Gas Exchange

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1. Organisms must exchange ____ and ____ aka ______ gases. This is done via ______ along their concentration gradients. Gas exchange systems are made up of ______ and the ______ that ______ and ______ them.
• CO2 & O2
• respiratory gases
• diffusion
• surfaces
• mechanisms
• ventilate & perfuse
2. Partial pressure
Barometric pressure
• partial pressure: the concentration of a gas in a mixture
• barometric pressure: is the pressure exerted by the weight of air in the atmosphere of Earth (or that of another planet)
3. Fick's law of diffusion applies to all _____ _____ systems.

Q=DA(P1-P2/L)
What is Q?
What is D?
What is A?
gas exchange systems

• Q: rate of diffusion
• D: the diffusion coefficient (a charac. of the diffusing substance, the medium (like water vs air) and temp.)
• A: the area where diffusion occurs
4. Q=DA(P1-P2/L)
What are P1 & P2?
What is L?
What does (P1-P2)/L signify?
• P1 & P2: partial pressures of the gas at two locations
• L: the path length between the locations
• (P1-P2)/L: a partial pressure gradient
5. The _____ rate of diffusion of oxygen in water limits the ____ & _____ of species without internal systems for ____ ____. These species have evolved to have ______ surface areas, or _____ ______, or ________ _______ systems
• slow
• size and shape
• gas exchange
• larger
• central cavities
• specialized respiratory systems
6. _______ is easier to obtain from the air than from water

State 3 reasons why this is so.
Oxygen

• O2 content of air is higher than that of water
• O2 diffuses much faster through air
• Air and water must be moved by the animal over its gas exchange surfaces—requires more energy to move water than air
7. Respiratory gas exchange is a two-way process explain.
CO2 diffuses out of the body as O2 diffuses in
8. The concen. gradient of CO2 from air breathers to the environment is always ______. CO2 is _____ soluble in water and is easy for aquatic animals to _____.
• large
• very
• exchange
9. Some respiratory systems have adaptations to maximize the exchange of O2 and CO2. Name 4 such adaptations
• Increased surface area (A)
• Maximized partial pressure gradients (P1-P2)
• Minimized diffusion path length (L)
• Minimize the diffusion that takes place in an aqueous medium (D)
10. Name 4 ways Surface area is increased
• External gills—also minimize the diffusion path length (L) of O2 and CO2 in water
• Internal gills—protected from predators and damage
• Lungs—internal cavities for respiratory gas exchange with air
• Tracheae—air-filled tubes in insects
11. Air enters the human lungs through the ____ ____ or the ______ ______, both of which join in the _______.
• oral cavity
• nasal passage
• pharynx
12. Below the pharynx, the ______ (at the beginning is the voice box or _____)leads to the _____
• trachea
• larynx
• lungs
13. The trachea branches into two _____, then into _______, and then into _______ (the site of gas exchange)
• bronchi
• bronchioles
• alveoli
14. Capillaries surround and lie between the ______, here the _____ path between _____ & ____ is less than two micrometers.
• alveoli
• diffusion
• blood & air
15. ________ from smoking destroys alveoli
Emphysema
16. Respiratory gases are transported in the _____. Blood plasma carries _____ O2, however the blood contains molecules that _____ _____ to O2. O2 is picked up where its partial pressure is _____ and released where its partial pressure is ______.
• Blood
• little
• binds reversibly
• high
• lower
17. Hemoglobin is protein with four ______ ______ and is an O2 ______
• polypeptide subunits
• transporter
18. In hemoglobin, each polypeptide surrounds a _____ _____ that can bind a molecule of _____. One hemoglobin can bind up to ____ _____
• heme group
• O2
• four oxygens
19. The relationship between PO2 and O2 is that binds is ______. Low PO2 means one ______ binds O2.
• S-shaped
• subunit
20. Positive cooperativity
one subunit binds and changes shape, making it easier for the next one to bind—the affinity for O2 is increased.
21. When _____ subunits are bound, a larger increase in PO2 is needed.
three
22. Myoglobin is a single ______ _____ in
muscles and can bind ___ molecule of O2. It has a ______ affinity for O2, binds it at low PO2 values when ______ molecules would release their O2
• polypeptide molecule
• one
• higher
• hemoglobin
23. Myoglobin provides a reserve for high _______ demand for O2
metabolic
24. The affinity of hemoglobin for O2 varies. Three
factors are:
• Hemoglobin composition
• pH—in the Bohr effect, blood circulating through active tissues has a lower pH and H+ ions bind to the hemoglobin molecule in place of O2
• 2,3-bisphosphoglyceric acid (BPG)—also lowers the affinity for O2 (byproduct of glycolysis)
25. CO2 is transported ____ from the tissues after diffusing into the blood. In the blood plasma, CO2 is slowly converted into ______ ___. In endothelial cells and red blood cells ______ _______ speeds up the conversion.
• away
• bicarbonate ions (HCO3-)
• carbonic anyhydrase
26. The conversion of CO2 to bicarbonate (2)
• keeps PCO2 low
• facilitates diffusion away from the tissues.
27. Some CO2 binds to _______ molecules. In the lungs the conversion reaction is _______, CO2 diffuses from the _____ into the _____ and is ______
• hemoglobin
• reversed
• blood
• alveoli
• exhaled
28. Breathing is controlled in the _____ specifically the _____. In ______ and _______, the breathing rate is more sensitive to changes in PCO2 than to PO2. The PCO2 of blood is the _____ ______ ______ for breathing.
• brainstem
• medulla
• humans and mammals
• primary metabolic feedback
 Author: chikeokjr ID: 325499 Card Set: Gas Exchange Updated: 2016-11-17 08:03:01 Tags: biology Folders: Week 7 Description: Slides Show Answers: