1. Mechanics of Breathing
17 & 18

2. Respiratory System Functions & Structures
Fuctions:
Exchange of gases between the atmosphere and the blood- inhale O2 and exhale CO2
Homeostatic regulation of body pH- the amounts of CO2 in the blood affect the pH
Protection from inhaled pathogens and irritating substances- preventive mechanisms against pathogens that could cause harm
Vocalization- voice production is possible when one exhales
Structures or zones
Conducting system (zone)- components of the respiratory tract that are involved with the flow of air and not the exchange
Respiratory zones- site where gas exchange occurs
Alveoli- site for quick two-way transfer of substances between the blood and the lung tissue
Bones and muscle of thorax- (muscular pump) use to increase or decrease pressure. Includes the diaphram, internal/external intercostal, abdominals, ect.

3. Respiratory System Ventilation External Respiration Circulation
Pulmonary circulation:
Right ventricle  pulmonary trunk  lungs  pulmonary veins  left atrium
Ventilation
External Respiration
Circulation
Internal Respiration
Cellular Respiration
Figure 17-1

4. Conditioning
Functions performed by the respiratory epithelium found in the nasal cavity and trachea:
Warming air to body temperature
Adding water vapor
Filtering out foreign material

5. Respiratory System There are three sections to the pharynx.
The upper respiratory tract is purely a conduction zone. Lower respiratory tract includes conduction and respiratory zones
Lungs are surrounded by serous membranes called pleura
Figure 17-2a

6. Detailed Anatomy of Upper Respiratory Tract

7. The Plural Membranes
The relationship between the pleural sac and the lung
Pleural fluid reduces friction and protects the lungs
Figure 17-3

8. Muscles Used for Ventilation
Some muscles are only used during forceful expiration or inspiration
Figure 17-2b

9. Movement of the Diaphragm

10. Movement of the Rib Cage during Inspiration
Rib movement increases or decreases the width of the rib cage.

11. Branching of Airways
Branching of airways changes in ways similar to how it occurs in blood vessels. In the lungs airway diameter is also mediated by smooth muscle
Figure 17-2e

12. Branching of the Airways
As branching becomes more numerous the wall thins out. Alveoli design allows for increased surface area.
Figure 17-4

13. Alveolar Structure Type I cells make up the walls of the alveoli
Type II cells release surfactant to prevent alveolar collapse
Figure 17-2g

14. Alveoli & Capillary Walls

15. Principles of Bulk Flow
THESE ARE FACTORS THAT AFFECT THE FLOW OF AIR- NOTICE HOW THEY ARE THE SAME AS THOSE THAT AFFECT THE FLOW OF BLOOD
Flow from regions of higher to lower pressure
Boyle’s Law P1V1=P2V2
Decreasing volume increases collision & decreases pressure
Muscular pump creates pressure gradients
Muscular contractions increase or decrease the size of the thoracic cavity, changing the pressure so air moves in or out
Resistance to flow
Diameter of the bronchiole tubes changes size to increase or decrease resistance.
Bronchoconstriction increases resistance and reduces flow

16. Spirometer
This apparatus measure the air going into or out of the lungs. It does not measure the TOTAL air volume moving in the lungs because, like the heart, they are never completely empty.
Figure 17-6

17. Air Flow
Flow  P/R = air flows due to pressure gradient and decreased with increased resistance
Alveolar pressure or intrapleural pressure can be measured = the amount of air that moves in/out can be used to infer pressure
Single respiratory cycle consists of inspiration followed by expiration= remember- there is quiet and forced breathing

18. Lungs Volumes and Capacities
RV= residual volume ERV=air forcefully exhaled Vt= amount the is normally exhaled& inhaled IRV= additional air above Vt VC=maximum amount of air that can move in/out
Figure 17-7

19. Pressure Changes during Quiet Breathing
Notice the intrapleural pressure drops more than alveolar and it is not exactly aligned with alveolar changes
Figure 17-11

20. Pressure in the Pleural Cavity
The pull on the walls creates a pressure lower than atmospheric- allowing air to move in and keep the lung from collapsing. Pneumothorax results in collapsed lung that can not function normally
Figure 17-12a

21. Compliance and Elastance
Compliance: ability to stretch
High compliance- not a helpful condition in lungs
Stretches easily- but has low recoil thus its hard to exhale
Low compliance
Requires more force- more work is needed to stretch a stiff lung
Restrictive lung diseases- pathology decreasing compliance
Fibrotic lung diseases and inadequate surfactant production- inelastic scar tissue and alveolar walls that stick together
Elastance: returning to its resting volume when stretching force is released

22. Surface Tenstion and Surfactant
Surface tension is created by the thin fluid layer between alveolar cells and the air
Mixture containing proteins and phospholipids that reduces surface tension.
Increased surface tension would cause the alveolar walls to stick to each other
Newborn respiratory distress syndrome
Premature babies may have inadequate surfactant concentrations making difficult for them to breathe

23. Ventilation **** Total pulmonary ventilation and alveolar ventilation
Total pulmonary ventilation = ventilation rate  tidal volume
150 mL
350
2700 mL
2200 mL
Dead space filled with fresh air
PO2 = 160 mm Hg
PO2 ~ 100 mm Hg ~
Respiratory
cycle in
an adult
End of inspiration
Inhale 500 mL
of fresh air
(tidal volume).
Dead space filled
with stale air
KEY
Only
350 mL
reaches
alveoli.
The first exhaled
air comes out of
the dead space.
Only 350 mL leaves
the alveoli.
Dead space
is filled with
fresh air.
The first 150 mL
of air into the
alveoli is stale
air from the
dead space.
At the end of
expiration, the
dead space is
filled with
“stale” air from
500 mL
Atmospheric
air
Exhale 500 mL 1 2 3 4
Figure 17-14

24. Ventilation Figure 17-14, steps 1–2 Dead space filled with fresh air
150 mL
2700 mL
2200 mL
Dead space filled with fresh air
PO2 = 160 mm Hg
PO2 ~ 100 mm Hg ~
Respiratory
cycle in
an adult
End of inspiration
KEY
The first exhaled
air comes out of
the dead space.
Only 350 mL leaves
the alveoli.
350
Exhale 500 mL
(tidal volume). 1 2
Figure 17-14, steps 1–2

25. Ventilation Figure 17-14, steps 1–3 150 mL 2700 mL 2200 mL
Dead space filled with fresh air
PO2 = 160 mm Hg
PO2 ~ 100 mm Hg ~
Respiratory
cycle in
an adult
End of inspiration
Dead space filled
with stale air
KEY
The first exhaled
air comes out of
the dead space.
Only 350 mL leaves
the alveoli.
At the end of
expiration, the
dead space is
filled with
“stale” air from
alveoli.
350
Exhale 500 mL
(tidal volume). 1 2 3
Figure 17-14, steps 1–3

26. Ventilation Figure 17-14, steps 1–4 150 mL 350 2700 mL 2200 mL
Dead space filled with fresh air
PO2 = 160 mm Hg
PO2 ~ 100 mm Hg ~
Respiratory
cycle in
an adult
End of inspiration
Inhale 500 mL
of fresh air
(tidal volume).
Dead space filled
with stale air
KEY
Only
350 mL
reaches
alveoli.
The first exhaled
air comes out of
the dead space.
Only 350 mL leaves
the alveoli.
Dead space
is filled with
fresh air.
The first 150 mL
of air into the
alveoli is stale
air from the
dead space.
At the end of
expiration, the
dead space is
filled with
“stale” air from
500 mL
Atmospheric
air
Exhale 500 mL 1 2 3 4
Figure 17-14, steps 1–4

27. Ventilation Figure 17-14, steps 1–5 150 mL 350 2700 mL 2200 mL
Dead space filled with fresh air
PO2 = 160 mm Hg
PO2 ~ 100 mm Hg ~
Respiratory
cycle in
an adult
End of inspiration
Inhale 500 mL
of fresh air
(tidal volume).
Dead space filled
with stale air
KEY
Only
350 mL
reaches
alveoli.
The first exhaled
air comes out of
the dead space.
Only 350 mL leaves
the alveoli.
Dead space
is filled with
fresh air.
The first 150 mL
of air into the
alveoli is stale
air from the
dead space.
At the end of
expiration, the
dead space is
filled with
“stale” air from
500 mL
Atmospheric
air
Exhale 500 mL 1 2 3 4
Figure 17-14, steps 1–5

28. Ventilation Alveolar ventilation =
ventilation rate  (tidal volume – dead space volume)

29. Ventilation

30. Ventilation
Effects of changing alveolar ventilation on PO2 and PCO2 in the alveoli
Figure 17-15

31. Ventilation
Notice that the sytemic arterioles and bronchioles react the same and opposite to the pulmonary arterioles.

32. Ventilation
Auscultation = diagnostic technique- listening to breath sounds to resulting from different types of fluid accumulations or membrane changes
Obstructive lung diseases- cause narrowing of the bronchioles reducing the amount of air flow
Asthma- caused by allergies leading to inflammation or edema
Emphysema- reduction in alveolar surface area, decreased tissue elasticity, mucous build-up
Chronic bronchitis- also called COPD- inflammation of the bronchioles due to infection

33. Causes of Low Alveolar PO2 (Chapter 18)
Inspired air has abnormally low oxygen content
Altitude
Alveolar ventilation is inadequate
Decreased lung compliance
Increased airway resistance
Overdose of drugs
Pathological changes
Decrease in amount of alveolar surface area
Increase in thickness of alveolar membrane
Increase in diffusion distance between alveoli and blood

34. Alveolar Ventilation (Chapter 18)
Pathological conditions that reduce alveolar ventilation and gas exchange
-only high altitude reduces oxygen amounts in air
-most disorders are due to decreased lung compliance, increased resistance, or slow ventilation (CNS affected)
Figure 18-4a

35. Alveolar Ventilation (Chapter 18)
Diffusion rate is proportional to surface area- here the walls are broken down, the lung now has high-compliance, low-elasticity
Figure 18-4b

36. Healthy Lung Emphysema

37. Alveolar Ventilation (Chapter 18)
Diffusion rate is inversely proportional to membrane thickness- thickened by scar tissue
Figure 18-4c

38. Alveolar Ventilation (Chapter 18)
Diffusion rate is inversely proportional to distance
Figure 18-4d

39. Alveolar Ventilation (Chapter 18)
Decreased ventilation brings in low oxygen and thus the blood will have less oxygen dissolved in it
Figure 18-4e

40. Lung Cancer