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Transcript
Chapter 14
Digestive System
Organs divided into 2 groups:
 Alimentary Canal or
Gastrointestinal (GI) Tract:
 Functions are ingest, digest,
absorb, & defecate
 Ex. Mouth, Esophagus,
Stomach, Liver, Gall Bladder,
Pancreas, Small Intestine,
Large Intestine, Anus
 Accessory Digestive Organs:
 Assist in process of digestive
breakdown
 Ex. Teeth, Tongue, and
Digestive glands
How long is your GI tract?? About 30 feet long = 10 yards (FIRST DOWN!)
Mouth
 Mastication – the act of chewing food
 Digestion starts before you even take your first bite. Smell of
food makes salivary glands secrete saliva.
 Mechanical and chemical digestion occurs
 3 salivary glands involved: Parotid, Sublingual, Submandibular
 Saliva contains enzyme, Amylase, which breaks down
polysaccharides (starch) to disaccharides (maltose)
Pharynx
 Tube that connects mouth to
esophagus
 Epiglottis covers the opening to the
trachea (windpipe) so food does not
get there
 Walls of pharynx have two skeletal
muscle layers:
 Inner layer runs longitudinally
 Outer layer (constrictor muscles) run
around the wall in a circular fashion
 Peristalsis – alternating contractions
of muscles propels food along GI tract
Esophagus
 Tube that connects pharynx to stomach
 About 25 cm long
Stomach
 C-shaped organ located inferiorly to
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
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diaphragm and liver
Cardioesophageal sphincter is located
between esophagus and stomach
Chemical and mechanical digestion occurs
Breakdown of proteins starts here
Pyloric sphincter is located between
stomach and small intestine
Contains gastric juice that is made of
pepsinogens (protein-digesting enzymes)
and hydrochloric acid
After food is processed, the food is called
chyme which resembles a heavy cream.
Pancreas
 Soft, pink, triangular gland extends from spleen to duodenum
(start of small intestine)
 Produces enzymes in duodenum as an alkaline fluid to
neutralize acidic chyme from stomach and enzymes break
down digestible foods
Liver
 Largest gland in the body; located inferior to diaphragm
 Has 4 lobes
 Has many metabolic and regulatory functions including
producing bile and releasing it into duodenum
 Bile is yellow-to-green that contains bile salts that emsulify
(break down) fats
Gallbladder
 Small, green sac found inferior to liver
 Stores the bile made by liver
Small Intestine
 Tube connects stomach and large intestine
 Digestion of proteins, lipids (fats), & carbohydrates
 Primary function is absorption of food and nutrients found in food
 Diffusion of nutrients from food into bloodstream
 3 parts: Duodenum, Jejunum, Ileum
 Mesentery – membrane that contains blood vessels, lymph vessels,
& nerve that allows small intestine to coil
Large Intestine
 Tube that connects small intestine to anus
 Primary function is to absorb water from remaining food
matter and pass indigestible waste out body
 Appendix – first part of large intestine that serves on function
 4 parts: Ascending colon, Transverse colon, Descending colon,
Sigmoid colon, Rectum