The DIGESTIVE SystemThe DIGESTIVE System

Digestion definedDigestion defined

Breakdown of food into Breakdown of food into useable nutrientsuseable nutrients

Two kindsTwo kinds MechanicalMechanical ChemicalChemical

Chemical Vs Mechanical Digestion

Chemical: Enzymes break Chemical: Enzymes break down for absorption--ENZYMESdown for absorption--ENZYMES

Mechanical: broken down into Mechanical: broken down into smaller parts--MASTICATION smaller parts--MASTICATION AND MACERATIONAND MACERATION

Alimentary canalAlimentary canal

Tube food Tube food passes throughpasses through

Begins at Begins at mouth - ends mouth - ends with anuswith anus

Food is chewed Bolus created Bolus swallowed

Pharynx

Bolus moves Bolus moves into pharynxinto pharynx

fancy word for fancy word for throatthroat

has three partshas three parts– NasopharynxNasopharynx– OropharynxOropharynx– LaryngopharynxLaryngopharynx

EsophagusEsophagus 8-12 inches long8-12 inches long Smooth muscle Smooth muscle

contractions called:contractions called: Peristalsis-Peristalsis-

rhythmic rhythmic Cardiac (aka Cardiac (aka

Gastroesophageal) Gastroesophageal) sphincter sphincter

Has no mucous Has no mucous membrane to membrane to protect from Hcl protect from Hcl from stomachfrom stomach

StomachStomach J-shapedJ-shaped 3 sets of muscle in 3 sets of muscle in

different directionsdifferent directions Hcl= chemical Hcl= chemical

breakdownbreakdown Pepsin begins protein Pepsin begins protein

disgestiondisgestion Contain rugae to Contain rugae to

increase surface areaincrease surface area Change bolus into Change bolus into

chymechyme Mucus protects Mucus protects

stomach liningstomach lining

Small intestineSmall intestine 3 parts3 parts Duodenum--most Duodenum--most

chemical digestion chemical digestion takes place heretakes place here

Jejunum-absorption Jejunum-absorption continuescontinues

Ileum absorption Ileum absorption continuescontinues

15-22 ft long15-22 ft long Absorbs some of the Absorbs some of the

water in food & what water in food & what you drinkyou drink

VilliVilli

Nutrients are absorbed through Nutrients are absorbed through structures called villistructures called villi

Large intestineLarge intestine called the coloncalled the colon Main function Main function

water water absorption + Vit absorption + Vit K absorptionK absorption

Begins with Begins with cecum-contains cecum-contains lymphatic organ lymphatic organ called appendixcalled appendix

Ascending colonAscending colon

Large intestineLarge intestine Ascending colonAscending colon Transverse Transverse

colon-makes colon-makes hunger soundshunger sounds

Descending Descending coloncolon

Sigmoid colonSigmoid colon RectumRectum Anal canalAnal canal AnusAnus

Accessory organsAccessory organs CONTRIBUTE to digestion CONTRIBUTE to digestion

processprocess NOT part of the canal or tubeNOT part of the canal or tube Food Food DOES NOTDOES NOT pass through pass through

themthem

Tongue and teethTongue and teeth

Teeth break Teeth break food down into food down into smaller piecessmaller pieces

Tongue moves Tongue moves food to the food to the back of throatback of throat

Parts of a tooth Crown = exposed Crown = exposed

portion above portion above gum linegum line

Neck = between Neck = between crown & rootcrown & root

Gingivae-gumsGingivae-gums Root = one to Root = one to

three-- embedded three-- embedded in mandible & in mandible & maxillaemaxillae

Parts of a tooth Enamel = outermost Enamel = outermost

part, protects from part, protects from wear & tearwear & tear– the hardest the hardest

substance in the substance in the bodybody

Dentin = calcified Dentin = calcified connective tissue connective tissue

Gives tooth itGives tooth it’’s s basic shape & basic shape & rigidityrigidity

Parts of a tooth

Pulp Cavity = Pulp Cavity = large cavity large cavity enclosed by enclosed by dentin--filled dentin--filled with pulpwith pulp

Cementum = a Cementum = a bone-like bone-like substance substance covers--dentin covers--dentin of rootsof roots

Parts of a tooth Periodontal Periodontal

LigamentLigament an area of dense an area of dense

fibrous connective fibrous connective tissuetissue

anchors teeth in anchors teeth in positionposition

serves as a shock serves as a shock absorber when absorber when chewingchewing

Salivary glandsSalivary glands Saliva is:Saliva is: Mostly waterMostly water Enzymes that Enzymes that

digest carbs—digest carbs—Amylase—breaks Amylase—breaks starch into starch into maltosemaltose

Soften and Soften and moisten foodmoisten food

Salivary glandsSalivary glands

6 total--3 6 total--3 pairpair

Parotid, Parotid, submandibulsubmandibular, and ar, and sublingualsublingual

Liver and Gall BladderLiver and Gall Bladder

Liver makes bileLiver makes bile Bile is stored in Bile is stored in

gall bladder (sac)gall bladder (sac) Bile breaks down Bile breaks down

fats--fats--emulsificationemulsification

Secreted as it is Secreted as it is neededneeded

Eliminated Eliminated through intestinesthrough intestines

PancreasPancreas Located posterior to Located posterior to

stomachstomach Secretes enzymes to Secretes enzymes to

chemically chemically breakdown fats, breakdown fats, carbs, and proteinscarbs, and proteins

Increases pH of Increases pH of chymechyme

Pancreatic juice—thru Pancreatic juice—thru pancreatic duct—thru pancreatic duct—thru heptopancreatic heptopancreatic sphinctersphincter

MasticationMastication Chewing--Chewing--

makes bolusmakes bolus Teeth Teeth

mechanically mechanically break down break down foodfood

Food is mixed Food is mixed with salivawith saliva

DeglutitionDeglutition SwallowingSwallowing Tongue pushes Tongue pushes

food to back of food to back of throatthroat

Oropharynx--Oropharynx--second part of second part of throatthroat

Smooth Muscles Smooth Muscles contract causing contract causing peristalsisperistalsis

VoluntaryVoluntary

PeristalsisPeristalsis

General term General term for wave-like for wave-like contractions in contractions in esophagus and esophagus and intestinesintestines

Rhythmic Rhythmic smooth muscle smooth muscle contractionscontractions

MacerationMaceration Stomach Stomach

contracts and contracts and Bolus mixed with Bolus mixed with gastric juices and gastric juices and Hcl until it is Hcl until it is liquid-likeliquid-like

Bolus is changed Bolus is changed to chymeto chyme

Empties through Empties through pyloric sphincterpyloric sphincter

Segmental contractionSegmental contraction Each segment of Each segment of

small intestine small intestine contractscontracts

Helps mix bile Helps mix bile and pancreatic and pancreatic juices with chymejuices with chyme

Smooth Muscle Smooth Muscle contractions contractions peristalsis in each peristalsis in each segmentsegment

AbsorptionAbsorption Nutrients Nutrients absorbedabsorbed

in jejunum and in jejunum and illeumilleum

Some nutrients & Some nutrients & water awater absorbedbsorbed thru thru stomachstomach

Some water Some water absorbed absorbed through through small intestinesmall intestine

Most water Most water absorbedabsorbed through large through large intestineintestine

Haustral churningHaustral churning

Each segment in Each segment in large intestine is large intestine is called a haustracalled a haustra

Smooth muscle Smooth muscle contractions contractions move contents move contents along (type of along (type of peristalsis)peristalsis)

Water is Water is absorbed in absorbed in large intestinelarge intestine

DefecationDefecation

Elimination of Elimination of material that is material that is undigestibleundigestible

Plant fiber--Plant fiber--necessary for necessary for health of the health of the intestinesintestines

Formation of feces Formation of feces and elimination of and elimination of fecesfeces

Nutrients are broken down in Nutrients are broken down in different places in digestive different places in digestive

systemsystem CarbohydratesCarbohydrates Begin digestion in Begin digestion in

mouth with enzyme mouth with enzyme AMYLASE from AMYLASE from salivary glandssalivary glands

Amylase breakdown Amylase breakdown continues in stomachcontinues in stomach

Finish breakdown in Finish breakdown in duodenum duodenum (pancreatic juice)(pancreatic juice)

FatsFats Fats begin mixing Fats begin mixing

with gastric juices with gastric juices in stomachin stomach

Bile from gall Bile from gall bladder goes into bladder goes into small intestine to small intestine to break them downbreak them down

Pancreas secretes Pancreas secretes enzymes (lipase) enzymes (lipase) to finish chemical to finish chemical breakdownbreakdown

ProteinsProteins

Begin mixing Begin mixing with pepsin in with pepsin in stomachstomach

Finish with Finish with secretions from secretions from pancreas into pancreas into duodenumduodenum

Digestion system EndDigestion system End