1. Respiration

2. Mechanisms of Gas Exchange
Gas exchange has three phases:
breathing
transport of gases
exchange of gases with tissue cells
It provides O2 for cellular respiration and removes its waste product, CO2
Respiratory & Circulatory systems

3. The 3 Phases of Gas Exchange
1. Breathing
O2 is taken into lungs and blood vessels
CO2 diffuses out and leaves body
2. Transport of gases by the circulatory system
O2 attaches to hemoglobin and is carried in blood to body tissues
CO2 is transported from tissues back to lungs
3. Exchange of gases with tissue cells
Body cells take up O2 from blood and release CO2 back to the blood
This is diffusion through the plasma membrane (mitochondria internally)

4. LE 22-1 O2 Breathing CO2 Lung Circulatory system Transport of gases by
the circulatory
system
Mitochondria
Exchange of
gases with
body cells O2
CO2
Capillary
Cell

5. Human Air Pathway: Inhaled through the nostrils 
Passes through the pharynx and larynx (including vocal cords) 
Into the trachea, bronchi, and bronchioles*
* Bronchioles end in clusters of tiny alveoli, where gas exchange occurs
Cilia and mucus are the respiratory system's cleaning elements

6. Partner 1 - Describe how oxygen gets into your body
Partner 1 - Describe how oxygen gets into your body. Partner 2 – Describe how carbon dioxide leaves.

7. Oxygen-poor blood Oxygen-rich blood Bronchiole Alveoli Blood
LE 22-5b
Oxygen-poor
blood
Oxygen-rich
blood
Bronchiole
Alveoli
Blood
capillaries

9. Alveoli walls and gas exchange
6.4.U2 Type I pneumocytes are extremely thin alveolar cells that are adapted to carry out gas exchange. AND 6.4.U3 Type II pneumocytes secrete a solution containing surfactant that creates a moist surface inside the alveoli to prevent the sides of the alveolus adhering to each other by reducing surface tension.
Alveoli walls and gas exchange
Connective
tissue
Type I pneumocytes
A Single layer of cells form the walls of an alveolus
Extremely thin – short diffusion distance
Permeable – aids diffusion
Type II pneumocytes
Secrete fluid to moisten the inner surface of the alveolus
Fluid aids diffusion of gases
Fluid contains surfactant to prevent the walls sticking together – maintains the lumen
Can divide to form Type I pneumocytes – repair damage
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10. Smoking is a deadly assault on our respiratory system
Tobacco smoke irritates cells lining the bronchi
Inhibits or destroys cilia
Kills defensive macrophages
Causes: lung cancer, emphysema, cardiovascular disease
Choosing not to smoke is the most important lifestyle choice for health

11. LE 22-6
Lung
Heart

12. Breathing* ventilates the lungs
*alternation of inhalation and exhalation
Maintains high O2 and low CO2 at the respiratory surface

13. Negative pressure breathing
During inhalation, changes in lungs, diaphragm, and rib cage reduce air pressure in alveoli
Air rushes in due to higher pressure outside
During exhalation, decreased volume of chest cavity forces air out
A residual volume of air ("dead air") remains in lungs even after exhalation
Vital capacity is the maximum volume of air we can inhale and exhale during forced breathing

14. Rib cage gets
smaller as
rib muscles
relax
Rib cage
expands as
rib muscles
contract
Air
inhaled
Air
exhaled
Lung
Diaphragm
Diaphragm contracts
(moves down)
Diaphragm relaxes
(moves up)
Inhalation
Exhalation

15. Summary of the mechanics of ventilation
6.4.A3 External and internal intercostal muscles, and diaphragm and abdominal muscles as examples of antagonistic muscle action. AND 6.4.U5 Muscle contractions cause the pressure changes inside the thorax that force air in and out of the lungs to ventilate them.
Summary of the mechanics of ventilation
Inspiration
Expiration
pressure change
decrease in pressure
(draws air inwards)
increase in pressure
(pushes air outwards)
volume change
increase
decrease
ribcage movement
up and outward
down and inward
external intercostal muscles
contract
relax
internal intercostal muscles
diaphragm
Contract (flattens, moves downwards)
abdominal muscles
Contract (pushes diaphragm up)
diagrams
causes
causes