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© 2013 Pearson Education, Inc.

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Slides includes material (direct or modified) from © 2013 Pearson Education, Inc. Human Anatomy & Physiology, Ninth Edition and materialsupplied by Dr J Carnegie and other sources as referenced

The Respiratory System

Lectures 1&2

ANP 1105A&EAnthony Krantis, [email protected]

These slides contain material to be presented in lecture*.The information from the lecture should be used in combination with the

relevant chapters of the recommended Text book(s).Throughout this presentation, there are references to and use of figures

from the text book. In addition, specific animations/videosare also referenced and can be used by the student forstudy purposes, if they wish.*Slides marked with a STAR will not be covered in the lecture but are

provided as additional learning material

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Basics of the Respiratory SystemFunctional Anatomy

•

What structural aspects must be considered in theprocess of respiration? –

The conduction portion

–

The exchange portion

–

The structures involved withventilation

• Skeletal & musculature•

Pleural membranes

• Neural pathways

•

All divided into

–

Upper respiratory tract•

Entrance to larynx

–

Lower respiratory tract• Larynx to alveoli (trachea

to lungs)

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Figure 22.1 The major respiratory organs in relation to surrounding structures

Nasal cavity

Nostril

Larynx

Trachea

Carina oftrachea

Right main(primary)bronchusRightlung

Oral cavity

Pharynx

Left main(primary)

bronchusLeft lung

Diaphragm

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•

Conducting zone-conduits to gas exchange sites

– Includes all other respiratory structures;

cleanses, warms, humidifies air

•

Respiratory zone-site of gas exchange – Microscopic structures-respiratory

bronchioles, alveolar ducts, and alveoli

•

Diaphragm and other respiratory muscles promoteventilation


Functional Anatomy

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Figure 22.3b The upper respiratory tract.

Pharyngeal tonsil

Oropharynx

Cribriform plateof ethmoid bone

Sphenoid sinus

Posterior nasalaperture

Nasopharynx

Opening ofpharyngotympanic tube

Uvula

Palatine tonsil

Isthmus of thefauces

Laryngopharynx

Esophagus

Trachea

Frontal sinus

Nasal cavityNasal conchae(superior, middleand inferior)

Nasal meatuses(superior, middle,and inferior)

Nasal vestibule

Nostril

Hard palate

Soft palate

Tongue

Lingual tonsil

Hyoid boneLarynx

EpiglottisVestibular fold

Thyroid cartilage

Vocal fold

Cricoid cartilage

Thyroid gland

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Nasal Cavity

•

Olfactory mucosa contains olfactory epithelium

• Respiratory mucosa

– Pseudostratified ciliated columnarepithelium

–

Mucous and serous secretions containlysozyme and defensins

– Cilia move contaminated mucusposteriorly to throat

– Inspired air warmed by plexuses ofcapillaries and veins

– Sensory nerve endings trigger sneezing

Within and posterior to external nose

• During inhalation, conchae & nasal mucosa

– Filter, heat, & moisten air

• During exhalation these structures – Reclaim heat & moisture

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Paranasal Sinuses

Lighten skull; secrete mucus; help to warm and moisten air

• Rhinitis

– Inflammation of nasal mucosa

– Nasal mucosa continuous with mucosa ofrespiratory tract ! spreads from nose ! throat

! chest

– Spreads to tear ducts and paranasal sinusescausing

• Blocked sinus passageways! air absorbed! vacuum ! sinus headache

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Pharynx

Connects nasal cavity and mouth to larynx and esophagus

–

Composed of skeletal muscle

–

Three regions

Nasopharynx

Oropharynx

Laryngopharynx

Pharynx

Figure 22.3c The upper respiratory tract.

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Larynx

• Continuous with trachea

–

Provides patent airway

– Routes air and food intoproper channels

– Voice production

Nine cartilages : All hyaline

cartilage except epiglottis

Epiglottis-elastic cartilage;covers laryngeal inlet duringswallowing; covered in taste

bud-containing mucosa

Body of hyoid bone

Thyroid cartilage

Laryngeal prominence(Adam’s apple)

Cricothyroid ligament

Cricotracheal ligament

Thyrohyoidmembrane

Cricoid cartilage

Tracheal cartilages

Epiglottis

Figure 22.4a The larynx.

Trachea

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• Pulmonary ventilation (breathing)-movement of air into and out

of lungs

• External respiration-O2 and CO2 exchange between lungs and blood

• Transport-O2 and CO2 in blood

• Internal respiration-O2 and CO2

exchange between systemic blood

vessels and tissues

Respiratorysystem

Circulatorysystem

Processes of Respiration

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Trachea

Esophagus

Trachealis

muscle

Lumen oftrachea

Posterior

Mucosa

Submucosa

Hyaline cartilage

Adventitia

Seromucous glandin submucosa

Anterior

Cross section of the tracheaand esophagus

• Windpipe –from larynx into

mediastinum• 3 layers

– Mucosa-ciliated pseudo-stratified epithelium withgoblet cells

– Submucosa-connective tissue

– Adventitia-outermost layer ofconnective tissue; encases C-

shaped rings of hyaline

cartilage

Figure 22.6a Tissue composition of the tracheal wall.

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Figure 22.10c Anatomical relationships of organs in the thoracic cavity.

Transverse section through the thorax, viewed from above. Lungs, pleuralmembranes, and major organs in the mediastinum are shown.

Posterior

Parietal pleura

Visceral pleura

Pleural cavity

Pericardial

membranesSternum

Vertebra

Esophagus

(in mediastinum)Root of lungat hilum

• Left mainbronchus• Left pulmonaryartery

• Left pulmonaryvein

Thoracic wall

Heart (in mediastinum)

Anterior mediastinum

Anterior

Left lung

Pulmonary trunk

Right lung

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Figure 22.7 Conducting zone passages

Superior lobe

of right lung

Middle lobe

of right lung

Inferior lobe

of right lung

Trachea

Superior lobe

of left lung

Left main(primary)bronchus

Lobar (secondary)bronchus

Segmental (tertiary)bronchus

Inferior lobeof left lung

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Conducting Zone Structures

• Trachea! right and left main (primary) bronchi

•

Each main bronchus enters hilum of one lung

– Right main bronchus wider, shorter, morevertical than left

• Each main bronchus branches into lobar

(secondary) bronchi (three on right, two on left)

– Each lobar bronchus supplies one lobe

•

Air passages undergo 23 orders of branching !

bronchial (respiratory) tree •

From tips of bronchial tree ! conducting zonestructures ! respiratory zone structures

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Figure 22.11 A cast of the bronchial tree.

Right lung Left lung

Left superiorlobe(4 segments)

Left inferiorlobe(5 segments)

Rightinferior lobe(5 segments)

Right

middlelobe (2segments)

Rightsuperiorlobe (3segments)

• Lobar bronchus branches into segmental (tertiary) bronchi

–

segmental bronchi divide repeatedly

• Branches become smaller

Bronchioles- <1 mm in diameter Terminal bronchioles - < 0.5 mm

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Respiratory ZoneBegins as terminal bronchioles ! respiratory bronchioles !

alveolar ducts ! alveolar sacs

–

Alveolar sacs contain clusters of alveoli

•

~300 million alveoli make up most of lung volume

•

Sites of gas exchange

Alveolar duct

Respiratory bronchioles

Terminalbronchiole

Alveoli

Alveolar duct

Alveolarsac

Figure 22.8a Respiratory zone structures.

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Figure 22.9a Alveoli and the respiratory membrane.

Terminal bronchiole

Respiratory bronchiole

Smooth

muscle

Elasticfibers

Alveolus

Capillaries

Diagrammatic view of capillary-alveoli relationships

Alveolar and capillary walls and

their fused basement membranes

~0.5µm thick; gas exchange by

simple diffusion

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Figure 22.9c Alveoli and the respiratory membrane

Red bloodcell incapillary

Alveoli(gas-filledair spaces)

Type IIalveolarcell

Type Ialveolarcell

Capillary

Macrophage

Endothelial cellnucleus

Respiratorymembrane

Alveolarepithelium

Fused basementmembranes ofalveolarepithelium and

capillaryendothelium

Capillaryendothelium

Capillary

Alveolus

Nucleus of type Ialveolar cell

Alveolar pores

Red bloodcell

Alveolus

secrete surfactant and

antimicrobial proteins

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Blood Supply

• Pulmonary circulation (low P, high V)

–

Pulmonary arteries deliver systemic venous blood to lungs foroxygenation

• feed into pulmonary capillary networks

– Pulmonary veins carry oxygenated blood from respiratory zones toheart

• Bronchial arteries provide oxygenated blood to lung tissue

– Arise from aorta and enter lungs at hilum

– Part of systemic circulation (high P, low V)

– Supply all lung tissue except alveoli

–

Bronchial veins anastomose with pulmonary veins•

Pulmonary veins carry most venous blood back to heart

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22

Lungs and Pleura

Pleural cavity – slit-like potential space filled with pleuralfluid

"

Lungs can slide but separation from pleura is resisted(acts like film between 2 plates of glass)

" Lungs cling to thoracic wall and are forced to expand

and recoil as volume of thoracic cavity changesduring breathing

Around each lung is a flattenedsac of serous membrane called pleura

Parietal pleura – outer layer

Visceral pleura – directly on lung

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Pressure Relationships in the Thoracic Cavity

• Atmospheric pressure (Patm)

–

P exerted by air surrounding body

– 760 mm Hg at sea level = 1 atmos

• Respiratory pressures described relative to Patm

–

Negative respiratory pressure- less than Patm – Positive respiratory pressure- greater than Patm

– Zero respiratory pressure = Patm

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Intrapulmonary Pressure

• Intrapulmonary (intra-alveolar) pressure (Ppul)

–

Pressure in alveoli

–

Fluctuates with breathing

– Always eventually equalizes with Patm

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Intrapleural Pressure

• Intrapleural pressure (Pip)

–

Pressure in pleural cavity

– Fluctuates with breathing

– Always negative

–

Fluid level must be minimal• Pumped out by lymphatics

• If accumulates! positive Pip ! lung collapse

Disruption of the integrity of the pleuralmembrane will result in a rapid

equalization of pressure and loss ofventilation function = collapsed lung or

pneumothorax

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Figure 22.12 Intrapulmonary and intra-pleural pressure relationships.

Atmospheric pressure (P atm) 0 mm Hg (760 mm Hg)

Thoracic wall

Parietal pleura

Visceral pleura

Pleural cavity

Transpulmonarypressure 4 mm Hg(the differencebetween 0 mm Hgand !4 mm Hg)

Intrapleuralpressure (P ip) !4 mm Hg(756 mm Hg)

Intrapulmonarypressure (P pul) 0 mm Hg(760 mm Hg)

Diaphragm

Lung

0

– 4

• If Pip = Ppul or Patm ! lungs collapse

• (Ppul – Pip) = transpulmonary pressure

– Keeps airways open

– Greater transpulmonary pressure! larger lungs

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Figure 22.13 Changes in thoracic vol. and sequence of events duringinspiration

Inspiratory musclescontract (diaphragmdescends; rib cage rises).

Thoracic cavity Vincreases.

Lungs are stretched;intrapulmonary Vincreases.

Intrapulmonary Pdrops (to –1 mm Hg).

Air (gases) flows intolungs down its P gradientuntil intrapulmonaryP is 0 (= Atmos P).

I n s p i r a t i o n

SequenceChanges in anterior-posterior &

superior-inferior dimensions

Changes in lateral dimensions

(superior view)

1

2

3

4

5 Diaphragmmoves inferiorlyduringcontraction.

Ribs areelevated andsternumflares as

externalintercostalscontract.

Externalintercostalscontract

*** ACTIVE PROCESS

During deep or forced inspiration,

additional muscles recruited:

Scalenes

Sternocleidomastoid

Pectoralis minor

Quadratus lumborum on 12th rib

Erector spinae

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Figure 22.13 Changes in thoracic vol. and sequence of events during expiration

1

E x p i r a t i o

n

SequenceChanges in anterior-posterior and

superior-inferior dimensions

Changes in lateral dimensions

(superior view)

2

3

4

5 Diaphragmmovessuperiorlyas it relaxes.

Ribs andsternum aredepressed

as externalintercostalsrelax.

Externalintercostalsrelax

Inspiratory muscles relax(diaphragm rises; rib cagedescends due to recoil ofcostal cartilages).

Thoracic cavity volumedecreases.

Elastic lungs recoilpassively; intrapulmonaryVolume decreases.

Intrapulmonary P rises(to +1 mm Hg).

Air (gases) flows out oflungs down its P gradientuntil intrapulmonarypressure is 0.

PASSIVE PROCESS….but forced expiration- is active process; usesabdominal (oblique and transverse) and internal intercostal muscles

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Figure 22.14 Changes in intrapulmonary and intrapleural pressures during inspiration and expiration.

Intrapulmonary PPressure inside lung

decreases as lung volincreases duringinspiration; pressureincreases during expiration.

Intrapleural P Pleural cavity pressure

becomes more negative aschest wall expands duringinspiration. Returns to initial

value as chest wall recoils.

Volume of breath. Duringeach breath, the pressure

gradients move 0.5 liter ofair into and out of the lungs.

P r e s s u r e r e l a t i v e t o

a t m o s

p h e r i c p r e s s u r e

( m m H

g )

V o l u m

e ( L )

Inspiration Expiration

Intrapulmonarypressure

Trans-pulmonarypressure

Intrapleuralpressure

Volume of breath

5 seconds elapsed

+2

0

–2

–4

–6

–8

0.5

0

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Pulmonary Ventilation: Inspiration and Expiration

Mechanical processes due to volume changes in thoracic

cavity –

Volume (V) changes! P changes

–

P changes! gases flow to equalize P

Boyle's LawPressure (P) varies inversely

with volume (V): P1V1 = P2V2

Three factors hinder

air passage & pulmonary ventilation;

1. Airway resistance

2. Alveolar surface tension

3. Lung compliance

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Airway Resistance

• Friction- major nonelastic source of resistance to

gas flow; occurs in airways

• Relationship between flow (F), pressure (P), and

resistance (R) is:

– !P - pressure gradient between atmosphere and

alveoli (2 mm Hg or less during normal quiet

breathing)

–

Gas flow changes inversely with resistance

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Conductingzone

Respiratoryzone

Medium-sizedbronchi

R

e s i s t a n c e

Terminal

bronchioles

1 5 10 15 20 23

Airway generation(stage of branching)

Figure 22.15 Resistance in respiratory passageways

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Homeostatic Imbalance

• As airway resistance rises, breathing

movements become more strenuous

- Severe constriction or obstruction of

bronchioles

- Can prevent ventilation –

Eg. acute asthma attacks; stops ventilation

• Epinephrine dilates bronchioles, reduces air

resistance

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Alveolar Surface Tension

•

Surface tension

–

Attracts liquid molecules to one another at gas-liquidinterface

–

Resists any force that tends to increase surface area

of liquid

–

Water–high surface tension; coats alveolar walls !

reduces them to smallest size

• Surfactant

–

Detergent-like lipid protein complex produced by type II alveolarcells

–

Reduces surface tension of alveolar fluid and discouragesalveolar collapse

–

Insufficient quantity in premature infants causes infant

respiratory distress syndrome ! alveoli collapse after each

breath

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Lung Compliance

• Measure of change in lung V that occurs

with given change in transpulmonary P

• Higher lung compliance! easier to

expand lungs

•

Normally high due to

–

Distensibility of lung tissue

– Alveolar surface tension

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Pulmonary Function Tests

• Spirometer- measures respiratory volumes and

capacities

• Spirometry can distinguish between

– Obstructive pulmonary disease —increasedairway resistance (e.g., bronchitis)

•

TLC, FRC, RV may increase

– Restrictive disorders —reduced TLC due todisease or fibrosis

• VC, TLC, FRC, RV decline

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Figure 22.16a Respiratory volumes and capacities.

5000

4000

3000

2000

1000

0

M i l l i l i t e r s ( m l )

Spirographic record for a male

6000

Inspiratoryreserve volume

3100 ml

Expiratoryreserve volume

1200 ml

Residual volume1200 ml

Inspiratorycapacity3600 ml

Functionalresidualcapacity2400 ml

Vitalcapacity4800 ml

Total lungcapacity6000 ml

Tidal volume 500 ml

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Figure 22.16b Respiratory volumes and capacities.

Measurement

Adult male

ave value

Adult female

ave value Description

Respiratoryvolumes

Respiratorycapacities

Summary of respiratory volumes and capacities for males and females

Tidal volume (TV)

Inspiratory reservevolume (IRV)

Expiratory reservevolume (ERV)

Residual volume (RV)

500 ml 500 ml

3100 ml

1200 ml

1200 ml

1900 ml

700 ml

1100 ml

Amount of air inhaled or exhaled with each breath under restingconditions

Amount of air that can be forcefully inhaled after a normal tidalvolume inspiration

Amount of air that can be forcefully exhaled after a normal tidalvolume expiration

Amount of air remaining in the lungs after a forced expiration

Maximum amount of air contained in lungs after a maximuminspiratory effort: TLC = TV + IRV + ERV + RV

Maximum amount of air that can be expired after a maximuminspiratory effort: VC = TV + IRV + ERV

Maximum amount of air that can be inspired after a normal tidalvolume expiration: IC = TV + IRV

Volume of air remaining in the lungs after a normal tidal volumeexpiration: FRC = ERV + RV

6000 ml

4800 ml

3600 ml

2400 ml

4200 ml

3100 ml

2400 ml

1800 ml

Total lung capacity (TLC)

Vital capacity (VC)

Inspiratory capacity (IC)

Functional residualcapacity (FRC)

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Dead Space

• Anatomical dead space

–

No contribution to gas exchange

– Air remaining in passageways; ~150 ml

•

Alveolar dead space –non-functional alveoli

due to collapse or obstruction

•

Total dead space-sum of anatomical andalveolar dead space

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AVR = frequency X (TV – dead space)

(ml/min)

(breaths/min)

(ml/breath)

Alveolar Ventilation

• Good indicator of effective ventilation

•

Alveolar ventilation rate (AVR)-flow of gases into and out ofalveoli in one minute - rough estimate of respiratory efficiency

• Dead space normally constant

• Rapid, shallow breathing decreases AVR

AVR – Normal at rest = ~ 6 L/min

– Normal with exercise = up to 200 L/min

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Table 22.2 Effects of Breathing Rate and Depth on Alveolar ventilation

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