The Digestive System From Food to Nutrients

The Digestive System - Purpose The function of the digestive system is to break down food into small molecules which can diffuse into the blood stream where they can be delivered to all cells of the body to use for energy, cell activities, cell parts, making enzymes, growth, repair, and body defenses.

Overview of System The Digestive Tube: Accessory Organs Food actually passes through these organs: Mouth Pharynx Esophagus Stomach Small Intestine Large Intestine Rectum Anus Accessory Organs These organs produce chemicals that help with digestion: Salivary Glands Liver Gall Bladder Pancreas

Two Kinds of Digestion Physical Digestion: Food is broken into smaller PIECES Chemical Digestion: Food is broken into smaller molecules.

From Food to Nutrients – Pizza!

The Mouth –includes teeth & tongue Teeth break food into smaller pieces Saliva is secreted into the mouth from the salivary glands to help lubricate the food Tongue forms a bolus (ball) of food that can be swallowed easily Amylase begins some digestion of starch

The Pharynx – Don’t Choke! Part of both digestive and respiratory system When swallowing, a small flap called the epiglottis blocks the opening of your windpipe Allows food to go down the esophagus “Down the wrong tube”

The Esophagus 10 inch long, muscular tube Transports food from mouth to stomach Food doesn’t just slide down, muscles contract to push the food down – peristalsis 2-3 seconds to go down

The Stomach Stretchy, J-shaped sac Stomach is like a blender Slowly grinds food into mush called chyme Pepsin (proteinase) breaks down proteins into amino acids Acids denature bacteria

Small Intestine – First half! 1 inch in diameter, 21 ft long (stretched out) Food spends about 4 hours in the S.I. Bile (from liver) breaks fats into smaller pieces. Bicarbonate (from pancreas) neutralizes stomach acid. Lipases, starchases, and proteinases from small intestine and pancreas digest food.

Small Intestine – second half! Absorption By now, the food is digested into small and medium molecules. LOTS of thin finger shaped projections called villi line the small intestine. Nutrients diffuse through the villi into the blood stream and travel to your cells.

Surface are to volume ratio!!!!!!

The Appendix Tiny tube with closed end coming off the L.I.

The Large Intestine 2-3 inches thick 5-6 feet long Undigested food and water passes through Absorbs water as waste passes through forming feces (solid waste)

The Last Stop: Rectum & Anus 5 inch, muscular sac Waste is solidified Storage for feces. Anus Ring shaped muscle Releases feces

The Liver and the Gallbladder Liver is the largest organ – small football Produces bile which changes large fat drops into smaller droplets. Gallbladder – small 1 inch sac behind liver Stores bile from liver Bile secreted into the small intestine as needed

The Pancreas 6 inches long – spongy – behind stomach Secretes: Bicarbonate to neutralize stomach acid Proteinases to digest protein Starchases to digest starches Lipases to digest fats

Very Important! The digestive system is very important because without it, your body couldn’t get the nutrients it needs in order to grow big and strong!