diffuses into blood
🫁HUMAN ANATOMY STUDY GUIDE
Respiratory System and Gas Exchange
Follow airflow, ventilation mechanics, alveolar exchange, gas transport, and breathing control.
8 key ideas8 flashcards5 practice questions
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Each gas moves down its own partial-pressure gradient.
alveolus plus capillary
diffuses into alveolus
Key ideas to know
Start with the relationships between ideas. Then close the notes and explain each one from memory.
- 01
The conducting zone moves, warms, humidifies, and filters air.
- 02
The respiratory zone contains bronchioles and alveoli where gas exchange occurs.
- 03
Diaphragm contraction increases thoracic volume during quiet inhalation.
- 04
Air flows when pressure differs between atmosphere and alveoli.
- 05
Surfactant lowers alveolar surface tension and resists collapse.
- 06
Oxygen and carbon dioxide diffuse down partial-pressure gradients.
- 07
Most oxygen travels bound to hemoglobin.
- 08
Most carbon dioxide travels as bicarbonate in plasma.
PART OF THE HUMAN ANATOMY GUIDE
See every set in this course and follow a focused review order.
Open the full Human Anatomy guide →Two ideas worth correcting now
NOT QUITE
→Inhalation pulls air in like suction
USE THIS INSTEAD
Air enters because muscle action creates a pressure difference.
NOT QUITE
→All carbon dioxide is carried dissolved in plasma
USE THIS INSTEAD
Most is converted to bicarbonate.
Flashcards
Answer before opening each card. The effort to retrieve is part of the learning.
1What divides the upper and lower respiratory tracts?Show answer ＋
Definitions vary, but the lower tract commonly begins at the larynx or trachea.
2What is the main muscle of quiet inhalation?Show answer ＋
The diaphragm.
3What happens to alveolar pressure during inhalation?Show answer ＋
It falls below atmospheric pressure.
4What do type II alveolar cells secrete?Show answer ＋
Surfactant.
5What drives gas diffusion?Show answer ＋
Partial-pressure differences.
6How is most oxygen transported?Show answer ＋
Bound to hemoglobin.
7How is most carbon dioxide transported?Show answer ＋
As bicarbonate.
8Where is basic breathing rhythm generated?Show answer ＋
In brainstem respiratory centers.
Explain it in your own words
Use the answer as a check after you have written or spoken your response.
01Why does air enter when the diaphragm contracts?
Thoracic and lung volume rise, lowering alveolar pressure below atmospheric pressure.
02How does surfactant assist alveoli?
It lowers surface tension, reducing the work needed to inflate them and resisting collapse.
03Why are alveolar walls thin?
A short diffusion distance permits faster gas exchange.
04How does carbon dioxide become bicarbonate in red blood cells?
Carbonic anhydrase speeds its reaction with water; carbonic acid then dissociates.
05Why can ventilation and perfusion mismatch reduce gas exchange?
An alveolus needs both fresh air and nearby blood flow for efficient transfer.
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