Chapter 41 ~ Animal Nutrition

Nutritional requirements

Undernourishment : caloric deficiency

Overnourishment (obesity): excessive food intake

Malnourishment : essential nutrient deficiency

Essential nutrients : materials that must be obtained in preassembled form

Essential amino acids : the 8 amino acids that must be obtained in the diet

Essential fatty acids : unsaturated fatty acids

Vitamins : organic coenzymes

Minerals : inorganic cofactors

Weight

1 Calorie = amount of energy needed to raise 1 kg of water 1 o C

Calories in ß à Calories out

1 pound of body fat = 3500 Calories

1 g of fat = 9 Calories

1 g of protein/carbohydrate = 4 Calories

Food types/feeding mechanisms

Opportunistic

Herbivore : eat autotrophs

Carnivore : eat other animals

Omnivore : both

Detrivore, frugivore

Feeding Adaptations

Suspension-feeders : sift food from water (baleen whale)

Substrate-feeders : live in or on their food (leaf miner) (earthworm: deposit-feeder)

Fluid-feeders : suck fluids from a host (mosquito)

Bulk-feeders : eat large pieces of food (most animals)

Overview of food processing

1- Ingestion: act of eating

2- Digestion: process of food break down

enzymatic hydrolysis

intracellular : breakdown within cells (sponges)

extracellular : breakdown outside cells (most animals)

alimentary canals (digestive tract)

3- Absorption: cells take up small molecules

4- Elimination: removal of undigested material

Mammalian digestion, I

Peristalsis: rhythmic waves of contraction by smooth muscle

Sphincters: ring-like valves that regulate passage of material

Accessory glands: salivary glands; pancreas; liver; gall bladder

Human Digestive System

Oral cavity

Pharynx: uvula, epiglottis

Esophagus (esophageal sphincter)

Stomach (pyloric sphincter)

Small intestine: duodenum, jejunum, ilium) (ilial-cecal sphincter)

Large intestine: colon, rectum (anal sphincter)

Mammalian digestion, II

Oral cavity •salivary amylase •bolus

Pharynx •epiglottis, uvula

Esophagus

Stomach •gastric juice •pepsin/pepsinogen (HCl) •acid chyme •pyloric sphincter

Mammalian digestion, III

Small intestine •duodenum •bile

Intestinal digestion: a-carbohydrate b-protein c- nucleic acid d-fat

Mammalian digestion, IV

Small intestine Villi / microvilli

Lacteal (lymphatic)

Chylomicrons (fats mixed with cholesterol)

Hepatic portal vessel

Summary: adaptations of small intestine

Parts: duodenum (digestion), jejunum (absorption), ilium (absorption and emptying)

Length: 6 meters (duodenum = 10 inches)

Kinks/folds: direct chyme to absorptive surface

Villi/microvilli: increase absorptive surface area

Brush border enzymes: final digestion occurs on the absorptive surface

Increased blood supply

Lacteals: lymph vessels in villi for absorption of fats.

Mammalian digestion, V

Hormonal Action: allows for separate organs to communicate

Gastrin : food à stomach wall stretch à gastric juice à action

or released by duodenum to stimulate stomach action.

Enterogastrones (duodenum)

1 -Secretin acidic chyme à pancreas to release bicarbonate

2-Cholecystokinin (CCK) amino/fatty acids à pancreas to release enzymes and gall bladder to release bile

Both: slow stomach emptying

Large intestine (colon): compacts wastes /ferments undigested substances, absorbs water and minerals

Cecum: 1 st section of colon, enlarged, esp. in herbivores

Appendix: fights bacteria

Feces: fancy word for poop

Rectum/anus: stores/ eliminates wastes

Evolutionary adaptations

Dentition: an animal’s assortment of teeth

Digestive system length

Symbiosis (termites)

Ruminants

Specific Adaptations

Gastrovascular cavity: Used by cnidarians and flatworms for digestion and circulation

Crop: storage area for food in earthworms, insects, birds

Starfish and spiders: external digestion by secreting digestive enzymes and then ingesting partially digested food.

Generally: Herbivores have grinding teeth, long digestive systems. Carnivores have sharp, cutting teeth and shorter digestive systems.