1. Respiratory System Physiology

2. Respiratory Physiology
All tissues receive adequate Oxygen supply
Prompt removal of Carbon Dioxide
Efficient regulation of gas exchange
Acid – Base balance
Water balance

3. What is Breathing? Pulmonary Ventilation – “Breathing”
Inspiration – movement of air into the system
Expiration – movement of air out of the system
“Air” moves from an area of high concentration of molecules (high pressure) to an area of low concentration of molecules (low pressure)
Pressure is the normal force per unit area exerted on a surface in a fluid or a gas

4. BREATHING MECHANISM

5. Therefore……..
When the atmospheric pressure is greater than the pressure in the lungs (alveoli), then air flows into lungs (down the pressure gradient) – this is inspiration
When the pressure in the lungs (alveoli) is greater then the pressure in the atmosphere, then air flows out of the lungs (down the pressure gradient) – this is expiration

6. Breathing
Body changes the size of thoracic cavity by contraction and relaxation of respiratory muscles.
Diaphragm
Intercostals

7. (Assuming Constant Temperature)
Gas Laws: Boyle’s Law
Boyle’s Law is changing in volume
Gas’s volume (V) is inversely proportional to its pressure (P)
P1V1 = P2V2
(Assuming Constant Temperature)
When volume of a container increase, then pressure in the container decreases, air flows into the container.

8. Boyle’s Law
Boyle's Law Explanation

9. Contraction of the diaphragm and external intercostal muscles - increases thoracic volume, air flows into lungs (inspiration, p. 712)
Relaxation of diaphragm and intercostal muscles decreases thoracic volume, air flow out of lungs (expiration, p. 713)

10. Gas Laws: Charles Law Charles Law – changes in temperature.
Gas’s volume (V) is directly proportional to temperature (T) when pressure is constant.
As volume increases, temperature increases

11. NON RESPIRATORY MOVEMENTS
Coughing, sneezing, laughing, crying
Hiccup - spasm of the diaphragm
Yawn - possibly causes by low oxygen levels

12. Respiratory Air Volumes
Spirometer
measures the amount (volume) of air moving in and out of the lungs
Respiratory Cycle:1 inspiration and 1 expiration

13. Tidal Volume (TV) 
amount of air that enters the lungs during one cycle
*take a normal breath
Reserve volumes (RV)
air that can be forced out or in
*inhale normally, pause, and try to inhale more - that is your reserve inspiratory volume
*exhale, then exhale a little more

14. Vocabulary
Expiratory Reserve Volume (ERV) – volume of air one can forcibly expire after expiring tidal air
Inspiratory Reserve Volume (IRV) – volume of air one can forcibly inspire above normal inspiration

15. More Vocabulary
Residual volume – the amount of air that cannot be forcibly expired. Some air is trapped in alveoli and not removed
Vital Capacity is the sum of IRV + TV + ERV. It is the largest volume of air one can move in and out of the lungs.
Inspiratory capacity (IC) – maximal amount of air one can inspire after a normal expiration (TV + IRV)

16. OMG Even More Vocabulary
Functional Residual Capacity (FRC) – Amount of air left in the lungs at the end of normal expiration
Alveolar Ventilation – Volume of air that reaches the alveoli due to inspiration.
Anatomical Dead Space – area of the respiratory system that fills with air, but gas exchange does not take place (such as bronchioles, trachea)

17. Concentration is the amount of solute in a given amount of solution
Gas Law: Dalton’s Law
The pressure of a gas mixture is the sum of the partial pressures of the individual components of the gas mixture
Air is not one molecule but a mixture of several each at different concentrations.
Remember from Chemistry:
Concentration is the amount of solute in a given amount of solution