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Chapter 41 Animal Nutrition. Types of Feeders. Suspension feeders sift through water to obtain small food particles Fluid feeders suck nutrients from a host Substrate feeders live on their food sources Bulk feeders eat large pieces of food. Nutritional Needs.
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Types of Feeders • Suspension feeders sift through water to obtain small food particles • Fluid feeders suck nutrients from a host • Substrate feeders live on their food sources • Bulk feeders eat large pieces of food
To function properly an animal needs to consume… • Fuel. • Organic raw materials for biosynthesis. • Essential nutrients which can’t be synthesized through biosynthesis.
Fuel • Animals synthesize ATP from other fuel sources and use ATP to power many bodily functions. • Animals oxidize carbohydrates, fats, and proteins in that order as fuel for ATP synthesis. • Severe situations regarding fuel consumption are… • Undernourishment, a prolonged caloric deficit. • Overnourishment (obesity), a prolongued surplus of fat in a diet
Raw Organic Materials • An Animal needs to synthesize complex chemicals needed to function. This is called biosynthesis. • Carbon skeletons and sources of organic nitrogen are necessary to synthesize these molecules • These are readily available in the environment
Essential Nutrients • Essential Nutrients are important to bodily function but cannot be synthesized by the animal. An animal’s diet must provide these. • Essential amino acids: 8 different monomers necessary for protein synthesis • Essential fatty acids: Certain unsaturated fatty acids. • Vitamins: 13 different organic molecules which have a wide array of bodily uses. They can be either water soluble or fat soluble. • Minerals: Inorganic compounds • Malnutrition arises when an animal lacks essential nutrients.
Regulation • Glucose Regulation is controlled by the antagonistic hormones insulin and glucagon. • Insulin: Stimulates blood glucose levels to drop • Glucagon: Stimulates blood glucose levels to rise • Hunger Regulation is controlled by four hormones • Leptin, Insulin, and PYY suppress appetite • Ghrelin increases appetite
Food Processing • Step 1: Ingestion of nutrients • Step 2: Digestion of macromolecules • Step 3: Absorption of monomers • Step 4: Elimination of undigested waste
Types of Digestion • Intracellular digestion occurs when food is digested in the vacuoles of cells • Extracellular digestion occurs when some food is digested in designated cavities outside of cells. • There are two types of digestive cavities • The gastrovascular cavity is a sac with a single opening • The complete digestive tract (alimentary canal) has two openings. Food only moves in one direction. This cavity contains more specialized compartments for digestion. • Hydrolytic Enzymes break down polymers and are used in all types of digestion
The Oral Cavity, Pharynx, and Esophagus • During chewing in the oral cavity, salivary amylase helps break down carbohydrates • After chewing the tongue shapes the food into a bolus • The food is swallowed into the Pharynx (throat) next • The Pharynx opens to the trachea and esophagus • The epiglottis covers the trachea when swallowing • Peristalsis (rhythmic smooth muscle contraction) moves the food down the esophagus
The Stomach • A sphincter called the cardiac orifice regulates entrance to the stomach. • The stomach secretes gastric juice. • This mixes with the food to form acid chyme. • The acidity of the gastric juice activates the hydrolytic enzyme pepsin • The pyloric sphincter regulates flow of acid chyme into the small intestine
The Small Intestine • The first 25 cm of this is the duodenum. In the duodenum… • Juices from the Pancreas buffer the acid chyme. • The liver secretes bile salts to help digest fats • The epithelium contains and secretes hydrolytic enzymes • Structures in the epithelium called villi and their appendages called microvilli help absorb nutrients • In the villi are capillary beds and lacteals from the circulatory and lymphatic systems respectively • The lacteals drain into larger lymphatic vessels • The capillary beds drain into the hepatic portal vein of the liver
The Large Intestine (Colon) • A sphincter in a T-shaped junction controls the entrance into the Large Intestine • The colon reabsorbs most of the water which the small intestine left in the mixture • Undigested material moves through the colon by way of peristalsis into the rectum • The undigested material is now known as feces and is soon discarded
Evolutionary Adaptations to the Digestive System • Carnivores have developed sharper teeth while herbivores have developed broader and more rigid teeth • Herbivores have developed longer digestive tracts • Herbivores have developed symbiotic relationships with bacteria that digest cellulose