1. Respiratory Physiology
Ventilation Gas exchange Oxygen uptake & utilization

2. From this study you should be able to:
Describe the need to breath as a part of a metabolic process
Describe the function of the respiratory conducting zone
Describe pulmonary ventilation
Briefly explain how surface tension arises & is stabilized
Define lung volumes & lung capacities
Explain gas movement during external & internal respiration
Briefly describe neurological control of breathing with description of the stimulation of central chemoreceptors
State the role of Hb in gas movement
Explain how O2 & CO2 are carried in the blood

3. The Need to Breath Oxygen helps us to release energy from food we eat
Every cell in the body needs energy
Glucose + Oxygen = Energy + Carbondioxide + water
Waste products of
energy production
From the atmosphere

4. Dealing with waste products
Carbondioxide + water
CO2 plus H2O= COO + HHO
H2 CO3
A weak acid substance
CARBONIC ACID

5. Respiration Ventilation: Gas exchange: Oxygen (02 ) utilization:
Breathing.
Gas exchange:
Occurs between air and blood in the lungs.
Occurs between blood and tissues.
Oxygen (02 ) utilization:
Cellular respiration.

7. Quiet Inspiration - Process
Contract your diaphragm, to achieve vertical expansion of your lungs.
Contract your Intercostal Muscles, to increase thoracic volume laterally.

8. Pressure changes on Quiet Inspiration
Atmospheric pressure (at sea level) = 760 mmHg
The chest expands (actively)
Intrapulmonary press 757 mmHg so
air moves into the lungs
Pulmonary pressure rises by + 3 mm Hg.

9. Expiration Hold your breath-
Are your respiratory muscles getting tired?
After stretching the lungs) (by contracting both diaphragm and thoracic muscles) the diaphragm, thoracic muscles relax & the thorax, and lungs recoil
The decrease in lung volume raises the pressure inside to above 763mmHg
This is greater than atmospheric pressure- so air moves out of the lungs.

12. Recap

13. The Pleura 2 layers- Visceral & Parietal. Intrapleural space
-a film of fluid-secreted by the pleura & NO AIR
The lungs remain in contact with the chest wall –allowing them to move with the thoracic cavity

14. PRINCIPLE 1
Boyle’s Law
Changes in intrapulmonary pressure occur as a result of changes in lung volume.
(Pressure of gas is inversely proportional to its volume).
Increase in lung volume decreases intrapulmonary (alveolar) pressure.
Air goes in.
Decrease in lung volume, raises intrapulmonary pressure above atmosphere.
Air goes out.
animation

15. Dead Space
Air passes thro’ 150 ml of space before reaching the respiratory zone.
Air is Warmed and humidified, Filters and cleaned: (Mucous traps particles )
Mucus moved by cilia to be expectorated.

16. Lung Volumes Volume of gas inspired/expired in an unforced breath
Tidal volume
Volume of gas inspired/expired in an unforced breath
Inspiratory reserve volume
The maximum volume of air that can be inspired during forced breathing
Expiratory reserve volume
The maximum volume of gas that can be expired during forced breathing
Residual volume
The volume of gas remaining in the lungs after a maximum expiration

17. Lung Capacities Total lung capacity
The total amount of gas in the lungs after a maximum inspiration
Vital capacity
The maximum amount of gas that can be expired after a maximum inspiration
Inspiratory capacity
The maximum amount of gas that can be inspired after a normal tidal expiration
Functional residual capacity
The amount of gas remaining in the lungs after a normal tidal expiration

18. Respiratory Zone Where gas is exchanged between air and blood.
Gas exchange occurs by diffusion.

19. Alveoli Clustered like a honeycomb. 300 million air sacs.
Large surface area (60 – 80 m2).
Each alveolus is 1 cell thick.
2 types of cell:
Alveolar type I:
Structural cells.
Alveolar type II:
Secrete surfactant.

20. Surface Tension
H20 molecules at the surface are attracted to other H20 molecules by attractive forces.
What could happen to alveoli if this was not corrected?

21. Surfactant- reduces surface tension
A Phospholipid produced by alveolar type II cells.
Lowers surface tension.
Think of a detergent
Reduces attractive forces between H20 molecules.
As alveoli radius decreases, surfactant’s ability to lower surface tension increases.- so the alveolus does not collapse

22. Principle 2
Gases move from an area of high concentration to an area of low concentration
Gas movement relies on concentration gradients

23. Principle 3 Gas Exchange: Dalton’s Law
Total pressure of a gas mixture is = to the sum of the pressures that each gas in the mixture would exert independently.
Think of being in a crowded lift
Now think of Partial Pressure

24. External Respiration

25. Internal Respiration
animation

26. Recap-Blood P02 & PC02
After gas exchange, Arterial blood P02 is normally about 100 mm Hg & PC02 is 40mm Hg
P02 in systemic veins is about 40 mm Hg.
PC02 in systemic veins is 46 mm Hg.

27. Regulation of Breathing
Neurons in the medulla oblongata forms the rhythmicity center:
Controls automatic breathing.
Brain stem respiratory centers:
Medulla.
Pons.

28. Chemoreceptor Control
C02 + H2O
H+ cannot cross the blood brain barrier.
C02 can cross the blood brain barrier and will form Carbonic acid & then H+
H2C03 H+
HC03
This is Carbonic acid
What is this?
Bicarbonate
H+ is the trigger for the chemoreceptors

29. Haemoglobin and 02 Transport
Each haemoglobin has 4 protein chains and 4 hemes.
Each heme has 1 atom iron that can combine with an 02 molecule.

30. Clinical relevance point 1
Haemoglobin production controlled by erythropoietin.
(Produced re P02 delivery to kidneys).
Loading/unloading of gas on Hb depends on:
Hb level & capacity in the blood
Enzymes: ↑ 2,3 DPG - increases unloading of O2
Temp: ↑Heat increases unloading of O2
Acid/base: ↓pH increases unloading of O2
This enzyme is produced when Hb is low

31. C02 Transport C02 transported in the blood: HC03- (70%).
Dissolved C02 (10%).
Carbaminohemoglobin (20%).