Post on 13-Jan-2016
transcript
Digestive SystemDigestive System
I’m from Chiquita banana & I’m here to I’m from Chiquita banana & I’m here to say,say,
I’ve got a recipe for you today.I’ve got a recipe for you today.
You take a banana & you shove it down,You take a banana & you shove it down,
You wait a few minutes & it comes out You wait a few minutes & it comes out brown!brown!
http://www.gastrohttp://www.gastrolab.net/s92enjog.lab.net/s92enjog.htmhtmLet’s Tour The Let’s Tour The
Digestive System!Digestive System!
William BeaumontWilliam BeaumontFather of Gastric Father of Gastric
PhysiologyPhysiology Surgeon’s mate in US Surgeon’s mate in US
Army during War of Army during War of 18121812
Later observed musket Later observed musket wound in Alexis St. wound in Alexis St. Martin’s stomachMartin’s stomach Wound would not healWound would not heal Beaumont dangled food Beaumont dangled food
thru hole using stringthru hole using string 11stst person to observe person to observe
digestion in stomachdigestion in stomach Conclusions about Conclusions about
nature of gastric juice, nature of gastric juice, & observations of & observations of chemical digestionchemical digestion
http://www.james.com/bhttp://www.james.com/beaumont/dr_life.htmeaumont/dr_life.htm
Nutritional RequirementsNutritional Requirements All animals oxidize All animals oxidize
organic molecules in organic molecules in order to provide ATP for order to provide ATP for life processeslife processes Glucose is main fuel, but Glucose is main fuel, but
body may also use lipids & body may also use lipids & proteins-all under hormonal proteins-all under hormonal controlcontrol
Essential nutrients-Essential nutrients-organism cannot make, organism cannot make, must be taken in with must be taken in with foodfood Include amino acids, fatty Include amino acids, fatty
acids, vitamins (organic) & acids, vitamins (organic) & minerals (inorganic)minerals (inorganic)
Too few Too few calories=undernourishmecalories=undernourishmentnt
Too few essential Too few essential nutrients-malnourishmentnutrients-malnourishment
Feeding MechanismsFeeding Mechanisms Herbivores, Herbivores,
carnivores, omnivorescarnivores, omnivores Suspension feedersSuspension feeders
Sift from waterSift from water Substrate feedersSubstrate feeders
Live on or in food Live on or in food source, eat their way source, eat their way through itthrough it
Fluid feedersFluid feeders Suck nutrients from Suck nutrients from
host body fluidhost body fluid Bulk feedersBulk feeders
Eat relatively large Eat relatively large pieces of foodpieces of food
Stages of Food processingStages of Food processing Ingestion-chemical & Ingestion-chemical &
physicalphysical Mouth,teethMouth,teeth
Digestion-mechanical & Digestion-mechanical & chemicalchemical Breakdown food into Breakdown food into
smaller particlessmaller particles Saliva, gastric juice, Saliva, gastric juice,
accessory glands, teeth, accessory glands, teeth, peristalsisperistalsis
Absorption-keeping the Absorption-keeping the good stuffgood stuff Mainly sm. Intestine, water Mainly sm. Intestine, water
in colonin colon Elimination-getting rid of Elimination-getting rid of
the bad stuff, or excessthe bad stuff, or excess
Intracellular Intracellular digestiondigestion
Food broken down Food broken down in vacuoles, fused in vacuoles, fused w/ lysosomesw/ lysosomes
Heterotrophic Heterotrophic protists & spongesprotists & sponges
Extracellular digestionExtracellular digestion Food broken down Food broken down
outside cells in outside cells in compartments compartments continuous w/ the continuous w/ the outside environmentoutside environment gastrovascular gastrovascular
cavities(incomplete)-cavities(incomplete)-single openings, function single openings, function in digestion & in digestion & distributiondistribution
Alimentary canals Alimentary canals (complete)-2 openings(complete)-2 openings
More specialized, better More specialized, better isolation of enzymes, isolation of enzymes, ability to digest more ability to digest more food even if previous food even if previous food remains undigestedfood remains undigested
Comparative AnatomyComparative Anatomy
Crops-food storage(stomach)Gizzards-grind & fragment
Mammalian SystemMammalian System Breaks down food chemically & Breaks down food chemically &
physically/mechanicallyphysically/mechanically Mammalian digestive system is a complete Mammalian digestive system is a complete
system (alimentary canal)system (alimentary canal) Food only travels through one way(normally)Food only travels through one way(normally) Has 2 openings to external environment(mouth & Has 2 openings to external environment(mouth &
anus)anus) Vulnerable to outside pathogensVulnerable to outside pathogens
Digestive tract is completely isolated from the rest Digestive tract is completely isolated from the rest of the bodyof the body
Digestive enzymes can be isolatedDigestive enzymes can be isolated Toxins are kept away from rest of bodyToxins are kept away from rest of body
PeristalsisPeristalsis Smooth muscle along entire digestive tract Smooth muscle along entire digestive tract
contracts to move foodcontracts to move food
Pathway of FoodPathway of Food Oral cavity-mechanical & chemicalOral cavity-mechanical & chemical
Mastication-chewing-increases surface area for enzymesMastication-chewing-increases surface area for enzymes SalivaSaliva
Mucin-protects mouth & lubricatesMucin-protects mouth & lubricates Buffers-neutralize acid, prevent tooth decayBuffers-neutralize acid, prevent tooth decay Salivary amylase-hydrolyzes starch & glycogenSalivary amylase-hydrolyzes starch & glycogen
Tongue- tastes, shapes into bolus, pushes backTongue- tastes, shapes into bolus, pushes back Pharynx-intersection of digestive & respiratory systemsPharynx-intersection of digestive & respiratory systems
Epiglottis-cartilaginous flap that covers opening to trachea(glottis) Epiglottis-cartilaginous flap that covers opening to trachea(glottis) during swallowingduring swallowing
Esophagus-chemical digestion continues(salivary amylase)Esophagus-chemical digestion continues(salivary amylase) Top part contains voluntary, striated muscle, bottom has Top part contains voluntary, striated muscle, bottom has
smooth, involuntarysmooth, involuntary
Pathway of FoodPathway of Food Stomach-mechanical & chemicalStomach-mechanical & chemical
3 muscle layers contract to 3 muscle layers contract to break up food(longitudinal, break up food(longitudinal, vertical, diagonal)vertical, diagonal)
Cardiac sphincter-between Cardiac sphincter-between esophagus & stomachesophagus & stomach
Gastric juice-secreted by Gastric juice-secreted by epithelial cellsepithelial cells
HCL-disrupts ECM to break HCL-disrupts ECM to break up plant & animal tissue, kills up plant & animal tissue, kills bacteriabacteria
Pepsin-protein hydrolysisPepsin-protein hydrolysis Mucus-protects lining from Mucus-protects lining from
HCLHCL End product of stomach End product of stomach
process results in a mixture process results in a mixture called acid chymecalled acid chyme
Cells of stomach liningCells of stomach lining Mucus cells-mucin & gastrinMucus cells-mucin & gastrin Chief cells-Chief cells-
pepsinogen(inactive) pepsinogen(inactive) converted to pepsin by HCLconverted to pepsin by HCL
Parietal cells-HCLParietal cells-HCL Pyloric sphincter-between Pyloric sphincter-between
stomach & small intestinestomach & small intestine
ulcer
Pathway of FoodPathway of Food
Small intestine-21 ft longSmall intestine-21 ft long Major site of digestion(duodenum) & absorption (jejunum & ileum)Major site of digestion(duodenum) & absorption (jejunum & ileum) Structure(see fig. 41.15)Structure(see fig. 41.15)
Villi & microvilli increase surface area for absorptionVilli & microvilli increase surface area for absorption Capillary & lacteal in each villiCapillary & lacteal in each villi
Duodenum-1Duodenum-1stst 25cm 25cm Functions in breakdown of lipids, CBH, & proteins-most Functions in breakdown of lipids, CBH, & proteins-most
digestion takes place heredigestion takes place here Secretes its own enzymes, & also receives enzymes from Secretes its own enzymes, & also receives enzymes from
accessory glandsaccessory glands Jejunum & ileum-function in absorbing nutrients-diffusion & Jejunum & ileum-function in absorbing nutrients-diffusion &
active transportactive transport All capillaries from small intestine pass into hepatic portal vein All capillaries from small intestine pass into hepatic portal vein
& go to liver before anywhere else!!& go to liver before anywhere else!!
Pathway of FoodPathway of Food Colon/large intestineColon/large intestine
Ascending, transverse, Ascending, transverse, descendingdescending
Cells absorb water back Cells absorb water back into body, and produce into body, and produce mucus to lubricatemucus to lubricate
Contains high amount of Contains high amount of bacteria to aid in bacteria to aid in digestiondigestion
Appendix-remnant of Appendix-remnant of large cecum in large cecum in herbivoresherbivores
Rectum-stores feces Rectum-stores feces before eliminationbefore elimination
Anus-Anus- 2 sphincter muscles-1 2 sphincter muscles-1
voluntary, 1 involuntaryvoluntary, 1 involuntary
Enzymatic DigestionEnzymatic Digestion
Accessory OrgansAccessory Organs PancreasPancreas
Secretes enzymes into sm. Int., regulates Secretes enzymes into sm. Int., regulates blood sugarblood sugar
Gall bladderGall bladder Stores liver secretions (bile) for fat Stores liver secretions (bile) for fat
digestiondigestion Secretes into duodenumSecretes into duodenum
LiverLiver Produces bile salts, regulates cholesterol, Produces bile salts, regulates cholesterol,
stores fat soluble vitamins, breaks down Hb stores fat soluble vitamins, breaks down Hb into bilirubin, regulates blood sugarinto bilirubin, regulates blood sugar
Digestive HormonesDigestive Hormones
GastrinGastrin Secreted by cells of stomach wallSecreted by cells of stomach wall Stimulates gastric juiceStimulates gastric juice
SecretinSecretin Cells of duodenumCells of duodenum Stimulates pancreas to release Stimulates pancreas to release
bicarbonatebicarbonate CholecystokininCholecystokinin
Cells of duodenumCells of duodenum Causes gall bladder to release bileCauses gall bladder to release bile