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OCR Biology AS H020 > Exchange Surfaces and Breathing > Flashcards

Exchange Surfaces and Breathing Flashcards

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1
Q

How do you calculate the volume of a sphere?

A

4/3pieR3

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2
Q

How do you calculate the surface area of a sphere?

A

4pieR2

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3
Q

Name 4 features common to all effective gas exchange systems…

A

Increased surface area, thin layers, good blood supply and ventilation to maintain diffusion gradient.

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4
Q

What is the passage of air in the human gaseous exchange system?

A

Nostril/mouth, nasal cavity, trachea, bronchus, bronchioles.

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5
Q

What are the 3 important features of the nasal cavity?

A

It has a large SA with a good blood supply to warm the air. It has a hairy lining which secretes mucus to trap dust and bacteria. It has a moist surface which increases the humidity of the air, reducing evaporation.

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6
Q

What happens to the air passing through the nasal cavity?

A

It becomes the same temperature and humidity of the air already in the lungs.

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7
Q

Describe the cartilage in the trachea…

A

There are C shaped rings of strong flexible cartilage.

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8
Q

Why are the rings of cartilage in the trachea incomplete?

A

So food can move down the oesophagus behind the trachea.

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9
Q

Why is there cartilage in the trachea?

A

To stop the trachea collapsing.

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10
Q

What is the trachea lined with?

A

Ciliated epithelium and goblet cells.

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11
Q

What are the purpose of goblet cells in the trachea?

A

They secrete mucus on to the lining if the trachea to trap dust and microorganisms.

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12
Q

What is the purpose of the ciliated epithelium in the trachea?

A

To move the mucus up and away from the lungs, it is swallowed and digested.

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13
Q

What is an effect of cigarette smoke?

A

It stops the cilia beating.

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14
Q

What is the plural of bronchus?

A

Bronchi

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15
Q

Describe the structure of the bronchi…

A

Similar to the trachea (cartilage) but smaller.

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16
Q

What do the walls of the bronchioles contain?

A

Smooth muscle, no cartilage.

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17
Q

What is the function of the smooth muscle in the bronchioles?

A

To contract and relax so they constrict and dilate controlling how much air Reaches the lungs.m

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18
Q

What allow some gaseous exchange in the bronchioles?

A

They are lined with a thin layer of flattened epithelium.

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19
Q

What are the alveoli?

A

Tiny air sacs that are the main has exchange surfaces if the body.

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20
Q

What is the diameter of an alveolus?

A

200-300um

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21
Q

What are alveoli composed of?

A

A layer of thin flattened epithelial cells, collagen and elastic fibres made of elastin.

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22
Q

What Is the relevance of elastic fibres in the alveoli?

A

Elastic recoil. The alveoli can stretch as air is drawn in and when they return to their resting size they squeeze air out.

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23
Q

What are the main adaptions of the alveoli for effective gaseous exchange?

A

Large surface area, thin layers, good blood supply and good ventilation.

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24
Q

What is lung surfactant?

A

A solution on that coats the surface of the alveoli and stops them collapsing after every breath.

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25
Q

Describe the process of inspiration…

A

The diaphragm contracts moving down/lowering/flattening. The intercostal muscles contract moving the ribs upwards and outwards. The volume of the thorax increases so the pressure inside of the thorax falls/decreases to below atmospheric pressure so air is drawn into the lungs equalising the pressure.

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26
Q

Describe the process of expiration…

A

The diaphragm relaxes moving upwards and outwards into a dome shape. The intercostal muscles relax so the ribs move down and inwards under gravity. The elastic fibres in the alveoli return to their normal length. The volume of the thorax decreases tbsp the pressure inside the thorax increases to above atmospheric pressure so air is moved out if the lungs equalising the pressure.

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27
Q

What are the 3 methods of measuring the volume of air that is drawn in and out of the lungs?

A

A peak flow meter, vitalographs and spirometers.

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28
Q

What is a peak flow meter?

A

Measures the rate at which air can be expelled from the lungs.

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29
Q

What is a vitalograph?

A

Measures the forced expiratory volume in 1 second.

30
Q

What is a spirometer?

A

Used to measure different aspects of the lung volume/breathing patterns. There is an airtight chamber filled with oxygen which changes the water level as the subject breathes.

31
Q

Why is there a canister of soda lime in a spirometer?

A

To remove the carbon dioxide produced.

32
Q

What is the tidal volume?

A

The volume of air that moves in and out of the lungs with each resting breath.

33
Q

What is the average tidal volume in adults at rest?

A

500cm3, around 15% of the vital capacity.

34
Q

What is the vital capacity?

A

The volume of air that can be breathed in when the strongest possible exhalation is followed by the deepest possible intake of breath.

35
Q

What is the inspiratory reserve volume?

A

The maximum volume of air you can breathe in over and above a normal inhalation.

36
Q

What is the expiratory reserve volume?

A

The extra amount of air you can force out of your lungs over and above the normal tidal volume of air you breathe out.

37
Q

What is the residual volume?

A

The volume of air that is left in your lungs when you have exhaled as hard as possible.

38
Q

What is the total long capacity?

A

The sum of the vital capacity and residual volume.

39
Q

What is the breathing rate?

A

The number of breaths taken per minute.

40
Q

How is the ventilation rate calculated?

A

Tidal volume X breathing rate

41
Q

What increases during exercise?

A

The tidal volume and breathing rate.

42
Q

What means that insects can have little/no gaseous exchange?

A

Tough exoskeleton

43
Q

Where are spiracles found in insects?

A

Along the thorax and abdomen.

44
Q

What is the function of the spiracles in insects?

A

Air enters and leaves through the spiracles.

45
Q

What is the main problem of spiracles?

A

Water loss

46
Q

How is water loss prevented from the spiracles in insects?

A

The spiracles can be opened or closed by sphincters.

47
Q

What leads away from the spiracles?

A

Tracheae

48
Q

What is the size of insect tracheae?

A

1mm

49
Q

What lines the tracheae?

A

Spirals of chitin which keep them open

50
Q

Why does little gas exchange occur in the tracheae?

A

The spirals of chitin are relatively impermeable.

51
Q

What do the tracheae branch to form?

A

Tracheoles

52
Q

What is the diameter of the tracheoles?

A

0.6-0.8um

53
Q

Describe the tracheoles…

A

Each tracheole is a single greatly elongated cell with no chitin lining, they spread through all the tissues running through individual cells, providing a large SA.

54
Q

How does air mostly move along the tracheoles/tracheae?

A

Diffusion

55
Q

What is tracheal fluid?

A

When oxygen demands build up, a lactic acid build up results in water moving out of the tracheoles my osmosis, exposing more SA for gaseous exchange.

56
Q

Where is tracheal fluid found?

A

At the end of the tracheoles where it reduces penetration.

57
Q

What are the 2 reasons why large organisms need a specialised exchange surface…

A

They have high metabolic demands hence more O2 is needed and CO2 needs to be removed. They have a small SA:V so simple diffusion will not work as it cannot be exchanged fast enough.

58
Q

Describe how mechanical ventilation works in in insects…

A

Air is actively pumped into the system by muscular pumping of the thorax and abdomen. Thus changes the pressure in the tracheae/tracheoles so air is drawn in/out.

59
Q

What are the purpose of air sacs in insects?

A

They act as air reservoirs and are usually inflated/deflated by mechanical movements of the thorax/abdomen.

60
Q

What gaseous related difficulties do fish experience?

A

Water is more dense and viscous that air, it also has a much lower oxygen content.

61
Q

What do fish not need to worry about?

A

Water loss

62
Q

What are fishes organs of gaseous exchange?

A

Gills

63
Q

Describe the position of the gills…

A

They are contained in a Gill cavity and cover erred by a protective operculum.

64
Q

What is an operculum?

A

A bony flap

65
Q

How are gills adapted?

A

They have a large SA, good blood supply and thin layers.

66
Q

What does the bony Gill arch do?

A

Supports the structure of the gills.

67
Q

Gill filaments occur in large stacks (Gill plates), whey do they need a constant flow of water?

A

To keep them apart and expose their large SA needed for gas exchange.

68
Q

What is ram ventilation?

A

Swimming to provide a constant flow of water.

69
Q

Describe the process of ventilation in fish…

A

The mouth is opened lowering the floor if the buccal cavity. The volume of the buccal cavity increases decreasing the pressure so water moves in. The fishes mouth closes and the floor of the buccal cavity is raised. The volume in the buccal cavity decrease and the pressure increases so water is forced out if the cavity over the Gill filaments. The increase in pressure causes the operculum to open and allows the water to leave the gills.

70
Q

What is the countercurrent system in fish?

A

Blood and water flow in opposite directions so a steep concentration gradient is maintained along the Gill so a high O2 saturation of the blood is maintained/achieved and diffusion is constant.

71
Q

Name an extra adaption of the water gaseous exchange system…

A

The tips of adjacent gills overlap, increasing the resistance to flow slowing the water so there is more time for gaseous exchange to take place.

OCR Biology AS H020 (10 decks)

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