1. The Respiratory System
PSK4U

2. The Respiratory System
Composed of structures that allow:
Passage of air from outside the body to the lungs
Gas exchange to occur

3. The Respiratory System
Three main functions:
Supply O2 to the blood
Remove CO2 from the blood
Regulate blood pH (acid-base balance)

4. The Respiratory System
External Respiration
Internal Respiration
Cellular Respiration
Divided into two zones:
Conductive zone
Respiratory zone

5. Respiratory System Structure
Nasal cavity
Mouth
Pharynx
Epiglottis
Larynx
Trachea
Right and left primary bronchi
Smooth muscle
Secondary bronchi
Terminal bronchiole
Respiratory bronchiole
Tertiary bronchioles
Alveolar sacs
Pulmonary venule
Pulmonary arteriole

6. Respiratory System Structure

7. The Conductive Zone
The conductive zone is composed of structures that transport air to the lungs:
Mouth and nose
Larynx
Trachea
Primary and secondary bronchi
Tertiary and terminal bronchioles
Filters, warms and humidifies air taken in with each breath
Filtration by nasal hairs and mucus membranes
37oC and saturated

8. The Respiratory Zone
The respiratory zone is composed of structures involved with the exchange of gases between inspired air and blood:
Respiratory bronchioles
Alveolar ducts

9. The Respiratory Zone Alveolar sacs (alveoli) Grape like structures
Large surface area for diffusion of gas into and out blood
Surrounded by capillaries and elastic fibers
Walls are only one cell thick

10. Mechanisms of Breathing
Inspiration:
Contraction of diaphragm
Stimulation from brain
Thoracic cavity expands
Air pressure in thoracic cavity is lower than air pressure outside the body
Air rushes in to lungs to restore balance
Lung pressure = atmospheric pressure
Active process
Require respiratory muscles
See diagram on page 250

11. Mechanisms of Breathing
Expiration:
Alveolar sacs recoil as diaphragm relaxes
Air is expelled
Thoracic cavity reduces
Lung pressure>atmospheric pressure
Passive
Quiet breathing
Alveolar sacs recoil passively
Active
Forced Breathing
Muscles of the thoracic and abdominal cavity contract actively
Decreasing the volume of the thoracic cavity and increase pressure in lungs

12. Ventilation Volume of air in each breath At rest 0.5L/breath
Ventilation (VE) is the volume of air moved by the lungs in 1 minute
Combination of inspiration and expiration
Influenced by two factors:
1. Tidal volume (VT)
Volume of air in each breath
At rest 0.5L/breath
Exercise 3-4L/breath

13. Ventilation VE = VT x f Number of breaths taken per minute
2. Respiratory frequency (f)
Number of breaths taken per minute
At rest 12 breaths/minute
Exercise breaths per minute
VE = VT x f

14. Respiratory Control Centers
Breathing is result of contraction and relaxation of inspiratory and expiratory muscles
Stimulate by CNS-special areas of brain and feedback loops
Associated with overall need of O2, metabolic processes, muscle activity and CO2 production

15. Respiratory Control Centers
Respiratory control centres found within brain stem (not under conscious control)
Medulla oblongata
Inspiratory centre
Sends messages to respiratory muscles, diaphragm and external intercostals-rhythmic pattern
15-20 breaths per minute at rest
During exercise the rate is increases do to feedback mechanism
Expiratory centre
Two main functions:
Ensure the inspiratory muscles never completely relax
Stimulate forceful expiration when required (during exercise)

16. Respiratory Control Centres
Pons
Pneumotaxic and apneustic centres
Ensure smooth transition of inhalation to exhalation
Fine-tune the breathing pattern
Other areas of brain can influence ventilation
Stimulation of skeletal muscle also leads to stimulation of breathing control centres
Specialized sensory systems in order to provide feedback to control centres
For example monitor blood pH level

17. Lung Volumes Lung Volumes are divided into two categories:
Static lung volumes
Determined by the actual structure of the lung
Not influenced by breathing or flow of air
Dynamic lung volumes
Dependent on volume as well as movement/flow of air

18. Static Lung Volume Three important static lung volumes:
Total lung capacity (TLC)
Maximum volume of air that lungs can hold
Sum of vital capacity and residual volume

19. Static Lung Volume Three important static lung volumes:
2. Vital capacity (VC)
Maximum amount of air that can be exhaled following a maximal inhalation
Measured using a Forced Vital Capacity (FVC)

20. Static Lung Volume Three important static lung volumes: TLC = VC + RV
3. Residual volume (RV)
Air that remains in lungs following a maximal exhalation
TLC = VC + RV

21. Dynamic Lung Volume
Tests that involve the measurement of the movement of air by breathing
Forced Expiratory Volume (FEV)
Over 1 or 3 seconds of FVC

22. Dynamic Lung Volume
Tests that involve the measurement of the movement of air by breathing
Maximal Voluntary Ventilation (MVV)
Amount of air an individual can move over 15 seconds
Inhale and exhale
Multiply value to give value for 1 minute

23. Gas Exchange Diffusion mediates gas exchange
Diffusion is the movement of a gas, liquid, or solid from a region of high concentration to low concentration
Can only occur if a difference in concentration exists
Concentration gradient

24. Gas Exchange
Concentration for specific gases involved in respiration are measured using partial pressure

25. Fractional Concentrations and Partial Pressures of Main Gasses Found in Air

26. Gas Exchange Diffusion pathway
Area through which gases move from the lungs into the blood; from the blood into the tissue, and back
Rates of diffusion depend on:
Size of concentration gradient
Increase gradient, increase rate
Governed by Henry’s Law
Gas will dissolve into a liquid until equilibrium has been reached
Thickness of barrier between two areas
Decrease thickness, increase rate
Alveoli and capillary is only 2 cells thick
Surface area between two areas
Increase surface area, increase rate
Alveoli have large surface area, folded on top of another

28. Represents 2% of O2 found in the blood
Oxygen Transport
Oxygen (O2) transport within the blood achieved in two ways:
1. O2 dissolved within the plasma
Represents 2% of O2 found in the blood
0.05 mL O2/100 mL of blood

29. 1.34 mL of O2 for each gram of Hgb 16g Hgb/100 mL of blood
Oxygen Transport
Oxygen (O2) transport within the blood achieved in two ways: 2. Binds to Hemoglobin
1.34 mL of O2 for each gram of Hgb
16g Hgb/100 mL of blood
21.4 mL O2/100 mL blood

30. Oxygen Transport
Amount of O2 that can be carried by Hgb is termed percent saturation of hemoglobin
Sb%O
Main factor that determine % saturation is PO2 within the blood

31. Carbon Dioxide Transport
Carbon dioxide (CO2)
Moved from tissues back to lungs
Moved into alveoli and then exhaled and removed from body
Transport achieved in three ways:
1. Trace amounts of CO2 dissolved within the plasma (5-10%)

32. Carbon Dioxide Transport
2. Binds to hemoglobin (20%)-binds to globin rather than heme
Forming carbaminohemoglobin when [O2] is low, depends on PCO2
Once it arrives at the lungs the high [O2] stimulate the exchange
CO2 then diffuses into alveoli and is exhaled

33. Carbon Dioxide Transport
Transport achieved in three ways:
3. Bicarbonate system (70-75%)
Chemical reaction with H2O in RBCs forming carbonic acid (H2CO3)
Carbonic anhydrase is enzyme responsible
H2CO H+ + HCO3- where proton is carried by Hgb and bicarbonate is in the plasma
At lungs the process is reversed because the PCO2 reduced
H+ + HCO H2CO CO2 + H2O
CO2 then diffuses from blood to alveoli to be exhaled

34. Carbon Dioxide Transport
Transport achieved in three ways:
3. Bicarbonate system (70-75%)
At lungs the process is reversed because the PCO2 reduced
H+ + HCO H2CO CO2 + H2O
CO2 then diffuses from blood to alveoli to be exhaled

35. Ventilation and Control of Blood pH
Measure of how acidic or basic the blood is
Usually maintain at 7.4
Lactic acid release during exercise will result in a decline in blood pH
Due to increase in H+

36. Ventilation and Control of Blood pH
Ventilation helps regulate the amount of H+ ions in the blood
Bicarbonate system
Increase in ventilation, expel extra amounts of CO2
Cause H+ to combine with HCO3
Lowers the H+ therefore increases the pH level back to normal