The respiratory system functions to supply oxygen to tissues and remove carbon dioxide. It includes the nose, pharynx, larynx, trachea, bronchi, bronchioles and lungs. During inhalation, the diaphragm contracts and the thoracic cavity expands, causing air to flow into the lungs. During exhalation, the diaphragm relaxes and air flows out. Gas exchange occurs in the alveoli where oxygen diffuses into blood and carbon dioxide diffuses out. External respiration is the exchange of gases between the lungs and blood, while internal respiration is the exchange between blood and tissues.

1. Chapter 18 Respiratory System
Note-taking Guide
Functions of the Respiratory System
• 1.
• 2.
• 3.
Respiratory Organs
• Nose-
• Pharynx-

2. • Larynx-
• Trachea-
• Bronchi and bronchioles- primary bronchi-àsecondary bronchiàtertiary
bronchiàbronchiolesàterminal bronchioles
Lungs- pleural membrane encloses and protects each lung, parietal membrane attaches
lungs to diaphragm, inner layer visceral pleura, pleural cavity contains a lubricating fluid,
contains alveoli
Inhalation and Exhalation
• At rest (no breathing): ___________________ inside lungs and out
_______________________
• Inhalation:
– Diaphragm _________________________and drops
– Volume of thoracic cavity increases
– _______________ inside lungs _______________ than outside
– Air ________________ and lungs ______________________

3. • Exhalation:
– Diaphragm _____________ and moves up
– Volume of thoracic cavity decreases
– ________________ inside lungs _________________ than outside
– Air ___________________ and lungs ______________________
• What affect on breathing would occur if there was a hole in the thoracic cavity?
Gas Exchange

4. • Alveoli
– _____________________is fluid that lubricates and prevents collapse of
sacs
– ___________________________ exchange between alveolar walls and
capillary walls by diffusion
Respiration
External Respiration
– Diffusion of _______________________________ in alveoli to
____________________________________ and CO2 from capillaries to
alveoli
– PO2 in alveoli < air, PCO2 in alveoli > air

5. – Travels to ______________________________
Internal Respiration
– Diffusion of _____________________ from _____________________ in
to tissue cells and _________________from tissue cells to
______________________
– PO2 in cells < capillaries, PCO2 in cells > capillaries
– Travels back to ______________________

6. Factors affecting amount of oxygen released by hemoglobin
• 1. PO2
• 2. CO2
• 3. Acidity
• 4. Temperature

7. Transport of Carbon Dioxide
• Dissolved in plasma
• Bound to amino acids
• Bicarbonate ions
Vocabulary Words:
Gas exchange
Alveoli
Inhalation
Exhalation
Diaphragm