IF

Biology 114 Lab: Animal Nutrition, Digestion, and Homeostasis

Animal Digestion

  • All animals are heterotrophs, meaning they must consume food to convert it to usable energy.
  • Simple animals digest food intercellularly whereas larger animals digest food extracellularly.
    • This allows them to:
    • Consume larger prey
    • Have anatomical specialization
    • Separate digestive processes

Comparative Digestive Anatomy

  • Gastrovascular cavities:

    • Found in cnidarians and free-living flatworms.
    • Have only one opening that serves as both a mouth and anus.
    • Incoming food may mix with outgoing waste.
    • Cavity may branch for increased surface area.

  • Complete digestive tract:

    • Separate mouth and anus, allowing food to flow in one direction.
    • Anatomy includes:
    • Mouth
    • Pharynx
    • Gut
    • Anus
    • Gut modifications occur as the diet changes to suit the needs of the animal.

Annelid Modifications:

  • Crop: Storage
  • Gizzard: Mechanical grinding
  • Digestive layout:
    • Crop, Gizzard, Esophagus, Intestine, Pharynx, Mouth, Anus

Arthropod Modifications:

  • Foregut, Midgut, Hindgut:
    • Foregut: Mouth, pharynx, esophagus, crop
    • Midgut: Digestive glands
    • Hindgut: Intestines and rectum

Cephalochordate Modifications:

  • Diverticulum: Pouches leading to accessory digestive glands (liver, gall bladder, pancreas).
  • Stomach and intestine modifications cater to diet specifics.

Chondrichthyes Modifications:

  • Large jaws with multiple rows of teeth.
  • Large stomach for bulk feeding.
  • Spiral valve: Increases surface area for protein digestion.

Osteichthyes:

  • Typical features include nostrils, swim bladder, and various fins.
  • Digestive organs to identify:
    • Esophagus, stomach, liver, pancreas, intestine

Amphibian Modifications:

  • Extendable tongues and changes in intestine length after metamorphosis.
  • Structures to identify:
    • Esophagus, stomach, liver, pancreas, gall bladder, small intestine, colon, cloaca.

Mammal Modifications:

  • Differentiation of teeth based on diet.
  • Ruminant stomach assists in cellulose digestion in herbivores, aided by symbiotic bacteria.

Animal Nutrition

  • Nutrition: The science of food and food supplement uptake.
  • Essential nutrients must come from diet; cannot be synthesized.
  • Types of nutrients:
    • Carbohydrates, lipids, proteins
    • Vitamins: Organic coenzymes
    • Minerals: Inorganic elements used in metabolism
  • Macronutrients: Needed in large quantities
  • Micronutrients: Needed in smaller quantities.

Osmoregulation

  • Development of osmoregulatory organs to regulate water levels, often coinciding with excretory organs (kidneys).
  • Water moves to areas with more negative water potential (higher solute concentration).
  • Defined tonic solutions: Isosmotic, hyposmotic, hyperosmotic.
    • Excretion of solutes leads to water loss.

Control of Solute Concentrations:

  • Osmoconformers: Allow environment to dictate concentration.
  • Osmoregulators: Control their own internal concentration.

Nitrogenous Waste:

  • Must be removed through excretory organs:
    • Ammonia: Requires largest water loss, typical in aquatic animals.
    • Urea: Less water loss, found in mammals and amphibians.
    • Uric Acid: Minimal water loss, typical in reptiles, birds, and insects.

Comparative Excretory Anatomy

  • Protonephridia in free-living flatworms; uses flame cells to collect body fluids, exiting through nephidiopore.
  • Metanephridia in annelids; collects fluid from each body segment, with secretion and reabsorption occurring.
  • Malpighian Tubules in insects; collect fluid from hemolymph, draining into the digestive tract.
  • Nephrons: Functional units of kidneys, crucial components include:
    • Glomerulus
    • Bowman's capsule
    • Proximal tubule, etc.

Nephron Function:

  • Nephron tubules secrete and reabsorb solutes.
  • Fluid surrounding the loop of henle has high solute concentration, causing water to flow out of the descending loop.

Urinalysis

  • Tests for the presence of substances that may indicate dysfunctions:
    • pH, glucose levels, protein, ketones, bilirubin, hemoglobin, specific gravity.
  • Test strips are commonly used.

Graded Work

  • A quiz will be conducted next lab to assess knowledge from Lab 11 and prepare for the final lab practical.
  • Instructor must check lab manuals to ensure all exercises are completed before leaving.