animal nutrition chapter 41. figure 41.0 animals eating: foal, bear, and stork
TRANSCRIPT
Figure 41.5 Storing protein for growth by increasing muscle mass. Proteins are used for molting (growing new feathers).
Figure 41.2 A ravenous rodent. The obese rat has a defective gene which normally produces an appetite-regulating protein.
DIETARY CATEGORIES
•Herbivores – eat mainly autotrophs
•Carnivores – eat mainly animals
•Omnivores – eat animals, plants,and/or algae
FEEDING MECHANISMS
•Suspension-feeders – sift small food particles from water–clams, oysters, baleen whales
•Substrate-feeders – live in or on their food source, eating their way through the food–Leaf miners (tunnel through leaves)
–Earthworms (more specifically deposit feeders)
FOUR MAIN STAGES OF FOOD PROCESSING
• Ingestion•Digestion
–Enzymatic hydrolysis•Absorption•Elimination
INTRACELLULAR DIGESTION•Food vacuoles fuse with
lysosomes that have hydrolytic enzymes to digest food–Sponges (entirely intracellular digestion)
–Paramecium – oral groove leads to making food vacuole
EXTRACELLULAR DIGESTION
•Breakdown food outside of cells in gastrovascular cavities
•Some have single opening (Incomplete digestive tract)–Cnidarians and flatworms
•Two openings (Complete digestive tract or alimentary canal) – tube with mouth and anus–Most animals–Mouth, pharynx, esophagus, (crop, gizzard), stomach, intestine, and anus
MAMMALIAN DIGESTIVE SYSTEM
•Peristalsis – contraction of smooth muscles in wall of canal
•Sphincters – ring-like valves
•Salivary glands, pancreas, liver, gall bladder
HUMAN DIGESTIVE SYSTEM
•Oral Cavity–Mucin (glycoprotein) – protects soft lining
–Salivary amylase – hydrolyzes starch
–Bolus- food ball that is swallowed
•The Pharynx–Epiglottis (cartilaginous flap)
–Esophageal sphincter contracts, epiglottis up
–Esophageal sphincter relaxed, epiglottis covers trachea, food moves into esophagus
•Stomach–Secretes gastric juice (high amounts of HCl)
–pH is approximately 2–Pepsin (in gastric juice) hydrolyzes proteins•Chief cells secrete inactive pepsinogen
•Parietal cells secrete HCl that converts pepsinogen into pepsin
–Stomach lining replaced every 3 days
–Ulcers normally caused by acid-tolerant bacteria (Helicobacter pylori)
–Churning produces acid chyme–Closed at esophagus end by cardiac orifice
–Closed to small intestine at pyloric sphincter
•Small Intestine –Longest section of canal–Where most absorption occurs
–First 25 cm = duodenum–In duodenum
•digestive juices from pancreas, liver, gall bladder, and gland cells enter
•Pancreas–Produces hydrolytic enzymes and bicarbonate (to reduce acidity)
•Liver–Production of bile (with bile salts) that aids in digestion of fats
•Gall bladder–Stores bile
•Small Intestine (in duodenum)•Carbohydrate digestion
–Pancreatic amylases hydrolyze polysaccharides
•Protein Digestion–Trypsin and Chymotrypsin break bonds between certain amino acids
–Carboxypeptidase splits off one amino acid at a time at carboxyl end
–Aminopeptidase chops off one amino acid at amino end
–Dipeptidase, enteropeptidase also involved
•Fat digestion–Fat insoluble in water–Bile salts emulsify fat droplets to keep them from coalescing
–Lipase hydrolyzes fat•Nucleic acid digestion
–Nucleases
– Absorption of nutrients (mostly in jejunum and ileum)
– Increased surface area by villi and microvilli
– Each villi contains capillaries and lacteal (small lymphatic vessel); each only one cell thick
– Nutrients move via diffusion and active transport
– Fats move into lacteal– All other nutrients empty into
capillaries and eventually move into hepatic vessel to liver
•Large Intestine (colon) –Connected to small intestine at T-shaped junction•One arm is cecum that leads to appendix in humans
•Other arm is the colon–Reabsorbs water–Leftover waste is feces–Feces stored in rectum and released through anus
–E. coli in colon
EVOLUTIONARY ADAPTIONS
•Teeth vary according to what the animal eats–Fangs, incisors, canines, “grinders”
•Herbivores and omnivores longer alimentary canals than carnivores due to cellulose digestion
•Special chambers to digest cellulose with help of prokaryotes and some protists –Ruminants (examples: cattle and sheep)