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biology a level > CHAPTER 7 - EXCHANGE SURFACES AND BREATHING > Flashcards

CHAPTER 7 - EXCHANGE SURFACES AND BREATHING Flashcards

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AP® Biology flashcards
1
Q

What are the two min reasons why diffusion is enough to supply the needs of a single-celled organism

A

The metabolic activity of a single celled organism is usually low, so the oxygen demands and carbon dioxide production of the cell are relatively low

The Surface area to volume ratio of the organism is large

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2
Q

Why do larger organisms have a higher metabolic activity than most single celled organisms?

A

Amount of energy used in moving means oxygen demands of the muscle cells deep in the body will be high and they produce more CO2

Distance is too far for diffusion to take place, so exchange surfaces are required

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3
Q

What is the usual shape used to calculate SA:V

A

A sphere - SA: 4 pi r2
V: 4/3 pi r3

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4
Q

What are some features of specialised exchange surfaces

A

Very high SA:V - Diffusion rates
Thin layers - Short diffusion distance
Good blood supply - Ensures gradient is maintained for diffusion
Ventilation to maintain diffusion gradient

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5
Q

Explain why single-celled organisms do not need specialised exchanged surfaces

A

Metabolic activity relatively low

so relatively little oxygen needed or carbon dioxide produced

SA : V is large

so diffusion distances small

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6
Q

Describe the main features of any efficient exchange surfaces and explain how the structures relate to their functions

A

Large SA for exchange to overcome limitations of SA : V ratio of larger organisms

thin layers so
distances substances have to diffuse short, making the process fast and efficient

good blood
supply so substances constantly delivered to and removed from exchange surface which maintains
steep concentration gradient for diffusion

ventilation (for gaseous systems) maintains
concentration gradients and makes process more efficient

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7
Q

One roughly spherical organism has a radius of 2au. Another has a radius of 6au. Compare the SA:V ratios of the organisms and use these to explain why the larger organisms need specialised exchange surfaces

A

Radius 2 au = 3:2 Radius 6 au = 1:2

The SA : V ratio of smaller animal is three times bigger than that of larger animal, this illustrates how
the SA : V ratios of larger animals are much smaller than those of smaller animals

as a result they
need specialised exchange systems to get enough oxygen in, or carbon dioxide out of the system

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8
Q

Why do mammals have such a high metabolic rate

A

They are active and maintain their body temperature independent of the environment

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9
Q

Where does exchange of gases occur in a mammal

A

Lungs

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10
Q

What are the key structures in the mammalian gas exchange system

A

Nasal cavity
Trachea
Broncrhus
Bronchioles
Alveoli

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11
Q

What are the important features of the nasal cavity

A

A large SA with a good blood supply, warms air to body temperature

Hairy lining, secretes mucus to trap dust and bacteria, prevents delicate lung tissue

Moist surfaces, increase humidity of incoming air, reducing evaporation from the exchange surfaces

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12
Q

What is the trachea and what is it supported by

A

The main airway carrying clean, warm and moist air from the nose down into the chest

Wide tube supported by strong flexible incomplete rings of cartilage which stops the trachea from collapsing

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13
Q

Why are the cartilage rings of the trachea incomplete

A

So food can move easily down the oesophagus behind the trachea

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13
Q

What are the trachea lined with?

A

Ciliated epithelium with goblet cells between and below the epithelial cells

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14
Q

What are the jobs of cilia and goblet cells lining the trachea and its branches

A

Goblet: secretes mucus onto lining of trachea to trap dust and microorganisms that have escaped nose lining

Cilia: Waft away microorganisms from the lungs so that they are swallowed and digested

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15
Q

What are the bronchi

A

Divisions of the trachea that go to the separate lungs, with the same supporting rings of cartilage

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16
Q

What are Bronchioles and what do they contain

A

Divisions of the Bronchi, without any cartilage rings.

They contain smooth muscle in the walls that constrict then the muscle contracts, and dilate when the muscle relaxes

Also continue smooth layer of flattened epithelium to allow some gaseous exchange

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17
Q

What are Alveoli

A

Tiny air sacs at the end of bronchioles which are the main gas exchange surfaces of the body

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18
Q

What do alveoli contain to allow it to function

A

Flattened epithelial cells - gas exchange

Collagen and elastin (elastic fibres) to allow the stretch and recoil as air is drawn in

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19
Q

What are the main adaptions of the alveoli that allow for effective gaseous exchange

A

Large Surface area

High number - 300-500 million alveoli per lung

Thin layers

Good blood supply - brings CO2 and takes O2

Ventilation - keeps diffusion gradients for O2 and CO2

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20
Q

What are the inner walls of the lungs coated in?

A

Water, salts and lung surfactant

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21
Q

What is the importance of lung surfactant

A

Makes it possible for the alveoli to remain inflated, so the alveoli don’t stick together

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22
Q

What is the job of water on the inside lining of the alveoli

A

Oxygen dissolves in the water before diffusing into the blood, but water can also evaporate into the air in the alveoli

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23
Q

How does air move in and out of the lungs?

A

Result of pressure changes in thorax (chest cavity) brought about by breathing movements

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24
Q

What is ventilation

A

The movement of air

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25
Q

What does the ribcage provide

A

A semi-rigid case within which the pressure can be lowered compared to the air outside it

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26
Q

What is the Diaphragm

A

A broad domed shaped muscle, which forms the floor of the thorax

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27
Q

Where are the intercostal muscles found?

A

Between the ribs

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28
Q

What are the pleural membranes

A

The membrane that line the thorax

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29
Q

What are the pleural cavities and what is it filled with and why

A

The space between pleural membranes which is filled with a thin layer of lubricating fluid so the membranes can slide easily over each other as you breathe

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30
Q

What is inspiration

A

The taking in of air (also known as Inhalation)

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31
Q

Is inspiration an active or passive process?

A

Active

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32
Q

Describe the events in inspiration

A

Diaphragm contracts, flattening and lowering

External intercostal muscles contract, moving ribs upwards and outwards

Volume of thorax increases, so pressure reduces in thorax

This is lower than outside, so air is drawn into the lungs, so the pressure equalises inside and outside the chest

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33
Q

What is Expiration

A

The breathing out of air (also called exhalation)

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34
Q

Is expiration an active or passive process?

A

passive - most of the time

35
Q

Describe the events in expiration (normal)

A

Diaphragm relaxes, moves up to its resting domed shape

External intercostal muscles relax, so ribs move downwards and inwards under gravity

Alveoli return to normal size due to elastic fibres

Decreases volume of thorax, increased pressure, greater than outside

Air moves out until pressure is equal again

36
Q

Describe the events in forcible expiration

A

Internal intercostal muscles contract,

pulling ribs down hard and fast,

and the abdominal muscles contract,

Pulling the diaphragm up to increase the pressure in the lungs rapidly

37
Q

Asthma? 161

A
38
Q

Explain how the nose is adapted to make gaseous exchange possible

A

large SA with good blood supply warms the air to body temperature

hairy lining secretes mucus which traps dust and bacteria, protecting delicate lung tissue from irritation and infection

moist surfaces increase humidity of incoming air, reducing evaporation from exchange surfaces

produces air at similar temperature and humidity to air already in lungs

39
Q

Explain how the trachea is adapted to make gaseous exchange possible

A

wide tube, supported by incomplete rings of strong, flexible cartilage that stop tube collapsing

rings incomplete so food moves easily down oesophagus behind trachea

lined with ciliated epithelium with goblet cells between epithelial cells

goblet cells secrete mucus to trap dust and bacteria

cilia beat and move mucus and trapped particles away from lungs to throat to be swallowed and digested.

40
Q

Explain how the bronchioles are adapted to make gaseous exchange possible

A

Small tubes spreading into both lungs

the smaller bronchioles (diameter 1mm or less) have no cartilage rings. The walls contain smooth muscle which contracts to close up bronchioles and relaxes to dilate them, changing the amount of air entering the lungs

lined with thin layer of flattened epithelium, making some gaseous exchange possible

41
Q

Explain how the alveoli are adapted for gaseous exchange

A

large SA of (~50–75 m2) for gaseous exchange

thin layers so short diffusion distances

good blood supply with large capillary network supplying alveoli bringing carbon dioxide and picking up oxygen, maintains steep concentration gradient for carbon dioxide and oxygen between air in alveoli and blood in capillaries

good ventilation as breathing moves air in and out of alveoli, helping maintain steep diffusion gradients for oxygen and carbon dioxide between blood and air in lungs

42
Q

In some diseases, the alveoli breaks down to give much bigger air sacs. Explain how this reduces their effectiveness for gaseous exchange

A

Alveolar structure breaks down giving air sacs with much bigger radii

this reduces surface to volume ratio which makes them much less effective for gaseous exchange

43
Q

Smokers get more infections of the breathing system than non-smokers. Suggest Why

A

Trachea lined with ciliated epithelium with goblet cells that secrete mucus

mucus traps dust and bacteria

cilia beat to move mucus and trapped particles away from lungs to throat to be swallowed and digested

in smokers cilia anaesthetised so do not beat

mucus with its load of bacteria and dust moves down into the lungs

more pathogens reach lungs so smokers more likely to get infections of breathing system than non-smokers with active cilia

44
Q

What are the different ways to measure the capacity of the lungs

A

Peak flow meter
Vitalograph
Spirometer

45
Q

What is a peak flow meter

A

A simple device that measures the rate at which air can be expelled from the lungs

People who have asthma often use these to monitor how well their lungs are working (I HAVE ONE)

46
Q

What are vitalograph and how does it work

A

A more sophisticated version of the peak flow meter.

The patient being tested breathes out as quickly as they can through a mouthpiece, and the instrument produces a graph of the amount of air they breathe out and how quickly it was breathes out.

This volume of air is called the first expiratory volume in one .

47
Q

What is a spirometer used to measure

A

Difference of the lung volume, or to investigate breathing patterns
(pg 163)

48
Q

What aspects of the lung volumes can a spirometer measure

A

Tidal volume
Vital capacity
Inspiratory reserve volume
Expiratory reserve volume
Residual volume
Total lung capacity

49
Q

What is tidal volume

A

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

50
Q

What is 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

51
Q

What is the inspiratory reserve volume

A

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

52
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

53
Q

What is the residual volume

A

The volume of air that is left indoor lungs when you have exhaled as hard as possible. This cannot be measured directly

54
Q

What is the total lung capacity

A

The sum of the vital capacity and the residual volume

55
Q

Read graphs and fill in gaps for lung graphs!!

A
56
Q

What is breathing rate

A

The number of breaths taken per minute

57
Q

What is ventilation rate

A

The total volume of air inhaled in one minute

58
Q

What is the formula to calculate ventilation rate

A

Ventilation rate = tidal volume x Breathing rate

59
Q

Describe how you could investigate breathing rates in a school laboratory

A

Record number of breaths for a timed period and repeat

calculate means of results under different conditions

use spirometer to observe breathing rate

60
Q

Describe the relationships between tidal volume, breathing rate and oxygen uptake

A

Ventilation rate is tidal volume of air breathed in at each breath, multiplied by number of breaths per minute (breathing rate)

units are cm3 or litres per minute.
VR = TV × bpm

Oxygen uptake closely related to ventilation rate, the more air is moved into the lungs, the more oxygen can be taken up by haemoglobin in blood

so as ventilation rate increases oxygen uptake also increases

61
Q

Why can’t insects use a similar gas exchange system to mammals

A

Tough Exoskeleton, very limited diffusion

No blood pigments to cary oxygen

62
Q

What are spiracles

A

Small openings along the thorax and abdomen, in which air enters and leaves the insect, but water is also lost

63
Q

How do insects minimise water loss in gas exchange

A

have spiracle sphincters which keep spiracles closed as much as possible to minimise water loss

64
Q

What are the tracheae

A

Largest tubes in the insect respiratory system leading away from the spiracles, up to 1mm in diameter which carry air into the body

65
Q

What are the tracheae lined by and what job does it do

A

Chitin

Keeps them open even if they are bent or pressed

66
Q

What parts of the insect are made from chitin

A

Exoskeleton and linings of tracheae

67
Q

What do the tracheae branch into

A

tracheoles

68
Q

What are tracheoles

A

A branch of the tracheae which is a single elongated cell without any chitin and is permeable to gases

69
Q

Is chitin permeable to gases

A

no

70
Q

What is gas exchange controlled by in insects

A

Opening and closing of spiracles

71
Q

In insects that have very high energy demands, how do they supply the extra oxygen necessary

A

Mechanical ventilation of the tracheal system - air is actively pumped into the system by muscular pumping movements of the thorax. Changes volume of air in the body through pressure changes

Collapsible enlarged tracheae - act as reservoirs, increase amount of air moved through the system - inflated and deflated by movements of thorax and abdomen

72
Q

Although animals that get their oxygen from water dont have to prevent water loss, what challenges do they face?

A

Water is 1000 times denser than air, and 100 times thicker - and has a low oxygen content

73
Q

Why do bony fish, especially big active fish like trout and cod, need specialised exchange systems

A

As they are active, their cells have a high oxygen demand, and due to their SA:V, diffusion wouldn’t be enough to supply their inner cells with the oxygen they need, and their scaly outer covering doesn’t allow for gaseous exchange

74
Q

What is the protective structure that protects the gills

A

Operculum (a bony flap)

75
Q

Aside from protecting the the gills, what job do the operculum have

A

maintaining a flow of water over the gills

76
Q

What are the components of the gills

A

Gill operculum
Gill cavity
Gill arches (and gill rakers)
Gill lamellae
Gill filaments (and Gill plates)

(pg 168)

77
Q

What do the Gill lamellae do

A

Provide rich blood supply and large surface area, are the main site for gaseous exchange in fish`

78
Q

What do gill filaments need

A

A constant supply of water to keep them apart, exposing a large surface area needed for gaseous exchange

79
Q

What are gill plates

A

Stacks of gill filaments

80
Q

How do bony fish maintain moving water over the gills

A

Simply opening their mouth and operculum, (when moving) but when the fish stops moving, the flow of water also stops
(operculum movement)

81
Q

What is ram ventilation

A

The technique used by more primitive cartilaginous fish eg. sharks and rays which relies on continual movement past the gills

Most bony fish dont rely on movement-generated water flow over the gills

82
Q

Describe the operculum movement to allow for oxygen to pass the gills without the fish moving

A

Mouth (buccal cavity) is lowered, increasing in volume

Pressure in cavity drops, drawing water in

At the same time, opercular valve shuts and opercular cavity expands

This lowers pressure in opercular cavity containing the gills

Floor of buccal cavity starts to move up, increasing pressure there so water moves from buccal cavity over the gills

Mouth closes and sides of the opercular cavity moves inwards, increasing pressure and forcing water over the gills

(pg 169)

83
Q

How do fish have an efficient gas exchange system

A

USUAL DIFFUSION POINTS PLUS
Tips of gill filaments overlap - increasing resistance to flow of water to slow down movement of water, to allow for more gaseous exchange to take place

Countercurrent flow - maintains a steep concentration gradient, so oxygen will continue to diffuse quickly into the blood and saturation doesnt occur

(pg 170)

84
Q

Suggest why a fish will die when it is left out of water for too long

A

In air gill filaments all stick together

SA for gas exchange is greatly reduced and so fish dies
from lack of oxygen

85
Q

Explain how insects that have particularly high energy requirements can increase the amount of gaseous exchange taking place in their bodies

A

Fluid towards end of tracheole limits penetration of air for diffusion

when energy demands high
lactic acid build up in tissues, water moves out of tracheoles by osmosis, exposing more surface area for gaseous exchange (1);

tracheal system can be mechanically ventilated with air actively pumped
into system by muscular pumping movements of thorax and/or the abdomen

movements change
volume of body, changing pressure in tracheae and tracheoles so air drawn into trachea and
tracheoles, or forced out, as pressure changes, making gaseous exchange more efficient

Some very active insects have collapsible enlarged tracheae or air sacs which act as air reservoirs, used to
increase amount of air moved through gas exchange system

they are usually inflated and
deflated by ventilating movements of thorax and abdomen

86
Q

Explain how the structure of the gas exchange system of bony fish maximises the amount of oxygen that can be taken from the water

A

Gills have large stacks of gill filaments carrying gill lamellae that have large surface area

good blood supply

and thin layers

needed for successful gaseous exchange. Constant flow of water
maintained over gills so best possible diffusion gradient for the respiratory gases

tips of gill
filaments overlap – increasing resistance to flow of water, slowing it down for more effective gaseous
exchange

water and blood flow in opposite directions.

Countercurrent exchange system
maximises the potential exchange of gases

biology a level (24 decks)

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