Animal Respiration Notes

Overview of Animal Respiration

  • Animals require a continuous supply of O2 for metabolic reactions.
  • Key process: Respiration involves the exchange of gases (O2 and CO2) between the atmosphere, lungs, blood, and cells.

Types of Respiratory Systems

  • Lungs, Gills, and Other Structures:
    • Lungs: Found in land vertebrates and aquatic mammals (air as respiratory medium).
    • Gills: Present in fish and aquatic animals (water as respiratory medium).
    • Tracheae: Used by insects (air as respiratory medium).

Mammalian Respiratory Anatomy

  • Lungs:

    • Air enters through nasal/oral cavity.
    • Primary Bronchus: One per lung, branches into secondary bronchi within each lobe.
    • Bronchioles: Smaller branches ending in alveolar sacs where gas exchange occurs.

  • Alveoli: Small sacs at the end of bronchioles for gas exchange, surrounded by capillaries.

  • Diaphragm: Dome-shaped muscle plays a crucial role in breathing, separating thoracic from abdominal cavity.

Pulmonary Ventilation

  • Definition: The process of breathing; air moves in and out of the lungs due to changes in pressure.
  • Boyle's Law:
    • If the size of a container increases, pressure inside decreases.
    • If the size decreases, pressure inside increases.
Steps of Pulmonary Ventilation
  1. Inspiration:
    • Diaphragm contracts, moving downwards, lung volume increases, pressure drops.
  2. Expiration:
    • Diaphragm relaxes, moves upwards, lung volume decreases, pressure increases.

Pulmonary Volumes

  • Tidal Volume: Volume of air inspired or expired during normal respiration (~500 ml, ~350 ml reaches alveoli).
  • Anatomic Dead Space: Air in passages not reaching alveoli (~150 ml).
  • Vital Capacity: Max air that can be exhaled after a deep breath (~3,000 - 4,000 ml).
  • Residual Volume: Air remaining in the lungs after forceful exhalation (~1200 ml).

Modified Respiratory Movements

  • Cough: Strong contraction of respiratory muscles to expel air, triggered by irritation in the throat or trachea.
  • Sneeze: Strong spasm expelling air through the nose/mouth, triggered by nasal irritation.
  • Yawn: Deep inspiration followed by prolonged expiration, associated with boredom, tiredness, brain activation, brain cooling, and pressure equalization in ears.
  • Hiccup: Spasmodic contractions of the diaphragm; can be triggered by various factors such as overeating, excitement, or temp changes.

External vs Internal Respiration

  • External Respiration: Gas exchange between alveoli and blood.
  • Internal Respiration: Gas exchange between blood and body cells.

Marine Mammal Adaptations

  • Specialized adaptations for gas exchange in oxygen-poor environments (e.g., high efficiency of O2 extraction from water).

Problems of the Respiratory System

  • Common issues include conditions affecting gas exchange efficiency, infections, irritations, or structural abnormalities affecting airflow.