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Biology > 3.1.1 - Exchange surfaces > Flashcards

3.1.1 - Exchange surfaces Flashcards

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1
Q

What are the two main reasons that diffusion is enough for single celled organisms ?

A
  • The metabolic activity is low, so the oxygen demand carbon dioxide production of the cell are relatively low
  • The SA:V ratio of the organism is large
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2
Q

What happens as organisms get larger ?

A
  • Their metabolic activity is usually much higher
  • Their SA:V ratio is smaller. So gases cant be exchanged fast enough or in large enough amounts for the organism to survive
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3
Q

How have large organisms evolved ?

A

Large multicellular organisms have evolved specialised systems for the exchange of the substances they need and the substances they must remove

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4
Q

What are the common features of effective exchange surfaces ?

A
  • Increased surface area
  • Thin layers
  • Good blood supply
  • Ventilation to maintain diffusion gradient
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5
Q

Why does an increased surface area make an exchange surface efficient ?

A

It provides the area needed for exchange to overcome the limitations of low SA:V ratio

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6
Q

Why do thin layers make an exchange surface efficient ?

A

The distances that substances have to diffuse across are short, making it fast and efficient

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7
Q

Why does a good supply make an exchange surface efficient ?

A
  • The greater the difference in concentration the greater the rate of diffusion.
  • A good supply means substances are constantly being delivered and removed, maintaining the steep concentration gradient
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8
Q

Why does ventilation make an exchange surface efficient ?

A

For gases ventilation helps to maintain concentration gradients

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9
Q

Why are specialised exchange surfaces needed by some organisms ?

A
  • They have a low SA:V ratio so exchange surfaces increase that
  • Maximise efficiency of diffusion
  • Ensure that the demand for glucose and oxygen is met
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10
Q

How is the nasal cavity adapted for the gas exchange system ?

A
  • Good blood supply warms air to body temperature
  • Cells secrete mucus to trap dust and bacteria to protect the lung tissue
  • Moist surfaces which increase the humidity of the incoming air, reduce evaporation from the exchange surfaces
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11
Q

What is the trachea ?

A

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

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12
Q

How is the trachea adapted for the gas exchange system ?

A
  • Supported by incomplete rings of strong, flexible cartilage to allow for movement and prevent the trachea from collapsing
  • Lined with ciliated epithelium and goblet cells
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13
Q

What is the function of the goblet cells ?

A

To secrete mucus which traps dust and microorganisms that have escaped the nose lining

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14
Q

What is the function of ciliated epithelial cells ?

A
  • The cilia beat and move mucus away from the lungs, protecting them
  • Most of it goes into the throat and is then swallowed and digested
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15
Q

What are the bronchi ?

A

They are similar in structure to the trachea, with the same supporting rings of cartilage, but are smaller

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16
Q

How are the bronchi adapted for the gas exchange system?

A

They are supported by small rings of cartilage

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17
Q

How are bronchioles adapted for the gas exchange system ?

A
  • They contain no cartilage
  • Contain smooth muscle
  • Smooth muscle contracts when bronchioles constrict and relaxes when they dilate
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18
Q

What are alveoli ?

A
  • The alveoli are tiny air sacs, which are the main gaseous exchange surfaces of the body
  • They are unique to the mammalian structure
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19
Q

How are the alveoli adapted for the gas exchange system ?

A
  • Very thin walls
  • Contain elastic fibres which allow alveoli to stretch as air is drawn in and when they return to size help to squeeze air out
  • Good capillary blood supply
  • Coated in surfactant
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20
Q

What is elastic recoil ?

A

Elastic recoil is the ability of the alveoli to stretch to allow more air in and to return back to normal size to squeeze the air out

21
Q

What is breathing ?

A

The movement of air in and out of the lungs

22
Q

What is breathing also known as ?

A

Ventilation

23
Q

What is the thorax ?

A

The thorax is basically all of the chest cavity

24
Q

What is the rib cage ?

A

The rib cage provides a semi rigid case within which pressure can be lowered with respect to the air outside it

25
Q

What is the diaphragm ?

A

The diaphragm is a broad, domed sheet of muscle, which forms the floor of the thorax

26
Q

What is the pleural membrane ?

A

The thorax is lined with the pleural membrane, which surround the lungs

27
Q

What is the pleural cavity ?

A
  • The pleural cavity is the space inbetween the pleural membranes
  • It is usually filled with a thin layer of lubricating fluid so that the membranes slide over each other easier
28
Q

What is inspiration ?

A

The movement of air into the lungs

29
Q

Does inspiration require energy ?

A

Yes

30
Q

Outline the steps in inspiration

A
  • Diaphragm flattens and contracts
  • External intercostal muscles contract making the ribs move up and out
  • This increases the volume of the thorax so reduces pressure
  • Pressure in the thorax is lower than that of outside
  • Air is drawn into the lungs to equalise the pressures inside and outside the chest
31
Q

What is expiration ?

A

The movement of air out of the lungs

32
Q

Does expiration require energy ?

A
  • No, it is a passive process
33
Q

Outline the steps in normal expiration

A
  • Diaphragm relaxes and curves upwards
  • External intercostal muscles relax so ribs move in
  • Decreases volume of the thorax
  • Pressure in the lungs is less negative than atmospheric air
  • Air moves out of the lungs until pressure inside and out is equal
34
Q

Outline the steps in forced expiration

A
  • Abdominal muscles contract, pushing diaphragm upward quickly making lung pressure less negative
  • Internal intercostal muscles contract pulling ribs down hard and fast
35
Q

What are the three ways that the volume of air can be measured ?

A
  • A peak flow meter
  • Vitalograph
  • Spirometer
36
Q

What is a peak flow meter ?

A

A peak flow meter is a simple device that measure the rate at which air can be expelled from the lungs

37
Q

What is a vitalograph ?

A
  • More sophisticated versions of the peak flow meter

- Measures the amount of air breathed out and how quickly it is breathed out

38
Q

What is a spirometer ?

A

Commonly used to measure different aspects of the lung volume, or to investigate breathing patterns

39
Q

What is tidal volume ?

A
  • Tidal volume is the volume of air that moves into and out of the lungs with each resting breath
  • Typically 15% of the vital capacity of the lungs, can be 50% during exercise
40
Q

What is vital capacity ?

A

Vital capacity is the max volume of air that can be breathed in when the strongest possible exhalation is followed by the deepest possible intake of breath

41
Q

What is inspiratory reserve volume ?

A

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

42
Q

What is expiratory reserve volume ?

A

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

43
Q

What is residual volume ?

A

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

44
Q

What is total lung capacity ?

A

The sum of the vital capacity and the residual volume

45
Q

What is the breathing rate ?

A

The number of breaths taken per minute

46
Q

What is the ventilation rate ?

A

The total volume of air inhaled in one minute

47
Q

How do you calculate ventilation rate ?

A

Tidal volume x Breathing rate

48
Q

As organisms get larger, what happens to the size of the diffusion distance ?

A

The diffusion distance increases

49
Q

As organisms get larger, what happens to the size of the surface area ?

A

The surface area increases

Biology (30 decks)

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