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Y12 AS Biology > Gas exchange in humans > Flashcards

Gas exchange in humans Flashcards

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1
Q

What are the parts in the human gas exchange system?

A 
Trachea
Ribcage
Intercostal muscles 
Bronchus 
Bronchiole
Diaphragm 
Alveoli
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2
Q

Where does the air go to as it enters through breathing?

A

Trachea

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3
Q

What does the trachea split into?

A

2 bronchi

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4
Q

What does the bronchi branch off into?

A

Bronchioles

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5
Q

What are the two types of intercostal muscles?

A

External

Internal

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6
Q

What is ventilation?

A

Process of inspiration (breathing in) and expiration (breathing out)

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7
Q

What happens during inspiration?

A

External intercostal muscles and diaphragm contract, it flattens

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8
Q

How does the ribcage move during inspiration?

A

Upwards and outwards

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9
Q

How do the movements of the diaphragm and intercostal muscles affect volume and pressure? How does this affect the movement of air?

A

Volume increases
Pressure decreases
The air flows down the trachea down a pressure and diffusion gradient to an area of low pressure

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10
Q

Is inspiration an active or a passive process?

A

Active

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11
Q

What happens during expiration?

A

External intercostal muscles and diaphragm relax, it domes

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12
Q

How does the ribcage move during expiration?

A

Downwards and inwards

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13
Q

What happens to the volume and the pressure during expiration?

A

Volume decreases

Pressure increases

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14
Q

Is expiration passive or active?

A

Passive

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15
Q

What happens during forced expiration?

A

The external intercostal muscles relax and the internal intercostal muscles contract which pulls the ribcage further down and in

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16
Q

What are alveoli?

A

Microscopic air sacs

17
Q

What surrounds alveoli?

A

Capillaries

18
Q

What is the structure of the alveoli?

A

Single, thin layer of alveolar epithelium cells

19
Q

What are the walls of capillaries made from?

A

Capillary endothelium

20
Q

What protein is in the walls of the alveoli?

A

Elastin

21
Q

How does elastin benefit the alveoli?

A

Helps alveoli return to normal shape after exhaling and inhaling air

22
Q

What diffuses out of the alveoli?

A

Oxygen

23
Q

What are the factors which affect the rate of diffusion?

A

A thin exchange surface - short diffusion pathway
A large surface area - there’s lots of alveoli, large area for exchange to take place
Concentration gradient

24
Q

What is there between the alveoli and the capillaries?

A

A steep concentration gradient of oxygen and carbon dioxide

25
Q

What are the two layers that the air has to diffuse across in order to get to the capillaries?

A

Alveolar epithelium

Capillary endothelium

26
Q

Just before a person starts to exhale, the composition of the air in an alveolus differs the composition of the air in the trachea. Give two ways in which the composition would differ. (1 marks)

A

1) More CO2

2) More O2 in alveoli

27
Q

Suggest why blood returning to the heart from the lungs contains some carbon dioxide (2 marks)

A
  • Not all CO2 will diffuse into the lungs

- The concentration gradient will become equal when there is an equal amount of CO2 into the blood and the lungs

28
Q

Describe and explain how the structure of the mammalian breathing system enables efficient uptake of oxygen into the blood (5 marks)

A
  • Alveoli have a large surface area
  • Thin alveolar walls
  • Cell membrane permeable to gases
  • Wide trachea with cartilage rings
  • Capillary walls are thin
29
Q

Describe and explain the mechanism that causes forced expiration. (4 marks)

A
  • external intercostal muscles and diaphragm are relaxed
  • Internal intercostal muscles contract
  • decreases the volume and increases the pressure
  • air is forced out down a pressure gradient, out of the lungs
30
Q

People who have been fire-breathers for many years often find they cannot breathe out properly. Explain why. (2 marks)

A
  • Thick layers of scar tissue
  • Lose elasticity
  • Less recoil
31
Q

Explain how downward movement of the diaphragm leads to air entering the lungs (2 marks)

A
  • Increases the volume
  • Decreases the pressure
  • Air moves in down pressure gradient

Y12 AS Biology (57 decks)

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