A.P. Biology Notes
Mammalian Digestion Part 1
I. Mammalian Digestive System
A. General Info.
1. Includes alimentary canal and accessory glands that secrete juices into the
alim. canal
2. Has a 4-layered wall called the lumen
a.
b.
c.
d.
3. Peristalsis4. Sphincters
5. Accessory organs are 3 pairs of salivary glands, the pancreas, the liver, and
the gall bladder
B. Specialized compartments
1. Oral cavity-where physical and chemical digestion begins
a. Mastication-purpose??
b. Salivary glands-presence of food causes salivary glands to
secrete saliva.
1. lubricates
2. protects mouth
3. buffers acids
4. is antibacterial
5. contains amylase6. tongue forms food into bolus before swallowing
2. Pharynx-common passageway for food and air. Epiglottis??
3. Esophagus-carries food from pharynx to stomach
a. peristalsis moves food
b. swallowing is voluntary, peristalsis is not
4. Stomach-large, saclike, left side, below diaphram, elastic, Jshaped
a. Digestion in
1. Epithelium of lumen secretes gastric juice with HCl and
pepsin
a. HCl roles-???
b. pepsin rolec. a coating of mucous secreted by epithelial cells
protects stomach from digestion
2. Controlled by nerve impulses and the hormone gastrin in
blood that stimulates secretion of gastric juice (3 L/day)
3. Mechanical digestion by churning action of smooth muscles
4. Pyloric sphincter-regulates passage of acid chyme into small intestine