They secrete saliva into ducts, which empty into the oral cavity
What are the three salivary glands
Parotid, submandibular and sublingual
Where is the parotid canal located?
near the ear
What is the parotid glands?
Duct opens near the second molar, saliva is enzyme
Where is the submandibular glands?
What does the submandibular glands do?
duct opens on either side of the lingual frenulum. Saliva secretion is both mucus and enzyme
Where is the sublingual glands?
under the tongue
What does the sublingual glands do?
Duct opens into the floor of the oral cavity and secretion here is mucus
What are the components of saliva?
99% water and 1 % solutes (Na, CL-, K) Ph 6.35-6.85
What are the solutes of saliva?
Mucin, amylase and lysozyme
What is mucin?
a protein that forms mucus when dissolved in water
what is amylase?
a starch digesting enzyme
what is lysozyme?
protects mucus membrane
What are the functions of saliva?
Cleanses the teeth; dissolves the food via the amylase enzymes; moistens the food and compacts into "bolus"
What is a bolus?
Food going through the digestive system
What is the pharynx
contains both skeletal and smooth muscle to move bolus to the esophogus
What is the esophagus
posterior to the trachea; muscular, collapsible tube about 10" long
What does the lower esophangeal sphincter or cardiac sphincter do?
tonically contracts until pressure of the bolus causes the sphincter to relax
What are the two walls of the esophagus?
Circular muscle (inner) and longitudinal muscle (outer)
What is the gastrointestinal tract?
the GI tract
what are the four layers to the gastrointestinal tract - inside going out
Mucosa; submucosa; muscularis and serosa
What is the mucosa?
inner most layer of wall which absorbs, secretes and protects
What are the three parts of the mucosa?
Columnar epithelium; lamina propria and muscularis mucosa
Describe the columnar epithelium?
it's in direct contact with the GI tract; stratified in lower part of esophagus and simple in remainder
Describe the lamina propria?
Contains capillaries and lacteals (lacteals are part of the lymphatic system)
Describe the muscularis mucosa
smooth muscle, increases digestion and absorption
What layer is the submucosa
2nd layer of the GI tract
What is a plexus?
a group of nerves
Describe the submucosa
dense CT which binds the mucosa to the muscularis; highly vascular, lymph and nerve endings; contains meissner nerve plexus, controls GI secretions and motility
What layer is the muscularis
What are the two layers of the muscularis layer of the esophagus
Circular layer is inner (sphincters) and longitudinal layer is outer (breaks down bolus)
Describe the muscularis (externa) layer
contains the auerbach nerve plexus, controls GI secretions and motility
What is segmentation?
muscular movement that occurs in the small intestine. The alternating forward and backward movements of segmentation further mix the partially digested food and digestive juices and bring this mixture (called chyme) into contact with the intestinal wall
what is peristalsis
processing of food through the GI tract
What layer is the serosa in the esophagus
describe the serosa layer
areolar CT and simple squamous; referred to as the peritoneum; largest serous membrane in the body; contains large folds
What are the names of the large folds in the serosa layer?
greater omentum; lesser omentum; falciform ligament and mesentery
what is the greater omentum?
"fatty apron"; goes over greater curvature of stomach
what is the lesser omentum?
between the liver and stomach
what is the falciform ligament?
attaches the liver to the diaphragm
what is the mesentery
attaches the intestines together - in folds of the intestines
what are the modifications of the stomach?
mucosa - has large folds Rugae allows for extensibility; contains gastric pits