final exam Flashcards
Why can’t a trout breathe air? Please answer this question in terms of the physical properties water and air
There is more concentration of oxygen in air and less in H2O
Why can’t a trout breathe air in terms of ventilatory mechanics
Ventilation in trouts occurs at a high rate, where water flow (convection) across the gills is countercurrent and unidirectional. Here, water comes into contact with less oxygenated blood and creates a diffusion gradient. As a result, countercurrent gas exchange results in the most complete extraction of oxygen from the water
Gills are ventilated by a buccal and opercular pump: open mouth creates (-)pressure -> water flows from buccal to opercular -> opercular opens, pulling water in -> mouth closes and buccal pump pushes water across gills
Why can’t a trout breathe air in terms of respiratory anatomy
Trouts have internal gills that are used as respiratory structures. As a result, they need a lot of water to pass over the gills so the lamellae can pick up oxygen through a direct diffusion gradient. The oxygen tension of the blood is less than that of water, thus maximizing oxygen uptake in the water
Gill structures collapse when taken out of water. When collapsed, the gills are not longer exposed to oxygen.
Define hypoxia, normoxia, and hyperoxia.
Hypoxia- deficiency in the amount of oxygen reaching the tissues, lower oxygen partial pressures
Normoxia- normal oxygen levels in the tissue, normal oxygen partial pressure in environment
Hyperoxia- high partial pressure of oxygen in environment
What about the physical and biological environments requires pupfish to be so hypoxia-tolerant
as salinity and temperature increase, gas solubility decreases, according to Henry’s law
Solution A: O– 100; PO2– 50
Solution B: O– 50; PO2– 100
which will have higher osmolarity
If all else is equal, there is a negligible effect on osmolarity, as gases dissolved at biological levels have a negligible effect on osmolaritylikely to have a higher osmolarity compared to Solution B with an oxygen concentration of 50 mol/L
Solution A: O– 100; PO2– 50
Solution B: O– 50; PO2– 100
which will have a higher temperature
Solution B
Oxygen saturation is the lowest in warmer water, because by Henry’s Law, gas solubility decreases as temperature increases
Solution A: O– 100; PO2– 50
Solution B: O– 50; PO2– 100
which is most like blood
Solution B
Blood’s Po2 range is within 75-100 mHg, which aligns with Solution B’s Po2
Solution A: O– 100; PO2– 50
Solution B: O– 50; PO2– 100
which has the higher O2 solubility
Solution A
solubility = [Gas] / Pgas
= 100/50 = 2
2 is higher than 1/2 in Sol B
Solution A: O– 100; PO2– 50
Solution B: O– 50; PO2– 100
If solutions A and B were separated by a gas permeable membrane (like gill epithelium), what direction will oxygen diffuse?
B - > A
There is a pressure gradient created, as B has a higher Po2 than A
Describe the basic model of how a fish ventilates its gills. (summer and ferry)
Action of 2 pumps:
- a pressure pump that pushes water across the gills from the oropharyngeal to the parabranchial cavity
- suction pump that draws water across the gills from the oropharyngeal into the parabranchial. Together, they keep water flowing continuously
the flow is continuous and counter-current
methods (summer and fairy– fish gill ventillation)
measured KINEMATICS with SONOMICROMETRY and found displacement in mouth and gills
measured PRESSURE simultaneously from the oropharyngeal and parabrancial chamber with TRANSDUCER BRIDGE AMPLIFIERS
measured FLOW through IMAGES taken through ENDOSCOPY methods
purpose (summer and fairy)
what about the status quo ?
evidence that the pressure and suction pumps do not always work in perfect phase in elasmobranch fishes, leading to periods of higher pressure in the parabranchial than in the oropharyngeal cavity.
We investigated the existence and consequence of such pressure reversals”
What finding challenged the accepted model of gill ventilation in fishes?
What are the implications for gas exchange?
Pressure and suction pumps do not always work perfectly in some fish, creating a pressure differential where for some portion of the respiratory cycle, the water flow is co-current with the blood flow, rather than counter-current, as it should be. This would require changes of the models of gas exchange
The greatest efficiency for gas exchange is not always required. The skate, for example, only needs the bare minimum to survive and they can choose one mode over the other based on their situation. Like it may not need a lot of O2 from water, esp if theyre sluggish
What is costal breathing, who uses it, and for those who don’t, what do they do ?
costal breathing: expansion and contraction of the lung cavity through movement of the ribs
use it: birds, mammals, lizards
crocs and turtles
what do crocs and turtles do instead of costal breathing
crocs–use piston pumping, diaphragmaticus muscle retracts liver, expanding thoracic cavity, resembling a piston sliding in a cylinder.
turtles– use internal oblique. oblique increases the volume of the abdominal cavity causing lung inflation.
What is the arrangement of air flow relative to blood flow called in the bird lung?
the arrangement of airflow relative to blood is cross current exchange
How does the Po2 of the arterial blood compare to the Po2 of the expired air?
How does this compare to reptilian and mammalian lungs? (Bretz and Schmidt)
in the avian lung the PO2 in arterial blood is higher than the PO2 of expelled air
in reptilian and mammalian lungs, the PO2 of the arterial blood is not as high as the PO2 of expired air; “sort of. At best, its equal”
what are two other differences between bird and non-croc reptile lungs
- Birds have air sacs in their respiratory system, these air sacs provide continuous flow of air through the lungs.
-Avians lungs also have unidirectional air flow, which enhances the efficiency of gas exchange
What is the purpose of the study of Bretz and Schmidt-Nielsen?
investigate the respiratory system of the ducks.
understand the patterns of airflow through the respiratory system during different phases of the ventilation cycle
Describe the design of their experiment (Bretz and Schmidt)
- ducks rested in natural upright position
- tube was inserted into various airsacks and air sac pressure was recorded
-ducks inhaled marker gas (argon), the partial pressures of argon was measured. - Argon partial pressures and air sack pressures were compared against each other
What was the most important finding of the study by Bretz and Schmidt-Nielsen?
the avian respiratory system functions as a two cycle pump
Describe how air flows in the avian respiratory system during a single ventilatory cycle
- during the 1st cycle of inspiration, fresh air goes to the posterior air sac, and expands
- during the 1st cycle of expiration, the posterior air sacs shrink and inspired gas moves from the posterior air sacs, pushing through the lung
- during the 2nd cycle of inspiration, after passing through the lung, has fills the anterior air sac, which expands
- during the 2nd cycle of expiration, the anterior sacs shrink and gas from the anterior sacs flows to the main bronchus, trachea, and out of the body
this is a continuous, unidirectional process where cycle 1 and 2 inspiration occur simultaneously
What conventional wisdom are Farmer and Sanders challenging
alligators are tidal, coastal breathers like humans. They change the shape of their chest wall and volume of lungs.