Digestion

Nitty Gritty TermsIntracellular Intracellular

Digestion:Digestion:- digestion occurs - digestion occurs within the cellwithin the cell

Extracellular Extracellular Digestion:Digestion:

- digestion occurs - digestion occurs outside of the cell outside of the cell in body cavities in body cavities (ex: sm intestine)(ex: sm intestine)

Mechanical Digestion:Mechanical Digestion:- changing the size - changing the size or shape of foodsor shape of foods

Chemical Digestion:Chemical Digestion:- changing the - changing the chemical chemical composition of foods composition of foods (ex: converting a (ex: converting a protein into several protein into several amino acids)amino acids)

Digestive System Tasks Digesting (breaking down) large Digesting (breaking down) large

food particles into smaller food particles into smaller particles.particles.

mixing and moving food materialmixing and moving food material Secreting enzymes into tube Secreting enzymes into tube

where digestion occurswhere digestion occurs Absorb nutrients & fluidsAbsorb nutrients & fluids Eliminate wastesEliminate wastes

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Major Components Mouth (oral Mouth (oral

cavity)cavity) Pharynx (throat)Pharynx (throat) EsophagusEsophagus StomachStomach Small IntestineSmall Intestine Large IntestineLarge Intestine RectumRectum AnusAnus

Mouth

Salivary glands

StomachPancreas (behind stomach)Large intestine

Small intestine

Rectum

Gallbladder (behind liver)

Liver

Esophagus

Pharynx

Digestive SystemSection 38-2

Mouth TeethTeeth

Physically breakdown foodPhysically breakdown food Mechanical DigestionMechanical Digestion

TongueTongue Helps mix food w/ salivaHelps mix food w/ saliva Aids in swallowingAids in swallowing

SalivaSaliva Produced by salivary glands at back of Produced by salivary glands at back of

mouth and under tonguemouth and under tongue Starts chemical digestion Starts chemical digestion of starchesof starches Salivary amylase Salivary amylase

Esophagus Muscular tubeMuscular tube Connects mouth & stomachConnects mouth & stomach Peristalsis moves food from mouth Peristalsis moves food from mouth

to stomachto stomach Epiglottis keeps food out of the Epiglottis keeps food out of the

windpipe (so it doesn’t reach the windpipe (so it doesn’t reach the lungs).lungs).

Stomach Muscular sacMuscular sac Mixes food, enzymes (pepsin), and Mixes food, enzymes (pepsin), and

HClHCl Protein digestionProtein digestion Mucus is secreted (protective)Mucus is secreted (protective)

Mixing Chyme A thick mixture of food and gastric A thick mixture of food and gastric

fluidfluid High acidity kills many pathogensHigh acidity kills many pathogens Mixed & moved by waves of Mixed & moved by waves of

stomach contractionsstomach contractions peristalsisperistalsis

Protein Digestion in Stomach

High acidity of gastric fluid High acidity of gastric fluid denatures proteins & exposes denatures proteins & exposes peptide bondspeptide bonds

Pepsin breaks proteins into Pepsin breaks proteins into fragmentsfragments

Small Intestine Long coiled tube w/ small diameter Long coiled tube w/ small diameter Contains glands that secrete Contains glands that secrete

digestive enzymesdigestive enzymes Digestion completed hereDigestion completed here Site of nutrient & vitamin Site of nutrient & vitamin

absorption absorption

Structures of Absorption of Nutrients

VilliVilli Finger like projectionsFinger like projections Micro-villiMicro-villi Made of epithelial tissue (one-cell thick)Made of epithelial tissue (one-cell thick) Contain a lacteal ( a lymphatic system Contain a lacteal ( a lymphatic system

vessel) & many capillariesvessel) & many capillaries Fatty acids & glycerolFatty acids & glycerol

Absorbed into lacteal & go to the Absorbed into lacteal & go to the circulatory system via lymphcirculatory system via lymph

Monosaccharides & amino acidsMonosaccharides & amino acids Go to liver via bloodstream.Go to liver via bloodstream.

Large Intestine Short tube w/ wider diameterShort tube w/ wider diameter No digestionNo digestion occurs here occurs here Function is water absorptionFunction is water absorption Moves waste via peristalsisMoves waste via peristalsis

Rectum Lower end of large intestineLower end of large intestine Semi-solid waste (feces) stay here Semi-solid waste (feces) stay here

until egested via the anusuntil egested via the anus

Accessory Organs Salivary GlandsSalivary Glands

Secrete salivaSecrete saliva LiverLiver

Secretes bile (emulsifies fats)Secretes bile (emulsifies fats) GallbladderGallbladder

Stores & secretes bileStores & secretes bile PancreasPancreas

Secretes digestive enzymes to Secretes digestive enzymes to small small intestineintestine

Protease, lipase & amylaseProtease, lipase & amylase

Digestive Enzymes

Site

Mouth

Stomach

Small intestine(from pancreas)

Small intestine

Enzyme Role in Digestion

Section 38-2

Salivary amylase

Pepsin

Amylase

Trypsin

Lipase

Maltase, sucrase, lactase

Peptidase

Breaks down starches into disaccharides

Breaks down proteins into large peptides

Continues the breakdown of starch

Continues the breakdown of protein

Breaks down fat

Breaks down remaining disaccharides into monosaccharides

Breaks down dipeptides into amino acids.