Chapter 40
Respiration: A Summary
AP Biology
Spring 2011
The Basis of Gas Exchange
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Respiration: sum of physiological processes that move
oxygen gas from surrounds to all metabolically active
tissues in animal body and carbon dioxide from tissues to
outside
Relies on diffusion of gases down pressure gradients
Gases enter and leave internal environment by crossing
moist respiratory surfaces
Factors Influencing Gas Exchange
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Surface to volume ratio
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As animal grows, its surface area increases at a lesser rate than
its volume
Makes diffusion of gases into interior a problem
Animals either must have a small flattened body that keeps
internal cells close to surface or they must have specialized
respiratory organs to move gases inward
Factors Influencing Gas Exchange
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Ventilation
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Moving air or water past a respiratory surface keeps pressure
gradient across the surface high and thus increases rate of gas
exchange
Humans and frogs breathe in and out to move air in and out of
the lungs
Fish and other animals that live in the water have mechanisms
that move water across their respiratory surfaces
Factors Influencing Gas Exchange
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Respiratory Pigments
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The main transport pigment is hemoglobin (are proteins)
Each molecule of hemoglobin binds 4 molecules of oxygen in
the lungs (high concentration) and releases them in the tissues
where oxygen is low
Myoglobin is another iron-containing respiratory, which is a
good storage molecule
of oxygen because it has
a higher affinity for
oxygen
Invertebrate Respiration
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Integumentary exchange: gases diffuse directly across
a moist body surface
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Adequate for small animals such as sponges, cnidarians,
flatworms
Invertebrate Respiration
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Gills: highly folded, thin walled projections from the body
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Enhance exchange rates between blood of aquatic animals and
their watery environment
Snails and slugs live on land and water, have lungs in
addition to gills
Invertebrate
Respiration
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Tracheal System: consists of
repeatedly branching, air-filled
tubes reinforced with chitin
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Tubes start at tiny openings
(spiracles) across the integument
Tube branches, then branches again;
fluid fills tips of finest branches
which end next to body cells
Insects and spiders
Spiders have book lungs in
addition to tracheal tubes to
enhance respiration
Vertebrate Respiration
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The Gills of Fish
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Gills contain filaments that hold many capillary beds where
gases are exchanged with blood
In all fish, respiration occurs when water flows into the mouth,
enters pharynx, then moves out of body through gill slits
Vertebrate Respiration
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The Gills of Fish
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Water flows over the gills and blood circulates through them
in opposing directions
Countercurrent flow: highly efficient in extracting oxygen
from water, whose oxygen content is lower than air
Vertebrate Respiration
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Evolution of Paired Lungs
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Lungs became increasingly important as aquatic tetrapods
spent more time on land
Vertebrate Respiration
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Various animals use different mechanisms for respiration
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Frogs in the larvae stage utilize gills and skin; as adults they use
paired lungs and skin for respiration
Amniotes have waterproof skin and no gills; they use well
developed lungs for respiration
Human Respiratory System
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Lungs accomplish gas exchange via alveoli
The respiratory system assists in sense of smell and in
speech
It also helps return venous blood to the heart and helps
rid the body of excess heat and water
Controls over breathing adjust the body’s acid-base
balance as well as the body’s temperature
Human Respiratory System: airways to
lungs
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Air enters or leaves
the respiratory system
through nasal cavities
where hair and cilia
filter dust and
particles, blood vessels
warm the air, and
mucus moistens the
air
Human Respiratory System: airways to
lungs
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Air moves via this route:
Pharynx
Larynx
(route
blocked by
epiglottis
during
swallowing)
Vocal Cords
(space
between is
glottis)
Trachea
Bronchi
Bronchioles
Alveoli
Human Respiratory System: airways to
lungs
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Vocal cord lies at entrance to larynx
When air is exhaled through the glottis, the folds of the
cords vibrate to produce sound
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Under regulation by nerve commands to the elastic ligaments
that regulate the glottal opening
Human Respiratory System: airways to
lungs
Human Respiratory System: paired lungs
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Human lungs are located in the thoracic cavity, one on each
side of the heart
Rib cage encloses and protects lungs
Each lung is covered with a plural membrane
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Covers lung’s outer surface and line inside of the thoracic cavity
Inside lungs, respiratory bronchioles bear outpouchings of
their walls called alveoli, which are usually clustered as
alveolar sacs
Alveoli provide a tremendous surface area for gaseous
exchange with the blood located in the dense capillary
network surrounding each alveolar sac
Human Respiratory System
Human Respiratory System: muscles and
respiration
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Diaphragm: sheet of smooth muscle beneath the lungs
Intercostal muscles: skeletal muscles between ribs
Diaphragm and intercostal muscles interact and exchange
the volume of the thoracic cavity breathing
Gas Exchange and Transport
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Exchanges at the respiratory membrane
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The alveolar epithelium, the capillary epithelium, and their
basement membranes form a respiratory membrane
Oxygen and carbon dioxide passively diffuse across the
membrane in response to partial pressure gradients
Gas Exchange and Transport
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Oxygen transport
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Blood cannot carry sufficient oxygen and carbon dioxide in
dissolved form to satisfy the body’s demands
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Hemoglobin helps enhance its capacity
Gas Exchange and Transport
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Oxygen transport
Oxygen diffuses down pressure
gradient into blood plasma
Red blood cells
Binds to hemoglobin (4
molecules per hemoglobin to
form oxyhemoglobin)
Gas Exchange and Transport
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Oxygen transport
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Hemoglobin gives up its oxygen in tissues where partial
pressure of oxygen is low, blood is warmer, partial pressure of
carbon dioxide is higher, and pH is lower
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All four conditions occur in tissues with high metabolism
Myoglobin is found in cardiac muscle and some skeletal
muscles
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Helps to store oxygen
Gas Exchange
and Transport
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Carbon Dioxide
transport
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Because carbon dioxide
is higher in body tissues,
it diffuses into the blood
Ten percent is dissolved
in plasma
Thirty percent binds
with hemoglobin to
form
carbaminohemoglobin
Sixty percent is in
bicarbonate form
Gas Exchange and Transport
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Carbon Dioxide exchange
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Bicarbonate and carbonic acid formation is enhanced by the
enzyme carbonic anhydrase, which is located in the red blood
cells
Hemoglobin buffers these reactions, keeping the blood from
becoming too acidic
Gas Exchange and Transport
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Carbon monoxide threat
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Hemoglobin has a higher affinity for carbon monoxide than
oxygen
Carbon monoxide prevents proper oxygen transport causing
carbon monoxide poisoning
Cyclic Reversals in Air Pressure Gradients
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The Respiratory Cycle
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In inhalation, diaphragm contracts and flattens
Muscles lift rib cage upward and outward
Chest cavity volume increases
Internal pressure decresaes
Air rushes in
Yc2AOJ3
Cyclic Reversals in Air Pressure Gradients
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The Respiratory Cycle
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In exhalation
The actions in inhalation are reversed
Elastic lung tissue recoils passivly
Yc2AOJ3
Cyclic Reversals in Air Pressure Gradients
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The Respiratory Cycle
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Pressure gradients between air inside and outside respiratory
tact change in each respiratory cycle of inhalation and
exhalation
Exhalation is passive when you are quietly breathing; it is active
and energy requiring when exercising with the need to expel
more air
The Heimlich maneuver forces air out of lungs into the trachea
and can dislodge the food, allowing victim to resume breathing
Cyclic Reversals in Air Pressure Gradients
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Respiratory Volumes
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The maximum volume that the lungs can hold is the vital
capacity
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Vital capacity is 5.7 liters in men and 4.2 liters in females
Tidal volume: the volume of air flowing in and out of the
lungs during one respiratory cycle
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Tidal volume is about 0.5 liters
Cyclic Reversals in Air Pressure Gradients
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Control of Breathing
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Respiratory centers in the brain control the rate and depth of
breathing
When activity levels increase, chemoreceptors sense changes
in the blood pH and signal the respiratory center to alter
breathing levels
Reflexes, such as swelling or coughing, and commands from the
sympathetic nerves alter breathing patters
Control of Breathing
Respiratory Diseases and Disorders
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Interrupted breathing
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Infections
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Sleep apnea, SIDS
TB, pneumonia
Bronchitis, Emphysema
Smoking (cigarettes, marijunana)
High Climbers and Deep Divers
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Explain what occurs to those who are at high altitudes
and those who deep-sea dive in terms of respiration
Review
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http://www.youtube.com/watch?v=HiT621PrrO0
http://www.youtube.com/watch?v=TaAvhG2SInM&feature
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