ch 17 respiratory mechanics 07

POWERPOINT® LECTURE SLIDE PRESENTATIONby LYNN CIALDELLA, MA, MBA, The University of Texas at AustinAdditional Text by J Padilla exclusively for physiology at ECC

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

HUMAN PHYSIOLOGYAN INTEGRATED APPROACH FOURTH EDITION

DEE UNGLAUB SILVERTHORN

UNIT 3UNIT 3

17Mechanics of Breathing


About this Chapter

The respiratory system

Gas laws

Ventilation


Respiratory System

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


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

Muscular pump creates pressure gradients

Resistance to flow Diameter of tubes


Respiratory System

Right ventricle pulmonary trunk lungs pulmonary veins left atrium

Figure 17-1

Ventilation

External Respiration

Circulation

Internal Respiration

Cellular Respiration

Ventilation

External Respiration

Circulation

Internal Respiration

Cellular Respiration


Respiratory System

Conducting system- components of the respiratory tract that are involved with the flow of air and not the exchange

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 to create. Includes the diaphram, internal/external intercostal, abdominals, ect.

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 17-2a

Respiratory System

Lungs are surrounded by serous membranes that make up the pleura

Lungs are surrounded by serous membranes that make up the pleura

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 17-2b

Muscles Used for Ventilation

Some muscles are only used during forceful expiration or inspiration

Some muscles are only used during forceful expiration or inspiration

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 17-3

The Respiratory System

The relationship between the pleural sac and the lung

Pleural fluid reduces friction and protects the lungsPleural fluid reduces friction and protects the lungs

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 17-2e

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

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


Branching of the Airways

As branching becomes more numerous the wall thin out. Alveoli design allows for increased surface area.As branching becomes more numerous the wall thin out. Alveoli design allows for increased surface area.

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 17-2g

Alveolar Structure

Type I cells make up the walls of the alveoli

Type II cells release surfactant to prevent alveolar collapse

Type I cells make up the walls of the alveoli

Type II cells release surfactant to prevent alveolar collapse


Gas Laws

Keep these laws in mind as you learn how respiration occurs.Keep these laws in mind as you learn how respiration occurs.


Gas Laws

Pgas = Patm % of gas in atmosphere

Temperature and humidity affect how much a gas expandsTemperature and humidity affect how much a gas expands


Boyle’s Law

Gases move from areas of high pressure to areas of low pressure


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.

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.


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

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


Conditioning

Functions performed by the nasal epithelium:

Warming air to body temperature

Adding water vapor

Filtering out foreign material


Ciliated Respiratory Epithelium


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


Movement of the Diaphragm


Movement of the Rib Cage during Inspiration

Rib movement increases or decreases the width of the rib cage.


Pressure Changes during Quiet Breathing

Notice the intrapleural pressure drops more than alveolar and it is not exactly aligned with alveolar changes

Notice the intrapleural pressure drops more than alveolar and it is not exactly aligned with alveolar changes


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

The pull on the walls creates a pressure lower than atmospheric- allowing air to move in and keep the lung from collapsing


Pressure in the Pleural Cavity

Pneumothorax results in collapsed lung that can not function normally


Compliance and Elastance

Compliance: ability to stretch High compliance- not a helpful condition in lungs

Stretches easily- but has low recoil Low compliance

Requires more force- more work is needed to stretch a stiff lung

Restrictive lung diseases- pathology decreasing copliance 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


Law of LaPlace

Surface tension is created by the thin fluid layer between alveolar cells and the air


Surfactant

More concentrated in smaller alveoli

Mixture containing proteins and phospholipids

Newborn respiratory distress syndrome Premature babies

Inadequate surfactant concentrations


Air Flow

Animation: Respiratory System: Pulmonary VentilationPLAY

As in circulatory system the major factor affecting resistance is vessel diameter

As in circulatory system the major factor affecting resistance is vessel diameter


150

150mL

350

150

2700 mL

2200 mL

2200 mL

Dead space filled with fresh air

PO2 = 160 mm HgPO2 ~ 100 mm Hg~

150mL

2200 mL

150mL

Respiratorycycle inan adult

End of inspiration

Inhale 500 mLof fresh air (tidal volume).

Dead space filled with stale air

KEY

Only 350 mL

of fresh airreachesalveoli.

The first exhaledair comes out ofthe dead space.Only 350 mL leavesthe alveoli.

Dead spaceis filled with

fresh air.

The first 150 mLof air into the

alveoli is staleair from thedead space.

At the end of expiration, the dead space is filled with “stale” air from alveoli.

500 mL

150

350

Atmosphericair

Exhale 500 mL(tidal volume).

1

1

2

3

4

2

3

4

Figure 17-14

Ventilation ****

Total pulmonary ventilation and alveolar ventilation

Total pulmonary ventilation = ventilation rate tidal volume

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 17-14, step 1

Ventilation

150mL

2700 mL


PO2 = 160 mm HgPO2 ~ 100 mm Hg~


KEY

1

End of inspiration1

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 17-14, steps 1–2

Ventilation

150mL

2700 mL

2200 mL


PO2 = 160 mm HgPO2 ~ 100 mm Hg~

150mL


End of inspiration

KEY


150

350


1

1

22


Ventilation

150mL

2700 mL

2200 mL


PO2 = 160 mm HgPO2 ~ 100 mm Hg~

150mL

2200 mL

150mL


End of inspiration


KEY



150

350


1

1

2

3

2

3


Ventilation

150

150mL

350

150

2700 mL

2200 mL

2200 mL


PO2 = 160 mm HgPO2 ~ 100 mm Hg~

150mL

2200 mL

150mL


End of inspiration



KEY

Only 350 mL




fresh air.




500 mL

150

350

Atmosphericair


1

1

2

3

4

2

3

4


Ventilation

Alveolar ventilation =

ventilation rate (tidal volume – dead space volume)


Ventilation


Ventilation

Effects of changing alveolar ventilation on PO2 and PCO2 in the alveoli

Figure 17-15


Ventilation

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

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


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


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


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)



Diffusion rate is proportional to surface area- here the walls are broken down, the lung now has high-compliance, low-elasticity

Diffusion rate is proportional to surface area- here the walls are broken down, the lung now has high-compliance, low-elasticity


Healthy Lung Emphysema

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18-4c


Diffusion rate is inversely proportional to membrane thickness- thickened by scar tissue

Diffusion rate is inversely proportional to membrane thickness- thickened by scar tissue

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18-4d

Alveolar Ventilation (Chapter 18)Diffusion rate is inversely proportional to distanceDiffusion rate is inversely proportional to distance

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18-4e


Decreased ventilation brings in low oxygen and thus the blood will have less oxygen dissolved in it

Decreased ventilation brings in low oxygen and thus the blood will have less oxygen dissolved in it


Lung Cancer

ch 17 respiratory mechanics 07

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