digestion Flashcards
suspension feeders
filter feeders
-eat floating microscopic particles consisting of plankton and organic debris
-use ciliated surfaces to draw drifting food into mouth
-trap food on mucous sheets that convey food to digestive tract
-sweeping movements
deposit feeders
extract organic material or debris from substrate
deposit feeders annelids and hemichordates deposit feeders:
pass substrate through bodies as they move and remove nutrients
mulluscs and tube dwelling annelids deposit feeders:
use apendages
fluid feeders
-common in parasites
-internal parasites: absorb nutrients around them through their integument
-external parasites: pierce or rasp tissues of the host to access blood
feeding on food masses
predators locate, capture, hold, and swallow prey
predators use ___ and ___ to seize prey
jaws and teeth
mammals use ___ mastication
true
incisors
bite, cut, strip food
canines
seize, pierce and tear food
premolars and molars
grind and crush
mechanical and chemical digestion breaks down food into small units for absorption for cells
example: carbs, proteins, etc into monomers
intracellular digestion is present in
sponges and protozoa
describe the processes of intracellular digestion
-only small foods
-food particles are phagocytized
-lysosomes with digestive enzymes fuse with food vacuoles
-usable products are absorbed into cyto
-undigestible wastes exit through exocytosis
extracellular digestion uses ___
alimentary system: specialized lining of cells for digestion and absorption
extracellular digestion relies on digestive enzymes that use ___
hydrolysis
what are the alimentary canal stages
-reception
-conduction and storage
-grinding and early digestion
-terminal digestion
-water absorption and conc. of solids
reception
-mouthparts: jaws, teeth, radula, bills
-inner chamber: buccal cavity and pharynx
-salivary glands: produce lubricating secretions. can also produce digestive enzymes, toxins, anesthetics, and anticoagulants
conduction
-structure: esophagus; leads from pharynx to stomach
-uses peristalsis: propels food by rhythmic smooth muscular contraction
storage in vertebrates
stomach except birds
storage in insects, birds, annelids, octopods
esophagus expands to a crop; food storage area
-birds: softens grain and allows mild fermentation
grinding and early digestion
-vertebrates and some invertebrate stomach: region for initial digestion and storage of food. secrete acidic gastric juices for extracellular digestion
-herbivores: continue grinding and crushing plants in stomach
-oligochaetes and birds: swallowed stones and grit assist muscular gizzard
terminal digestion and absorption
place: small intestines
-cells of small intestines: have digestive enzymes embedded as transmembrane proteins- absorbed by villi
water absorption and concentration of solids
-large intestine: turns undigested material as semisolid feces
-insects: need reabsorption of water- have specialized rectal glands that absorb water and ions leaving dry fecal pellets
-reptiles and birds: most water is reabsorbed in cloaca- leaving paste like feces
-adult humans: 1/3 of feces is bacteria; plays a role on degrading organic wastes and providing vitamins
