1. Topic 6.4
Gas Exchange

2. Why do we need Oxygen??? Aerobic cellular respiration
Biochemical pathway
Chemical bonds within a glucose molecule are broken..releasing Energy
This E is stored as ATP
Requires O2 and gives off CO2
Each of the 6 C in glucose are given off as CO2

3. 6.4.1 Distinguish between ventilation, gas exchange and cellular respiration
Ventilation = breathing (filling lungs with air and exhaling)
Gas exchange = the movement of gases
O2 in the lung tissues diffuses into the bloodstream
CO2 from blood diffuses into lung tissues
Occurs in two locations:
In the lungs
In capillary beds where CO2 diffuses into blood and O2 diffuses into body cells

4. Relationship between ventilation, gas exchange and cell respiration
Lung air air
ventilation
CO2 diffuses out of alveolus O2 diffuses into alveolus
Capillary
gas exchange
Body Cell cell respiration
O2 is a reactant for aerobic cellular respiration
CO2 is a product of aerobic cellular respiration
O2 diffuses into
lung capillaries
Co2 diffuses out of
lung capillaries
O2 diffuses out of
body capillaries
Co2 diffuses into
body capillaries

5. 6.4.2 Explain the need for a ventilation system
Amoeba has no ventilation system????
They need gas exchange????
Our bodies are so thick-only our outside cells are exposed to air
All our cells need O2 and are too far away to make use of diffusion of O2 and CO2
Maintain [ ] levels of gases within the lungs

6. Anatomy of the Ventilation System

8. Pathway of the Ventilation System
Air enters your trachea
Passes into your right and left 1◦ bronchi
Branches smaller and smaller
Smallest branches = bronchioles
Finally, air enters the small air sacs called alveoli
Clustered at the ends of the smallest bronchioles
Appearance similar to “bunch of grapes”
Approx. 300 million in lungs
Surrounded by capillary bed

9. 6.4.3 Features of Alveoli that adapt them to gas exchange
Adaptation
Advantage
spherical shape
provides a large surface area for respiratory gases to diffuse through
flattened, single cell thickness
prevents respiratory gases from having to diffuse through more cell layers
moist inner lining
allows for efficient diffusion
associated capillary bed nearby
respiratory gases do not have to diffuse far to reach single cell thick capillaries

10. 6.4.5 Mechanisms of Ventilation
Tissues that make up our lungs are passive…not muscular
Muscles surround the lungs
Diaphragm
Abdominal muscles
Intercostal (rib) muscles
Breathing is based on the inverse relationship between pressure and volume
in volume leads to a in pressure
Lungs are in thoracic cavity (thorax) which is a closed environment
Lungs have opening through the trachea (via nose and mouth)
These 2 environments (lungs and thorax) affect each other

11. 6.4.5 Mechanisms of Ventilation (cont.)
Mechanisms of Inspiration: (steps reversed for expiration)
Diaphragm contracts while abdominal and intercostal muscles raise the rib cage…this the volume of thoracic cavity
Since volume in thoracic cavity, the pressure which leads to less pressure pushing on the passive lung tissue
Lung tissue in volume since there is less pressure
in pressure inside lungs is known as partial vacuum
Air comes in through mouth and nose to counter the partial vacuum (fills alveoli with air)

16. 2 Questions
Create a list of steps which represent what your body would do to accomplish a single expiration (breathing out).
Pneumonia (excess mucus) and smoking (tar) create an extra lining inside of each of the alveoli. Describe how and why this could become life threatening.