Chapter 41: Animal Nutrition

Overview

• Animal Nutrition: Involves taking in food, breaking it down, absorbing nutrients, and eliminating waste.
• Three types of animals based on diet:
  • Herbivores
  • Carnivores
  • Omnivores

Nutritional Requirements

• Dietary Needs:
  • Energy: Converted to ATP.
  • Building Blocks: For macromolecules.
  • Nutrients: Assist in chemical reactions; includes essential amino acids, fatty acids, vitamins, and minerals.

Essential Nutrients

• Amino Acids:
  • 20 types; half can be synthesized, the rest must be ingested.
  • Meat, eggs, cheese provide complete proteins.
• Fatty Acids:
  • Animals synthesize some, must obtain unsaturated fatty acids from diet.
• Vitamins:
  • 13 types; fat-soluble and water-soluble.
• Minerals:
  • Trace elements essential for health, e.g., iron.

Malnutrition

• Malnourishment: Missing essential nutrients.
• Undernutrition: Not enough energy intake, leading to depletion of body reserves.

Food Processing Stages

1. Ingestion: Taking in food.
2. Digestion:
   • Mechanical: Increases surface area.
   • Chemical: Enzymatic breakdown.
3. Absorption: Nutrients absorbed into body.
4. Elimination: Removal of waste.

Digestive Systems

• Compartments: Specialized for processing food.
  • Intracellular: Via phagocytosis.
  • Extracellular: In compartments with digestive enzymes.

Types of Digestive Systems

• Gastrovascular Cavity: Simple body plan, e.g., Hydra.
• Alimentary Canal: Complex, with mouth and anus.

The Mammalian Digestive System

• Alimentary Canal: Main digestive tract.
• Accessory Glands:
  • Salivary glands, pancreas, liver, gallbladder.
• Processes:
  • Peristalsis: Smooth muscle contractions move food.
  • Sphincters: Control entry and exit of food.

Digestion in the Oral Cavity

• Mechanical Breakdown: Teeth and saliva.
• Chemical Digestion: Salivary amylase.

Stomach Digestion

• Gastric Juice: Hydrochloric acid and pepsin.
• Protective Mucus: Guards stomach lining.

Small Intestine Digestion

• Duodenum: Main site for digestion and absorption.
  • Mixes chyme with enzymes from accessory glands.
• Pancreas: Provides digestive enzymes.
• Liver & Gallbladder: Produce and store bile for fat digestion.

Nutrient Absorption

• Small Intestine: Major absorption site.
• Liver: Processes nutrients before distribution.

Large Intestine and Waste Elimination

• Water Absorption: Reabsorbs water from waste.
• Rectum: Stores feces for elimination.

Evolutionary Adaptations

• Dentition: Adapts to diet (carnivores vs. herbivores).
• Digestive Tract Length: Longer in herbivores for plant material fermentation.

Mutualistic Relationships

• Ruminants: E.g., cows, have microorganisms that aid in plant digestion.

Energy Storage and Regulation

• Glycogen Storage: Liver and muscle cells.
• Insulin and Glucagon: Regulate blood glucose levels.

Hormonal Regulation and Appetite

• Hormones: Insulin, glucagon, leptin, ghrelin, PYY.
• Leptin: Produced by adipose tissue, affects appetite.

Obesity and Evolution

• Evolutionary Role: Energy storage as a survival mechanism.
• Modern Health Implications: Linked to diseases like diabetes and heart disease.