1. The Upper Alimentary System

2. Layers of the Alimentary Canal
Mucosa – Mucous Membrane
innermost layer
adjacent to lumen
Primarily epithelial tissue
Secretes mucous and other products to aid in digestion.
Submucosa
Below mucosa
Dense connective tissue
Contains blood vessels, lymphatic, vessels, nerves

3. Layers of the Alimentary Canal
Muscularis Externa
Two layers of smooth muscle to aid in peristalisis and mechanical digestion
Serosa
Thin, slippery membranes that minimize friction between organs and cavity wall.
Also known as peritoneum
visceral
Parietal
Connected together by the mesentery

7. THE ALIMENTARY CANAL

8. Accessory Organs/Structures
Alimentary Canal
Also known as the gastrointestinal tract (gi tract)
The tube that runs through the body from the mouth to the anus.
30 feet long and includes the pharynx, esophagus, stomach, small and large intestines.
Accessory Organs/Structures
Teeth Liver
Salivary glands Pancreas
Gallbladder

10. Upper Alimentary/Organs
Oral Cavity
Ingestion
Mechanical breakdown- mastication (chewing)
Chemical breakdown- salivary enzymes
Propulsion- pushing food back to throat to swallow
Teeth, gingiva, tongue, salivary glands, cheeks and lips all assist

11. Teeth Responsible for mechanically breaking down food Anatomy of Tooth
Crown – visible portion doing the chewing, covered in enamel
Root – below the gums and bone; anchored to the jaw via ligaments
Pulp- Cavity inside tooth with blood and nerve supply
Three tissue layers
Enamel- Outer most layer of tooth, mineral calcium phosphate
similar to bone but much harder
Cementum and dentin are underlying
tissues within the tooth
Periodontium- tissue surrounding teeth
Gingiva (gums)- soft
Boney socket for tooth to anchor

12. Salivary Glands
Responsible for chemically breaking down food by secreting saliva into mouth
Saliva- moistens food, protects mouth and body from infection
Water, enzymes, mucous, antibodies
Three pairs of salivary glands
Parotid
Submandibular
Sublingual

14. Pharynx & esophagus
The pathway (within alimentary canal) food takes on its way to the stomach from the mouth
Pharynx- the throat
Esophagus- muscular food tube
to stomach
peristalsis begins
(wave of muscular contraction
to push food through
the gi tract
*** note we share this space with the
respiratory system… so don’t get
these structures confused!!

16. Stomach
Responsible for mechanically & chemically breaking down food by secreting gastric juices
Anatomy of Stomach
Cardioesophageal sphincter

17. Stomach
The stomach is basically a reservoir, a holding tank for food and stretches out to hold 2 liters of contents. Food takes a while to break down and must be broken down before entering the small intestine for nutrient absorption. The stomach does most of the heavy work for digestion
Rugae- folds of tissue that allow the stomach to expand when full with food
Mechanical digestion
Lined with three layers of muscles to churn food, continue chopping after the teeth are done
Chemical digestion
Inner layer of the stomach
Simple columnar epithelium that secretes mucus.
Gastric pits that secrete juices
Hydrochloric acid (HCl)
food + gastric juices = CHYME!