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prepared by
Betsy C. Brantley
Valencia College
CHAPTER
14
The
Respiratory
System
© 2013 Pearson Education, Inc.
Chapter 14 Learning Outcomes
• Section 1: Functional Anatomy of the Respiratory System
• 14.1
• Describe the role of the respiratory mucosa, and identify the
organs of the upper respiratory system and describe their
functions.
• 14.2
• Describe the structures and functions of the airways outside the
lungs and the superficial anatomy of the lungs.
• 14.3
• Describe the functional anatomy of the alveoli.
© 2013 Pearson Education, Inc.
Chapter 14 Learning Outcomes
• Section 2: Respiratory Physiology
• 14.4
• Summarize the physical principles governing the movement of
air into and out of the lungs.
• 14.5
• Name the respiratory muscles and describe the actions of the
muscles responsible for respiratory movements.
• 14.6
• Describe the diffusion of oxygen and carbon dioxide during
external and internal respiration, and explain how the
bloodstream transports these gases.
• 14.7
• Describe the brain stem structures that influence the control of
respiration and the effects of carbon dioxide on the respiratory
rate.
© 2013 Pearson Education, Inc.
Chapter 14 Learning Outcomes
• 14.8
• CLINICAL MODULE Explain how pulmonary disease and
smoking can affect airflow and describe age-related changes in
the respiratory system.
© 2013 Pearson Education, Inc.
Respiratory System Overview (Section 1)
• Section 1 – Functional Anatomy
• The "what" and "where"
• Section 2 – Respiratory Physiology
• The "how"
© 2013 Pearson Education, Inc.
Major Functions of the Respiratory System
(Section 1)
• Provide a large surface area for gas exchange between air
and circulating blood
• Move air to and from the exchange surfaces of the lungs
along the respiratory tract
• Protect respiratory surfaces from dehydration and
temperature changes, and defend against invasion by
pathogens
• Produce sounds involved in speaking, singing, and other
forms of communication
• Aid the sense of smell by olfactory receptors in the superior
portions of the nasal cavity
© 2013 Pearson Education, Inc.
Functional Anatomy of the Respiratory System
– Divisions (Section 1)
• Upper respiratory system
• Lower respiratory system
© 2013 Pearson Education, Inc.
Respiratory system anatomy
Tongue
Larynx
Trachea
Bronchi
Bronchioles
Smallest bronchioles
Esophagus
Clavicle
Ribs
Nose
Nasal cavity
Sinuses
Pharynx
Right
lung
Left
lung
Diaphragm
Alveoli
© 2013 Pearson Education, Inc.
Figure 14 Section 1 1 1
Upper Respiratory System (Section 1)
• Filters, warms, humidifies incoming air
• Protects more sensitive lower tract
• Reabsorbs heat and water in outgoing air
• Structures
• Nose
• Nasal cavity
• Sinuses
• Pharynx
© 2013 Pearson Education, Inc.
Upper respiratory system
Upper Respiratory System
Tongue
Right
lung
© 2013 Pearson Education, Inc.
Nose
Nasal cavity
Sinuses
Pharynx
Left
lung
Figure 14 Section 1 1 1
Lower Respiratory System (Section 1)
• Moves air to gas exchange surfaces
• Exchanges gases with capillaries
• Structures
• Larynx
• Trachea
• Bronchi
• Bronchioles
• Alveoli
© 2013 Pearson Education, Inc.
Lower respiratory system
Lower Respiratory System
Larynx
Trachea
Bronchi
Bronchioles
Smallest bronchioles
Right
lung
Left
lung
Alveoli
© 2013 Pearson Education, Inc.
Figure 14 Section 1 1 1
Respiratory Tract (Section 1)
• Passageways carrying air to and from gas
exchange surfaces
• Conducting portion
• Nasal cavity to bronchioles
• "Conducts" air to the exchange area
• Respiratory portion
• Smallest bronchioles and alveoli
• Where gas exchange occurs
© 2013 Pearson Education, Inc.
Respiratory Mucosa (14.1)
• Lines conducting portion of respiratory tract
• Composition
• Epithelium
• Lamina propria
© 2013 Pearson Education, Inc.
Respiratory Mucosa – Epithelium (14.1)
• Epithelium
• Specific type varies along respiratory tract
• Pseudostratified ciliated columnar epithelium with many
mucous cells found in:
• Nasal cavity
• Superior portion of pharynx
• Trachea
• Bronchi
• Large bronchioles
© 2013 Pearson Education, Inc.
Respiratory Mucosa – Lamina Propria (14.1)
• Lamina propria
• Areolar tissue
• Supports respiratory epithelium
© 2013 Pearson Education, Inc.
Respiratory mucosa
Mucous cell
Beating cilia
sweep mucus
upward
Ciliated columnar
epithelial cell
Mucus layer
Lamina propria
© 2013 Pearson Education, Inc.
Figure 14.1 11
Respiratory Mucosa – Functions (14.1)
• Warms
• Network of blood vessels radiates heat into nasal
cavities
• Moistens
• Mucous gland secretions humidify air
• Protects
• Prevents more delicate lower respiratory surfaces from
drying out
© 2013 Pearson Education, Inc.
Cystic Fibrosis – Affects the Respiratory
Mucosa (14.1)
• Inherited disease
• Results in production of thick, sticky mucus
• Mucus restricts airflow
• Increases respiratory infections and damage to
respiratory system
• Breathing treatments temporarily thin mucus
© 2013 Pearson Education, Inc.
Breathing treatment for cystic fibrosis
© 2013 Pearson Education, Inc.
Figure 14.1 22
Upper Respiratory System – From Nose to
Pharynx (14.1)
• Air passes through the:
• Nose
• External nares (nostrils)
• Nasal vestibule
• Coarse hairs trap airborne particles
• Nasal cavity
• Floor composed of hard palate and soft palate
• Internal nares
• To the:
• Pharynx
© 2013 Pearson Education, Inc.
Regions of the Pharynx (14.1)
•
The pharynx is divided into three regions
1. Nasopharynx
•
Area between the internal nares and soft palate
•
Lined with pseudostratified columnar epithelium
2. Oropharynx
•
Area between soft palate and base of tongue or level of hyoid
bone
•
Lined with stratified squamous epithelium
3. Laryngopharynx
•
Area between hyoid bone and entrance to larynx and
esophagus
•
Lined with stratified squamous epithelium
© 2013 Pearson Education, Inc.
Divisions of the pharynx
Internal nares
Nasal vestibule
Nasal cavity
External nares
Pharynx
Nasopharynx
Oropharynx
Hard palate
Tongue
Laryngopharynx
Soft palate
Hyoid bone
Glottis
Trachea
Larynx
© 2013 Pearson Education, Inc.
3
Figure 14.1 33
Respiratory System – From Pharynx to Trachea
(14.1)
• Air passes through the:
• Pharynx
• To the:
• Larynx
• The beginning of the lower respiratory system
• Surrounds the glottis or narrow opening for air to pass
• To the:
• Trachea
• Also known as the "windpipe"
© 2013 Pearson Education, Inc.
Module 14.1 Review
a. What is the role of cilia lining the respiratory
mucosa?
b. Why can cystic fibrosis become lethal?
c. How is inhaled air warmed?
© 2013 Pearson Education, Inc.
Trachea and Primary Bronchi (14.2)
• From the larynx, air continues into the:
• Trachea (windpipe)
• The trachea branches to form the right and left:
• Primary bronchi
© 2013 Pearson Education, Inc.
Trachea to bronchioles
Hyoid bone
Larynx
Tracheal
cartilages
Trachea
Right primary
bronchus
Left primary
bronchus
Smaller
bronchi
Right lung
Cartilage plates
Visceral pleura
Left lung
© 2013 Pearson Education, Inc.
Figure 14.2 11
Trachea (14.2)
• Or windpipe
• About 2.5 cm (1 in.) in diameter
• Lined with C-shaped, incomplete rings of tracheal
cartilage
• Posterior wall (adjacent to esophagus) formed from
trachealis muscle
• Allows for constriction and expansion of trachea
• Allows shape change when food passes down esophagus
• Branches to form the right and left primary bronchi
© 2013 Pearson Education, Inc.
Esophagus and trachea cross-section
Esophagus
Incomplete tracheal
cartilages
Trachealis muscle
Respiratory
epithelium
Tracheal cartilage
Lumen of trachea
© 2013 Pearson Education, Inc.
Mucous gland
Figure 14.2 22
Bronchi to Bronchioles (14.2)
• Two primary bronchi
1. Right primary bronchus (slightly larger diameter and
steeper angle)
2. Left primary bronchus
• Bronchi branch into smaller tubes called
bronchioles
© 2013 Pearson Education, Inc.
Bronchi to Bronchioles (14.2)
• Bronchioles
• Lined with smooth muscle (no cartilage)
• Sympathetic nervous system causes bronchodilation
• Relaxation of the muscle = increased diameter and airflow
• Parasympathetic nervous system causes
bronchoconstriction
• Contraction of the muscle = decreased diameter and
airflow
© 2013 Pearson Education, Inc.
Bronchiole cross-section
Bronchiole
Respiratory
epithelium
Smooth muscle
© 2013 Pearson Education, Inc.
Figure 14.2 11
Asthma (14.2)
• Allergic reaction
• Extreme bronchoconstriction and inflammation
• Severely restricts or stops airflow
© 2013 Pearson Education, Inc.
Lung Anatomy (14.2)
• Primary bronchi lead into lungs
• Right primary bronchus into right lung
• Left primary bronchus into left lung
• Lungs are cone-shaped
• Concave inferior portion (base) rests on
diaphragm
• Groove near the superior point (apex) is the
hilum
• Allows passage of bronchi, pulmonary vessels,
nerves, and lymphatics
© 2013 Pearson Education, Inc.
Lung Anatomy (14.2)
• Each lung is divided into lobes
• Right lung
• Superior lobe
• Middle lobe
• Inferior lobe
• Left lung
• Superior lobe
• Cardiac notch for heart
• Inferior lobe
• Lobes are divided by fissures
• Horizontal fissure in right lung only
• Oblique fissure in both lungs
© 2013 Pearson Education, Inc.
Lung structures
Apex
Hilum
Superior
lobe
Horizontal
fissure
Superior
lobe
Middle lobe
Oblique
fissure
Cardiac notch
Inferior
lobe
Inferior
lobe
Base
© 2013 Pearson Education, Inc.
Oblique
fissure
Figure 14.2 33
Pleura and Pericardium (14.2)
• Surrounding each lung is a pleural cavity,
consisting of:
• Parietal pleura
• Lines the inner surface of the chest wall
• Visceral pleura
• Covers the surface of the lungs
• The pericardial cavity surrounds the heart
© 2013 Pearson Education, Inc.
Transverse section through lungs
Parietal pleura
Right pleural cavity
Visceral pleura
Mediastinum
Right Lung
Left Lung
Heart
Pericardial cavity
© 2013 Pearson Education, Inc.
Left
pleural
cavity
Figure 14.2 44
Module 14.2 Review
a. Why are the tracheal cartilages C-shaped
rather than complete rings?
b. If food accidentally enters the trachea, in which
bronchus is it more likely to lodge? Why?
c. Which lung features the cardiac notch? What
is the purpose of the cardiac notch?
© 2013 Pearson Education, Inc.
Gas Exchange at the Alveoli (14.3)
• Alveoli
• Are tiny sacs
• Each lung has about 150 million
• Are surrounded by capillaries
• Occur in clusters (like grapes)
• Are surrounded by elastic fibers
• Allow for expansion and recoil with air movement in and
out
© 2013 Pearson Education, Inc.
Bronchioles to alveoli
Primary bronchus
Secondary bronchi
Small bronchi
Cluster of alveoli
Bronchioles
Smooth muscle
bands
Pulmonary
vein
branches
Alveolar
capillary
networks
Elastic
fibers
© 2013 Pearson Education, Inc.
Pulmonary
artery
branches
Alveoli
Figure 14.3 11- 2– 2
Blood Flow and Gas Exchange (14.3)
• Branches of pulmonary artery bring deoxygenated
blood
• From heart to the capillary networks around alveoli
• Gas exchange occurs
• Between air in alveoli and blood in surrounding
capillaries
• Branches of pulmonary vein collect oxygenated
blood
• From capillary networks and carry to the heart
© 2013 Pearson Education, Inc.
Alveolar Epithelium (14.3)
•
Epithelium lining alveoli very thin to allow for
easy gas exchange
•
•
Primarily simple squamous epithelium
Two other types of cells found in alveoli
1. Surfactant-secreting cells
•
Surfactant – oily secretion forms a coating over thin layer
of water, results in reduced surface tension
2. Alveolar macrophages
•
© 2013 Pearson Education, Inc.
Phagocytize (eat) debris, particulates, etc. that could
clog alveoli
Alveoli clusters to alveoli
Squamous
epithelial cells
Surfactant
secreting cells
Roaming
alveolar
macrophages
Elastic fibers
Interconnection
between
adjacent alveoli
Capillary
Endothelial
cell of capillary
Smooth muscle
bands
Pulmonary
vein
branches
Alveolar macrophage
Pulmonary
artery
branches
Alveolar
capillary
networks
Elastic
fibers
© 2013 Pearson Education, Inc.
Alveoli
Figure 14.3 22- 3– 3
Respiratory Membrane (14.3)
• Oxygen and carbon dioxide move by diffusion
• Move across the respiratory membrane, a very
thin (~0.5-µm) membrane composed of:
• Alveolar epithelium (simple squamous epithelium)
• Fused basement membrane
• Capillary endothelium (simple squamous epithelium)
© 2013 Pearson Education, Inc.
Alveoli to respiratory membrane Squamous
Surfactant
secreting cells
epithelial cells
Roaming
alveolar
macrophages
Elastic fibers
Interconnection
between
adjacent alveoli
Capillary
Endothelial
cell of capillary
Alveolar macrophage
Alveolar air
space
Alveolar surface
The Respiratory Membrane
Alveolar epithelium
Fused basement membranes
Capillary endothelium
© 2013 Pearson Education, Inc.
Nucleus of
endothelial cell
Capillary lumen
Red blood cell
Figure 14.3 33- 4– 4
Module 14.3 Review
a. Describe the roles of the three types of cells
associated with alveoli.
b. Describe how the structure of the respiratory
membrane enhances gas diffusion.
c. What would happen to the alveoli if surfactant
were not produced?
© 2013 Pearson Education, Inc.
Respiratory Physiology (Section 2)
• Respiration includes:
• External respiration
• Exchange of oxygen and carbon dioxide between the
body's tissues and external environment
• Internal respiration
• Absorption of oxygen and release of carbon dioxide by
tissue cells
© 2013 Pearson Education, Inc.
External Respiration (Section 2)
• Includes:
• Pulmonary ventilation
• Physical movement of air into and out of lungs
• Helps maintain alveolar ventilation – movement of air
into and out of alveoli
• Gas diffusion
• Movement of oxygen and carbon dioxide
• Across respiratory membrane in lungs and
• Across capillary walls between blood and other tissue
© 2013 Pearson Education, Inc.
External Respiration (Section 2)
• Impaired gas exchange can lead to:
• Hypoxia – low oxygen levels
• Anoxia – no oxygen supply, which leads to tissue death
© 2013 Pearson Education, Inc.
External and internal respiration
Respiration
External Respiration
Internal Respiration
O2 transport
Tissues
Gas
diffusion
Gas
diffusion
Gas
diffusion
Gas
diffusion
Lungs
© 2013 Pearson Education, Inc.
CO2 transport
Figure 14 Section 2 11
Pressure Changes and Pulmonary Ventilation
(14.4)
• In a closed system (like the lungs), a change in
volume = a change in pressure
• Increased volume = decreased pressure
• Decreased volume = increased pressure
© 2013 Pearson Education, Inc.
Volume and pressure relationship
Decreased volume =
increased pressure
Increased volume =
decreased pressure
© 2013 Pearson Education, Inc.
Figure 14.4 11
Pulmonary Ventilation – How to Change the
Volume (14.4)
• Changing the shape of thoracic cavity results in a
change in volume
• Increasing volume by:
• Contracting diaphragm (moves inferiorly)
• Moving rib cage superiorly
© 2013 Pearson Education, Inc.
Thoracic cavity shape changes
Moving the rib cage
upward increases
thoracic cavity
volume, decreasing
thoracic cavity
pressure
Contracting the
diaphragm increases
thoracic cavity
volume, decreasing
thoracic cavity
pressure
© 2013 Pearson Education, Inc.
Figure 14.4 22
Pulmonary Ventilation Detail (14.4)
• Expanding the thoracic cavity expands the lungs
because of the pleura and pleural fluid
• Parietal pleura is attached to the thoracic wall
• Visceral pleura is attached to the lungs
• Pleural fluid forms bond between parietal and visceral
layer
• Atelectasis is the collapse of a lung (or part of a
lung)
• When air enters the pleural cavity
• The connection between visceral and parietal pleura
is lost
© 2013 Pearson Education, Inc.
Pressures at the start of inhalation
Thoracic wall
Parietal pleura
Pleural fluid
Lung
Visceral
pleura
Pleural
cavity
Diaphragm
Poutside = Pinside
Pressure outside and inside are
equal, so no air movement occurs
© 2013 Pearson Education, Inc.
Figure 14.4 33
Pressures during inhalation
Inhalation: volume increases
Poutside > Pinside
Pressure inside falls, so air flows in
© 2013 Pearson Education, Inc.
Figure 14.4 44
Pressures during exhalation
Exhalation: volume decreases
Poutside < Pinside
Pressure inside rises, so air flows out
© 2013 Pearson Education, Inc.
Figure 14.4 44
Air Moves from High Pressure to Low Pressure
(14.4)
• Specific pressures
• Atmospheric pressure – air pressure outside the lungs
• Intrapulmonary pressure – air pressure inside the
lungs, specifically the respiratory tract
• Alveolar pressure – air pressure in the alveoli
PLAY
Respiration: Pressure Gradients
© 2013 Pearson Education, Inc.
Graph of pressure changes during ventilation
Inhalation Exhalation
+2
Alveolar +1
pressure
(relative to 0
atmospheric
pressure) –1
–2
0
© 2013 Pearson Education, Inc.
1
3
2
Time (sec)
Figure 14.4 55
4
Graph of tidal volume during ventilation
Inhalation
Exhalation
500
Tidal
volume
(mL)
250
0
0
© 2013 Pearson Education, Inc.
1
3
2
Time (sec)
4
Figure 14.4 55
Module 14.4 Review
a. Describe the relationship between volume and
pressure for a gas.
b. What physical changes affect the volume of the
lungs?
c. What pressures determine the direction of airflow
within the respiratory tract?
© 2013 Pearson Education, Inc.
Respiratory Muscles (14.5)
• Various muscles change the volume of the
thoracic cavity
• Muscles involved with inhalation
• Inspiratory muscles
• Muscles involved with exhalation
• Expiratory muscles
© 2013 Pearson Education, Inc.
Respiratory Muscles – Inhalation (14.5)
• Primary inspiratory muscles
• Involved in quiet breathing (active inhalation, passive exhalation)
• Diaphragm
• External intercostals
• Accessory inspiratory muscles
• Increase the speed and amount of rib movement (allowing deeper
breathing and greater oxygen intake)
• Sternocleidomastoid
• Scalenes
• Pectoralis minor
© 2013 Pearson Education, Inc.
Respiratory muscles
Accessory
Inspiratory
Muscles
Sternocleidomastoid muscle
Scalene
muscles
Pectoralis
minor muscle
Serratus
anterior muscle
Primary
Inspiratory
Muscle
Diaphragm
© 2013 Pearson Education, Inc.
Primary Inspiratory Muscle
External intercostal muscles
Accessory
Expiratory
Muscles
Internal
intercostal
muscles
Transversus
thoracis
muscle
External
oblique
muscle
Rectus
abdominis
Internal
oblique
muscle
Figure 14.5 11
Accessory inspiratory muscles
Accessory Inspiratory
Muscles (active when needed)
Primary Inspiratory Muscles
External intercostal muscles
Diaphragm
© 2013 Pearson Education, Inc.
Figure 14.5 22
Respiratory Muscles – Exhalation (14.5)
• There are no primary expiratory muscles
• With quiet breathing, exhalation is a passive process
• Accessory expiratory muscles
• Depress the ribs and push the diaphragm upwards
• Decreasing thoracic cavity volume quickly
• Allowing greater pressure change and faster airflow out of lungs
• Internal intercostals
• Transversus thoracis
• External obliques
• Internal obliques
• Rectus abdominis
© 2013 Pearson Education, Inc.
Respiratory muscles
Accessory
Inspiratory
Muscles
Sternocleidomastoid muscle
Scalene
muscles
Pectoralis
minor muscle
Serratus
anterior muscle
Primary
Inspiratory
Muscle
Diaphragm
© 2013 Pearson Education, Inc.
Primary Inspiratory Muscle
External intercostal muscles
Accessory
Expiratory
Muscles
Internal
intercostal
muscles
Transversus
thoracis
muscle
External
oblique
muscle
Rectus
abdominis
Internal
oblique
muscle
Figure 14.5 11
Accessory expiratory muscles
Accessory expiratory
muscles
Rectus abdominis
© 2013 Pearson Education, Inc.
Figure 14.5 33
Pulmonary Volumes and Capacities (14.5)
• Tidal volume (VT)
• Amount of air moved into or out of lungs during one cycle
(inhalation and exhalation)
• Averages 500 mL
• About 350 mL is involved in gas exchange
• Other 150 mL in the conducting zone is called:
• Dead space of the lungs
• Inspiratory reserve volume (IRV)
• Amount of air can breathe in beyond tidal volume
• Expiratory reserve volume (ERV)
• Amount of air can breathe out beyond normal, quiet exhalation
© 2013 Pearson Education, Inc.
Pulmonary Volumes and Capacities (14.5)
• Vital capacity
• Maximum amount of air can move in or out of lungs in
one cycle
• Residual volume
• Amount of air left in lungs after maximum exhalation
• Total lung capacity
• Total volume of lungs (vital capacity + residual volume)
• Averages 4200 mL in females; 6000 mL in males
© 2013 Pearson Education, Inc.
Pulmonary volumes and capacities
Pulmonary Volumes and Capacities (adult male)
Inspiratory reserve
volume (IRV)
The vital capacity is the maximum
amount of air that
you can move into
or out of your
lungs in a single
respiratory cycle.
The vital capacity
is the sum of the
expiratory reserve
volume, the tidal
volume, and the
inspiratory reserve
volume.
6000
Tidal volume (TV)
Volume 2700
(mL) 2200
Expiratory reserve
volume (ERV)
1200
0
Time
The residual
volume is the
amount of air that
remains in your
lungs even after a
maximal exhalation.
The total lung capacity is the total volume of air in your lungs,
calculated by adding the vital capacity and the residual volume.
The total lung capacity averages around 6000 mL in males and
4200 mL in females.
© 2013 Pearson Education, Inc.
Figure 14.5 44
Module 14.5 Review
a. Name the various measurable pulmonary
volumes.
b. Identify the primary inspiratory muscles.
c. When do the accessory respiratory muscles
become active?
© 2013 Pearson Education, Inc.
Gas Diffusion (14.6)
• Oxygen moves
• From where there is more oxygen to where there is less
oxygen
• Carbon dioxide moves
• From where there is more carbon dioxide to where there
is less carbon dioxide
© 2013 Pearson Education, Inc.
Gas diffusion in external and internal respiration
External Respiration
Alveolus
Systemic
circuit
Respiratory
membrane
Pulmonary
circuit
Pulmonary
capillary
Internal Respiration
Systemic
circuit
Interstitial fluid
Systemic
capillary
© 2013 Pearson Education, Inc.
Figure 14.6 11
Gas Diffusion – External Respiration (14.6)
• Blood in pulmonary arteries has:
• Low oxygen and high carbon dioxide content compared
to alveoli
• Oxygen tends to flow
• From alveoli into capillary
• Carbon dioxide tends to flow
• From capillary to alveoli
© 2013 Pearson Education, Inc.
Gas diffusion in external respiration
External Respiration
Alveolus
Respiratory
membrane
Pulmonary
capillary
© 2013 Pearson Education, Inc.
Figure 14.6 11
Gas Diffusion – Internal Respiration (14.6)
• Cells in tissues use oxygen and give off carbon
dioxide, so:
• Oxygen levels are low in interstitial fluid and:
• Carbon dioxide levels are high compared to arterial
capillaries
• Oxygen tends to flow
• From capillary into interstitial fluid
• Carbon dioxide tends to flow
• From interstitial fluid into capillaries
PLAY
Respiration: Oxygen and Carbon Dioxide Transport
© 2013 Pearson Education, Inc.
Gas diffusion in internal respiration
Internal Respiration
Interstitial fluid
Systemic
capillary
© 2013 Pearson Education, Inc.
Figure 14.6 11
Gas Transport – Oxygen (14.6)
• Oxygen is:
• Picked up in the pulmonary capillaries
• Carried bound to hemoglobin on the red blood cells
Hb + O2
HbO2
• In the systemic capillaries, the process is reversed
• Hemoglobin releases the oxygen
• Which then diffuses into the tissues
HbO2
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Hb + O2
Gas Transport – Carbon Dioxide (14.6)
•
Carbon dioxide is picked up in the systemic capillaries
and carried in one of three ways
1. Dissolved in plasma
2. Bound to hemoglobin on the red blood cells
CO2 + Hb
HbCO2
3. Converted to carbonic acid
CO2 + H2O
•
H2CO3
Which then dissociates to bicarbonate and hydrogen
H2CO3
•
Bicarbonate is exchanged into the plasma for chloride (Cl–)
•
© 2013 Pearson Education, Inc.
H+ + HCO3–
Called the chloride shift
Gas Transport – Carbon Dioxide (14.6)
• In the pulmonary capillaries, the process is
reversed
• Bicarbonate is exchanged for chloride (Cl–) back into the
red blood cells
• Bicarbonate combines with hydrogen to form carbonic
acid
• HCO3– + H+
H2CO3
• Carbonic acid is converted to carbon dioxide and water
• H2CO3
CO2 + H2O
• Carbon dioxide then diffuses into the alveoli
© 2013 Pearson Education, Inc.
Oxygen and carbon dioxide pickup and delivery
Oxygen pickup
Slide 1
Pulmonary
capillary
Plasma
Red blood cell
Hemoglobin
Alveolar
air space
© 2013 Pearson Education, Inc.
Figure 14.6 21
2
Oxygen and carbon dioxide pickup and delivery
Oxygen pickup
Slide 2
Oxygen delivery
Pulmonary
capillary
Plasma
Red blood cell
Systemic
capillary
Cells in
peripheral
tissues
Red blood cell
Hemoglobin
Alveolar
air space
© 2013 Pearson Education, Inc.
Figure 14.6 21
2
Oxygen and carbon dioxide pickup and delivery
Oxygen pickup
Slide 3
Oxygen delivery
Pulmonary
capillary
Plasma
Red blood cell
Systemic
capillary
Cells in
peripheral
tissues
Red blood cell
Hemoglobin
Alveolar
air space
Carbon dioxide pickup
Systemic
capillary
© 2013 Pearson Education, Inc.
Figure 14.6 21
2
Oxygen and carbon dioxide pickup and delivery
Oxygen pickup
Slide 4
Oxygen delivery
Pulmonary
capillary
Plasma
Red blood cell
Systemic
capillary
Cells in
peripheral
tissues
Red blood cell
Hemoglobin
Alveolar
air space
Carbon dioxide pickup
Carbon dioxide delivery
Alveolar
air space
Pulmonary
capillary
© 2013 Pearson Education, Inc.
Systemic
capillary
Figure 14.6 21
2
Module 14.6 Review
a. Describe the forces that move oxygen and
carbon dioxide across the respiratory membrane.
b. What molecule binds oxygen in the RBC?
c. Describe the three ways that carbon dioxide is
transported in the bloodstream.
© 2013 Pearson Education, Inc.
Respiratory Control (14.7)
• Subconscious control centers for respiration in the medulla
oblongata and pons
• Medulla oblongata
• Dorsal respiratory group (DRG)
• Inspiratory center
• Controls external intercostal muscles and diaphragm
• Functions in every respiratory cycle
• Ventral respiratory group (VRG)
• Both inspiratory and expiratory centers
• Centers function only when increased oxygen demands
require accessory inspiratory muscles
© 2013 Pearson Education, Inc.
Respiratory Control (14.7)
• Subconscious control centers for respiration in the
medulla oblongata and pons
• Pons
• Respiratory centers
• Adjust the rate set by the medulla oblongata
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Respiratory control centers
Pons
The respiratory centers in the pons adjust the
pace of respiration set by those of the medulla
oblongata.
Pons
Medulla oblongata
Dorsal respiratory group (DRG)
Ventral respiratory group (VRG)
Medulla
oblongata
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Figure 14.7 11
Quiet breathing processes
Quiet Breathing
INHALATION
(2 seconds)
Diaphragm and external
intercostal muscles
contract. Inhalation occurs.
Activity in the
DRG stimulates
the primary
inspiratory
muscles.
Neurons in the DRG
become inactive. They
remain quiet for the next
3 seconds and allow the
primary inspiratory
muscles to relax.
Diaphragm and external
intercostal muscles relax
and passive exhalation
occurs.
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EXHALATION
(3 seconds)
Figure 14.7 22
Forced breathing processes
Forced Breathing
INHALATION
Inspiratory muscles
contract, and expiratory
muscles relax. Inhalation
occurs.
Increased activity in
the DRG stimulates the
VRG to activate the
accessory muscles
involved in inhalation.
The expiratory center
of the VRG is inhibited.
The expiratory center of
the VRG stimulates the
appropriate accessory
muscles and active
exhalation occurs. The
inspiratory muscles are
relaxed over this period.
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DRG and
Inspiratory
center of VRG
are inhibited.
Expiratory
center of VRG
is activated.
EXHALATION
Figure 14.7 33
Respiratory Control – Homeostasis (14.7)
• Usually, carbon dioxide levels are the "trigger" for breathing
• Increased arterial carbon dioxide (hypercapnia)
• Usually caused by low respiratory rate (hypoventilation)
• This situation stimulates chemoreceptors and the body responds by
increasing respiratory rate
• Decreased arterial carbon dioxide (hypocapnia)
• Caused by faster than normal rate and depth of breathing
(hyperventilation)
• In response to low carbon dioxide levels, body decreases
respiratory rate
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Changes in breathing to maintain homeostasis
Stimulation
of arterial
chemoreceptors
Stimulation of
respiratory muscles
Increased CO2
levels in CSF,
decreased pH
Stimulation of CSF
chemoreceptors at
medulla oblongata
HOMEOSTASIS
DISTURBED
Increased respiratory
rate with increased
elimination of CO2
levels at the alveoli
Increased
arterial CO2 levels
(hypercapnia)
HOMEOSTASIS
RESTORED
HOMEOSTASIS
Start
Normal arterial
CO2 levels
Normal arterial
CO2 levels
HOMEOSTASIS
DISTURBED
Decreased respiratory
rate with decreased
elimination of CO2 at
the alveoli
Decreased
arterial CO2 levels
(hypocapnia)
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Inhibition
of arterial
chemoreceptors
Inhibition of
respiratory muscles
Decreased CO2
levels in CSF
Reduced stimulation
of CSF chemoreceptors
Figure 14.7 44
Shallow Water Blackout (14.7)
• The body's trigger to breathe is high carbon
dioxide
• Hyperventilating before going underwater causes
decreased carbon dioxide
• Levels of oxygen can drop enough to cause
fainting (blackout) BEFORE levels of carbon
dioxide rise enough to cause urge to breathe
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Module 14.7 Review
a. Where are the centers that adjust the pace of
respiration located?
b. Describe the two respiratory groups found in the
medulla oblongata.
c. What conditions are caused by hyperventilation
and hypoventilation?
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Chronic Obstructive Pulmonary Disease (14.8)
• Also known as COPD
• General term for a series of disorders that restrict
airflow
• Asthma
• Chronic bronchitis
• Emphysema
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Asthma (14.8)
• Extreme sensitivity to irritation
• Response is constriction of airway, increased mucus
production, and inflammation
• Attack triggers include:
• Allergies
• Toxins
• Exercise
• Cold weather
• Stress
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Chronic Bronchitis (14.8)
• Long-term inflammation and swelling of bronchial lining
• Overproduction of mucus – can clog airways
• Cigarette smoking leading cause; also caused by other
environmental irritants
• Often leads to chronic bacterial infection in lungs
• Subsequent heart failure may cause edema (swelling)
• Low oxygen levels gives skin bluish tint
• Swelling and bluish skin has led to term blue bloaters
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Emphysema (14.8)
• Chronic, progressive condition
• Alveoli gradually expand and merge with adjacent
alveoli
• To form large air spaces, but with little elastic connective
tissue to recoil
• Loss of respiratory surface area causes shortness
of breath
• But with enlarged/overexpanded lungs
• Heavy breathing and pink tint to skin has led to
term pink puffers
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Lung Cancer (14.8)
• Accounts for over 12 percent of new cancer cases
in both men and women
• Over 50 percent die within a year of diagnosis
• 85–90 percent of cases are a direct result of
cigarette smoking including secondhand smoke
• Nonsmoker living with a smoker has 20–30
percent greater chance of developing lung cancer
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Effects of Aging on the Respiratory System
(14.8)
• Skeletal system and connective tissues become
less elastic and flexible
• Over age 50, expect some degree of emphysema
from loss of elastic connective tissue
• Decline in respiratory performance inevitable, but
greatly influenced by smoking
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Module 14.8 Review
a. Describe chronic obstructive pulmonary disease
(COPD).
b. List two important risk factors for developing lung
cancer.
c. Name several age-related factors that affect the
respiratory system.
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