1. SPO1003
Respiratory System

2. Aims To understand The structure and function of the respiratory tract
The process of ventilation and respiration
Gaseous Laws

3. Ventilation & Respiration
Introduction:

4. Respiratory Function Three major functions: Get Oxygen (O2)
Remove Carbon dioxide (CO2)
Maintain Acid / Base balance (regulate acidity)

5. Respiratory Function Inspired air Expired air
CO %
Expired air
O2 - 16%
CO2 - 4%
Expired values change dictated by level of activity

6. Boyle’s Law: Inverse relationship As the volume of a gas ↑ pressure ↓

8. Dalton's Law:
The total pressure of a mixture of gases equals the sum of the partial pressures of the individual gases in the mixture

9. Atmospheric pressure at sea level = 101.3 kPa (Kilopascal)
In practice…….
Atmospheric pressure at sea level = kPa (Kilopascal)
N2 + O2 + H2O + Ar + CO2
= 101.3

10. Henry's Law:
Gases dissolve in liquids in proportion to their partial pressures, depending on their solubility in the specific fluids and depending on the temperature

11. Ventilation & Respiration
Pulmonary ventilation
Inspiration and Expiration
Respiration
Exchange of oxygen and carbon dioxide between the lungs (i.e. the air) and the blood (external)
Exchange of oxygen and carbon dioxide in musculature (internal)

12. Ventilatory Anatomy

13. Ventilation Muscles of Ventilation Intercostal muscles Diaphragm
Between ribs
Internal and External intercostal muscles
Work in opposing directions External raise rib cage internal lower it
Diaphragm
Sits in thorax underneath the lungs
During contraction moves away from lungs
During relaxation moves towards lungs

14. Ventilation At rest pressure in lungs = air pressure Inspiration
Diaphragm contracts
Moves downwards increasing thoracic volume
Lungs attached to rib cage and diaphragm
Thus increase chest volume - increase lung volume

15. Ventilation Expiration So the opposite occurs
In order to breath out pressure in lungs must increase above atmospheric pressure
So the opposite occurs
Diaphragm relaxes & moves upwards - volume decreases

16. If air pressure within the lungs is greater than atmospheric pressure, air will move out of the lungs (expiration).
If intrapulmonic pressure is less than atmospheric pressure, air will move into the lungs (inspiration)

18. Boyle’s Law

19. Respiration
External: process of inhaling the air into the lungs and expelling the air that contains more CO2 from the lungs to the outer environment.
Internal: a metabolic process during which oxygen is released to tissues and carbon dioxide is absorbed by the blood. Once inside the cell the oxygen is utilized for production of energy in the form of ATP
Gas exchange occurs via diffusion

20. External Respiration
Diffusion of O2 & CO2 across membrane

21. Dalton’s Law
Pressure of a mixture of gases equals the sum of the partial pressures:
Inspired air has a high PO2 and low PCO2
Blood has lower PO2 and higher PCO2
Diffusion occurs by movement of gasses from high pressures to low pressures
Thus the high O2 in the alveoli diffuses into the blood and the high CO2 in the blood diffuses into the air

22. Partial Pressure of O2 & CO2

23. Partial Pressure of O2 & CO2
Total O CO
Partial pressure (mmHg)
% in Dry Alveolar Venous Diffusion Gas dry air air air blood gradient

24. Gaseous Laws Boyle’s Law: Dalton's Law: Henry's Law:
As the volume of a gas increases, pressure decreases, and as the volume decreases, pressure increases
Dalton's Law:
The total pressure of a mixture of gases equals the sum of the partial pressures of the individual gases in the mixture
Henry's Law:
Gases dissolve in liquids in proportion to their partial pressures, depending on their solubility in the specific fluids and depending on the temperature

25. Important Points Ensure you understand the following:
Ventilatory structures
Respiratory mechanisms
Gaseous laws and their importance to ventilation and respiration

26. QUESTIONS