2. Respiratory Physiology Flashcards
All organisms require oxygen which has to be?
derived or removed from some respiratory medium.
What is a respiratory medium?
The source of oxygen for animals
The main respiratory media are
- Air
- Freshwater
- Salt water
What is the respiratory surface?
the area or space where the gas exchange takes place.
Respiratory surfaces should have what?
-Larger surface to volume ratio
-moist inner surface
-thin wall in contact with blood capillaries
Examples of respiratory surfaces
-external gills
-internal gills
-lungs
What is gaseous exchange?
the supplying of oxygen for cellular respiration and the disposing of carbon dioxide.
How do organisms obtain oxygen from the medium (the source of oxygen)?
the organism must be able to move the respiratory medium over the respiratory surface, where extraction can occur
Why is there more oxygen in air than in water?
There is Much more oxygen in air than in water in equilibrium with air, because of the low solubility coefficient α.
What is solubility coefficient?
The volume of gas which dissolves in one unit volume of the liquid at the temperature concerned.
1 L of air contains 210 mL oxygen, while
1 L water contains 7.7 mL oxygen (at 12°C)
what does this mean?
at the same amount of L air contains more oxygen
So, the concentration of oxygen in air is x what that in water at the same partial pressure / tension?
So, the concentration of oxygen in air is 30 × that in water at the same partial pressure / tension.
The concentration of oxygen in air is 30 × that in water at the same partial pressure / tension which means that the respiratory surface can be
smaller for same oxygen uptake.
To obtain 1L of Oxygen from the different media would have to process what?
4.8L of air; 98L of freshwater: 125L of seawater.
Which requires less work? Moving air or moving water?
Much less work has to be done moving air than moving water, to obtain the same oxygen.
This has implications for the design of the respiratory structures. In air, one way flow is less important.
An aquatic organism has to do more work and pass a greater volume of water over its Respiratory surface to obtain the same amount of oxygen as an air breather.
much less work has to be done moving air than moving water to obtain the same oxygen which has implications for
the design of the respiratory structures. In air, one way flow is less important.
for the respiratory structures in air one way flow is
less important
what does an aquatic organism have to do to obtain the same amount of oxygen as an air breather
an aquatic organism has to do more work and pass a greater volume of water over its respiratory surface to obtain the same amount of oxygen as an air breather
To obtain a given mass of Oxygen from water, you would have to move
100000x its mass in water.
When does the oxygen content of both air and water media decrease?
The oxygen content of both media decreases with increasing temperature
What happens to oxygen and water at constant oxygen tension?
At constant oxygen tension:
Oxygen concentration falls about 8% as temperature changes from
0-24°C
However, in water it falls as much as 40% for a similar change in temperature.
How much denser and viscous is water than air?
Water is about 800x denser than air. And about 63x more viscous
Why do aquatic organisms require more work to obtain a given volume of oxygen compared to air breathing organisms?
the amount of dissolved oxygen is fairly lower in water than air and also aquatic organisms like fishes obtain oxygen from water present in the dissolved state.
Since the quantity of dissolved oxygen in water is very much less as compared to the quantity of oxygen present in the air aquatic animals can breathe only dissolved oxygen, so to fulfill the need of required amounts of oxygen to the body cells for proper functioning the aquatic animals have to breathe faster as compared to terrestrial animals
What % of metabolic activity is involved in ventilation in humans and fish?
In resting humans, 1-2% of the metabolic activity is involved in ventilation of the lungs.
In resting fish, about 10-20% is directed at ventilation of the gills.
Advantages of living on water:
- the density of water is close to that of plasma, therefore respiratory
structure such as gills are supported near neutral buoyancy.
This keeps the entire filament suspended and in contact with the water. - Air Breathing can cause evaporative loss of water. Therefore
breathing structure must be kept moist.
why do gills stay suspended and in contact with water
the density of water is close to that of plasma, therefore gills are supported near neutral buoyancy which keeps the entire filament suspended and in contact with the water.
what are the fundamental concepts of respiration?
-Oxygen must come in contact with the respiratory surface
-Oxygen must cross the gas exchange membrane by diffusion.
-Oxygen would only enter the organism if the partial pressure of oxygen
on the outside of the membrane is higher than on the inside.
Oxygen must cross the gas exchange membrane by
diffusion
Oxygen would only enter the organism if
the partial pressure of oxygen on the outside of the membrane is higher than on the inside.
What are the different types of respiratory surfaces?
- Lungs
- External gills
- Internal gills
what are lungs as a respiratory surface?
Lungs are Invaginations that contain the respiratory medium.
Lungs are invaginated into the body and contain the environmental medium
what are external gills as a respiratory surface?
External gills – evaginations from the body which project directly
into the environment.
what are internal gills as a respiratory surface?
evaginations of the body and enclosed in a superficial cavity.
It projects into the environmental medium where it is pumped through a superficial body cavity
What is Ventilation?
forced movement of respiratory media to and from the respiratory surface.
Ventilation can be either what?
can either be active or passive and it can also either be unidirectional or tidal
What is the Difference between active and passive ventilation ?
In active - organism creates a ventilation current
In passive – environmental currents induced flow.
What is the difference between unidirectional and tidal ventilation?
In Unidirectional
– the medium is pumped over the respiratory surface in only one direction
- New medium continuously flows over surfaces
In Tidal
– medium is inhaled and exhaled via the same path.
- Incoming medium mixed with “used” medium
What are the types of flow at exchange surfaces?
- Concurrent flow
- Countercurrent flow
- Crosscurrent flow
What are the Patterns of Flow at Exchange Surfaces?
- Concurrent Flow
– Body fluid and respiratory medium flow in same direction
– Gradient reduced with distance - Countercurrent Flow
– Body fluid and respiratory medium flow in opposite
directions
– Gradients sustained over distance - Crosscurrent Flow
– Body fluid and respiratory medium flow at nonparallel angles
to each other
– Gradient slowly decreases with distance
what happens in active ventillation
the organism creates a ventilation current
what happens in passive ventilation
environmental currents induced flow
what happens in unidirectional ventilation
-the medium is pumped over the respiratory surface in only one direction
-new medium continususly flows over surface
what happens in tidal ventilation
-medium is inhaled and exhaled via the same path
-incoming medium mixed with “used” medium
what happens in concurrent flow?
– Body fluid and respiratory medium flow in same direction
– Gradient reduced with distance
what happens in Counter current flow?
– Body fluid and respiratory medium flow in opposite
directions
– Gradients sustained over distance
what happens in Crosscurrent flow?
– Body fluid and respiratory medium flow at nonparallel angles
to each other
– Gradient slowly decreases with distance
What is the difference between ventilation and respiration?
Ventilation is mechanical and involves the movement of air while respiration is physiologic and involves the exchanges of gases in the alveoli and the cells.
What is the formula for the rate of O2 uptake?
Rate of O2 uptake (mLO2/min) =
Vmedium (CI – CE)
Rate of flow of the respiratory medium through the breathing organs = conc. Of oxygen in the inhaled air – conc. Of oxygen in exhaled air (the amount of O2 removed per unit volume of the respiratory medium.
What Vmedium does stand for?
Rate of flow of the respiratory medium through the breathing organs
What CI does stand for?
Conc. Of O2 in the inhaled medium
What CE does stand for?
conc. Of O2 in the exhaled medium.
What does CI – CE equal?
the amount of O2 removed per unit volume of the respiratory medium
How do you calculate the % of O2 removal?
(CI – CE)/ CI * 100
What does β stand for?
β = O2 utilization coefficient
an expression of how well an animal is able to use the O2 available in the medium
Diagram of General Model of a Respiratory structure
What does respiratory gas exchange efficiency depend on?
- Ventilation
- Diffusion
- Perfusion
- Relative direction of flow of blood and air or H2O (eg- concurrent vs countercurrent)
how is gas exchange between medium and blood determined?
By 3 main processes:
- Ventilation = rate at which O2 is brought to respiratory surface
- Diffusion = rate of transfer of O2 from medium to blood across the
respiratory surface - Perfusion = rate of removal of blood from the respiratory surface
Each of these processes can be compared using the parameter:
Gas Conductance:
what are the 3 process that determine how gas is exchanged between medium and blood
- ventilation
- diffusion
- perfusion
how does ventilation determine how gas is exchanged between medium and blood
it determines the rate at which O2 is brought to the respiratory surface
how does diffusion determine how gas is exchanged between medium and blood
it determines the rate of transfer of O2 from medium to blood across the
respiratory surface
how does perfusion determine how gas is exchanged between medium and blood
it determines the rate of removal of blood from the respiratory surface
each of the processes that determines how gas is exchanged between medium and blood can be compared using
the parameter gas conductance
what does G mean?
Volume of gas transferred in ml per min per mm Hg partial pressure difference
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