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Objectives for Respiratory System
1. State the function of the respiratory system
2. Name the 2 organization of the respiratory system
3. Describe the structure of the conduction airway & the function of this airway
4. Describe the structure of the nasal cavity
5. List the divisions of the pharynx and the types of cells involved in its make-up
6. Explain the structure of the laryngotracheal airway
7. State the importance of the structure and function of the glottis
8. Describe the branching of the tracheobronchial tree
9. Discuss the structure and the function of the alveolar sacs
10. Explain the type of cells & circulation process of the respiratory membrane
11. Describe the structure of the lung tissue
12. State the function & divisions of the lungs
13. List the types & function of the alveolar cells
14. Explain the process of ventilation
15. Discuss the concepts of alveolar pressure, intrapleural pressure & intrathoracic pressure
16. Explain the principal of lung compliance
17. Discuss the importance, structure & function of surfactant
18. Compare the difference of pulmonary & alveolar ventilation
19. Describe the pulmonary blood flow
20. Explain the principal of diffusion in regards to the respiratory system
21. Explain the concepts of dead space & shunting
22. Discuss oxygen transport for the respiratory system
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23. Describe the structure & function of the hemoglobin molecule
24. Discuss the carbon dioxide transport in the respiratory system
25. Explain the factors that control breathing
26. Review the concepts involved in lung volumes
27. Discuss and compare the various diseases of the respiratory system along with the various
traumas of the respiratory system.
28. Discuss challenges of patient care challenges and categories of blast injuries
29. Describe the patient care challenges of lung injury related to blast injury
30. Describe the related injuries noted with blast injury
31. Describe the challenges of system challenges noted with blast injury
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Lecture 6: The Respiratory System
I. Respiratory System (pulmonary ventilation – physical movement of air in and out body
physiology – air exchange & gas transport)
A. Functions
1. Move air in & out for exchange via diffusion
2. Provide nonspecific defenses against pathogen
3. Permits vocal communication
4. Help control pH of body fluids
B. Organization
1. Conducting airways – air movement between atmosphere & lungs
2. Respiratory tissue – gas exchange site
C. Structures in respiratory tract
1. Conducting airways (warms, filters, & moistens the air)
a. Tissues of the airways
1) Mucosal lining – epithelial & connective tissue
a) Mucus-secreting gland cell (mucociliary blanket)
b) Protects against foreign substances
c) Cilia hairlike projections –secrete antibacterial enzyme
(1) Slowed by heat, smoke, high or low O2
d) Cell epithelial changes from pseudostratified to
cuboidal to squamous as moves down tract
e) About 1 pint H2O/day in secretions = moisture
2) Smooth muscles
3) Supporting connective tissue
2. Nasopharyngeal (nose, mouth to epiglottis)
a. Entrance point mostly nose
1) External nares - opening
2) Nasal cavity
a) Vestibule – anterior portion
b) Bones – maxillary, nasal, frontal, ethmoid, sphenoid
c) Hard palate
d) Soft palate
e) Nasal septum
f) Internal nares – opens into nasophrynx
g) Conchae (superior, middle, inferior) – warms, filters,
humidifies
3) Mucous membrane – lots blood vessels
a) Goblet cells
4) Paranasal sinuses (frontal, sphenoid, ethmoid, maxillary)
5) Tears – flush cavity
c. Mouth – alternate entry point
d. Neural control of tongue & pharyngeal muscles
1) Swelling, muscle or neural loss, or tongue = obstruction
2) Cranial nerves= V,VII,IX, XI, XII
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e. Pharynx (throat) – shares digestive & respiratory functions
1) Divisions
a) Nasopharynx – nares to posterior soft palate
b) Oropharynx – soft palate to hyoid
c) Laryngopharynx – hyoid to esophagus
2) Cells – epithelium to stratified squamous in lower
3) Connects
4) Tonsils = lymph tissue
a) Pharyngeal- 2 = posterior throat
b) Palatine -2 = tongue base
c) Adenoid -1
3. Laryngotracheal airway (larynx)
a. Connects oropharynx to trachea
b. Wall are rigid cartilaginous
c. Function
1) Speech
2) Protection
d. 2x2 mucous membrane folds
1) Vestibular fold
2) Vocal fold
e. Glottis –muscles between folds
1) Epiglottis – projects above & moves down to cover with food
2) Leaf shaped
3) Above vocal cords
4) Cartilage
f. Thyroid cartilage –
g. Cricoid cartilage – posterior support
h. Other cartilage – arytenoids, corniculate, cuneiform – supported by
cricoid
i. Ligaments – enclose folds of epithelium & between thyroid cartilage
(reduce size glottis)
j. Vocal cords (sound produced by vibrations of true cords)
1) False
2) True
4. Tracheobronchial Tree (trachea, bronchi, bronchioles)
a. Trachea – windpipe, flexible tube 6th vertebra & 5th thoracic
1) Branches
2) Tracheal cartilages – support (C-shaped rings)
a) Food passage on posterior side
b) Sympathetic stimulation changes size
b. Bronchi – right & left (primary bronchi & branches)
1) Carina – between bronchi = mucous sensitive = cough
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2) Airway lined with mucosal surface & cartilage support rings
3) Has pulmonary arteries, veins, lymph vessels
4) Enters lungs via Hilus (slit)
5) Primary, secondary, tertiary
c. Bronchioles – smaller branches of bronchi = exchange areas
1) Structure
a) Decreasing cartilage as move down
b) Increase in smooth muscle & elastin
(1) Help maintain patency of airway
2) Terminal bronchioles – air supply to lung lobule
a) Lobule – lung tissue bounded by connective tissue
d. Alveolar ducts & alveoli
1) Ducts – bronchioles open into these chambers
2) Alveolar sacs
3) Alveoli – exchange surfaces (150 million)
a) Surface – simple squamous epithelium – thin
b) Alveolar macrophages – phagocytizing
c) Surfactant cells – reduce surface tension,
prevent alveolar collapse
e. Respiratory membrane
1) Cells
a) Squamous epithelial – line alveolus
b) Endothelial cells – adjacent capillary
c) Fused basement membranes – line alveolar &
endothelial cells
d) Alveolar macrophages
e) Surfactant cells
2) Diffusion (short distance & O2 & CO2 – lipid soluble)
3) Circulation – pulmonary circuit (entire Cardiac output)
a) Pulmonary arteries
b) Pulmonary veins
c) Pressure lower than systemic
d) Duel supply from pulmonary & bronchial
(1) Pulmonary – exchange
(2) Bronchial – airways & supporting structure
(a) Warms & humidifies
(b) Come from thoracic aorta
(c) Drains into bronchial vein to vena
Cava
(d) No gas exchange
(e) Angiogenesis
5. Pleural Cavities – potential space
a. Parietal & visceral usually close contact
b. Layer of fluid
6. Changes at birth
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D. Lungs & respiratory airways
1. Lungs – functional units
a. Structure
1) Soft, sponge cone-shaped bilateral pairs
2) Separated by mediastinum
3) Apex
4) Base
5) Lobes (3 on right & 2 on left)
b. Functions
1) Gas exchange
2) Convert angiotensin I to angiotensin II
3) Reservoir for blood
4) Heparin producing cells
c. Division
1) Right (3 lobes)
2) Left (2 lobes)
d. Pleura or pleural cavities
1) Single cavity lined by serous membrane (pleura)
a) Parietal pleura – outer on thoracic wall
b) Visceral pleura – inner on lung surface
c) Pleural cavity – space between parietal & visceral
(1) Serous fluid contained – sliding pleura
e. Alveolar Cells
1) Type I – flat squamous epithelial cells = gas exchange
2) Type II – surfactant producer
3) Alveolar macrophages – protectors
f. Process
1) Rest
2) Inhalation
3) Exhalation
2. Changes from Fetus to Neonate ( 25th tolerate/28th week surfactant)
a. Pulmonary vessels collapsed
b. High pulmonary vascular resistance
c. Rib cage compressed with fluid no air in lungs
d. Birth and breath opens passages & fluid pushed out
e. Alveoli continue developing until 5-6th year life (1/6th at birth)
f. Chemoreceptors not operational at birth until 72 hours post - apnea
II Properties & Mechanisms of Gas Exchange
A. Properties (breathe a mixture of gases)
1. Physiology
a. Pulmonary ventilation – physical movement
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b. Gas diffusion across membrane
c. Storage & transport of O2 & CO2
d. Exchange of O2 & CO2
2. Ventilation occurs because of pressure differences
a. Movement is from greater to lower pressure
b. Volume changes gases moves
c. Pressure status in respiration
1) Beginning respiration pressures equal
2) Lungs expand pressure inside drops
3) Air comes in
4) Pressure rises
5) Contraction lungs air leaves
d. Membranes parietal & visceral slide over each other but stick to surface
B. Mechanisms of breathing
1. Alveolar pressure – pressure in the airways
a. Communicates with atmospheric pressure
2. Intrapleural pressure – pressure in pleural cavity & always negative to alveolar
a. Lungs & chest wall pull in opposite directions
b. Inspiration with elastic recoil of lungs = increase in intrapleural pressure
3. Intrathoracic pressure – pressure in the thoracic cavity that lungs, heart &
vessels exposed to
4. Process of breathing (inspiration – active & expiration - passive)
a. Initiate breathing the diaphragm contracts ( phrenic nerve), chest
wall & intercostals muscles (intercostals nerve) pull chest out & up
b. Interpleural pressure decreases, air moves in
c. Interpleural pressure now increases, diaphragm relaxes (moves up),
chest wall & intercostals muscles move in & down; air out
d. Accessory muscles –
1) Scalene muscle – move first 2 ribs
2) Sternocleidomastoid – raises sternum
5. Compliance – ease of lung inflation (200ml/cm H2O) –balloon theory
a. Lower or poor compliance = harder inflation
b. Determined by elastin & collagen fibers of lung, water content,
surface tension & thoracic cage compliance
1) Elastin = easy stretch & inflation
2) Collagen – resist stretch
3) Elastic recoil = ability to return to original position
6. Surfactant (produced in fetal gestation at 26-28 weeks)
a. Surface tension – tension in alveoli between air & liquid
1) Liquid tension is stronger than air
2) Smaller alveoli (exchange sites) in equal settings
Would empty into large since smaller > tension
3) Surfactant reduces this tension & keeps air in sac & open
(Laplace law)
4) Make-up
a) Lipoproteins mostly phospholipids
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b) Type II alveolar cells produce
c) Head & tail appearance
5) Function
a) Reduces surface tension
b) Increases compliance & ease inflation
c) Provides stability
d) Keeps alveoli dry & prevent pulmonary edema
C. Exchange and Gas Transport
1. Ventilation – exchange of gases in the system involving inspiration & expiration
a. Pulmonary – total exchange between lungs & atmosphere
b. Alveolar – exchange of the gases in lungs
2. Distribution of ventilation
a. Varies with body position, gravity, & lung compliance
b. Varies with lung volumes
3. Perfusion – blood flow
a. Pulmonary – moves blood from heart, lungs to body
1) Moves deoxygenated blood from heart to lungs where
oxygenated back to heart to body
2) Move through the pulmonary artery to lungs to pulmonary vein
to left atrium
3) Vascular system lower in pressure, thinner vessels, more
compliant vessels
4) Volume of flow 500ml with 100ml of flow in capillary beds
5) Constant flow when output equal input in heart
6) Pulmonary artery pressure is higher than pulmonary vein to
flow
4. Diffusion
a. Bulk flow – conducting airways affected by atmospheric & mouth
pressure
b. Diffusion – movement gases in alveoli & across the membrane
1) Affected by thickness & partial pressure of gas
2) Movement is from higher to lower
3) Lungs on the alveolar side: O2 is higher than on capillary so
movement is into capillary and out of alveolar
CO2 is higher in capillary than alveolar so movement
is from capillary to alveolar
5. Matching of Ventilation & Perfusion – must be equal
a. Dead air space – amount air moved in breath but not involved
In exchanged – 150ml never reaches conducting
1) Anatomic dead space – conducting airways
(1) Air in nose, mouth, pharynx, trachea, bronchi
(2) 150-200ml
2) Alveolar dead space – respiratory portion
(1) 5-10ml
3) Physiologic dead space –both alveolar & anatomic
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b. Shunt
1) Anatomic shunt – movement from venous to arterial
without moving through the lungs
2) Physiologic shunt – decrease in ventilation without
changes in alveolar capillary perfusion
6. Gas Transport – blood function of carries dissolved O2 & CO2
a. Oxygen transport
1) Chemical combination with hemoglobin (98-99%)
a) Oxyhemoglobin – O2 carried by heme
b) Moves across alveolar and loose but reversible
bond formed with hemoglobin
c) Oxyhemoglobin carries O2 to peripheral capillaries
releases to tissues
d) Hemoglobin affinity for O2 will vary causing release or
holding
e) Hemoglobin molecule
(1) 4 polypeptide units in 1 molecule with heme
group (4 O2 / hemoglobin molecule)
st
(2) 1 bonding changes shape allowing nest 3
to bound easily – same with release
(3) Holding of O2 influenced by
(a) pH
(b) CO2
(c) Temperature
(d) 2,3-diphosphoglycerate
(4) Increased affinity with increased pH &
decreased PCO2 & temperature
(5) Increased metabolism/need increased
release of O2/decreased affinity
2) Dissolved states (1.5%) –reserve sector with CO poisoning
3) Oxyhemoglobin Dissociation Curve
b. Carbon Dioxide Transport (CO2 – aerobic metabolism)
1) CO2 transportation
a) Dissolved CO2 (7-10%) in plasma
b) Attached to hemoglobin (23%)
(1) Hemoglobin once O2 leaves CO2 comes on
(2) Carbaminohemoglobin – hemoglobin binding
(3) Transported to lungs for release
c) Bicarbonate (70%)
(1) Conversion to carbonic acid through enzyme
Carbonic anhydrase- enzyme H2O
removal (70% converted)
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(2) Almost immediate breakdown to H ion &
Bicarbonate ion – reversible reaction
CO2 + H2O leads to H + HCO3(3) Most H ions tied up by hemoglobin
(4) Most HCO3 ions go to tissue & form NaHCO3
7. Control of Breathing (voluntary & involuntary) – 12-20/minute
a. Respiratory Centers – reticular formation of pons & medulla
1) Respiratory rhythmicity center – medulla oblongata - pace
a) Inspiratory center – continuous function for stimulation
(1) Maintains basic rhythm
b) Expiratory center – used only during forced breathing
2) Pneumotaxic center – upper pons – rate & inspiratory volume;
Off switch
3) Apneustic center – lower pons – prolong inspiration
b. Reflex Control
1) Mechanoreceptor reflexes (airway resistance & lung
expansion)
a) Stretch – smooth muscle layers conducting airway
(1) Respond to changes in pressure
b) Irritant – airway epithelial cells
(1) Stimulated by noxious gases
c) Juxtacapillary or J receptors – alveolar wall
(1) Sense lung congestion
(2) Rapid, shallow breathing
2) Chemoreceptor reflexes
a) Central – respiratory center in medulla
& bathed in CSF
(1) Monitor CO2 levels
(2) Stimulus is H ions in CSF
(3) Separated by blood/brain barrier
(4) CO2 levels regulates ventilation
b) Peripheral – located in carotid & aortic bodies
(bifurcation common carotid arteries &
aortic arch)
(1) Monitor O2 levels in arterial blood
3) Cough Reflex – watchdog of respiratory system
a) Stimulated by receptors in tracheobronchial wall
b) Stimulated to vagus to medullary center
c) Can cause exhaustion with prolonged cough
4) Hypoxic Drive
a) Controlled mainly by CO2 levels
b) COPD diseases opposite and function on O2 levels
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5) Higher Center Control – hold breath & depth = limbic (short)
c. Dyspnea – shortness of breath (Subjective)
1) Mechanisms
a) Stimulation of lung receptors
b) Increased sensitivity to ventilation changes CNS
c) Reduced ventilation reserves
d) Stimulation neural receptors in lung muscles
8. Lung Volumes
a. Tidal volume (500ml) – amount air moves in & out in normal breath
b. Inspiratory reserve volume – maximum air inspired above TV
c. Expiratory reserve volume – maximum air expired above TV
d. Residual volume – air always in lungs after forced expiration (1200)
e. Vital capacity – IRV + TV+ ERV & amount exhaled above that
f. Inspiratory capacity – TV+IVR amount breathe in at normal expiratory
g. Functional residual capacity (FRC) – amount air remains normal
expiration
h. Total lung capacity (TLC) – sum of all volumes in lungs
9. Work of Breathing
a. Minute volume – amount air exchanged in 1 minute
10. Age
a. Newborn/infant – immature lungs, immune system, stomach breather
b. Pediatric
b. Elderly – Arthritic changes, decrease elastic tissue, stiffening, diseases
11. Diseases of Respiratory System
a. Obstructive Lung Disease – asthma, emphysema, chronic bronchitis
1)Characteristic
a) Abnormal ventilation
b) Bronchospasms – reversed beta adrenergic stimulant
c) Increased mucus production
d) Inflammatory bronchial passages
e) Reversible or not
2) COPD – genetic, smoking, environmental - irreversible
a) Destruction of alveolar walls distal to terminal bronchial
b) Loses elasticity
c) Residual volume increased
d) Lip breathing
e) Decrease O2 levels, increased RBC production
f) Increased CO2 levels = hypoxic drive
g) Types
(1) Pink puffer
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(2) Blue Bloater
h) Alpha 1-antitrypsin – genetic – Autosomal recessive
(1) Alpha 1 antitrypsin – made liver, protects lung
tissue from enzymes of inflammation
(2) Elastase – enzyme
(3) Elastase breaks Elastin = less compliant
i) Centriacinar
j) Panacinar
k) Paraseptal
3) Chronic Bronchitis – increased goblet cell numbers
a) Large sputum production
b) Environmental exposure
c) Alveoli NOT affected & diffusion normal
d) Alveolar ventilation decreased
e) PCO2 increased = vasoconstriction = pulmonary HTN
4) Asthma – chronic inflammatory disorder airways with variable
airway obstruction – hyperresponsive airways
a) Triggers
b) Phases
(1) Histamine release – bronchial smooth muscle
contraction & fluid leak from capillaries
(edema & constriction)
(2) No response to beta agonist drug – steroids
c) Status asthmaticus – servere prolonged attack
5) Pneumonia
6) Upper respiratory Infection
7) Cancer
8) TB (Mycobacterium tuberculosis)
9) Cystic Fibrosis – Autosomal recessive, chronic respiratory
10) ARDS (acute respiratory distress syndrome) = 50-60% death
11) Trauma
a) Pneumothorax
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b) Hemothorax
c) Rib fracture
d) Flail Chest
e) Pulmonary contusion
f) Tension pneumothorax
12) Pulmonary embolism
13) Pulmonary HTN
a) Primary
b) Secondary
14) Cor Pulmonale
15) Congestive Heart Failure & lung failure
16) Pleural Effusion
17) Sarcoidosis
18) Pediatric Emergencies
a) Whooping cough
b) Spasmodic – allergic
c) Respiratory distress syndrome
d) Bronchopulmonary Dysplasia
e) Respiratory failure
f) Upper & lower respiratory infections
(1) Croup
(2) Epiglottitis
(3) Viral acute laryngotracheobronchitis
19) Respiratory Failues
a) Causes
b) Hypoventilation
c) Ventilation/perfusion mismatch
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d) Impaired diffusion
e) Symptoms
12. Blast Injury
a. History
b. Categories of blast injury
1) Primary injury
a) Blast wave
2) Secondary
a) Flying debris
3) Tertiary
a) Blast wind
4) Quaternary
a) Other vectors (heat, radiation)
c. Lung injury
1) Signs & Symptoms
2) Treatments
d. Other injury
1) Head
2) Abdominal
3) Ear
4) Other injury (fractures, inhalation, eye, amputation,
contaminated wounds, burns,
prolonged extrications, renal failure)
e. Mental Health issues
f. Military issues
1) Treatments
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g. System challenges
1) Pre-hospital
2) Hospital