消化系統(tǒng)英文名稱TheDigestiveSystem課件

1、Human DigestionHuman DigestionNutrition Process by which organisms obtain and utilize their food. There are two parts to Nutrition:1. Ingestion- process of taking food into the digestive system so that it may be hydrolized or digested.2. Digestion- the breakdown of food (either chemically or mechani

2、cally) in order to utilize nutrientsNutrition Process by which orgTypes of Nutrients Micronutrients- vitamins, minerals, & waterMacronutrients- proteins, lipids, carbohydrates, etcTypes of Nutrients MicronutrieHuman digestive systemHuman digestive systemGI (gastrointestinal) tract = alimentary canal

3、 GI (gastrointestinal) tract = IngestionMouthmechanical digestionteethbreaking up foodchemical digestionsalivaamylaseenzyme digests starchmucin slippery protein (mucus)protects soft lining of digestive systemlubricates food for easier swallowingbuffers neutralizes acid to prevent tooth decayanti-bac

4、terial chemicals kill bacteria that enter mouth with foodIngestionMouthmouthbreak up fooddigest starchkill germsmoisten foodmouthMouthChemical and mechanical digestion.Food is chewed (masticated) mechanically.A bolus (lump) is formed with saliva and the tongue.MouthChemical and mechanical dSwallowin

5、g (& not choking) Epiglottis flap of cartilagecloses trachea (windpipe) when swallowingfood travels down esophagusPeristalsis involuntary muscle contractions to move food along Swallowing (& not choking) EpiWhich type of digestion is the following? Chewing a saltine? -2. Saliva breaking the saltine

6、down into molecules of glucose? -3. Your tongue breaking pieces of a hamburger apart? 4. Pepsin (an enzyme) in your stomach breaking the hamburger into amino acids? MechanicalMechanicalChemicalChemicalWhich type of digestion is thePharynxThe back of the throat.Larynx- passage for air, closes when we

7、 swallow.Is approximately 15cm long.PharynxThe back of the throat.Digestive GlandsGroups of specialized secretory cells.Found in the lining of the alimentary canal or accessory organs.Digestive GlandsGroups of specseries of involuntary wave-like muscle contractions which move food along the digestiv

8、e tractPeristalsisseries of involuntary wave-likStomachFood is temporarily stored here.Gastric juices are secreted.Has layers of muscle that line the inside.Mechanically and chemically breaks down food.StomachFood is temporarily stoStomachFunctionsfood storagecan stretch to fit 2L food disinfect foo

9、dHCl = pH 2kills bacteria chemical digestionpepsinenzyme breaks down proteinsBut the stomach is made out of protein!What stops the stomach from digesting itself?mucus secreted by stomach cells protects stomach liningStomachFunctionsBut the stomacstomachkills germs break up fooddigest proteinsstore f

10、oodsphinctersphinctermouthbreak up fooddigest starchkill germsmoisten foodstomachsphinctersphinctermouthGastric JuicesSecreted by the stomach.Acidic (pH 1.5-2.5) (HCl).Pepsin- an enzyme that breaks down large proteins into amino acids.Food is further broken down into a thin liquid called chyme.Gastr

11、ic JuicesSecreted by the 消化系統(tǒng)英文名稱TheDigestiveSystem課件Accessory OrgansPancreasGall BladderSpleenAccessory OrgansPancreasGall bladder Pouch structure located near the liver which concentrates and stores bileBile duct a long tube that carries BILE. The top half of the common bile duct is associated wit

12、h the liver, while the bottom half of the common bile duct is associated with the pancreas, through which it passes on its way to the intestine. Gall bladder Pouch structure lBILEBile emulsifies lipids (physically breaks apart FATS)Bile is a bitter, greenish-yellow alkaline fluid, stored in the gall

13、bladder between meals and upon eating is discharged into the duodenum where it aids the process of digestion. BILEBile emulsifies lipids (phPancreas An organ which secretes both digestive enzymes (exocrine) and hormones (endocrine)* Pancreatic juice digests all major nutrient types. Nearly all diges

14、tion occurs in the small intestine & all digestion is completed in the SI. Pancreas An organ which secretPancreas Digestive enzymes digest proteinstrypsin, chymotrypsindigest starchamylaseBuffers neutralizes acid from stomachPancreas Digestive enzymes 消化系統(tǒng)英文名稱TheDigestiveSystem課件Liver Functionproduc

15、es bilebile stored in gallbladder until neededbreaks up fats act like detergents to breakup fatsbile contains colors from old red blood cells collected in liver =iron in RBC rusts & makes feces brownLiver Functionbile contains copancreasproduces enzymes to digest proteins & starchstomachkills germs

16、break up fooddigest proteinsstore foodmouthbreak up fooddigest starchkill germsmoisten foodliverproduces bile- stored in gall bladderbreak up fatspancreasstomachmouthliverSmall IntestineMost chemical digestion takes place here.Simple sugars and proteins are absorbed into the inner lining.Fatty acids

17、 and glycerol go to lymphatic system.Lined with villi, which increase surface area for absorption, one cell thick.Small IntestineMost chemical dSmall intestineFunctionchemical digestionmajor organ of digestion & absorptionabsorption through liningover 6 meters! small intestine has huge surface area

18、= 300m2 (size of tennis court) Structure3 sectionsduodenum = most digestionjejunum = absorption of nutrients & waterileum = absorption of nutrients & waterSmall intestineFunctionDuodenum 1st section of small intestinesacid food from stomach mixes with digestive juices from:pancreas livergall bladder

19、Duodenum 1st section of small stomachkills germs break up fooddigest proteinsstore foodmouthbreak up fooddigest starchkill germsmoisten foodpancreasproduces enzymes to digest proteins & starchstomachmouthpancreasAbsorption in the SI Much absorption is thought to occur directly through the wall witho

20、ut the need for special adaptations Almost 90% of our daily fluid intake is absorbed in the small intestine.Villi - increase the surface area of the small intestines, thus providing better absorption of materialsAbsorption in the SI Much absoAbsorption by Small IntestinesAbsorption through villi & m

21、icrovillifinger-like projectionsincrease surface area for absorptionAbsorption by Small IntestinesVILLIVILLILarge intestines (colon)Functionre-absorb wateruse 9 liters of water every day in digestive juices 90% of water reabsorbednot enough water absorbed diarrhea too much water absorbedconstipation

22、Large intestines (colon)FunctiLarge IntestineSolid materials pass through the large intestine.These are undigestible solids (fibers).Water is absorbed.Vitamins K and B are reabsorbed with the water.Rectum- solid wastes exit the body.Large IntestineSolid materialsYouve got company!Living in the large

23、 intestine is a community of helpful bacteriaEscherichia coli (E. coli)produce vitamins vitamin K; B vitaminsgenerate gasesby-product of bacterial metabolism methane, hydrogen sulfideYouve got company!Living in tAppendixVestigial organAppendixVestigial organRectum Last section of colon (large intest

24、ines)eliminate fecesundigested materialsextracellular wastemainly cellulose from plantsroughage or fiber masses of bacteriaRectum Last section of colon (Digestive Homeostasis DisordersULCERS erosion of the surface of the alimentary canal generally associated with some kind of irritantDigestive Homeo

25、stasis DisorderCONSTIPATION a condition in which the large intestine is emptied with difficulty. Too much water is reabsorbed and the solid waste hardensDigestive Homeostasis DisordersCONSTIPATION a condition in Digestive Homeostasis DisordersDIARRHEA a gastrointestinal disturbance characterized by decreased water absorption and increased peristaltic activity of the large intestine. This results in increased, multiple, watery feces. This condition may result in severe dehydration, especially in in