Respiratory System

Why do we need a respiratory system?

Respiratory systems in diverse animals

  1. Aquatic Invertebrates have gills
  2. Insects have hollow tubes called tracheae
  3. Fish have complex gills
  4. Frogs breathe through their skin and lungs
  5. Birds have a one-way respiratory system
  6. Mammals have lungs with many branches

Structure of the mammalian respiratory system

  1. Oral cavity & Nose: Filter, warm and humidify air
  2. Trachea: Conduct air to lungs & trap particles
  3. Bronchi & bronchioles branch ~ 23 times
  4. Alveoli: tiny sacs for gas exchange
  5. Pulmonary circulation

How breathing (ventilation) works

Negative pressure breathing
  1. Inhaling
  2. Exhaling
  3. Forced respiration (e.g. exercise)
  4. Control of breathing


Gas exchange and transport

  1. Oxygen transport
  2. CO2 transport

Respiratory disorders

  1. Emphysema: breakdown of alveoli
  2. Smoking
  3. Carbon monoxide poisoning
  4. Anemia