This page will give you a more comprehensive look at each structure of the digestive system.

Tissue layers within the digestive tract

• Mucosa
• Submucosa
• Muscularis

Alimentary Canal:
First process of the digestive system starts with the:

Mouth

• mastication

• mechanical digestion
• teeth
• tongue
• gums
• Salivary Glands~create saliva
• parotid
• sublingual
• submandibular

STRUCTURE	FUNCTION
Lips	Closes the mouth (oral cavity) during the chewing process; and when sipping liquids
Salivary glands	Produce Saliva
Teeth	Chewing and grinding of food (mastication)
Tongue	Senses tastes via taste buds and manipulates food and assists in deglutition
Tonsils	Antigen detector in processed foods and drink as we swallow; initiates a immune response if needed
Uvula	Assists in closing off entryway to nasopharynx when swallowing
Hard palate	Seperates oral cavity from nasal cavity
Soft palate	Aides uvula in closing off entryway to nasopharynx when swallowing
Vestibule	Space where ingested food and drink are mixed with saliva and mechanically digested
Ginivae	Around the neck of the tooth and covers the alveolar processes
Cheeks	Helps to hold the food and drink in the oral cavity

Pharynx

• Fibromuscular passageway that connects the nasal and oral cavities to the larynx and esphogaus.
  
• Two purposes:
  • Serves the respiratory system as a channel air.
  • Serves the digestive system as a channel for food.
• Upper region of the pharynx is called the Nasopharynx. It has no function in the digestive system, but is the canal posterior to the nasal cavity, containing the pharyngeal tonsils and adenoids.
  
• Middle region of the pharynx is called the Oropharynx. It is located posterior to the oral canal, hence the word "ORO". It is the first region food hits when it is swallowed.
  
• Lower region of the pharynx is called the Laryngopharynx. It is located posterior the the larynx, hence the word "Laryn". It opens into the esophagus, which takes the food to the stomach, or it opens to the larynx, which takes air down to the lungs.
  
• The epiglottis is a small flap that drops downward to prevent food from going into the larynx in the swallowing process of food.
• The uvula will elevate to prevent food from passing into the nasopharynx region. Uvula also has other functions but in this unit will only be mentioned for the digestive usage.
  

Esophagus

• Collapsible muscular tube that serves as a passageway from the pharynx to the stomach.
  
• Located posterior to the trachea and anterior to the vertebral column as it descends down to the stomach.
  
• Passes through the esophageal hiatus (opening through the diaphragm) and empties into the stomach.
  
• Mucosa of the esophagus has glands that secrete mucos to help keep the lining moist and well lubricated to help the food pass along.
• Sphincters in the upper and lower part of the esophagus help to control the movement of food through the esophagus.
  
  • The lower sphincter is also known as the "cardiac sphincter" and is located at the esophagogastic junction.
    

Stomach

holds food
chemical digestion
stomach acid-gastric juice
- hydrochloric acid
- pepsin
lining-mucous membrane


Small Intestine

1. Duodenum
digestion, breakdown carbs, proteins, fats. Receives bile from gallbladder & liver.
2. Jejunum
absorption
3. Ileum
absorption

Pancreas

releases enzymes to break down carbs & proteins.
Insulin production

Large Intestine

no digestion
removes h2o
create & compact feces.

Rectum

Anus- external opening of the rectum.

Accessory Organs
Throat Liver passageway to esophagus Gallbladder Pancreas kidney Bladder