Textbook Notes (381,222)
CA (168,408)
UTSC (19,325)
BIOA02H3 (153)
Chapter

Gas Exchange

5 Pages
52 Views

Department
Biological Sciences
Course Code
BIOA02H3
Professor
Mary Olaveson

This preview shows pages 1-2. Sign up to view the full 5 pages of the document.
Chapter 48 Gas Exchanges in Animals
48.1 What Physical Factors Govern Respiratory Gas Exchange? (1025)
- CO2 and O2 are the respiratory gases that animals must exchange.
- Diffusion (random movement of molecules or other particles, resulting in even distribution of the particles when no
barriers are present) is the only means of gas exchange between the internal body fluids of an animal and the outside
medium (water or air). Diffusion is a physical process. Diffusion is faster in higher temperatures and faster in air than
water.
Diffusion is Driven by Concentration Differences (1025)
- Net movement of molecules via diffusion is always down its concentration gradient.
- Partial pressure of the gases is one way biologists express the concentrations of different gases in a mixture.
- Solubility of a gas in liquid is a factor that makes it more difficult to describe of respiratory gases in a liquid such as
water.
- Actual amount of a gas in a liquid depends on the partial pressure of that gas in the gas phase in contact with the liquid
as well as on the solubility of that gas in that liquid.
Ficks Law Applies to All Systems of Gas Exchange (1026)
- Ficks law of diffusion describes diffusion quantitatively with an equation (all environmental variables that limit
respiratory gas exchange and all adaptations that maximize respiratory has exchange are included):
Q = DA-
- Q is the rate at which a gas such as O2 diffuses between two locations.
- D is the diffusion coefficient (i.e. perfume has a higher D than motor oil vapour).
- A is the cross-sectional area through which the gas is diffusion.
- P1 and P2 are the partial pressures of the gas at the two locations.
- L is the path length, or distance, between the two locations.
- (P1-P2)/L is a partial pressure gradient.
Air is a Better Respiratory Medium than Water (1026)
- Oxygen can be obtained easier from air than from water because:
- O2 content of air is much higher than in water.
- O2 diffuses about 8000 times more rapidly in air than in water.
- More energy is done to move water than to move air, because water is 800x more dense.
- Eukaryotic cells carry out cellular respiration in the mitochondrion which is in the cytoplasman aqueous mediumas
well as they are bathed in extracellular fluids which is also an aqueous medium.
- Animals in liquid mediums (i.e. fish) have gills which are very efficient in gas exchange – provide large surface area for
gas exchange).
High Temperatures Create Respiratory Problems for Aquatic Animals (1026)
- Because most water breathers are ectotherms, their body temperature and metabolic rate increases as the environments
temperature increases; they need more O2 as the water gets warmer and warm water hold less dissolved gas than cold
water.
O2 Availability Decreases with Altitude (1026)
- Rise in altitude reduces O2 availability. The P02 (partial pressure of oxygen) decreases as well, and since diffusion (gas
exchange) relies on this, gas exchange is less efficient and O2 uptake is constrained.
C O2 is Lost by Diffusion (1027)
- CO2 diffuses out of the body as O2 diffuses in. Direction and rate of diffusion across the respiratory exchange surfaces
depend on the partial pressure gradients of the gases.
- Partial pressure of CO2 does not change with altitude.
www.notesolution.com
- Getting rid of CO2 is not a problem for water breathers because if is more soluble in water than O2.
48.2 What Adaptations Maximize Gas Exchange? (1028)
Respiratory Organs Have Large Surface Areas (1028)
- Larger surface areas = greater rate of gas exchange/diffusion.
- External gills provide a large surface area for gas exchange with water. They minimize the path length (L) (i.e. larval
amphibians).
- Internal gills are similar to external gills but have protective body cavities (i.e. fish).
- Lungs are the internal cavities for respiratory has exchange with air. They have a large surface area because they are
highly divided, and they are elastic so that they can be inflated with air and deflated.
- Most abundant air-breathing invertebrate are insects which have a gas exchange system consisting of a network of air-
filled tubes called tracheae that branch through all tissues of the insects body.
*Look at Lecture notes for ventilation and perfusion*
- Minimizing the path length, higher surface area, and low volume is good for gas exchange/diffusion.
- An animals gas exchange system is made up of its gas exchange surfaces and the mechanisms it uses to ventilate and
perfuse those surfaces.
Insects Have Airways Throughout their Bodies (1028)
- Respiratory gases diffuse through air most of the way to and from every cell in insects.
- Spiracles are gated opening in which the insect repiratiory system communicates with the outside environment. Spiracles
can open to allow gas exchange and close to decrease water loss.
- Spiracles extend and become smaller and smallerfrom spiracles to tracheae, tracheoles, and then air capillaries.
Fish Gills Use Countercurrent Flow to Maximize Gas Exchange (1029)
- In fish, water flow unidirectionally into the fishs mouth, over the gills, and out forom under the opercular flaps. The
constant, one-way flow of water moving over the gills maximizes P02 on the external gills surfaces. Gills have a large
surface area for gas exchange because they are so highly divided.
- The lamellae which cover the gill filaments are the actual gas exchange surfaces, and they minimize L.
- Flow of blood perfusing the inner surfaces of the lamellae is unidirectional as well.
- Affarent blood vessels bring blood to the gills, and efferent blood vessels do the opposite.
- The blood flow of the lamellae is opposite to the flow of water over the gills countercurrent flow optimizes PO2
gradient between water and blood.
Birds Use Unidirectional Ventilation to maximize Gas Exchange (1030)
- Air flows through the lungs in the parabronchi and diffuse into the air capillaries, which are the gas exchange surfaces
provide a large surface area because they are so numerous. Birds take two breaths instead of one and their non-ventilated
volume (dead space) is less; they do not as much extra air left after breathing unlike mammals.
Tidal Ventilation Produces Dead Space that Limits Gas Exchange Efficiency (1031)
- Lungs structures have evolved, but still remain dead-end sacs in all air-breathing vertebrates except birds. Ventilation
cannot be constant and unidirectional because lungs are dead-end sacs, but must be tidal: air flows in and exhaled gases
flow out by the same route.
- The residual air in the lungs after exhalation represents dead space.
- Spirometer is a device that measures the volumes of air that a person breathes in or breathes out.
- Tidal volume: Amount of air that moves in and out per breath when we are at rest.
- Inspiratory Reserve Volume: the additional volume of air we can take in above normal tidal volume.
- Expiratory Reserve Volume: The extra air that we can forcefully breathe out after normal exhalation.
- Vital Capacity: Tidal volume + inspiratory reserve volume + expiratory reserve volume. Vital capacity decreases with
age and is greater in an athlete than in a non-athlete.
- Even after the deepest exhalation, there is still some air in the dead space; vital capacity is not the entire lung volume.
The total lung capacity is the residual volume + vital capacity.
- Tidal breathing limits the partial pressure gradient available to drive the diffusion of oxygen from air into the blood.
- Fresh air is not moving into the lungs during part of the breathing cycle; therefore, the average PO2 of air in the lungs is
considerably less than it is outside the lungs.
www.notesolution.com

Loved by over 2.2 million students

Over 90% improved by at least one letter grade.

Leah — University of Toronto

OneClass has been such a huge help in my studies at UofT especially since I am a transfer student. OneClass is the study buddy I never had before and definitely gives me the extra push to get from a B to an A!

Leah — University of Toronto
Saarim — University of Michigan

Balancing social life With academics can be difficult, that is why I'm so glad that OneClass is out there where I can find the top notes for all of my classes. Now I can be the all-star student I want to be.

Saarim — University of Michigan
Jenna — University of Wisconsin

As a college student living on a college budget, I love how easy it is to earn gift cards just by submitting my notes.

Jenna — University of Wisconsin
Anne — University of California

OneClass has allowed me to catch up with my most difficult course! #lifesaver

Anne — University of California
Description
Chapter 48 Gas Exchanges in Animals 48.1 What Physical Factors Govern Respiratory Gas Exchange? (1025) - CO 2nd O are2the respiratory gases that animals must exchange. - Diffusion (random movement of molecules or other particles, resulting in even distribution of the particles when no barriers are present) is the only means of gas exchange between the internal body fluids of an animal and the outside medium (water or air). Diffusion is a physical process. Diffusion is faster in higher temperatures and faster in air than water. Diffusion is Driven by Concentration Differences (1025) - Net movement of molecules via diffusion is always down its concentration gradient. - Partial pressure of the gases is one way biologists express the concentrations of different gases in a mixture. - Solubility of a gas in liquid is a factor that makes it more difficult to describe of respiratory gases in a liquid such as water. - Actual amount of a gas in a liquid depends on the partial pressure of that gas in the gas phase in contact with the liquid as well as on the solubility of that gas in that liquid. Ficks Law Applies to All Systems of Gas Exchange (1026) - Ficks law of diffusion describes diffusion quantitatively with an equation (all environmental variables that limit respiratory gas exchange and all adaptations that maximize respiratory has exchange are included): Q = DA- - Q is the rate at which a gas such as O di2fuses between two locations. - D is the diffusion coefficient (i.e. perfume has a higher D than motor oil vapour). - A is the cross-sectional area through which the gas is diffusion. - P1and P a2e the partial pressures of the gas at the two locations. - L is the path length, or distance, between the two locations. - (P -P )L is a partial pressure gradient. 1 2 Air is a Better Respiratory Medium than Water (1026) - Oxygen can be obtained easier from air than from water because: - O2content of air is much higher than in water. - O2diffuses about 8000 times more rapidly in air than in water. - More energy is done to move water than to move air, because water is 800x more dense. - Eukaryotic cells carry out cellular respiration in the mitochondrion which is in the cytoplasm an aqueous medium as well as they are bathed in extracellular fluids which is also an aqueous medium. - Animals in liquid mediums (i.e. fish) have gills which are very efficient in gas exchange provide large surface area for gas exchange). High Temperatures Create Respiratory Problems for Aquatic Animals (1026) - Because most water breathers are ectotherms, their body temperature and metabolic rate increases as the environments temperature increases; they need more O as th2 water gets warmer and warm water hold less dissolved gas than cold water. O Availability Decreases with Altitude (1026) 2 - Rise in altitude reduces O a2ailability. The P (p02tial pressure of oxygen) decreases as well, and since diffusion (gas exchange) relies on this, gas exchange is less efficient and O upt2ke is constrained. C O i2 Lost by Diffusion (1027) - CO 2 diffuses out of the body as O d2ffuses in. Direction and rate of diffusion across the respiratory exchange surfaces depend on the partial pressure gradients of the gases. - Partial pressure of CO d2es not change with altitude. www.notesolution.com
More Less
Unlock Document


Only pages 1-2 are available for preview. Some parts have been intentionally blurred.

Unlock Document
You're Reading a Preview

Unlock to view full version

Unlock Document

Log In


OR

Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit