1. Respiratory System WEB

Chapter 23
The Respiratory System
• Provides a means of gas exchange between
the environment and the body
The Components of the Respiratory System
1. Upper Respiratory Passages: nose/mouth,
pharynx (back of the mouth), larynx (voice box),
trachea, bronchi & bronchioles
• Filter, warm & moisten air
• Trachea & bronchi are lined with cilia that move
mucus towards throat
2. Lower Respiratory Passages: alveoli
• Thin walled sacs where diffusion of O2 and CO2
takes place
• Inhalation – ribcage expands, diaphragm
contracts downward, space in chest cavity ↑,
pressure in chest cavity ↓, and air from outside
rushes in
• Exhalation – ribs drop, diaphragm relaxes
upward, space in chest cavity ↓ , pressure in chest
cavity ↑, and air from inside rushes out
Control of Respiration
• Breathing is usually an involuntary process
• Controlled by medulla oblongata
• When levels of CO2 ↑, it sends nerve signals to
contract the intercostals & diaphragm
Common Disorders
• Cystic Fibrosis – genetic disease, too much
respiratory mucus is produced, breathing is
• Pneumonia – fluids leak into alveoli due to
inflammation (typically from an infection),
bronchioles swell and constrict
• Emphysema – shortness of breath due to damage
of alveoli, mainly due to smoking
• Lung cancer – deadliest type of cancer