Transcript Understanding Our Environment

Respiration
Chapter 53
Copyright © McGraw-Hill Companies Permission required for reproduction or display
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Fick’s Law of Diffusion
•
•
Gas exchange is accomplished by diffusion
Rate of diffusion between two regions is
governed by Fick’s Law.
R = D x A ( p/d)
 R = Rate of diffusion
 D = Diffusion Constant
 A = Area over which diffusion takes place.
 p = Differences in concentrations
 d = Distance across which diffusion takes
place.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
How Animals Maximize the Rate of Diffusion
•
•
•
Beating cilia producing water current.
Respiratory organs that increase surface
area available for diffusion.
 Bring external environment close to
internal fluid.
Atmospheric Pressure and Partial Pressures
 One atmosphere is 760 mm Hg.
 Partial Pressure is fraction contributed by a
gas.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
The Gill as a Respiratory Structure
•
•
External gills provide a
greatly increased
surface area for gas
exchange.
 Disadvantages are
that they must be
moved constantly
and are easily
damaged.
Gills of Bony Fish
 Located between
buccal cavity and
opercular cavity.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
The Gill as a Respiratory Structure
•
•
Buccal cavity can be opened
and closed by opening and
closing the mouth.
Opercular cavity can be
opened and closed by
movements of the operculum.
 Ram ventilation
- Blood flows in an
opposite direction to
the flow of water, thus
maximizing
oxygenation of blood.
 Countercurrent
Flow.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Respiration in Air-Breathing Animals
•
•
Gills replaced in terrestrial animals because:
 Air is less buoyant than water.
 Water vapor diffuses into the air through
evaporation.
Two Main terrestrial respiratory organs:
 Tracheae
 Lung
- Lungs use a uniform pool of air in
constant contact with gas exchange
surface.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Respiration in Amphibians and Reptiles
•
Lungs of amphibians are formed
as saclike outpouching of the
gut.
 Amphibians force air into
their lungs creating positive
pressure.
- Fill buccal cavity with air,
and then close mouth and
nostrils and elevate floor
of oral cavity.
 Reptiles expand their rib
cages by muscular
contraction and take air into
lungs via negative pressure
breathing.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Respiration in Mammals
•
Lungs of mammals packed with
Alveoli.
 Air brought to alveoli through
system of air passages.
- Inhaled air taken to the
larynx, passes through
glottis into the trachea.
 Bifurcates into right and
left bronchi which enter
each lung and further
subdivide into
bronchioles that deliver
air into alveoli.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Respiration in Birds
•
•
•
Bird lung channels air through tiny air
vessels called parabronchi, where gas
exchange occurs.
 Uni-directional flow.
When air sacs are expanded during
inspiration, they take in air.
When they are compressed during
expiration, they push air into and through the
lungs.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Respiration in Birds
•
Avian respiration occurs in
two cycles.
 Each cycle has an
inspiration and an
expiration phase.
- Cross-current flow
has the capacity to
extract more oxygen
from the air than a
mammalian lung.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Structures and Mechanisms of Breathing
•
The outside of each lung is
covered by a visceral
pleural membrane.
 Second parietal pleural
membrane lines inner
wall of thoracic cavity.
- Pleural cavity
between the two
membranes.
•
Mechanics of Breathing
 Boyle’s Law - When the
volume of a given
quantity of gas
increases, its pressure
decreases.
- When the pressure
within the lungs is
lower than the
atmospheric
pressure, air enters
the lungs.
 Thoracic volume
increased by contraction
of external intercostals
and the diaphragm.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Structures and Mechanisms of Breathing
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Structures and Mechanisms of Breathing
•
Breathing Measurements
 Tidal Volume - Volume of air moving into
and out of the lungs.
 Vital Capacity - Maximum amount of air
that can be expired after a forceful
inspiration.
 Hypoventilating - Slow breathing - Too
much carbon dioxide.
 Hyperventilating - Rapid Breathing - Not
enough carbon dioxide.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Mechanisms That Regulate Breathing
•
Rise in carbon dioxide
causes blood pH to lower,
stimulating neurons in the
aortic and carotid bodies
to send impulses to the
control center in the
medulla oblongata.
 Sends impulses to
diaphragm and
external intercostal
muscles, stimulating
them to contract,
expanding chest cavity.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Hemoglobin and Oxygen Transport
•
•
Hemoglobin is a protein
composed of four polypeptide
chains and four organic heme
groups.
 Iron atom at center of each
heme group.
Hemoglobin loads up with
oxygen in the lungs, forming
oxyhemoglobin.
 As blood passes through the
capillaries, some of the
oxyhemoglobin releases
oxygen and become
deoxyhemoglobin.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Hemoglobin and Oxygen Transport
•
Oxygen Transport
 Oxygen transport in the blood is affected
by many conditions.
- pH - Bohr’s Effect.
Copyright © McGraw-Hill Companies Permission required for reproduction or display
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Carbon Dioxide and Nitric Oxide Transport
•
•
About 8% of CO2 in blood is dissolved in
plasma and another 20% is bound to
hemoglobin.
 Remaining 72% of CO2 diffuses into red
blood cells where carbonic anhydrase
catalyzes the combination of CO2 with
water to form carbonic acid.
Blood flow and blood pressure are also
regulated by the amount of NO released into
the bloodstream.
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies
Copyright © McGraw-Hill Companies Permission required for reproduction or display
Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies