Chapter 41 - Animal Nutrition

Negative feedback

I. Types of Digestion- mechanical & chemical breakdown of food into smaller molecules that can be absorbed by the cells A. intracellular- ◦1. digestion inside a cell ◦2. occurs when a lysosome w/digestive enzymes merges w/ a food vacuole ◦3. ex: paramecium

B. extracellular digestion – ◦1. food digested in a gastrovascular cavity ◦2. then absorbed by individual cells ◦3. most animals use this process

II. Nutrition – determined food need A. Organic cmpds. ◦1. carbohydrates-  a. contain CHO  b. broken down into glucose to be used as a supply of energy  c. ex: sugars, starches

2. lipids – fats ◦a. saturated – all carbons bonded with single bonds, mostly from animals, solid at room temp ◦b. unsaturated – some carbons have double bonds, mostly from plants, liquid at room temp ◦c. used for energy storage, protection, insulation, cell membrane ◦d. broken down into glycerol & fatty acids

3. proteins ◦a. made of amino acids – your body breaks them down into these aa’s & makes new proteins with them ◦b. animal products provide all necessary aa’s ◦c. plant products lack some…(vegans?)

4. nucleid acids – broken down into nucleotides ◦a. nucleotide = sugar, phosphate, & nitrogenous base ◦b. only 2 in the known universe – DNA & RNA

5. vitamins – organic cmpds needed in minute amts to help body use other nutrients appropriately *6. inorganic cmpds – ◦a. minerals –  1) don’t contain carbon  2) needed in minute amts

B. Nutritional requirements 1. Undernourishment: caloric deficiency 2. Overnourishment (obesity): excessive food intake 3. Malnourishment: essential nutrient deficiency 4. Essential nutrients: materials that must be obtained in preassembled form 5. Essential amino acids: the 8 amino acids that must be obtained in the diet 6. Essential fatty acids: unsaturated fatty acids

Nutritional requirements

III. Feeding mechanisms A. Opportunistic ◦1. Herbivore: eat autotrophs ◦2. Carnivore: eat other animals ◦3. Omnivore: both B. Feeding Adaptations ◦1. Suspension-feeders: aka filter feeders - sift food from water (baleen whale) ◦2. Substrate-feeders: live in or on their food (leaf miner) (earthworm: deposit-feeder) ◦3. Fluid-feeders: suck fluids from a host (mosquito) ◦4. Bulk-feeders: eat large pieces of food (most animals)

Suspension, substrate, fluid, or bulk????

IV. Food processing A. overview ◦1-Ingestion: act of eating ◦2-Digestion: process of food break down  a. enzymatic hydrolysis ◦ 1) intracellular: breakdown within cells (sponges) ◦ 2) extracellular: breakdown outside cells (most animals)  b. alimentary canals (digestive tract) ◦3- Absorption: cells take up small molecules ◦4- Elimination: removal of undigested material

B. Mammalian Digestion (human) 1. Mouth--food is masticated in the mouth ◦a. mixed with saliva which contains amylase  1) enzyme that begins the chem breakdown of starch into maltose (disaccharide)  2) food is shaped into a ball or bolus swallowed

2. Pharynx – bolus passes through back of mouth ◦a. uvula raises up to cover opening to nose ◦b. epiglottis drops down to cover top of trachea

3. esophagus – bolus passes through tube leading from mouth to stomach ◦a. peristalsis – muscle action that pushes food through digestive tract

4. stomach – functions ◦a. food is stored – can expand to store 2-4L ◦b. mixes food to produce a mixture called chyme ◦c. physical dig occurs ◦d. produces gastrin (sight, smell, food in stomach) which stimulates cells to produce gastric juices

e. chem digestion occurs ◦1) HCl denatures/unfolds the proteins (& kills bacteria) ◦2) secretes gastric juice – mix of enzymes & HCl ◦3) proteins broken down by pepsin  a) pepsinogen (inactive form of pepsin) produced by stomach cells  b) pepsinogen activated by HCl  c) stomach protected from HCl by mucus lining  d) when mucus lining is “eaten” through – peptic ulcers occur ◦ -caused by bacteria ---treated w/ antibiotics

5. small intestine – bulk of digestion occurs here – 3 sections (duodenum, jejunum, & ileum ◦a. continues digestion of starch & protein ◦b. starts digestion of fats & nucleic acids ◦c. enzymes  1) wall of SI secretes ◦ a) secretes secretin – stimulates the pancreas to produce bicarbonate ◦ b) proteases – digest proteins (ex: aminopeptidase) ◦ c) phosphatases – digests nucleic acids ◦ d) maltase & lactase – digests disaccharides ◦ e) cholecystokinin – stims gallbladder to release bile & pancreas to release enzymes

2) pancreas – secretes enzymes in an alkaline solution to neutralize HCl ◦a) trypsin – protease (break down proteins) ◦b) chymotrypsin – protease ◦c) lipase – fat break down ◦d) pancreatic amylase – starch breakdown

3) liver ◦a) produces bile (alkaline – not an enzyme -- stored in gall bladder) ◦b) bile emulsifies fat – breaks it up into smaller globules so enzymes have a greater surface area to work on 4) villi & microvilli – finger-like projections “fringe” ◦a) increase surface area for absorption of digested materials

4. Large Intestine – reabsorbs water from what’s left over of the “food” to form feces or solid wastes ◦a. feces stored in end of LI, rectum, & pushed out of the body (Valsalva muscle movement) through the anus

V. Evolutionary adaptations A. Dentition: an animal’s assortment of teeth B. Digestive system length C. Symbiosis D. Ruminants