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Chapter 41Animal Nutrition

Kaia Morrow, Jeff Cooper, Kat Malek and Zoë Atlas

Glucose Regulation• Energy is stored as

glycogen, which can be secreted if needed

• Insulin decreases blood glucose

• Glucagon increases blood glucose

• Glucose regulation is maintained by a negative feedback mechanism

Deficiency Diseases

• Malnutrition - lack of essential nutrients

Ex. The protein deficiency Kwashiorkor causes the swelling of the belly because blood cannot absorb as much water from the body cavity through osmosis because of the lack of blood proteins

• Undernourishment - calorie deficiency that can lead to starvation and death

Essential Nutrients - Proteins, Carbohydrates and Lipids

• Proteins - broken down and used as fuel

• Carbohydrates - oxidized for the generation of ATP, energy-rich, organic

• Lipids - provide ATP when oxidized during cellular respiration, energy-rich, organic, stores energy in the form of glycogen

Essential Nutrients - Vitamins and Water

• Vitamins - organic molecules, necessary in small amounts (0.01 to 100 mg/day), have diverse physiological functions

• Water - used by water-soluble vitamins that function as coenzymes in metabolic processes

Essential Nutrients - Minerals

• Minerals - inorganic compounds, required in small amounts (less than 1 to 2,500 mg/day)

Essential Amino Acids

• Amino acids are required to make proteins

• Essential amino acids cannot be synthesized by the body, so they must be consumed though diet

Modes of Heterotrophic Nutrition

• Carnivores - eat meat• Herbivore - eat

vegetation• Omnivores - eat both

meat and vegetation

Four Main Stages of Food Processing

• Ingestion - the act of eating• Digestion - the act of breaking

up food into molecules small enough for the body to absorb

• Absorption - animal cells take up small molecules such as amino acids and simple sugars from the digestive compartment

• Elimination - wastes are eliminated from the body

Intracellular Digestion

• Food particles are taken in by endocytosis and digested inside of food vacuoles

• Occurs safely within a compartment that is enclosed by a membrane

food vacuole

Food Vacuoles

• Simplest digestive compartment

• Used by heterotrophic protists

• Fuse with lysosomes

Extracellular Digestion

• In extracellular digestion, Hydrolysis occurs outside of cells (in an alimentary canal or gastrovascular cavity)

• Advantage - it allows an animal to digest larger prey than can be intracellularly digested

Adaptive Value of the Alimentary Canal

• The alimentary canal moves food one way down the canal and can be organized into special regions for digestion

Changes to Food in the Mouth

• Bacteria is killed by the saliva in the mouth

• Food shape

changes and

becomes a

bolus

Oral Cavity, Pharynx, and Esophagus

• Lubricate food and begin digestion

• Carry food into the stomach through peristalsis

• Salivary amylase breaks down food for preparation of full digestion

Stomach• Churns and digests food

with hydrochloric acid and the enzyme pepsin

• Porous walls of stomach secrete hydrochloric acid and pepsin to digest food

• Walls of the stomach are coated with mucus to protect them from gastric juices

Secretions of the Duodenum

• Acid chyme from the stomach is combined with digestive juices fromthe pancreas, gallbladder, liver, and gland cells of the intestinal wall

• Hydrolytic enzymes from the pancreas are activated in the duodenum

• Bile is produced by the liver and secreted into the duodenum, aiding in fat digestion

• Digestive enzymes enter the duodenum from the epithelial lining

Pancreas Peptidases

• The pancreas prevents digesting itself by producing enzymes and bicarbonate-rich solutions

• Bicarbonate is a buffer that offsets the enzyme’s acidity, and allows their secretion in an inactive form

• Once in the intestine, the enzymes are activated

Human Digestive System

Location of Carbohydrate, Protein, Nucleic Acid, and Fat Digestion

• Carbohydrates- oral cavity, pharynx, esophagus, lumen of small intestine, epithelium of small intestine

• Protein – stomach, lumen of small intestine, epithelium of small intestine

• Nucleic Acid – lumen and epithelium of small intestine

• Fat – lumen of small intestine

Small Intestine and Features that Improve Its

Function• Major organ of digestion and

absorption• The brush border, or epithelial lining

of the duodenum, provides many digestive enzymes

• Microvilli increase the surface area and rate of nutrient absorption

• Lacteals are vessels of villi that carry lymph and absorb nutrients, putting them into the bloodstream

• The hepatic portal vein leads directly to the liver, ensuring that it is supplied with the nutrients absorbed in the small intestine

Roles of Gastrin, Secretin, and Cholecystokinin

• Gastrin - begins gastric juice production• Secretin - discharge into the filtrate from wastes of the body• Cholecystokinin -

Causesdigestive enzyme release

Large Intestine

• Functions as a home for vitamin-synthesizing bacteria

• Aids in the absorption of water

Dental Adaptations

• Dentistry of

mammals is usually

specialized for their

diet

Stomach and Intestinal Adaptations of Herbivores

• As vegetation has cell walls that are difficult to digest, herbivores have longer alimentary canals than carnivores

• Many herbivores have fermentation chambers specialized for cellulose digestion