2. Respiratory Physiology

Question 1

All organisms require oxygen which has to be?

Answer 1

derived or removed from some respiratory medium.

Question 2

What is a respiratory medium?

Answer 2

The source of oxygen for animals

Question 3

The main respiratory media are

Answer 3

• Air
• Freshwater
• Salt water

Question 4

What is the respiratory surface?

Answer 4

the area or space where the gas exchange takes place.

Question 5

Respiratory surfaces should have what?

Answer 5

-Larger surface to volume ratio
-moist inner surface
-thin wall in contact with blood capillaries

Question 6

Examples of respiratory surfaces

Answer 6

-external gills
-internal gills
-lungs

Question 7

What is gaseous exchange?

Answer 7

the supplying of oxygen for cellular respiration and the disposing of carbon dioxide.

Question 8

How do organisms obtain oxygen from the medium (the source of oxygen)?

Answer 8

the organism must be able to move the respiratory medium over the respiratory surface, where extraction can occur

Question 9

Why is there more oxygen in air than in water?

Answer 9

There is Much more oxygen in air than in water in equilibrium with air, because of the low solubility coefficient α.

Question 10

What is solubility coefficient?

Answer 10

The volume of gas which dissolves in one unit volume of the liquid at the temperature concerned.

Question 11

1 L of air contains 210 mL oxygen, while
1 L water contains 7.7 mL oxygen (at 12°C)

what does this mean?

Answer 11

at the same amount of L air contains more oxygen

Question 12

So, the concentration of oxygen in air is x what that in water at the same partial pressure / tension?

Answer 12

So, the concentration of oxygen in air is 30 × that in water at the same partial pressure / tension.

Question 13

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

Answer 13

smaller for same oxygen uptake.

Question 14

To obtain 1L of Oxygen from the different media would have to process what?

Answer 14

4.8L of air; 98L of freshwater: 125L of seawater.

Question 15

Which requires less work? Moving air or moving water?

Answer 15

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.

Question 16

much less work has to be done moving air than moving water to obtain the same oxygen which has implications for

Answer 16

the design of the respiratory structures. In air, one way flow is less important.

Question 17

for the respiratory structures in air one way flow is

Answer 17

less important

Question 18

what does an aquatic organism have to do to obtain the same amount of oxygen as an air breather

Answer 18

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

Question 19

To obtain a given mass of Oxygen from water, you would have to move

Answer 19

100000x its mass in water.

Question 20

When does the oxygen content of both air and water media decrease?

Answer 20

The oxygen content of both media decreases with increasing temperature

Question 21

What happens to oxygen and water at constant oxygen tension?
At constant oxygen tension:

Answer 21

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.

Question 22

How much denser and viscous is water than air?

Answer 22

Water is about 800x denser than air. And about 63x more viscous

Question 23

Why do aquatic organisms require more work to obtain a given volume of oxygen compared to air breathing organisms?

Answer 23

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

Question 24

What % of metabolic activity is involved in ventilation in humans and fish?

Answer 24

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.

Question 25

Advantages of living on water:

Answer 25

1. 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. 2. Air Breathing can cause evaporative loss of water. Therefore breathing structure must be kept moist.

Question 26

why do gills stay suspended and in contact with water

Answer 26

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.

Question 27

what are the fundamental concepts of respiration?

Answer 27

-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.

Question 28

Oxygen must cross the gas exchange membrane by

Answer 28

diffusion

Question 29

Oxygen would only enter the organism if

Answer 29

the partial pressure of oxygen on the outside of the membrane is higher than on the inside.

Question 30

What are the different types of respiratory surfaces?

Answer 30

1. Lungs 2. External gills 3. Internal gills

Question 31

what are lungs as a respiratory surface?

Answer 31

Lungs are Invaginations that contain the respiratory medium. Lungs are invaginated into the body and contain the environmental medium

Question 32

what are external gills as a respiratory surface?

Answer 32

External gills – evaginations from the body which project directly into the environment.

Question 33

what are internal gills as a respiratory surface?

Answer 33

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

Question 34

What is Ventilation?

Answer 34

forced movement of respiratory media to and from the respiratory surface.

Question 35

Ventilation can be either what?

Answer 35

can either be active or passive and it can also either be unidirectional or tidal

Question 36

What is the Difference between active and passive ventilation ?

Answer 36

In active - organism creates a ventilation current In passive – environmental currents induced flow.

Question 37

What is the difference between unidirectional and tidal ventilation?

Answer 37

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

Question 38

What are the types of flow at exchange surfaces?

Answer 38

1. Concurrent flow 2. Countercurrent flow 3. Crosscurrent flow

Question 39

What are the Patterns of Flow at Exchange Surfaces?

Answer 39

* 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

Question 40

what happens in active ventillation

Answer 40

the organism creates a ventilation current

Question 41

what happens in passive ventilation

Answer 41

environmental currents induced flow

Question 42

what happens in unidirectional ventilation

Answer 42

-the medium is pumped over the respiratory surface in only one direction -new medium continususly flows over surface

Question 43

what happens in tidal ventilation

Answer 43

-medium is inhaled and exhaled via the same path -incoming medium mixed with "used" medium

Question 44

what happens in concurrent flow?

Answer 44

– Body fluid and respiratory medium flow in same direction – Gradient reduced with distance

Question 45

what happens in Counter current flow?

Answer 45

– Body fluid and respiratory medium flow in opposite directions – Gradients sustained over distance

Question 46

what happens in Crosscurrent flow?

Answer 46

– Body fluid and respiratory medium flow at nonparallel angles to each other – Gradient slowly decreases with distance

Question 47

What is the difference between ventilation and respiration?

Answer 47

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.

Question 48

What is the formula for the rate of O2 uptake?

Answer 48

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.

Question 49

What Vmedium does stand for?

Answer 49

Rate of flow of the respiratory medium through the breathing organs

Question 50

What CI does stand for?

Answer 50

Conc. Of O2 in the inhaled medium

Question 51

What CE does stand for?

Answer 51

conc. Of O2 in the exhaled medium.

Question 52

What does CI – CE equal?

Answer 52

the amount of O2 removed per unit volume of the respiratory medium

Question 53

How do you calculate the % of O2 removal?

Answer 53

(CI – CE)/ CI * 100

Question 54

What does β stand for?

Answer 54

β = O2 utilization coefficient an expression of how well an animal is able to use the O2 available in the medium

Question 55

Diagram of General Model of a Respiratory structure

Answer 55

Question 56

What does respiratory gas exchange efficiency depend on?

Answer 56

1. Ventilation 2. Diffusion 3. Perfusion 4. Relative direction of flow of blood and air or H2O (eg- concurrent vs countercurrent)

Question 57

how is gas exchange between medium and blood determined?

Answer 57

By 3 main processes: 1. Ventilation = rate at which O2 is brought to respiratory surface 2. Diffusion = rate of transfer of O2 from medium to blood across the respiratory surface 3. Perfusion = rate of removal of blood from the respiratory surface Each of these processes can be compared using the parameter: Gas Conductance:

Question 58

what are the 3 process that determine how gas is exchanged between medium and blood

Answer 58

1. ventilation 2. diffusion 3. perfusion

Question 59

how does ventilation determine how gas is exchanged between medium and blood

Answer 59

it determines the rate at which O2 is brought to the respiratory surface

Question 60

how does diffusion determine how gas is exchanged between medium and blood

Answer 60

it determines the rate of transfer of O2 from medium to blood across the respiratory surface

Question 61

how does perfusion determine how gas is exchanged between medium and blood

Answer 61

it determines the rate of removal of blood from the respiratory surface

Question 62

each of the processes that determines how gas is exchanged between medium and blood can be compared using

Answer 62

the parameter gas conductance

Question 63

what does G mean?

Answer 63

Volume of gas transferred in ml per min per mm Hg partial pressure difference

Question 64

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