Download Larynx

Chapter 13
The Respiratory
System
Lecture Presentation by
Patty Bostwick-Taylor
Florence-Darlington Technical College
© 2015 Pearson Education, Inc.
Organs of the Respiratory System
 Nose
 Pharynx
 Larynx
 Trachea
 Bronchi
 Lungs—alveoli
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Figure 13.1 The major respiratory organs shown in relation to surrounding structures.
Nasal cavity
Nostril
Oral cavity
Pharynx
Larynx
Trachea
Right main
(primary)
bronchus
Left main
(primary)
bronchus
Left lung
Right lung
Diaphragm
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Functions of the Respiratory System
 Gas exchanges between the blood and external
environment
 Occur in the alveoli of the lungs
 Passageways to the lungs purify, humidify, and
warm the incoming air
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The Nose
 The only externally visible part of the respiratory
system
 Air enters the nose through the external nostrils
(nares)
 Interior of the nose consists of a nasal cavity divided
by a nasal septum
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Concept Link
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Figure 13.2b Basic anatomy of the upper respiratory tract, sagittal section.
Cribriform plate
of ethmoid bone
Sphenoidal sinus
Posterior nasal
aperture
Nasopharynx
• Pharyngeal tonsil
• Opening of
pharyngotympanic
tube
• Uvula
Oropharynx
• Palatine tonsil
• Lingual tonsil
Laryngopharynx
Esophagus
Trachea
Frontal sinus
Nasal cavity
• Nasal conchae (superior,
middle and inferior)
• Nasal meatuses (superior,
middle, and inferior)
• Nasal vestibule
• Nostril
Hard palate
Soft palate
Tongue
Hyoid bone
Larynx
• Epiglottis
• Thyroid cartilage
• Vocal fold
• Cricoid cartilage
(b) Detailed anatomy of the upper respiratory tract
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The Nose
 Olfactory receptors are located in the mucosa on
the superior surface
 The rest of the cavity is lined with respiratory
mucosa, which:
 Moistens air
 Traps incoming foreign particles
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The Nose
 Lateral walls have projections called conchae
 Increase surface area
 Increase air turbulence within the nasal cavity
 The nasal cavity is separated from the oral cavity by
the palate
 Anterior hard palate (bone)
 Posterior soft palate (unsupported)
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Paranasal Sinuses
 Cavities within bones surrounding the nasal cavity
are called sinuses
 Sinuses are located in the following bones:
 Frontal
 Sphenoid
 Ethmoid
 Maxillary
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Figure 13.2b Basic anatomy of the upper respiratory tract, sagittal section.
Cribriform plate
of ethmoid bone
Sphenoidal sinus
Posterior nasal
aperture
Nasopharynx
• Pharyngeal tonsil
• Opening of
pharyngotympanic
tube
• Uvula
Oropharynx
• Palatine tonsil
• Lingual tonsil
Laryngopharynx
Esophagus
Trachea
Frontal sinus
Nasal cavity
• Nasal conchae (superior,
middle and inferior)
• Nasal meatuses (superior,
middle, and inferior)
• Nasal vestibule
• Nostril
Hard palate
Soft palate
Tongue
Hyoid bone
Larynx
• Epiglottis
• Thyroid cartilage
• Vocal fold
• Cricoid cartilage
(b) Detailed anatomy of the upper respiratory tract
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Paranasal Sinuses
 Functions of the sinuses:
 Lighten the skull
 Act as resonance chambers for speech
 Produce mucus that drains into the nasal cavity
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Pharynx (Throat)
 Muscular passage from nasal cavity to larynx
 Three regions of the pharynx:
1. Nasopharynx—superior region behind nasal cavity
2. Oropharynx—middle region behind mouth
3. Laryngopharynx—inferior region attached to larynx
 The oropharynx and laryngopharynx are common
passageways for air and food
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Figure 13.2a Basic anatomy of the upper respiratory tract, sagittal section.
Pharynx
• Nasopharynx
• Oropharynx
• Laryngopharynx
(a) Regions of the pharynx
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Pharynx (Throat)
 Pharyngotympanic tubes open into the nasopharynx
 Tonsils of the pharynx
 Pharyngeal tonsil (adenoid) is located in the
nasopharynx
 Palatine tonsils are located in the oropharynx
 Lingual tonsils are found at the base of the tongue
© 2015 Pearson Education, Inc.
Figure 13.2b Basic anatomy of the upper respiratory tract, sagittal section.
Cribriform plate
of ethmoid bone
Sphenoidal sinus
Posterior nasal
aperture
Nasopharynx
• Pharyngeal tonsil
• Opening of
pharyngotympanic
tube
• Uvula
Oropharynx
• Palatine tonsil
• Lingual tonsil
Laryngopharynx
Esophagus
Trachea
Frontal sinus
Nasal cavity
• Nasal conchae (superior,
middle and inferior)
• Nasal meatuses (superior,
middle, and inferior)
• Nasal vestibule
• Nostril
Hard palate
Soft palate
Tongue
Hyoid bone
Larynx
• Epiglottis
• Thyroid cartilage
• Vocal fold
• Cricoid cartilage
(b) Detailed anatomy of the upper respiratory tract
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Larynx (Voice Box)
 Routes air and food into proper channels
 Plays a role in speech
 Made of eight rigid hyaline cartilages and a spoonshaped flap of elastic cartilage (epiglottis)
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Larynx (Voice Box)
 Thyroid cartilage
 Largest of the hyaline cartilages
 Protrudes anteriorly (Adam’s apple)
 Epiglottis
 Protects the superior opening of the larynx
 Routes food to the posteriorly situated esophagus
and routes air toward the trachea
 When swallowing, the epiglottis rises and forms a lid
over the opening of the larynx
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Larynx (Voice Box)
 Vocal folds (true vocal cords)
 Vibrate with expelled air
 The glottis consists of the vocal cords and the
slitlike pathway (opening)
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Figure 13.2b Basic anatomy of the upper respiratory tract, sagittal section.
Cribriform plate
of ethmoid bone
Sphenoidal sinus
Posterior nasal
aperture
Nasopharynx
• Pharyngeal tonsil
• Opening of
pharyngotympanic
tube
• Uvula
Oropharynx
• Palatine tonsil
• Lingual tonsil
Laryngopharynx
Esophagus
Trachea
Frontal sinus
Nasal cavity
• Nasal conchae (superior,
middle and inferior)
• Nasal meatuses (superior,
middle, and inferior)
• Nasal vestibule
• Nostril
Hard palate
Soft palate
Tongue
Hyoid bone
Larynx
• Epiglottis
• Thyroid cartilage
• Vocal fold
• Cricoid cartilage
(b) Detailed anatomy of the upper respiratory tract
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Trachea (Windpipe)
 4-inch-long tube that connects larynx with bronchi
 Walls are reinforced with C-shaped hyaline
cartilage, which keeps the trachea patent
 Lined with ciliated mucosa
 Cilia beat continuously in the opposite direction of
incoming air
 Expel mucus loaded with dust and other debris away
from lungs
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Figure 13.3a Structural relationship of the trachea and esophagus.
Posterior
Mucosa
Submucosa
Esophagus
Trachealis
muscle
Lumen of
trachea
Seromucous
gland in
submucosa
Hyaline
cartilage
Adventitia
(a)
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Anterior
Figure 13.3b Structural relationship of the trachea and esophagus.
(b)
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Main (Primary) Bronchi
 Formed by division of the trachea
 Each bronchus enters the lung at the hilum (medial
depression)
 Right bronchus is wider, shorter, and straighter than
left
 Bronchi subdivide into smaller and smaller
branches
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Figure 13.1 The major respiratory organs shown in relation to surrounding structures.
Nasal cavity
Nostril
Oral cavity
Pharynx
Larynx
Trachea
Right main
(primary)
bronchus
Left main
(primary)
bronchus
Left lung
Right lung
Diaphragm
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Lungs
 Occupy most of the thoracic cavity
 Heart occupies central portion called mediastinum
 Apex is near the clavicle (superior portion)
 Base rests on the diaphragm (inferior portion)
 Each lung is divided into lobes by fissures
 Left lung—two lobes
 Right lung—three lobes
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Coverings of the Lungs
 Serosa covers the outer surface of the lungs
 Pulmonary (visceral) pleura covers the lung surface
 Parietal pleura lines the walls of the thoracic cavity
 Pleural fluid fills the area between layers to allow
gliding and decrease friction during breathing
 Pleural space (between the layers) is more of a
potential space
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Figure 13.4a Anatomical relationships of organs in the thoracic cavity.
Intercostal muscle
Rib
Trachea
Parietal pleura
Pleural cavity
Visceral pleura
Lung
Thymus
Apex of lung
Right superior lobe
Horizontal fissure
Right middle lobe
Oblique fissure
Right inferior lobe
Heart
(in pericardial cavity
of mediastinum)
Diaphragm
Base of lung
Left superior lobe
Oblique fissure
Left inferior lobe
(a) Anterior view. The lungs flank mediastinal structures laterally.
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Figure 13.4b Anatomical relationships of organs in the thoracic cavity.
Vertebra
Posterior
Esophagus
(in posterior mediastinum)
Root of lung at hilum
• Left main bronchus
• Left pulmonary artery
• Left pulmonary vein
Right lung
Parietal pleura
Visceral pleura
Left lung
Pleural cavity
Thoracic wall
Pulmonary trunk
Pericardial
membranes
Sternum
Heart (in mediastinum)
Anterior mediastinum
Anterior
(b) Transverse section through the thorax, viewed from above.
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Bronchial (Respiratory) Tree Divisions
 All but the smallest of these passageways have
reinforcing cartilage in their walls
 Conduits to and from the respiratory zone
 Primary bronchi
 Secondary bronchi
 Tertiary bronchi
 Bronchioles
 Terminal bronchioles
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Respiratory Zone Structures
 Respiratory bronchioles
 Alveolar ducts
 Alveolar sacs
 Alveoli (air sacs)
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Figure 13.5a Respiratory zone structures.
Alveolar duct
Respiratory
bronchioles
Terminal
bronchiole
(a) Diagrammatic view of respiratory
bronchioles, alveolar ducts, and alveoli
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Alveoli
Alveolar duct
Alveolar
sac
Figure 13.5b Respiratory zone structures.
Alveolar
duct
Alveolus
(b) Light micrograph of human lung tissue,
showing the final divisions of the
respiratory tree (120×)
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Alveolar
pores
The Respiratory Membrane
 Thin squamous epithelial layer lines alveolar walls
 Alveolar pores connect neighboring air sacs
 Pulmonary capillaries cover external surfaces of
alveoli
 Respiratory membrane (air-blood barrier)
 On one side of the membrane is air, and on the other
side is blood flowing past
 Formed by alveolar and capillary walls
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The Respiratory Membrane
 Gas crosses the respiratory membrane by diffusion
 Oxygen enters the blood
 Carbon dioxide enters the alveoli
 Alveolar macrophages (“dust cells”) add protection
by picking up bacteria, carbon particles, and other
debris
 Surfactant (a lipid molecule) coats gas-exposed
alveolar surfaces
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Figure 13.6 Anatomy of the respiratory membrane (air-blood barrier).
Red blood cell
Capillary
Endothelial cell
nucleus
Alveolar pores
Capillary
O2
CO2
Macrophage
Nucleus of
squamous
epithelial cell
Respiratory
membrane
Alveolus
Alveolar epithelium
Fused basement
membranes
Capillary endothelium
Alveoli (gasfilled air
spaces)
Squamous
Red blood Surfactantcell in
secreting cell epithelial cell
of alveolar wall
capillary
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Four Events of Respiration
1. Pulmonary ventilation—moving air into and out of
the lungs (commonly called breathing)
2. External respiration—gas exchange between
pulmonary blood and alveoli
 Oxygen is loaded into the blood
 Carbon dioxide is unloaded from the blood
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Four Events of Respiration
3. Respiratory gas transport—transport of oxygen
and carbon dioxide via the bloodstream
4. Internal respiration—gas exchange between blood
and tissue cells in systemic capillaries
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Mechanics of Breathing (Pulmonary
Ventilation)
 Completely mechanical process that depends on
volume changes in the thoracic cavity
 Volume changes lead to pressure changes, which
lead to the flow of gases to equalize pressure
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Mechanics of Breathing (Pulmonary
Ventilation)
 Two phases
 Inspiration = inhalation
 Flow of air into lungs
 Expiration = exhalation
 Air leaving lungs
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Mechanics of Breathing (Pulmonary
Ventilation)
 Inspiration
 Diaphragm and external intercostal muscles contract
 The size of the thoracic cavity increases
 External air is pulled into the lungs as a result of:
 Increase in intrapulmonary volume
 Decrease in gas pressure
 Air is sucked into the lungs
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Figure 13.7a Rib cage and diaphragm positions during breathing.
Changes in anterior-posterior and
superior-inferior dimensions
Ribs elevated
as external
intercostals
contract
External
intercostal
muscles
Changes in lateral
dimensions
Full inspiration
(External
intercostals contract)
Diaphragm moves
inferiorly during
contraction
(a) Inspiration: Air (gases) flows into the lungs
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Pressure relative
to atmospheric pressure
Figure 13.8 Changes in intrapulmonary pressure and air flow during inspiration and expiration.
+2
+1
Inspiration
Expiration
Intrapulmonary
pressure
0
−1
−2
(a)
Volume of
breath
Volume (L)
0.5
0
−0.5
(b)
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Mechanics of Breathing (Pulmonary
Ventilation)
 Expiration
 Largely a passive process that depends on natural
lung elasticity
 As muscles relax, air is pushed out of the lungs as a
result of:
 Decrease in intrapulmonary volume
 Increase in gas pressure
 Forced expiration can occur mostly by contraction of
internal intercostal muscles to depress the rib cage
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Mechanics of Breathing (Pulmonary
Ventilation)
 Normal pressure within the pleural space is always
negative (intrapleural pressure)
 Differences in lung and pleural space pressures
keep lungs from collapsing
 Atelectasis is collapsed lung
 Pneumothorax is the presence of air in the
intrapleural space
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Figure 13.7b Rib cage and diaphragm positions during breathing.
Changes in anterior-posterior and
superior-inferior dimensions
Changes in lateral
dimensions
Ribs depressed
as external
intercostals relax
External
intercostal
muscles
Diaphragm moves
superiorly as
it relaxes
(b) Expiration: Air (gases) flows out of the lungs
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Expiration
(External
intercostals relax)
Pressure relative
to atmospheric pressure
Figure 13.8 Changes in intrapulmonary pressure and air flow during inspiration and expiration.
+2
+1
Inspiration
Expiration
Intrapulmonary
pressure
0
−1
−2
(a)
Volume of
breath
Volume (L)
0.5
0
−0.5
(b)
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Respiratory Volumes and Capacities
 Normal breathing moves about 500 ml of air with
each breath
 This respiratory volume is tidal volume (TV)
 Many factors affect respiratory capacity
 A person’s size
 Sex
 Age
 Physical condition
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Respiratory Volumes and Capacities
 Inspiratory reserve volume (IRV)
 Amount of air that can be taken in forcibly over the
tidal volume
 Usually around 3,100 ml
 Expiratory reserve volume (ERV)
 Amount of air that can be forcibly exhaled after a
tidal expiration
 Approximately 1,200 ml
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Respiratory Volumes and Capacities
 Residual volume
 Air remaining in lung after expiration
 Allows gas exchange to go on continuously, even
between breaths, and helps keep alveoli open
(inflated)
 About 1,200 ml
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Respiratory Volumes and Capacities
 Vital capacity
 The total amount of exchangeable air
 Vital capacity = TV + IRV + ERV
 4,800 ml in men; 3,100 ml in women
 Dead space volume
 Air that remains in conducting zone and never
reaches alveoli
 About 150 ml
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Respiratory Volumes and Capacities
 Functional volume
 Air that actually reaches the respiratory zone
 Usually about 350 ml
 Respiratory capacities are measured with a
spirometer
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Figure 13.9 Idealized tracing of the various respiratory volumes of a healthy young adult male.
6,000
Milliliters (ml)
5,000
4,000
Inspiratory
reserve volume
3,100 ml
3,000
2,000
1,000
0
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Tidal volume 500 ml
Expiratory
reserve volume
1,200 ml
Residual volume
1,200 ml
Vital
capacity
4,800 ml
Total lung
capacity
6,000 ml
Nonrespiratory Air (Gas) Movements
 Can be caused by reflexes or voluntary actions
 Examples:
 Cough and sneeze—clears lungs of debris
 Crying—emotionally induced mechanism
 Laughing—similar to crying
 Hiccup—sudden inspirations
 Yawn—very deep inspiration
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Table 13.1 Nonrespiratory Air (Gas) Movements
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Respiratory Sounds
 Sounds are monitored with a stethoscope
 Two recognizable sounds can be heard with a
stethoscope:
1. Bronchial sounds—produced by air rushing
through large passageways such as the trachea
and bronchi
2. Vesicular breathing sounds—soft sounds of air
filling alveoli
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External Respiration, Gas Transport, and
Internal Respiration
 Gas exchanges occur as a result of diffusion
 Movement of the gas is toward the area of lower
concentration
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Figure 13.10 Gas exchanges in the body occur according to the laws of diffusion.
Inspired air:
Alveoli
of lungs:
CO2 O2
O2 CO2
O2 CO2
External
respiration
Pulmonary
arteries
Alveolar
capillaries
Blood
leaving
tissues and
entering
lungs:
Pulmonary
veins
Blood
leaving
lungs and
entering
tissue
capillaries:
Heart
O2 CO2
Tissue
capillaries
Systemic
veins
Internal
respiration
Systemic
arteries
CO2
O2
Tissue
cells:
O2 CO2
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O2 CO2
External Respiration
 Oxygen is loaded into the blood
 The alveoli always have more oxygen than the blood
 Oxygen moves by diffusion towards the area of lower
concentration
 Pulmonary capillary blood gains oxygen
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External Respiration
 Carbon dioxide is unloaded out of the blood
 Blood returning from tissues has higher
concentrations of carbon dioxide than air in the
alveoli
 Pulmonary capillary blood gives up carbon dioxide to
be exhaled
 Blood leaving the lungs is oxygen rich and carbon
dioxide poor
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Figure 13.11a Diagrammatic representation of the major means of oxygen (O 2) and carbon dioxide (CO2) loading and unloading in the body.
(a) External respiration in the lungs
(pulmonary gas exchange)
Oxygen is loaded into the blood
and carbon dioxide is unloaded.
Alveoli (air sacs)
O2
Loading
of O2
Hb + O2
HbO2
(Oxyhemoglobin
is formed)
CO2
Unloading
of CO2
HCO3−+ H+ H2CO3 CO2+ H2O
BicarCarbonic
Water
bonate
acid
ion
Plasma
Red blood cell
Pulmonary capillary
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Gas Transport in the Blood
 Oxygen transport in the blood
 Most oxygen travels attached to hemoglobin and
forms oxyhemoglobin (HbO2)
 A small dissolved amount is carried in the plasma
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Figure 13.11a Diagrammatic representation of the major means of oxygen (O 2) and carbon dioxide (CO2) loading and unloading in the body.
(a) External respiration in the lungs
(pulmonary gas exchange)
Oxygen is loaded into the blood
and carbon dioxide is unloaded.
Alveoli (air sacs)
O2
Loading
of O2
Hb + O2
HbO2
(Oxyhemoglobin
is formed)
CO2
Unloading
of CO2
HCO3−+ H+ H2CO3 CO2+ H2O
BicarCarbonic
Water
bonate
acid
ion
Plasma
Red blood cell
Pulmonary capillary
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Gas Transport in the Blood
 Carbon dioxide transport in the blood
 Most carbon dioxide is transported in the plasma as
bicarbonate ion (HCO3–)
 A small amount is carried inside red blood cells on
hemoglobin, but at different binding sites from those
of oxygen
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Concept Link
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Gas Transport in the Blood
 For carbon dioxide to diffuse out of blood into the
alveoli, it must be released from its bicarbonate
form:
 Bicarbonate ions enter RBC
 Combine with hydrogen ions
 Form carbonic acid (H2CO3)
 Carbonic acid splits to form water + CO2
 Carbon dioxide diffuses from blood into alveoli
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Figure 13.11a Diagrammatic representation of the major means of oxygen (O 2) and carbon dioxide (CO2) loading and unloading in the body.
(a) External respiration in the lungs
(pulmonary gas exchange)
Oxygen is loaded into the blood
and carbon dioxide is unloaded.
Alveoli (air sacs)
O2
Loading
of O2
Hb + O2
HbO2
(Oxyhemoglobin
is formed)
CO2
Unloading
of CO2
HCO3−+ H+ H2CO3 CO2+ H2O
BicarCarbonic
Water
bonate
acid
ion
Plasma
Red blood cell
Pulmonary capillary
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Internal Respiration
 Exchange of gases between blood and body cells
 An opposite reaction to what occurs in the lungs
 Carbon dioxide diffuses out of tissue to blood (called
loading)
 Oxygen diffuses from blood into tissue (called
unloading)
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Figure 13.11b Diagrammatic representation of the major means of oxygen (O 2) and carbon dioxide (CO2) loading and unloading in the body.
(b) Internal respiration in the body tissues
(systemic capillary gas exchange)
Oxygen is unloaded and carbon
dioxide is loaded into the blood.
Tissue cells
CO2
Loading
of CO2
CO2 +H2O
H2CO3
Water Carbonic
acid
Plasma
O2
Unloading
of O2
H++ HCO3−
Bicarbonate
ion
HbO2
Hb + O2
Systemic capillary
Red blood cell
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Neural Regulation of Respiration
 Activity of respiratory muscles is transmitted to and
from the brain by phrenic and intercostal nerves
 Neural centers that control rate and depth are
located in the medulla and pons
 Medulla—sets basic rhythm of breathing and
contains a pacemaker (self-exciting inspiratory
center) called the ventral respiratory group (VRG)
 Pons—appears to smooth out respiratory rate
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Neural Regulation of Respiration
 Normal respiratory rate (eupnea)
 12 to 15 respirations per minute
 Hyperpnea
 Increased respiratory rate, often due to extra oxygen
needs
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Figure 13.12 Breathing control centers, sensory inputs, and effector nerves.
Breathing control centers:
• Pons centers
• Medulla centers
Efferent nerve impulses from
medulla trigger contraction
of inspiratory muscles.
• Phrenic nerves
• Intercostal nerves
Afferent
impulses to
medulla
Breathing control centers
stimulated by:
CO2 increase in blood
(acts directly on medulla
centers by causing a
drop in pH of CSF)
CSF in
brain
sinus
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Nerve impulse
from O2 sensor
indicating O2
decrease
Intercostal
muscles
Diaphragm
O2 sensor
in aortic body
of aortic arch
Non-Neural Factors Influencing Respiratory
Rate and Depth
 Physical factors
 Increased body temperature
 Exercise
 Talking
 Coughing
 Volition (conscious control)
 Emotional factors such as fear, anger, and
excitement
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Non-Neural Factors Influencing Respiratory
Rate and Depth
 Chemical factors: CO2 levels
 The body’s need to rid itself of CO2 is the most
important stimulus for breathing
 Increased levels of carbon dioxide (and thus, a
decreased or acidic pH) in the blood increase the
rate and depth of breathing
 Changes in carbon dioxide act directly on the
medulla oblongata
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Non-Neural Factors Influencing Respiratory
Rate and Depth
 Chemical factors: oxygen levels
 Changes in oxygen concentration in the blood are
detected by chemoreceptors in the aorta and
common carotid artery
 Information is sent to the medulla
 Oxygen is the stimulus for those whose systems
have become accustomed to high levels of carbon
dioxide as a result of disease
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Non-Neural Factors Influencing Respiratory
Rate and Depth
 Chemical factors
 Hyperventilation
 Rising levels of CO2 in the blood (acidosis) result in
faster, deeper breathing
 Blows off more CO2 to restore normal blood pH
 May result in apnea and dizziness and lead to
alkalosis
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Non-Neural Factors Influencing Respiratory
Rate and Depth
 Chemical factors
 Hypoventilation
 Results when blood becomes alkaline (alkalosis)
 Extremely slow or shallow breathing
 Allows CO2 to accumulate in the blood
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Respiratory Disorders: Chronic Obstructive
Pulmonary Disease (COPD)
 Exemplified by chronic bronchitis and emphysema
 Major causes of death and disability in the United
States
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Respiratory Disorders: Chronic Obstructive
Pulmonary Disease (COPD)
 Features of these diseases
1. Patients almost always have a history of smoking
2. Labored breathing (dyspnea) becomes
progressively more severe
3. Coughing and frequent pulmonary infections are
common
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Respiratory Disorders: Chronic Obstructive
Pulmonary Disease (COPD)
 Features of these diseases (continued)
4. Most victims are hypoxic, retain carbon dioxide, and
have respiratory acidosis
 Those who acquire infections will ultimately develop
respiratory failure
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Respiratory Disorders: Chronic Bronchitis
 Mucosa of the lower respiratory passages becomes
severely inflamed
 Excessive mucus production impairs ventilation and
gas exchange
 Patients become cyanotic and are sometimes called
“blue bloaters” as a result of chronic hypoxia
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Respiratory Disorders: Emphysema
 Alveoli permanently enlarge as adjacent chambers
break through and are destroyed
 Chronic inflammation promotes lung fibrosis, and
lungs lose elasticity
 Patients use a large amount of energy to exhale as
exhalation becomes an active process
 Overinflation of the lungs leads to a permanently
expanded barrel chest
 Cyanosis appears late in the disease; sufferers are
often called “pink puffers”
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Figure 13.13 The pathogenesis of COPD.
• Tobacco smoke
• Air pollution
Continual bronchial
irritation and
inflammation
Breakdown of elastin
in connective tissue
of lungs
Chronic bronchitis
• Excessive mucus
produced,
• Chronic productive
cough
Emphysema
• Destruction of
alveolar walls
• Loss of lung elasticity
• Airway obstruction
or air trapping
• Dyspnea
• Frequent infections
Respiratory
failure
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Lung Cancer
 Extremely aggressive and metastasizes rapidly
 Accounts for one-third of all U.S. cancer deaths
 Increased incidence is associated with smoking
 Three common types:
1. Squamous cell carcinoma
2. Adenocarcinoma
3. Small cell carcinoma
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Developmental Aspects of the Respiratory
System
 Premature infants have problems keeping their
lungs inflated because of a lack of surfactant in their
alveoli. (Surfactant is formed late in pregnancy
around 28 to 30 weeks of pregnancy)
 Infant respiratory distress syndrome (IRDS)—
surfactant production is inadequate
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Developmental Aspects of the Respiratory
System
 Significant birth defects affecting the respiratory
system:
 Cleft palate
 Cystic fibrosis—oversecretion of thick mucus clogs
the respiratory system
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Developmental Aspects of the Respiratory
System
 Respiratory rate changes throughout life
 Newborns: 40 to 80 respirations per minute
 Infants: 30 respirations per minute
 Age 5: 25 respirations per minute
 Adults: 12 to 18 respirations per minute
 Rate often increases somewhat with old age
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Developmental Aspects of the Respiratory
System
 Sudden infant death syndrome (SIDS)
 Apparently healthy infant stops breathing and dies
during sleep
 Some cases are thought to be a problem of the
neural respiratory control center
 One-third of cases appear to be due to heart rhythm
abnormalities
 Recent research shows a genetic component
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Developmental Aspects of the Respiratory
System
 Asthma
 Chronically inflamed hypersensitive bronchiole
passages
 Respond to irritants with dyspnea, coughing, and
wheezing
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Developmental Aspects of the Respiratory
System
 During youth and middle age, most respiratory
system problems are a result of external factors,
such as infections and substances that physically
block respiratory passageways
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Developmental Aspects of the Respiratory
System
 Aging effects
 Elasticity of lungs decreases
 Vital capacity decreases
 Blood oxygen levels decrease
 Stimulating effects of carbon dioxide decrease
 Elderly are often hypoxic and exhibit sleep apnea
 More risks of respiratory tract infection
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