STUDY
This Information
Respiration
Part 1
Impacts, Issues
Up in Smoke
 Smoking immobilizes ciliated cells and kills white
blood cells that defend the respiratory system;
highly addictive nicotine discourages quitting
The Nature of Respiration
 All animals must supply their cells with oxygen
and rid their body of carbon dioxide
 Respiration
• The physiological process by which an animal
exchanges oxygen and carbon dioxide with its
environment
Interactions with Other Organ Systems
food, water intake
oxygen intake
Digestive
System
Respiratory
System
nutrients,
water,
salts
oxygen
elimination
of carbon
dioxide
carbon
dioxide
Circulatory
System
Urinary
System
water,
solutes
elimination
of food
residues
rapid transport
to and from all
living cells
elimination of
excess water, salts,
wastes
Fig. 39-2b, p. 682
The Basis of Gas Exchange
 Respiration depends on diffusion of gaseous
oxygen (O2) and carbon dioxide (CO2) down
their concentration gradients
 Gases enter and leave the internal environment
across a thin, moist layer (respiratory surface)
that dissolves the gases
Partial Pressure
 Partial pressure
• Of the total
atmospheric pressure
measured by a
mercury barometer
(760 mm Hg), O2
contributes 21% (160
mm Hg)
760 mm
Hg
Fig. 39-3, p. 682
Factors Affecting Diffusion Rates
STUDY
 Factors that increase diffusion of gases across a
respiratory surface:
• High partial pressure gradient of a gas across the
respiratory surface
• High surface-to-volume ratio
• High ventilation rate (movement of air or water
across the respiratory surface)
Respiratory Proteins
STUDY
 Respiratory proteins contain one or more
metal ions that reversibly bind to oxygen atoms
• Hemoglobin: An iron-containing respiratory
protein found in vertebrate red blood cells
• Myoglobin: A respiratory protein found in
muscles of vertebrates and some invertebrates
Gasping for Oxygen
 Rising water
temperatures,
slowing streams,
and organic
pollutants
reduce the
dissolved
oxygen (DO)
available for
aquatic species
Principles of Gas Exchange
 Respiration is the sum of processes that move
________ from air or water in the environment
to all metabolically active ________ and move
__________ from those tissues to the outside
 Oxygen levels are more stable in air than in
water
Principles of Gas Exchange
 Respiration is the sum of processes that move
oxygen from air or water in the environment to
all metabolically active tissues and move carbon
dioxide from those tissues to the outside
 Oxygen levels are more stable in air than in
water
Invertebrate Respiration
STUDY
 Integumentary exchange
• Some invertebrates that live in aquatic or damp
environments have no respiratory organs;
• Gases diffuse across the skin
 Gills
• Filamentous respiratory organs that increase
surface area for gas exchange in water
 Lungs
• Saclike respiratory organs with branching tubes
that deliver air to a respiratory surface
 Snails and slugs that spend some time on land
have a lung instead of, or in addition to, gills
Snails with Lungs
Invertebrate Respiration
STUDY
 Tracheal system
• Insects and spiders with a hard integument have
branching tracheal tubes that open to the surface
through spiracles (no respiratory protein required)
 Book lungs
• Some spiders also have thin sheets of respiratory
tissue that exchange oxygen with a respiratory
pigment (hemocyanin) in blood
trachea (tube
inside body)
spiracle (opening
to body surface)
STUDY
Insect Tracheal System
Fig. 39-7, p. 685
air-filled space
blood-filled space
STUDY
book lung
A Spider’s Book Lung
Fig. 39-8, p. 685
Key Concepts
Gas Exchange in Invertebrates
 Gas exchange occurs across the body surface
or gills of aquatic invertebrates
 In large invertebrates on land, it occurs across a
moist, internal respiratory surface or at fluid-filled
tips of branching tubes that extend from the
surface to internal tissues
Vertebrate Respiration
 Fishes use gills to extract oxygen from water
• Countercurrent flow aids exchange (blood flows
through gills in opposite direction of water flow)
 Amphibians exchange gases across their skin,
and at respiratory surfaces of paired lungs
• Larvae have external gills
Fish Gills
(a) Location of the gill
cover of a bony fish.
gill cover
Fig. 39-9a, p. 686
STUDY
mouth
open
gill
(b) Water is sucked into the mouth and
over the gills when a fish closes its gill
covers, opens its mouth, and expands its
oral cavity.
cover
closed
Fig. 39-9b, p. 686
mouth
closed
(c) The water moves out when
the fish closes its mouth,
opens its gill covers, and
squeezes the water past its
gills.
STUDY
gill
cover
open
Fig. 39-9c, p. 686
Countercurrent Flow
gill filaments
one gill arch
water is
sucked
into
mouth
STUDY
Water
exits
through
gill slits
A A bony fish with its gill cover removed. Water flows in through the mouth,
flows over the gills, then exits through gill slits. Each gill has bony gill
arches to which the gill filaments attach.
Fig. 39-10a, p. 686
STUDY
gill arch
respiratory surface
gill
filament
fold with a
capillary
bed inside
water
flow
direction of
blood flow
oxygen-poor blood
oxygenated blood from deep in body
back toward body
B Two gill arches with
filaments
C Countercurrent flow
of water and blood
Fig. 39-10 (b-c), p. 686
Frog Respiration
A
Lowering the floor
of the mouth
draws air inward
through nostrils.
STUDY
B
Closing nostrils
and raising the
floor of the
mouth pushes
air into lungs.
C
Rhythmically
raising and
lowering the
floor of the
mouth assists
gas exchange.
D
Contracting chest
muscles and
raising the floor of
the mouth forces
air out of lungs,
and the frog
exhales.
Fig. 39-11, p. 687
Vertebrate Respiration
 Reptiles, birds and mammals exchange gases
through paired lungs, ventilated by chest muscles
 Birds have the most efficient vertebrate lungs
• Air sacs allow oxygen-rich air to pass respiratory
surfaces on both inhalation and exhalation
A Inhalation 1
Muscles expand chest
cavity, drawing air in
through nostrils. Some
of the air flowing in
through the trachea
goes to lungs and some
goes to posterior air
sacs.
B Exhalation 1
Anterior air sacs
empty. Air from
posterior air sacs
moves into lungs.
Bird Respiratory
System
trachea
STUDY
anterior
air sacs
lung
posterior
air sacs
C Inhalation 2
Air in lungs moves to anterior
air sacs and is replaced by
newly inhaled air.
D Exhalation 2
Air in anterior air sacs moves out of the body
and air from posterior sacs flows into the
lungs.
Fig. 39-12, p. 687
Fig. 39-12 (inset), p. 687
Human Respiratory System
STUDY
 The human respiratory system functions in gas
exchange, sense of smell, voice production,
body defenses, acid-base balance, and
temperature regulation
Airways
STUDY
 Air enters through nose or mouth, flows through
the pharynx (throat) and the larynx (voice box)
• Vocal cords change the size of the glottis
 The epiglottis protects the trachea, which
branches into two bronchi, one to each lung
• Cilia and mucus-secreting cells clean airways
glottis
closed
vocal cords
glottis
open
glottis (closed)
epiglottis
tongue’s base
STUDY
Larynx: Vocal Cords and Glottis
Fig. 39-14, p. 689
From Airways to Alveoli
STUDY
 Inside each lung, bronchi branch into
bronchioles that deliver air to alveoli
 Alveoli are small sacs, one cell thick, where
gases are exchanged with pulmonary capillaries
Muscles and Respiration
STUDY
 Muscle movements change the volume of the
thoracic cavity during breathing
 Diaphragm
• A broad sheet of smooth muscle below the lungs
• Separates the thoracic and abdominal cavities
 Intercostal muscles
• Skeletal muscles between the ribs
Functions of the Respiratory System
Nasal Cavity
Chamber in which air is moistened,
warmed, and filtered, and in which
sounds resonate
Pharynx (Throat)
Airway connecting nasal cavity and
mouth with larynx; enhances sounds;
also connects with esophagus
Epiglottis
Closes off larynx during swallowing
Larynx (Voice Box)
Airway where sound is produced;
closed off during swallowing
Trachea (Windpipe)
Airway connecting larynx with two
bronchi that lead into the lungs
Oral Cavity (Mouth)
Supplemental airway
when breathing is
labored
Pleural Membrane
Double-layer membrane
with a fluid-filled space
between layers; keeps
lungs airtight and helps
them stick to chest wall
during breathing
Intercostal Muscles
At rib cage, skeletal
muscles with roles in
breathing. There are
two sets of intercostal
muscles (external and
internal)
Diaphragm
Muscle sheet between
the chest cavity and
abdominal cavity with
roles in breathing
Lung (One of a Pair)
Lobed, elastic organ of breathing;
enhances gas exchange between
internal environment and outside air
Bronchial Tree
Increasingly branched
airways starting with two
bronchi and ending at air
sacs (alveoli) of lung tissue
STUDY
Fig. 39-13a, p. 688
bronchiole
alveolar sac
(sectioned)
alveolar duct
alveoli
STUDY
Fig. 39-13b, p. 688
alveolar
sac
STUDY
pulmonary
capillary
Fig. 39-13c, p. 688
Cyclic Reversals
in Air Pressure Gradients
STUDY
 Respiratory cycle
• One inhalation and one exhalation
 Inhalation is always active
• Contraction of diaphragm and external intercostal
muscles increases volume of thoracic cavity
• Air pressure in alveoli drops below atmospheric
pressure; air moves inward
Cyclic Reversals
in Air Pressure Gradients
STUDY
 Exhalation is usually passive
• As muscles relax, the thoracic cavity shrinks
• Air pressure in the alveoli rises above
atmospheric pressure, air moves out
 Exhalation may be active
• Contraction of abdominal muscles forces air out
The Thoracic Cavity and
the Respiratory Cycle
Inward
flow of air
A Inhalation. Diaphragm
contracts, moves down.
External intercostal muscles
contract, lift rib cage upward
and outward. Lung volume
expands.
Fig. 39-15a, p. 690
Outward
flow of air
B Exhalation.
Diaphragm, external
intercostal muscles
return to resting
positions. Rib cage
moves down. Lungs
recoil passively.
Fig. 39-15b, p. 690
Supplemental: First Aid for Choking
 Heimlich maneuver
• Upward-directed force on the diaphragm forces
air out of lungs to dislodge an obstruction
Respiratory Volumes
 Air in lungs is partially replaced with each breath
• Lungs are never emptied of air (residual volume)
 Vital capacity
• Maximum volume of air the lungs can exchange
 Tidal volume
• Volume of air that moves in and out during a
normal respiratory cycle
Respiratory Volumes
Control of Breathing
 Neurons in the medulla oblongata of the brain
stem are the control center for respiration
• Rhythmic signals from the brain cause muscle
contractions that cause air to flow into the lungs
 Chemoreceptors in the medulla, carotid arteries,
and aorta wall detect chemical changes in blood,
and adjust breathing patterns
STIMULUS
CO2 concentration
and acidity rise in the
blood and cerebrospinal
fluid.
Respiratory Responses
RESPONSE
Chemoreceptors
in wall of carotid
arteries and aorta
Respiratory center
in brain stem
Diaphragm,
Intercostal muscles
CO2 concentration
and acidity decline
in the blood and
cerebrospinal fluid.
Tidal volume and rate of breathing change.
Stepped Art
Fig. 39-18, p. 691
Gas Exchange and Transport
 Gases diffuse between a pulmonary capillary
and an alveolus at the respiratory membrane
• Alveolar epithelium
• Capillary endothelium
• Fused basement membranes
 O2 and CO2 each follow their partial pressure
gradient across the membrane
The Respiratory Membrane
red blood
cell inside
pulmonary
capillary
pore for
air flow
between
adjoining
alveoli
air space
inside
alveolus
a Surface view of
capillaries associated
with alveoli
b Cutaway view of one of
the alveoli and adjacent
pulmonary capillaries
alveolar
epithelium
capillary
endothelium
fused
basement
membranes
of both
epithelial
tissues
c Three components
of the respiratory
membrane
Fig. 39-19, p. 692
Oxygen Transport
 In alveoli, partial pressure of O2 is high; oxygen
binds with hemoglobin in red blood cells to form
oxyhemoglobin (HbO2)
 In metabolically active tissues, partial pressure
of O2 is low; HbO2 releases oxygen
 Myoglobin, found in some muscle tissues, is
similar to hemoglobin but holds O2 more tightly
alpha globin
alpha globin
Structure of
hemoglobin, the
oxygentransporting
protein of red
blood cells. It
consists of four
globin chains,
each associated
with an ironcontaining heme
group, colorcoded red.
beta globin
Hemoglobin
beta globin
Fig. 39-20a, p. 693
Myoglobin
heme
Myoglobin, an oxygen-storing protein in
muscle cells. Its single chain associates with
a heme group. Compared to hemoglobin,
myoglobin has a higher affinity for oxygen,
so it helps speed the transfer of oxygen from
blood to muscle cells.
Fig. 39-20b, p. 693
Carbon Dioxide Transport
 Carbon dioxide is transported from metabolically
active tissues to the lungs in three forms
• 10% dissolved in plasma
• 30% carbaminohemoglobin (HbCO2)
• 60% bicarbonate (HCO3-)
 Carbonic anhydrase in red blood cells
catalyzes the formation of bicarbonate
CO2 + H2O
→ H2CO3 → HCO3- + H+
DRY
INHALED AIR 160 0.03
Partial
Pressures for
Oxygen and
Carbon Dioxide
Partial pressures (in mm Hg)
for oxygen (pink boxes) and
carbon dioxide (blue boxes) in
the atmosphere, blood, and
tissues.
Figure It Out: What is the
partial pressure of oxygen in
arteries that carry blood to
systemic capillary beds?
pulmonary
arteries
40 45
120 27
alveolar sacs
104 40
start of
systemic
veins
MOIST
EXHALED AIR
pulmonary
veins
100 40
start of
systemic
capillaries
100 40
40 45
Answer: 100 mm Hg
cells of body tissues
less than 40
more than 45
Stepped Art
Fig. 39-21, p. 693
The Carbon Monoxide Threat
 Carbon monoxide (CO)
• A colorless, odorless gas that can fill up O2
binding sites on hemoglobin, block O2 transport,
and cause carbon monoxide poisoning
 Carbon monoxide poisoning often results when
fuel-burning appliance are poorly ventilated
• Symptoms include nausea, headache, confusion,
dizziness, and weakness
Key Concepts
Gas Exchange in Vertebrates
 Gills or paired lungs are gas exchange organs in
most vertebrates
 The efficiency of gas exchange is improved by
mechanisms that cause blood and water to flow
in opposite directions at gills, and by muscle
contractions that move air into and out of lungs
Respiratory Diseases and Disorders
 Interrupted breathing
• Brain-stem damage, sleep apnea, SIDS
 Potentially deadly infections
• Tuberculosis, pneumonia
 Chronic bronchitis and emphysema
• Damage to ciliated lining of bronchioles and walls
of alveoli; tobacco smoke is the main risk factor
Cigarette Smoke and Ciliated Epithelium
Fig. 39-22a, p. 694
free surface
of a mucussecreting cell
free surface
of a cluster of
ciliated cells
Fig. 39-22b, p. 694
Risks Associated With Smoking
and Emphysema
(a) From the American Cancer Society, a list of
major risks incurred by smoking and the
benefits of quitting. (b) Appearance of normal
lung tissue in humans. (c) Appearance of lung
tissues from someone who was affected by
emphysema.
Key Concepts
Respiratory Problems
 Respiration can be disrupted by damage to
respiratory centers in the brain, physical
obstructions, infectious disease, and inhalation
of pollutants, including cigarette smoke
High Climbers and Deep Divers
 Altitude sickness
• Hypoxia can result when people who live at low
altitudes move suddenly to high altitudes
• People who grow up at high altitudes have more
alveoli and blood vessels in their lungs
 Acclimatization to altitude includes adjustments
in cardiac output, rate and volume of breathing
• Hypoxia stimulates erythropoietin secretion
Adaptation to High Altitude
 Llamas that live at high altitudes have special
hemoglobin that binds oxygen more efficiently
Deep-Sea Divers
 Water pressure increases with depth; human
divers using compressed air risk nitrogen
narcosis (disrupts neuron signaling)
 Returning too quickly to the surface from a deep
dive can release dangerous nitrogen bubbles
into the blood stream (‘the bends”)
 Without tanks, trained humans can dive to 210
meters; sperm whales can dive 2,200 meters
Adaptations for Deep Diving
 Leatherback turtles dive up to one hour
• Move air to cartilage-reinforced airways
• Flexible shell for compression
 Four ways diving animals conserve oxygen
•
•
•
•
Deep breathing before diving
High red-cell count, large amounts of myoglobin
Slowed heart rate and metabolism
Conservation of energy
Deep Divers
Key Concepts
Gas Exchange in Extreme Environments
 At high altitudes, the human body makes shortterm and long-term adjustments to thinner air
 Built-in respiratory mechanisms and specialized
behaviors allow sea turtles and diving marine
mammals to stay under water, at great depths,
for long periods
Video Supplements
Animation: Bird respiration
Animation: Human respiratory system
Animation: Examples of respiratory
surfaces
Animation: Vertebrate lungs
Animation: Bony fish respiration
Animation: Frog respiration
Animation: Respiratory cycle
Animation: Heimlich maneuver
Animation: Changes in lung volume and
pressure
Animation: Partial pressure gradients
Animation: Bicarbonate buffer system
Animation: Globin and hemoglobin
structure
Animation: Pressure-gradient changes
during respiration
Animation: Structure of an alveolus
Animation: Vocal cords
ABC video: Blood test for lung cancer
Video: Up in smoke