Respiratory System

• Function of the respiratory system

  • exchanges gas between organisms and their environment
• Air follows the following pathway:

  • Pharynx
  • air moves through the nose to a space at the back of the mouth
  • passage of both air & food
  • Trachea
  • rigid tubes leading to the lungs
  • epiglottis covers the trachea when swallowing so that food goes down the esophagus and not the trachea
  • mucus & cilia along the nose and pharynx trap dust and smoke
  • cilia pushes junk up - where it is either spit out or swallowed
• Air follows the following pathway:

  • Larynx
  • voice box - 2 folds of tissue that form a slit
  • when air moves up through them, sound is made
  • Bronchi
  • 2 large passages leading air to each lung
  • surrounded by smooth muscle
  • Bronchioles
  • smaller branch passageways that lead from each bronchus to clusters of alveoli
  • they help increase surface area of alveoli in the lungs
• Air follows the following pathway:

  • Alveoli
  • small sacs - clustered at end of bronchioles
  • richly supplied with capillaries
  • actual site of gas exchange
  • huge surface area (60 square meters)
  • Alveoli & gas exchange
  • there is a higher concentration of oxygen in inhaled air than in exhaled air
  • O2 diffuses from alveoli into capillaries
  • there is a higher concentration of carbon dioxide in exhaled air than inhaled air
  • CO2 diffuses from capillaries to the alveoli
• Breathing

  • no muscles connected to the lungs to help move them for breathing
  • lungs expand due to difference in pressure between the chest cavity and the atmosphere
  • Diaphragm
  • breath in, the diaphragm contracts and the rib cage expands
  • the volume of the chest cavity increases & the pressure decreases
  • The atmospheric pressure is greater and so air is forced into the lungs
• Control of breathing

  • breathing can be voluntary
  • much of breathing is autonomic
  • the brain monitors the levels of CO2 in the blood
  • If CO2 levels increase, impulses to the diaphragm cause more contractions and more air is brought in
  • When you exercise, you actually breath faster to release CO2, not so much to get O2
• Respiratory diseases

  • bronchitis: inflammation of bronchi
  • emphysema: loss of elasticity of lung tissue
  • alveoli can't expand for gas exchange - tobacco damages the tissue
  • asthma: narrowing of the bronchi and bronchioles due to the constriction of muscles around the airways
  • environmental, genetic
  • cystic fibrosis (CF): recessive, autosomal genetic disease in which lungs collect mucus and cause multiple infections
• Air follows the following passageway:

  1. pharynx
  2. trachea
  3. larynx
  4. bronchi
  5. bronchioles
  6. aveoli