Post on 18-Jan-2018
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Digestion: Obtaining & Digestion: Obtaining & Processing FoodProcessing Food
Herbivores = plant-eatersHerbivores = plant-eaters Carnivores = meat-eatersCarnivores = meat-eaters Omnivores = both plants and other Omnivores = both plants and other
animalsanimals
Digestion: Obtaining FoodDigestion: Obtaining FoodSolid foods Filtering from water
substrate feeders
fluid feeders
Digestion: 4 StagesDigestion: 4 Stages
DigestionDigestion Mechanical Breakdown: Mechanical Breakdown:
Physically breaking food apart (teeth, Physically breaking food apart (teeth, tongue, stomach, etc)tongue, stomach, etc)
Chemical Breakdown:Chemical Breakdown: enzymes and secretions to break down enzymes and secretions to break down
chemicallychemically
Digestion: Chemical Digestion: Chemical BreakdownBreakdown
Digestion: ProtozoansDigestion: Protozoans Intracellular digestion with oral Intracellular digestion with oral
groove or phagocytosisgroove or phagocytosis
DigestionDigestion Gastrovascular cavity vs specialized Gastrovascular cavity vs specialized
digestive tractdigestive tract Gastrovascular cavity: one openingGastrovascular cavity: one opening cnidarian & flatwormscnidarian & flatworms
Digestion: Alimentary CanalDigestion: Alimentary Canal Most have Most have alimentary alimentary
canalcanal Tube running from Tube running from
mouth to anusmouth to anus divided into divided into
specialized regions specialized regions that process food that process food sequentiallysequentially
Crop: stores foodCrop: stores food Gizzard: grinds food Gizzard: grinds food
(especially if no jaws (especially if no jaws or teeth)or teeth)
Digestion: HumanDigestion: Human Alimentary Canal vs Accessory Alimentary Canal vs Accessory
OrgansOrgans
Digestion: HumanDigestion: Human Alimentary CanalAlimentary Canal
mouth, esophagus, mouth, esophagus, stomach, small stomach, small intestines, large intestines, large intestines, rectum, intestines, rectum, anusanus
Accessory OrgansAccessory Organssalivary glands, salivary glands, liver, gall bladder, liver, gall bladder, pancreaspancreas
Digestion: MouthDigestion: Mouth Mechanical DigestionMechanical Digestion
Teeth, tongueTeeth, tongue Chemical DigestionChemical Digestion
Saliva moistens itSaliva moistens it Salivary enzymes Salivary enzymes amylaseamylase begin breakdown of begin breakdown of
starchstarch Tongue pushes the chewed food into the Tongue pushes the chewed food into the
pharynxpharynx
Digestion: EsophagusDigestion: Esophagus PeristalsisPeristalsis: :
muscle muscle contractions contractions pushing down pushing down bolusbolus (food) (food)
Digestion: StomachDigestion: Stomach
Digestion: StomachDigestion: Stomach Stomach mixes food with gastric juice from Stomach mixes food with gastric juice from
gastric glandsgastric glands Gastric glands – make HCl, pepsinogen, Gastric glands – make HCl, pepsinogen,
mucousmucous HCl activates HCl activates pepsinogenpepsinogen (inactive enzyme) to form (inactive enzyme) to form
pepsinpepsin (enzyme to breakdown protein) (enzyme to breakdown protein) HCl also kills germsHCl also kills germs Mucous – lines & protects stomach wallsMucous – lines & protects stomach walls
ChymeChyme (partially digested food) enters (partially digested food) enters duodenumduodenum (beginning of small intestines via (beginning of small intestines via pyloric sphincterpyloric sphincter
Digestion: Small IntestinesDigestion: Small Intestines
Digestion: Digestion: Small Intestine / Small Intestine / Pancreas / Liver / Gall BladderPancreas / Liver / Gall Bladder
Most of chemical digestion and absorption take Most of chemical digestion and absorption take place in small intestinesplace in small intestines
PancreasPancreas Makes bicarbonate (HCOMakes bicarbonate (HCO33
--), base that neutralizes ), base that neutralizes stomach acidstomach acid
Pancreatic enzymes digest polysaccharides, proteins, Pancreatic enzymes digest polysaccharides, proteins, nucleic acids, and fatsnucleic acids, and fats
BileBile (made in liver, stored in gall bladder) (made in liver, stored in gall bladder) emulsifiesemulsifies (mechanical breakdown) fat droplets (mechanical breakdown) fat droplets for attack by pancreatic for attack by pancreatic lipaselipase
TrypsinTrypsin breaks down protein in base environment breaks down protein in base environment
Digestion: Small IntestineDigestion: Small Intestine Absorption by Absorption by villi villi
Digestion: Large IntestinesDigestion: Large Intestines Absorption of Absorption of
waterwater E Coli live in LI, E Coli live in LI,
make Vitamin Kmake Vitamin K Undigested Undigested
material = material = fecesfeces
Digestion: Digestion: Evolutionary AdaptationsEvolutionary Adaptations
Plant harder Plant harder to digest to digest than meat than meat because of because of cellulosecellulose
Herbivores Herbivores have longer have longer digestive digestive tracttract
DigestionDigestion Cows have 4 stomach chambers to Cows have 4 stomach chambers to
break down cellulosebreak down cellulose