimentary tract that lie within the abdominal cavity
smooth and slippery and keeps the highly tortuous loops of bowel from being tangled up
continuous with the mesentery (CT attachment of the bowel that contains blood vessels, lymphatics and nerves)
peristalsis
waves of ms contractions carry a bolus of swallowed food down the esophagus, and a sphincter at the lower end of the esophagus prevents regurgitation
amylases
carb-splitting enzymes
from the salivary glads mic with food during mastication
trypsins
proteolytic enzymes that digest carbs, fat, and proteins
lipases
fat splitting enzymes released by pancreas
bile salts
main constitute of bile produced by the liver, emulsify lipids into small water-soluble packets so they can be transported and digested
