The lungs are responsible for gas exchange between inhaled air and blood. They have a branching structure from the trachea to bronchioles and alveoli where oxygen and carbon dioxide diffuse between the air and blood. Muscles like the diaphragm and intercostals expand and contract the lungs and chest cavity to inhale and exhale air, bringing oxygen into the body and removing carbon dioxide through diffusion based on partial pressures and concentrations.

1. Cardio - respiratory System
Structure and Function of the Lungs
Lloyd Dean

2. Aims
 Describe the structure of the lungs
 Identify the function of the lungs
 Recall how lungs perform their function

3. Recap
Concave Discs
Venule
Artery
Platelets
Arterioles
Capillary
Plasma
CO2
Lumen
Tunica Media (Smooth
Muscle)

4. TIME TO DO SOME COLOURING IN! (1 Pack per study
buddy)
Rule 1. Have fun
Rule 2. If you find a term that you do not know then research
it on your mobile device
Rule 3. Make as many notes on the sheets as possible to help
with your video!

6. Component
Epiglottis
Trachea
Bronchus
Bronchioles
Alveoli
Diaphragm
Intercostal
muscles
Structure
•Small flap of cartilage
•Tube which carriers air
•Covered in hairs (Cilia)
•Surrounded by C-shaped cartilage
rings (Protect)
•Cartilage rings
•Smooth muscle
•Further division of bronchi
•Very narrow tubes
•Lead to alveoli
•Air sacs
•Thin walls
•Muscle that sits underneath lungs
•Attached to the ribs and sternum
•Base of thoracic cavity
•Muscles that sit between the ribs
•Internal and external
Function
Prevents food entering the
trachea
Also known as the wind pipe;
passage for oxygen to travel
through
Splits trachea into two tube to
allow oxygen in right and left
lungs
Allows oxygen to filter into
alveoli
Site for exchange of gasses
Enables thoracic cavity to be
increased and decreased
Enables thoracic cavity to be
increased and decreased

7. Respiratory Volumes
• Tidal Volume
Amount of air moved in and out of the lungs in once breath
Residual Volume
Amount of air left in the lungs after exhalation
Vital Capacity
Maximum amount of air that can be inhaled and exhaled in
one breath

8. Gaseous Exchange

9. Inspiration
Diaphragm flattens and stretches lungs
downward
Intercostals pull the ribcage up and out
causing the lungs to stretch
Expansion of air causes a drop in air
pressure in the lungs
Air in the lungs is at a lower pressure than
the air outside, so air enters the lungs

10. Expiration
 Diaphragm relaxes
 Intercostals relax
 Lungs recoil
 Volume of air in the lungs decreases causing an increase in the air
pressure
 Air flows from higher to lower pressure so the air flows out of the
lungs

11. Intercostal and Diaphragm Muscles
(Dugdale, 2009)
Diaphragm
Dome shaped muscle
Separates thoracic cavity
from abdominals
Intercostal Muscles
 Changes the shape rib cage
during breathing
 External intercostals contract to
breathe in

12. Inspiration and Expiration During Exercise

13. Inhalation and Exhalation

14. External Respiration
•Exchange of Oxygen and Carbon dioxide between the lungs
and blood stream
•Occurs at Alveoli
(WebMD, 2009)

15. Diffusion
Oxygen (02) is required in tissues
Carbon dioxide (CO2) has to be removed
Exchange occurs through Diffusion
Movement of particles from a high concentration area, to a low
concentration area
Rule = Diffusion only occurs down a concentration gradient
Concentration (pressure ) oxygen in lungs must be higher than
concentration (pressure) in capillaries

16. Partial Pressure
•Individual pressure of a particular gas within a mixture of
gases
•Diffusion occurs from high to low concentrations
INHALED %
GAS
EXHALED %
79.04
Nitrogen
79
20.93
Oxygen
17
0.03
Carbon Dioxide
4

17. Exchange of Gases
Fast rate of diffusion occurs with:
 Large surface area
 Small distance between areas involved
Other Factors:
 Capillary size
 Moist surface of alveoli
 Slow capillary blood flow = Complete Oxygenation
 Haemoglobin – Magnet for oxygen
Internal Respiration
 Exchange of gases in the bodies cells
 Works similar to external respiration
 Cell use of oxygen to make ATP

18. Gas Exchange

19. Neural and Chemical Control of
Breathing
Medulla Oblongata (Respiratory centre)
Impulses
Stretch receptors
Chemoreceptors
Lactic acid