ch 40, 39, + ecology
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4 main stages of food processing
• ingestion • digestion • absorption • elimination
can animals use macromolecs in their polymer state?
no; must be broken down into monomers first
digestion
the process of breaking down food into molecs small enough to be absorbed
monomers
fuel for ATP prod or for biosynth
what does mechanical fragmentation do?
incs SA for digestive enzymes
food vacoules
organelles in which hydrolytic enzymes break down food (intracellular digestion)
what is one advantage of having extracellular digestion?
much larger food than by phagocytosis
what groups do not have complete digestive tracts (2)?
cnidaria, platy’s
complete digestive tract (3)
• mouth • digestive tube • anus
crop/stomach
storage & preliminary digestion
gizzard
grinding
intestine
absorption of nutrients into blood
what does a complete digestive tract enable?
ingestion of additional food before earlier meals are completely digested
peristalsis
rhythmic waves of contraction by smooth muscles in gut wall push food along
sphincters
muscular ring-like valves that regulate passage of material btwn specialized chambers
4 accessory glands
• gall bladder • liver • pancreas • salivary glands
what does saliva lubricate food with?
a glycoprotein (mucin) + salivary amylase
what does salivary amylase do?
hydrolyzes starch and glycogen into smaller polysaccharides
tongue
tastes, manipulates, shapes food into a bolus
pharynx opens to both
• esophagus - trachea
epiglottis
a cartilaginous flap that blocks the glottis when swallowing
rugae
accordion-like folds in the stomach that stretch to accommodate food
what does the stomach secrete and for what?
gastric juices to churn
what is the pH of the gastric juices in your stomach
2