Exam 1-- 4410 Flashcards
Why are mammals unable to breathe water in terms of the physical properties of water
Higher solubility of CO2 compared to O2 in water.
Mammals have lower ventilation rates due to the abundance of oxygen in air.
Thus, they are unfit to breathe in CO2 rich water without experiencing acidosis
Why are mammals unable to breathe water in terms of the physical properties of air
Oxygen content is 30 times higher in air than water. A mammal’s anatomy is unable to take in 30 times as much water in order to satisfy their oxygen demands.
Why are mammals unable to breathe water in terms of ventilatory mechanics
Tidal airflow through the respiratory system of mammals would require the water to move both in and out the same route to lungs.
The water cannot pass through quickly enough, with adequate oxygen uptake, leading to drowning.
Why are mammals unable to breathe water in terms of respiratory anatomy
As mammals evolved to survive on land, they developed more efficient ways to eliminate CO2 through pulmonary systems. Thus, mammals do not have gills as respiratory organs, which is the principle method of breathing water. The lungs of mammals do not have enough surface area to absorb appropriate amounts of oxygen from water.
Why can’t a trout breathe air in terms of the physical properties water
There is a low solubility of O2 in water. Therefore, trouts have high water ventilation rates fit to extract O2 from water. So, they are unfit to respirate in an environment with an abundance of O2.
Why can’t a trout breathe air in terms of the physical properties air
Solubility of O2 is greater in the air than in water. Water breathers always have less CO2 in their body fluids than air breathers. And, they are equipped to extract dissolved O2 from water, not the air where O2 concentrations are much higher
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.
Why do larval fish not require gills for gas exchange, but adults do
Larval fish only need diffusion to obtain adequate oxygen from their environment. Their thinness and smallness allows for greater diffusion cutaneously.
Adult animals grow larger and thicker, so, they must rely on both convection and diffusion to obtain adequate oxygen uptake from the environment.
Tuna vs Sole: gill morphology
tuna have more lamellae that are thinner and more densely packed than the sole
Tuna vs Sole: critical swimming speed
tuna have much higher swimming speeds than sole
Tuna vs Sole: myocardial properties
Tuna has 60-70% compact myocardium, while sole has 100% spongy myocardium
Tuna vs Sole: ventilatory mode
tuna ram ventilate due to their high swimming speed, making it more efficient to extract O2 through the mouth to gills via the force of motion through water. Rather than an active buccal pumping which decreases swimming speed
Tuna vs Sole: coronary blood supply
tuna has more coronary blood supply because it is dependent on the amount of compact myocardium. However, soles have none
which fish is high performance, and which is sluggish (tuna vs sole)
high– tuna
slug– sole
Hypoxia
deficiency in the amount of oxygen reaching the tissues and lower oxygen partial pressures
Normoxia
normal O2 levels in the tissue and normal O2 partial pressures in the environment
Hyperoxia
high partial pressure of oxygen in the 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
What is the primary respiratory organ of pupfish. What is its anatomical arrangement relative to the water and how does that allow a more efficient extraction of O2 from the water than other gas-exchange organs (lung)
primary organ– gills
arrangement– water and blood flow through the lamella in opposite directions, enabling countercurrent exchange, which enhances the efficiency of oxygen extraction from water. This arrangement maintains a concentration gradient along the entire length of the gill, ensuring that oxygen continually diffuses into the bloodstream, even when the oxygen concentration in the water becomes low. This is especially efficient in pupfish, as they live in extreme environments more prone to hypoxia, where they must be able to optimize O2 uptake
Under normal conditions, how does the arterial Pco2 of the pupfish compare to a dog? What, specifically, accounts for this difference?
PCO2 pupfish has lower arterial PCO2 than a dog because it ventilates more due to low concentration of oxygen in water.
Solution A: O– 100; PO2– 50
Solution B: O– 50; PO2– 100
which will have higher osmolarity
Solution A
osmolarity is directly proportional to solute concentration, Solution A with an oxygen concentration of 100 mol/L is likely 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, and a 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)
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
What finding challenged the accepted model of gill ventilation in fishes? What are the implications for gas exchange? (summer and ferry)
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
