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Biology > Exchange in lungs > Flashcards

Exchange in lungs Flashcards

1
Q

Why is the volume of oxygen and CO2 that has to be absorbed and removed in mammals large?

A
  • They are relatively large organisms with a large volume of living cells
  • They maintain a high body temperature which is due to them having high metabolic and respiratory rates
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2
Q

What are lungs the site of?

A

Gas exchange

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3
Q

What is one reason that lungs are located in the body due to their structure?

A

Air is not dense enough to support and protect these delicate structures

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4
Q

What is another reason that lungs are located in the body due to the body’s needs?

A

The body as a whole would otherwise lose a great deal of water and dry out

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5
Q

How are lungs supported and protected?

A

By the ribcage

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6
Q

How can ribs be moved?

A

By the muscles between them

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7
Q

What are lungs ventilated by?

A

A tidal stream of air, ensuring that the air within them is constantly replenished

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8
Q

What kind of structures are lungs?

A

Lobed structures

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9
Q

What are lungs made up of?

A

A series of highly branched tubules, bronchioles, which end in tiny air sacs called alveoli

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10
Q

What is a trachea?

A

A flexible airway that is supported by rings of cartilage

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11
Q

What does the cartilage do for the trachea?

A

Prevents the trachea collapsing as the air pressure inside falls when breathing in

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12
Q

What are the tracheal walls made up of?

A

Muscle, lined with ciliated epithelium and goblet cells

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13
Q

What are the bronchi?

A

2 divisions of the trachea, each leading to one lung

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14
Q

How are bronchi similar in structure to the trachea (mucus)?

A

Also produce mucus to trap dirt particles and have cilia

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15
Q

What do the cilia do in the bronchi?

A

Move dirt-laden mucus towards the throat

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16
Q

How are larger bronchi supported?

A

Supported by cartilage

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17
Q

What happens in terms of support as bronchi get smaller?

A

Amount of cartilage reduced

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18
Q

What are bronchioles?

A

A series of branching subdivisions of bronchi

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19
Q

What are the walls of bronchioles made of?

A

Muscle lined with epithelial cells

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20
Q

What do the muscle walls of the bronchioles allow them to do?

A

Constrict so that they can control the flow of air in and out of the alveoli

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21
Q

What are alveoli?

A

Minute air sacs at the end of the bronchioles

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22
Q

What is the diameter of the alveoli?

A

Between 100 micrometer - 300 micrometer

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23
Q

What is found between the alveoli?

A

Collagen and elastic fibres

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24
Q

What do the elastic fibres allow the alveoli to do?

A

To stretch as they fill with air when breathing in

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25
Q

What happens to alveoli when breathing out?

A

They spring back to their original shape in order to expel the CO2 rich air

26
Q

What are the alveoli lined with?

A

Epithelium

27
Q

What is the alveolar membrane?

A

The gas-exchange surface

28
Q

What is the equation for pulmonary ventilation rate?

A

Tidal wave x breathing rate = pulmonary ventilation rate

29
Q

How is the pressure change in the lungs brought about?

A

By the movement of 3 sets of muscles
- Diaphragm
- Intercostal muscles (there are internal and external)

30
Q

What is the diaphragm?

A

A sheet of muscle that separates the thorax from the the abdomen

31
Q

Where do the intercostal muscles lie?

A

Between the ribs

32
Q

What happens when the internal intercostal muscles contract?

A

Leads to expiration

33
Q

What happens when the external intercostal muscles contract?

A

Leads to inspiration

34
Q

What is the 1st step of inspiration?

A

The external intercostal muscles contract, while the internal relax

35
Q

What is the 2nd step of inspiration after (the external intercostal muscles contract)?

A

Ribs are pulled upwards and outwards, increasing volume of thorax

36
Q

What is the 3rd step of inspiration after (ribs are pulled upwards and outwards)?

A

Diaphragm muscles contract, causing it to flatten, which also increases volume of thorax

37
Q

What is the 4th step of inspiration after (diaphragm muscles contract)?

A

The increased volume of thorax results in reduction of pressure in the lungs

38
Q

What is the final step of inspiration?

A

Atmospheric pressure is now greater than pulmonary pressure so air is forced into lungs

39
Q

What is the 1st step of expiration?

A

Internal intercostal muscles contract, while external relax

40
Q

What is the 2nd step of expiration after (internal intercostal muscles contract)?

A

Ribs move downwards and inwards, decreasing thorax volume

41
Q

What is the 3rd step of expiration after (ribs move downwards and inwards)?

A

Diaphragm muscles relax so it is pushed up against contents of the abdomen that were compressed during inspiration
Thorax volume further decreased

42
Q

What is the 4th step of expiration after (diaphragm muscles relax)?

A

Decreased thorax volume increases pressure in lungs

43
Q

What is the final step of expiration?

A

Pulmonary pressure is now greater than atmospheric, so air is forced out of lungs

44
Q

What is the main cause of air being forced out during normal, quiet breathing?

A

The recoil of the elastic tissue in the lungs

45
Q

When do the various muscles play a major part in breathing?

A

Under more strenuous conditions

46
Q

How many alveoli are there in each human lung and what is their total surface area?

A

Around 300 million and their total surface area is 70m^2

47
Q

What is each alveolus lined with?

A

Epithelial cells that are only 0.05 - 0.3 micrometers thick

48
Q

What surrounds each alveolus?

A

A network of pulmonary capillaries

49
Q

Are the pulmonary capillaries narrow?

A

Yes

50
Q

What do the red blood cells do given that the pulmonary capillaries are so narrow when exchanging gases with the alveoli?

A

They are flattened against the capillary walls in order to squeeze through

51
Q

How thin are the walls of the pulmonary capillaries?

A

One cell thick

52
Q

How does the movement of red blood cells cause diffusion of gases between alveoli and the blood to be very rapid?

A

As the pulmonary capillaries are very narrow, red blood cells are slowed as they pass though them, allowing more time for diffusion

53
Q

What is also caused by the fact that red blood cells are flattened against the capillary walls in terms of diffusion?

A

The distance between the alveolar air and the red blood cells is reduced

54
Q

Why is the distance for diffusion very short in the lungs?

A

Walls of both alveoli and capillaries are very thin

55
Q

What is the total surface area of alveoli and pulmonary capillaries like?

A

Each one has a very large surface area

56
Q

How do breathing movements and heart action cause diffusion of gases between alveoli and the blood to be very rapid?

A
  • Breathing movements constantly ventilate the lungs
  • Heart action constantly circulates the blood around the alveoli
  • Together, these ensure that a steep concentration gradient of the gases to be exchanged is maintained
57
Q

What does blood flow through pulmonary capillaries maintain?

A

A concentration gradient

58
Q

What does COPD stand for?

A

Chronic obstructive pulmonary disease

59
Q

What does COPD include?

A

Emphysema and chronic bronchitis

60
Q

What are the risk factors for COPD?

A
  • Smoking
  • Air pollution, especially in heavy industry
  • Genetic make-up
  • Infections
  • Occupation (e.g. working with harmful chemicals)

Biology (15 decks)

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