The Digestive System. Organs and Functions

• Mechanical (physical)
◦ Chew, tear, grind, mash, and mix
• Chemical
◦ Enzymatic reactions to improve digestion of
carbohydrates, proteins, and lipids
Digestive System Organization
• Gastrointestinal (Gl) tract
◦ Structures
▪ Mouth
▪ Pharynx
▪ Esophagus
▪ Stomach
▪ Small intestine
▪ Large Intestine
▪ Rectum
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Mouth
down food into small pieces.
• Tongue mixes food with saliva (contains amylase, which helps break down starch).
• Teeth mechanically break • Epiglottis: flap-like structure
at the back of the throat.
• Closes over the trachea preventing food from entering it. It is located in the Pharynx.
Esophagus
• Approximately 20 cm long.
• Functions include: Secreting mucus and moving food from the throat to the stomach using muscle movement called peristalsis
Stomach
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• J-shaped muscular bag that stores the food and breaks it down into tiny pieces.
• Mixes food with gastric juices that contain enzymes to break down proteins and lipids.
• Hydrochloric acid in the stomach kills bacteria.
• Food found in the stomach is called chyme.
Small Intestine
• Small intestines are roughly 7 meters long
• Lining of intestine walls has finger-like projections
called villi, to increase surface area.
• The villi are covered in microvilli which further increases surface area for absorption.
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Small Intestine
• Nutrients from the food pass into the...

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