Gas exchange Flashcards

1
Q

What is the broad composition of gases in air?

A

79% N2

21% O2

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2
Q

What is the air pressure at sea level?

A

101 kPa

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3
Q

What is Dalton’s Law?

A

Each gas in a mixture contributes to the pressure in direct proportion to its percentage

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4
Q

What are the broad partial pressures of gases in air?

A

N2 79 kPa

O2 21 kPa

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5
Q

What is anoxia?

A

No oxygen

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6
Q

What is hypoxia?

A

Low oxygen levels

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7
Q

What is normoxia?

A

Normal oxygen levels

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8
Q

What is hyperoxia?

A

High oxygen levels

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9
Q

What is Fick’s Law?

A

Q=ΔP x A x D/ΔX

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10
Q

How have respiratory organs in animals been enhanced to increase the efficiency of diffusion?

A
High diffusion coefficient 
Low diffusion distance
Large surface area
Vascularisation
Conversion of gas to non-diffusable substance
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11
Q

How is the diffusion distance lowered?

A

Thin epithelia

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12
Q

How is the surface area increased?

A

Invaginations

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13
Q

How is gas converted to a non-diffusible substance?

A

Using respiratory proteins such as haemoglobin and haemocyanin

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14
Q

Is the viscosity and density of water high or low?

A

High

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15
Q

Why don’t aquatic organisms use tidal flow?

A

Too much energy is required to accelerate and decelerate a bulk of water

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16
Q

What do aquatic organisms use instead of tidal flow?

A

Flow-through system and a countercurrent

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17
Q

Describe an octopuses ventilation system

A

Water enters through the slit and exits through the siphon
The pressure in the upper mantle is higher than in the lower mantle
This gives a constant one-way ventilation

18
Q

Describe a fishes ventilation system

A

One way water flow is achieved by the sequential opening of the mouth and operculum
This sets up an almost continuous pressure difference between the 2 cavities
This ensures the water will flow through the dense sieve-like arrangement of lamellae

19
Q

How do animals keep their respiratory systems moist?

A

They themselves remain in moist areas

Have covered/ internal structures

20
Q

Describe the insect tracheal system

A

Discontinuous ventilation where the valves of the trachea open and close allowing gas to enter the tracheal system and the frequency of opening is varied depending on the oxygen requirement

21
Q

What is discontinuous ventilation?

A

The trachea are not ventilated constantly

22
Q

Describe the first step in aerial gas exchange in lungfish

A

The mouth opens, the buccal cavity expands and air enters the buccal cavity

23
Q

Describe the second step in aerial gas exchange in lungfish

A

The mouth closes, the buccal cavity compresses and air enters the anterior chamber of the air-breathing organ

24
Q

Describe the third step of aerial gas exchange in lungfish

A

The mouth is closed, the anterior chamber is closed and the posterior chamber contracts, and the spent air is exhaled from the posterior chamber through the operculum

25
Q

Describe the fourth step in aerial gas exchange in lungfish

A

The mouth is closed, the anterior chamber opens, the posterior chamber contracts and air flows into the posterior chamber, and gas exchange occurs

26
Q

What is the name for how frogs respire?

A

Buccopharyngeal pump

27
Q

Describe the mammalian respiratory system

A

Air enters the lungs from the oral cavity or nasal passages via the trachea and bronchi
The air then enters the alveoli
In the alveolus, the air is very close to the blood flowing through the capillary network surrounding them
The alveolar walls and capillary walls are very thin thus the diffusion distance is lowered to ~2mm

28
Q

Describe the process of inhalation

A
The diaphragm contracts 
The thoracic cavity expands
The intrapleural pressure becomes negative 
The lungs expand
Air enters the lungs
29
Q

Describe the process of exhalation

A
The diaphragm relaxes
The thoracic cavity contracts 
The intrapleural pressure becomes less negative 
The lungs contract 
Gas is expelled from the lungs
30
Q

What method of gas exchange do mammals use?

A

Tidal ventilation

31
Q

Describe bird lungs

A

Small
Rigid
No alveoli
Connected to air sacs

32
Q

What do birds use instead of alveoli?

A

Vascularised tubes called parabronchi

33
Q

What do air sacs do?

A

Penetrate viscera and many bones (pneumatisation)

They are poorly vascularised and play no role in air exchange

34
Q

Describe unidirectional flow in birds

A

Air travels through the lungs in one direction from the posterior to anterior air sacs

35
Q

How many cycles of inhalation/exhalation is required for the air to travel all of the way through a bird’s respiratory system?

A

2 but in reality, these 2 breaths happen simultaneously

36
Q

What system of gas exchange do fish gills use?

A

Countercurrent system

37
Q

What system of gas exchange do mammalian lungs use?

A

Tidal flow

38
Q

What system of gas exchange do bird lungs use?

A

Crosscurrent system

39
Q

What system of gas exchange does amphibian skin use?

A

Cocurrent system

40
Q

Describe the cocurrent system

A

Blood and medium flow in the same direction and gradually approach equilibrium with each other

41
Q

Describe the countercurrent system

A

Blood and medium flow in opposite directions so oxygen always diffuses from the medium into the blood

42
Q

Describe the tidal flow system

A

Fresh medium mixes with the stale medium in the lung so the partial pressure of oxygen at the exchange surface is lower than the environmental medium
Oxygen diffuses into the blood so the partial pressure increases in the blood but remains lower than the exhaled medium do won’t diffuse backward