Digestion begins in the mouth. As you chew your food, two processes are occurring: 1. TEETH- your teeth begin mechanical digestion by breaking down food into smaller pieces. 2. SALIVA- this enzyme helps break down starches chemically
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The mouth completes both mechanical and chemical digestion!
As you swallow, the food must pass several structures: • Pharynx- Back of the throat opens into esophagus
• Epiglottis- flap of tissue that keeps chewed food from going down the trachea to the lungs. As you swallow, the epiglottis flops closed. • Larynx- Vocal cords
• The esophagus is a long tube that runs from the mouth to the stomach. • After being chewed and swallowed, the food ball (bolus) enters the esophagus.
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• The food is deposited in the Stomach. • The stomach is a large, sac-like organ made of muscle.
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• The stomach churns food AND bathes it in gastric juice (acidic). • Food remains in the stomach for 2-4 hours, turning into a thin liquid soup called chyme.
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The stomach completes both mechanical and chemical digestion!
• The liquid chyme is the transported to the small intestine. • SI is a narrow muscular tube about 6 meters long, lined with villi.
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• Bile and other enzymes are injected into the Small Intestine to further break down the food. Is this mechanical or chemical digestion?
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Food remains in the SI for 3-5 hours
Don’t forget the Bacteria!
• Villi- finger-like extensions that absorb nutrients • Villus expand surface area of SI.
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• The function of the SI is to absorb all usable nutrients. • The villi are covered with capillaries which pick up the nutrients for ALL cells in the body.
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What system works with Digestive?
Blood vessels pick up nutrients from SI
• Anything (liquid or solid) that is not absorbed by the SI is sent to the Large Intestine. • The colon absorbs most excess liquids.
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Don’t forget the Bacteria!
• After about 18-24 hours… • The END process- solid waste (feces) is stored in the rectum until it is excreted through the anus.
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• The digestive system is also part of the Excretory system!
Your meal’s entire journey through the Digestive System has taken between 24 and 33 hours.
Many organs play a role in the digestion of foods but never come in contact with food, we call these accessory organs.
Three such organs are: – Liver – Gall Bladder – Pancreas
• Liver- large organ located above and in front of the stomach. • It filters toxins from the blood and makes bile (breaks down fats).
• Gall Bladder- small, sac-like organ located near the SI. • It stores and releases bile into the small intestine.
• Pancreas- an enzyme producing organ located below the stomach and above the intestines. • Enzymes from the pancreas aid in digestion of carbohydrates, fats and proteins in the small intestine.
