Respiration involves 4 processes:
 1) ventilation
 2) external respiration
 3) internal respiration
 4) transport of respiratory gases in the blood

Conducting Zone Structures - from the nose to the bronchioles; filter, warm, and moisten incoming air
Respiratory Zone Structures - respiratory bronchioles to alveoli; where gas exchanges occur

Nose

• provides an airway
• warms, moistens and cleans the air
• houses the olfactory receptors
• the external nose is made of bone and cartilage
• internally, the nose is divided by the nasal septum
• paranasal sinuses and nasolacrimal ducts drain into the nasal cavity

Pharynx

• from the base of the skull to the sixth cervical vertebrae
• nasopharynx: behind the nasal cavity; an air conduit
• oropharynx: behind the oral cavity; passageway for food and air
• laryngopharynx: in the throat; passageway for food and air
• pairs of tonsils are found in the oropharynx and nasopharynx

Larynx

• “voice box”
• contains the vocal cords
• serves as an airway
• serves as a switching mechanism to route food and air into the proper channels
• the epiglottis prevents food/liquids from entering the trachea

Trachea

• extends from the larynx to the primary bronchi
• it is reinforced by C-shaped cartilage rings that keep it open
• its mucuso (mucus membrane lining) is ciliated

Bronchi and bronchioles

• there are 2 bronchi, one that goes to the left lung and one that goes to the right lung
• the 2 bronchi branch off into smaller and smaller bronchioles
• the terminal bronchioles lead into the respiratory zone

Alveoli - air sacs at the end of the bronchioles; air exchange occurs across the respiratory membrane of the alveoli

Ventilation:
      A low pressure area is created in the lungs when the diaphragm moves down and the intercostal muscles contract
      The intercostals and the diaphragm relax, the pleural cavity collapses, and air is forced out.
 

External Respiration:  The process of air exchange that occurs in the lungs between the alveoli and the blood capillaries.
Internal respiration:   The gas exchange that occurs between the systemic capillaries and the body tissues.
Transport of respiratory gases

• Oxygen is carried in the blood bound to the hemoglobin of red blood cells.
• Carbon dioxide is primarily carried as a part of a bicarbonate ion.

Hypoxia - occurs when the body doesn’t get enough oxygen to its tissues
Acidosis - the accumulation of too much carbon dioxide
Major respiratory disorders:

• emphysema - permanent enlargement and destruction of alveoli; the lungs lose their elasticity
• chronic bronchitis - excessive mucus production in the lower respiratory passageways
• tuberculosis - caused by a bacteria
• lung cancer - aggressive; spreads rapidly
• asthma - the bronchioles constrict