FUNCTIONSOF THEDIGESTIVESYSTEMDigestion is the processthat breaks down foodinto small molecules sothat they can be absorbedand moved into the blood,then on to the cells.
FOOD ISPROCESSED INYOUR BODY IN4 STAGESingestiondigestionabsorptionelimination
MECHANICALDIGESTIONTakes place when food ischewed, mixed, andchurned. This mainlyoccurs in the mouth andstomach.
CHEMICALDIGESTIONoccurs when chemicalreactions occur that breakdown large molecules offood into smaller ones.
ENZYMES INDIGESTIONEnzymes help youdigest carbohydrates,fats and proteins.Amylase is an enzymeproduced in a glandnear the mouth.Amylase helps speedup the breakdown ofcomplex carbs, such asstarch, into simplercarbs - sugar.
ENZYMES INDIGESTIONIn your stomach, theenzyme pepsin helpsin the breakdown ofcomplex proteins intoless complex proteins.In your small intestine,many otherenzymes continue tospeed up thebreakdown of proteinsinto amino acids.
ENZYMES INDIGESTIONThe pancreas, an organon the back outside of thestomach, releasesseveral enzymesthrough a tube into thesmall intestine.They breakdown starchesthat started to be brokendown in the mouth. Thestarches are broken downinto glucose to be used bycells.Other enzymes from thepancreas are involved inthe breakdown of fattyacids and proteins.
The human digestive system is like a long tube withspecialized sections. If it is stretched out, it would be_________ meters long.6 to 9 meters!!!!!!!Absolutely mind-boggling!
DIGESTIVE SYSTEMHAS 2 PARTSthe digestive tract the accessory organsmouthesophagusstomachsmall intestinelarge intestinerectumanustongueteethsalivary glandslivergallbladderpancreasfood passes through food does notpass through
MOUTH•Mechanical and chemical digestion begins in the mouth.•Mechanical digestion - when you chew with your teethand mix with your tongue.•Chemical digestion - watery substances called saliva isadded to your mouth. Saliva is produced by 3 sets of glandsnear your mouth.•Saliva - mostly water, but also contains mucus and anenzyme that helps in the breakdown of starch into sugar.
MOUTH•Food mixed with saliva becomes a soft mass and is movedto the back of your mouth by your tongue.•It is swallowed and passes into your esophagus.•Ingestion is now complete.
ESOPHAGUS•Food that passes from the mouth into the esophagus, firstpasses the epiglottis.•Epiglottis - structure that automatically covers theopening to the wind pipe to prevent food from entering thelungs and causing you to choke.•Esophagus - muscular tube about 25 cm long. It takes4-10 seconds for food to travel through it.
ESOPHAGUS•No digestion takes place in the esophagus, but there aremucus glands in the wall to keep the food moist.•The walls are made of smooth muscles, which move thefood down to the stomach with a squeezing motion calledperistalsis.
STOMACH•Stomach - muscular bag, that when empty is sausageshaped with folds on the inside.•As food enters, the stomach expands and the folds smoothout.•Mechanical and chemical digestion take place here.•Mechanical - food is mixed by peristalsis•Chemical - food is mixed with enzymes and strong digestivesolutions, like hydrochloric acid.
STOMACH•Specialized cells in the walls of the stomach release about 2liters of HCl solution each day.•WOW!!•The acidic solution works with the enzyme pepsin to digestprotein. It also destroys bacteria that are present in the food.•The stomach also produces mucus, making the foodslippery and protects the stomach from the strong, digestivesolutions.
STOMACH•Food moves out of the stomach after 2-4 hours and ischanged into a thin, water liquid called chyme.•Little by little chyme leaves the stomach and moves to thesmall intestine.
SMALL INTESTINE•The small intestine is small in diameter, but is 4-7 meters longs!•Food from the stomach enters the first section of the smallintestine called the duodenum. Most digestion takes place here.•A greenish fluid, bile, is produced in the liver and stored in thegall bladder.•The acid from the stomach makes large fat particles float to thetop of the bile.•Bile breaks up the large fat particles, similar to the way detergentbreaks up grease.
SMALL INTESTINE•Chemical digestion of carbohydrates, proteins, and fatsoccurs when a digestive solution from the pancreas ismixed in.•The solution contains bicarbonate ions to neutralize thestomach acid and enzymes to continue the breakdown.•Your pancreas also makes insulin, a hormone that allowsglucose to pass from the blood stream into your cells.
SMALL INTESTINE•Absorption of food’s nutrients takes place in the smallintestine.•The wall of the small intestine has many ridges and foldsthat are covered with fingerlike projections called villi.•Villi increase the surface area so that the nutrients in thechyme have more places to be absorbed.•By how much do villi increase the surface area of the smallintestine?
IF YOU WERE TO STRETCH OUT THEVILLI OF THE SMALL INTESTINETHEY WOULD COVER.........a tennis court!!!!
SMALL INTESTINE•Peristalsis continues to move and mix the chyme.•Nutrients move into the blood vessels within the villi.•The blood transports the nutrients to all cells of your body.•Peristalsis continues to force the remaining undigested andunabsorbed materials slowly into the large intestine.
LARGE INTESTINE•When the chyme enters the large intestine it is still thin andwatery.•The main job of the large intestine is to absorb waterfrom the undigested mass.•This keeps large amounts of water in your body andmaintains homeostasis.•Peristalsis slows down in the large intestine.•The chyme might stay there for as long as 3 days.
LARGE INTESTINE•After the excess water is absorbed the undigested materialbecome more solid.•Muscles in the rectum (the last section of the largeintestine) and the anus control the release of semisolidwastes from the body in the form of feces.
BACTERIA AREIMPORTANTMany types of bacteria are in your body.They live in many of the organs in your digestive tract,including your mouth and large intestine, where both yourbody and the bacteria are benefitted.Bacteria in your large intestine feed on undigested materiallike cellulose. The bacteria make vitamins you need- vitaminK and 2 vitamin B’s.
BACTERIA AREIMPORTANTVitamin K is needed is needed for blood clotting. TheVitamin B’s are needed for your nervous system for otherbody functions.The breakdown of intestinal materials by bacteria producesgas.