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Transcript of Digestion
By Jason Ramos What is the Main Function of the Digestive System? The Mouth 1st Stop in Digestive System
Mechanical & Chemical Digestion begins Mechanical Digestion Chewing breaks food down into smaller pieces
The more you chew, the easier it is for the body to absorb nutrients from the food Chemical Digestion Salivary Glands secrete Saliva; mixed in w/ food by the tongue
Amylase, a digestive enzyme found in Saliva, breaks down carbohydrates stored in the food Swallowing Food Bolus - Ball of mushed-up food that is ready to be swallowed
Swallowing is accomplished by muscle movements in the mouth and tongue, pushing the bolus into the throat Swallowing Food (Cont.) Epiglottis - Flexible flap of tissue in the throat, reflexively closes over the windpipe when we swallow to prevent choking
From the throat, food travels down the Esophagus Esophagus Muscular tube; moves food from throat to stomach
Peristalsis - Series of wave-like muscle contractions that moves food through the digestive tract Stomach Muscular Sack
Can expand to hold up to 1.5 liters or more after a meal
Muscles churn and mix the food in with Gastric Juices Gastric Juice Inner lining of stomach contains millions of glands that secrete Gastric Juice
3 main components are: Hydrochloric Acid, Pepsinogen, and Mucus
Hydrochloric Acid kills bacteria, and converts Pepsinogen into Pepsin, which breaks down proteins in your food Stomach (Cont.) After 2-4 hours, food becomes Chyme - Partially digested food from the stomach
Consistency of Tomato Soup!
Peristaltic waves move Chyme into Small Intestine Gastric Juice (Cont.)
Mucus protects inner lining of stomach from the acidity of gastric juices; stomach doesn't digest itself Small Intestine Muscular Tube where digestion is completed
1.5 to 2 inches wide, 22 feet long
Made of 3 parts: the Duodenum, Jejunum and Ileum. Duodenum Chemical digestion & breakdown
Collects digestive juices from Gall Bladder, and Pancreas Bile Pancreatic Juice; Sodium Bicarbonate Breaks down fats Contains digestive enzymes; neutralizes harmful acid from the stomach Jejunum 4-7 feet long
Food passes over thousands of tiny finger-like structures called Villi; lines inner wall of small intestine
Nutrients are diffused into the villi and enter the Bloodstream
Fats; absorbed into lacteal
Glucose & Amino Acids; absorbed into blood vessel Ileum Last Section of Sm. Int.; Absorbs Vitamin B12 and Bile Salts
Once in bloodstream, nutrients are transported to tissue and organs of the body to support cell processes.
Any undigested and unabsorbed food passes into the Large Intestine Large Intestine Aka the Colon
5 feet long; 2.5 inches wide
Absorbs Water, leaving behind a more solid material; aka (Poop)
Anaerobic bacteria synthesize Vitamins B & K, which are absorbed and needed by body Elimination of Wastes Rectum - Final section of the Small Intestine; accumulates poop
Anus - Opening of the Rectum where waste leaves the body
After 18-24 hours, the remaining indigestible material, now called feces, is accumulated in the Rectum, and eliminated through the Anus
Your meal's entire journey has taken between 24-33 hours 1) Break down food
2) Absorb nutrients and distribute to cells
3) Eliminate undigested materials from the body "Disassembly Line" http://www.wisegeek.com/what-are-gastric-juices.htm