Selling an Idea or a Product

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The Insect Digestive System
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The Insect Digestive System I. Alimentary
System
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Insect gut has 3 regions
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The Insect Digestive System I. Alimentary
System A. Foregut stomadaeum -- lined
with intima (endocuticle epicuticle) --
little digestion occurs here
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The Insect Digestive System I. Alimentary
System A. Foregut stomadaeum crop
-- storage -- may have diverticula
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The Insect Digestive System I. Alimentary
System A. Foregut stomadaeum
proventriculus -- often has spines or
teeth (denticles) -- grinding
(gizzard-like function) -- sorting (ex
honey bee)
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Honey Bee Crop
proventriculus
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The Insect Digestive System I. Alimentary
System A. Foregut stomadaeum stomodael
valve
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• The Insect Digestive System
• I. Alimentary System
• A. Foregut
• salivary glands
• -- moisten food
• -- digestive enzymes
• amylase invertase
• extra-intestinal digestion

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The Insect Digestive System I. Alimentary
System A. Foregut salivary glands --
toxins -- anticoagulants
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The Insect Digestive System I. Alimentary
System A. Foregut salivary glands --
silk secretion (spinnerets labium, hypopharynx,
maxilla)
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The Insect Digestive System I. Alimentary
System B. Midgut -- site of digestion and
absorption -- not lined with intima 1.
structure a. gastric caeca b.
ventriculus
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midgut epithelium
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The Insect Digestive System I. Alimentary
System B. Midgut 1. structure c.
Midgut epithelium 1) columnar digestive
cells
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Columnar digestive cell
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The Insect Digestive System I. Alimentary
System B. Midgut 1. structure c.
midgut epithelium 1) columnar digestive
cells 2) regenerative cells 3)
endocrine cells
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The Insect Digestive System I. Alimentary
System B. Midgut 1. structure d.
peritrophic membrane
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The Insect Digestive System I. Alimentary
System B. Midgut 1. structure d.
peritrophic membrane
midgut epithelium
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The Insect Digestive System I. Alimentary
System B. Midgut 2. digestion a.
Functions of peritrophic membrane 1)
compartmentalization of gut
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Compartmentalization of midgut
gastric caecum
peritrophic membrane
ectoperitrophic space
endoperitrophic space
esophagus
crop
Midgut (ventriculus)
stomodael valve
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The Insect Digestive System I. Alimentary
System B. Midgut 2. digestion a.
Functions of peritrophic membrane 1)
compartmentalization of gut -- digestion
begins in endoperitrophic space -- products
move into ectoperitrophic space and
digestion is completed
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The Insect Digestive System I. Alimentary
System B. Midgut 2. digestion a.
Functions of peritrophic membrane 2)
maintenance of countercurrent flow
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Countercurrent flow in midgut
H2O
solutes solutes solutes solutes
H2O
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The Insect Digestive System I. Alimentary
System B. Midgut 2. digestion a.
Functions of peritrophic membrane 3) barrier
to pathogens
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The Insect Digestive System I. Alimentary
System B. Midgut 2. digestion b.
microvilli final site of digestion
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The Insect Digestive System I. Alimentary
System B. Midgut 2. digestion c.
digestive enzymes -- proteases --
lipases -- cellulase -- wax digestion

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Digestion of wax Galleria mellonella
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The Insect Digestive System I. Alimentary
System B. Midgut 3. Absorption
a. Food types 1) monosaccharides (glucose
fructose) diffusion 2) lipids diffusion,
esp. gastric caeca 3) amino acids active
transport 4) plant xenobiotics ex
monarch caterpillar and cardenolides
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Monarch caterpillar and adult
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(No Transcript)
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The Insect Digestive System I. Alimentary
System B. Midgut 3. Absorption
b. mechanisms for absorption 1) maintenance
of diffusion gradients glucose fructose ?
trehalose
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The Insect Digestive System I. Alimentary
System B. Midgut 3. Absorption
b. mechanisms for absorption 2) active
transport of Na
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Na
Na
Na
Na
(impermeable to Na)
Na
Na
Na
Na
H20
H20
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The Insect Digestive System I. Alimentary
System C. Hindgut -- has intima
permeable -- little or no digestion 1.
structure
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The Insect Digestive System I. Alimentary
System C. Hindgut 1. structure a.
pylorus c. Intestines e. anus
b. Malpighian tubules d. rectum
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The Insect Digestive System I. Alimentary
System C. Hindgut
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The Insect Digestive System I. Alimentary
System C. Hindgut 2. functions
-- homeostasis -- pheromone production

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The Insect Digestive System I. Alimentary
System C. Hindgut 2. functions --
pheromone production
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The Insect Digestive System I. Alimentary
System C. Hindgut 2. functions --
respiration
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The Insect Digestive System I. Alimentary
System C. Hindgut 2. functions --
house microorganisms Isoptera

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The Insect Digestive System I. Alimentary
System C. Hindgut 2. functions --
defense Bombardier beetle
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The Insect Digestive System II. Regulation of
Digestion A. Nervous control (review
previous notes) -- stomatogastric nervous
system (foregut) -- caudal nervous system
(hindgut) -- midgut has little nervous
innervation B. Hormonal regulation

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The Insect Digestive System III. Specialized
feeding niches A. Phytophagus insects 1.
mandibulate mouthparts -- plant toxins
protease inhibitors -- xenobiotics

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The Insect Digestive System III. Specialized
feeding niches A. Phytophagus insects 2.
haustellate mouthparts plant fluid feeders

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The Insect Digestive System III. Specialized
feeding niches A. Phytophagus insects 2.
haustellate mouthparts plant fluid
feeders -- ingest vast quantities of
fluid -- have cibarial or pharyngeal pump
-- have filter chamber in
esophagus -- produce honey dew

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Aphid honey dew on wheat plant
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The Insect Digestive System III. Specialized
feeding niches A. Phytophagus insects 2.
plant fluid feeders honeydew
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The Insect Digestive System III. Specialized
feeding niches B. hematophagus insects --
anticoagulant apyrase
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The Insect Digestive System III. Specialized
feeding niches C. Wood feeders

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The Insect Digestive System
Trichonympha
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The Insect Digestive System