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A Level Biology > Module 3 - chapter 7 > Flashcards

Module 3 - chapter 7 Flashcards

1
Q

Why do we have cells?

A

Cells allow a concentration of chemicals in one area.

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2
Q

Why can’t we diffuse oxygen and carbon dioxide in through the skin?

A

The skin is a complete barrier so diffusion can’t occur.

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3
Q

What features must an efficient gas exchange system have?

A

Moist, thin walls. (E.g. the lungs are moist so gases can diffuse into them.) blood supply and ventilation

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4
Q

What are some reasons for exchange systems?

A
  • Large multicellular organisms have a small surface area to volume ratio
  • cells in the centre of the organism would not receive any materials if multicellular organs survived on diffusion alone.
  • metabolic rate, multicellular organisms have a high metabolic rate
  • there is a need to exchange lots of materials fast.
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5
Q

Why can single felled organisms survive using diffusion alone?

A

They have a low metabolic rate, and a large surface area to volume ratio

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6
Q

As surface area to volume ratio of an organism increases is diffusion easier or harder?

A

The easier the exchange of substances by diffusion is

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7
Q

What is the equation for the volume of a cuboid?

A

Volume = length x width x height

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8
Q

What is the equation for the surface area of a cuboid?

A

Surface area = (4 x length x height) + (2 x height x width)

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9
Q

What is the equation for the area of a circle?

A

Area = πr²

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10
Q

What is the equation for the circumference of a circle?

A

Circumference = 2πr

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11
Q

What is the equation for the volume of a cylinder?

A

Volume = πr² x height

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12
Q

What is the equation for the surface area of a cylinder?

A

Surface area = (2πr x height) + 2πr²

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13
Q

What is the equation for the volume of a sphere?

A

Volume = 4/3 x πr³

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14
Q

What is the equation for the surface area of a sphere?

A

Surface area = 4πr²

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15
Q

Why are thin layers a feature of an efficient gas exchange system?

A

The thin layers create a short diffusion pass for gases, increasing the speed of exchange

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16
Q

Why is blood supply a feature of an efficient gas exchange system?

A

A good, constant blood supply maintains a large diffusion gradient and ensures the exchanges substance are constantly moving to the area needed

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17
Q

Why is ventilation a feature of an efficient gas exchange system?

A

Ventilation maintains the diffusion gradient which makes the process faster and more efficient

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18
Q

List the structures for gas exchange in and around the lungs in the human body

A

Nasal cavity, mouth cavity, trachea, rings of cartilage, lungs, bronchi, bronchioles, heart, ribs, diaphragm.

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19
Q

Why are exchange surfaces moist?

A

To aid diffusion by oxygen dissolving into the water.

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20
Q

What are the gas exchange surfaces in humans?

A

Alveoli and bronchioles

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21
Q

Why do humans exchange gas?

A

To maintain a steep concentration gradient to aid diffusion.

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22
Q

What type of membrane are cell membranes?

A

plasma membranes

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23
Q

How thick are plasma membranes?

A

7 nm thick

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24
Q

What are the membranes which surround the heart called?

A

Cardiac membranes

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25
Q

What type of membrane is each lung encased in?

A

the pleural membrane (a double membrane.)

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26
Q

What is the space between the pleural membranes called?

A

The pleural cavity.

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27
Q

What is the pleural cavity filled with?

A

pleural fluid (a water-based fluid)

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28
Q

what is the function of the pleural fluid?

A

to lubricate the lungs and to adhere the outer walls of the lungs to the thoracic cavity

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29
Q

what is the thoracic cavity?

A

the chest cavity

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30
Q

how does the pleural fluid adhere the outer walls of the lungs to the thoracic cavity? why?

A

by water cohesion so that the lungs expand with the chest while breathing

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31
Q

what are some important functions of the nasal cavity?

A
  • Large surface area (increased by the septum) and good blood supply to warm the air as it passes into the body.
  • Hairy lining to trap dust and bacteria in mucus and prevent them from reaching the lungs which could cause infection. The first filter in the nose.
  • Moist surfaces to increase the humidity of the incoming air to reduce the evaporation of water in the lungs.
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32
Q

Why is air outside “cleaner” than the air inside?

A

UV helps sterilise the air outside

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33
Q

Are the hairs in the nostrils cilia?

A

NO

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34
Q

What is the function of goblet cells?

A

to secrete mucus which is then used to trap dust and bacteria

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35
Q

What shape are cartilage rings? Why is this useful?

A

‘C’ shaped because the rings being incomplete allows the trachea and bronchi to bend and be more flexible.

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36
Q

why does the trachea need to be flexible?

A

to allow it to bend when food is swallowed down the oesophagus behind.

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37
Q

What is mucus made of?

A

Mucin

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38
Q

What are the bronchus?

A

Extensions of the trachea that split into two for for the left and right lung

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39
Q

What is the diameter of bronchioles?

A

1mm or less

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40
Q

What are the bronchioles held open by?

A

Smooth muscle

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41
Q

What makes some gas exchange possible in the bronchioles?

A

A lining of a thin layer of epithelial tissues

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42
Q

What type of muscle is the smooth muscle which holds open the bronchioles?

A

Skeletal muscle

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43
Q

What is the diameter of each alveoli?

A

200-300 micrometers

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44
Q

What are alveoli made up of?

A

A thin layer of flattened squamous epithelial cells as well as some collagen and elastic fibres

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45
Q

What is the function of the elastic fibres in the alveoli?

A

To recoil and help move air out of the alveoli - the elastic fibres stretch whilst the alveoli expand and recoil when expelling air

46
Q

How does the capillary wall being narrow affect the red blood cells?

A

The red blood cells bend against the capillary wall to flow through, this slows blood flow and minimises the distance gases have to diffuse

47
Q

What are the alveolar ducts?

A

The very last branches of the bronchioles

48
Q

How is the concentration gradient maintained in the alveoli?

A

Some air is replaced with each breath

49
Q

Describe the process of inspiration

A

1) the external intercostal muscles contract, lifting the rib cage and moving the ribs up and out
2) the diaphragm contracts to move downwards
3) the volume of the thorax/lungs increases
4) the pressure inside the lungs decreases to below atmospheric pressure, forming a pressure gradient
5) Air rushes into the lungs from the trachea to attain a pressure equilibrium

50
Q

Describe the process of resting expiration

A

1) the external intercostal muscles relax, the rib cage falls
2) the diaphragm muscles relax and it moves upwards
3) the volume of the lungs decreases
4) pressure inside the lungs increases
5) air rushes out of the lungs to attain a pressure equilibrium

51
Q

How does a spirometer work?

A
  • The static lower half of the tank is full of water which acts as a gas tight seal
  • The mobile upper half of the tank is full of oxygen
  • breathe out into the tank and the upper half will rise
  • breathe in from the tank and the upper half will fall
  • a trace marker is attached to the upper half so a trace is drawn on the revolving drum as the lid moves up and down.
52
Q

As the size of an object increases, what happens to the SA:V?

A

As the size of the object increases, the surface area to volume ratio decreases because the surface area and volume don’t increase proportionally, the volume increases more rapidly than the surface area.

53
Q

Why do mammals need transport systems?

A
  • Diffusion is not adequate
  • Gases/waste/food cannot be transported to cells quickly without transport systems
  • distance too great for diffusion to reach all cells in the body
  • mammals have a high metabolic rate
54
Q

What is the function of cartilage?

A

to hold the airways open/ to prevent airway collapse and prevents bursting of trachea/bronchi as the air pressure changes.

55
Q

Describe the mechanism by which oxygen gets from the inside of an alveolus to the red blood cells.

A

Oxygen dissolves in to the water film inside the alveolus. The oxygen then diffuses down the concentration gradient and crosses the cell membranes and plasma to get to the red blood cells.

56
Q

Why can mouth-to-mouth resuscitation effective?

A

Because in one breathing cycle, the air in the lungs loses only some of its oxygen content. Air is breathed in and air is breathed out.

57
Q

What does a peak flow meter measure?

A

The rate at which air can be expelled from the lungs

58
Q

What is a vitalograph?

A

A more complex version of the peak flow meter, when the peak flow is connected to a trace.

59
Q

What does the peak flow meter produce from the data it collects?

A

A graph about the amount of air breathed out and how quickly the air is breathed out.

60
Q

Should a healthy person have a lower or higher peak flow?

A

A higher peak flow

61
Q

When inspiring, does the trace go up or down on a spirometer graph? Why?

A

The trace goes down because the pressure and volume in the spirometer decreases.

62
Q

What are the x and y values on a spirometer graph?

A

volume of air (dm^3) against time (s)

63
Q

When expiring, does the trace go up or down on a spirometer graph? Why?

A

The trace goes up because the pressure and volume in the spirometer increases.

64
Q

How is the volume of a single breath shown on a spirometer graph?

A

The peak of expiration to trough/low of inspiration shows the volume of a single breath.

65
Q

How are lung volume graphs and spirometer graphs different?

A

Lung volume graphs are the opposite of spirometer graphs. Lung volume graphs measure the volume of gas in the lungs whereas spirometer graphs measure the volume of gas in the spirometer.

66
Q

Why does the overall volume of gas in the spirometer tank decrease over time?

A
  • The spirometer contains soda lime which absorbs carbon dioxide.
  • When breathing, oxygen is used up from the tank in respiration while the carbon dioxide breathed out is absorbed by the soda lime.
  • The overall volume of gas decreases throughout the experiment as the gas was at a fixed volume but as the carbon dioxide is absorbed, the volume decreases. The volume of oxygen used up would be replaced with the same volume of carbon dioxide but this is absorbed.
67
Q

What is tidal volume?

A

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

68
Q

What is the average adult tidal volume?

A

0.5 dm^3

69
Q

What percentage of the vital capacity is the tidal volume?

A

15%

70
Q

What is vital capacity?

A

The largest volume of air that can be breathed in (when the strongest exhale is followed by the strongest possible inhale.)

71
Q

What is the average adult vital capacity?

A

5dm^3

72
Q

What is inspiratory reserve volume?

A

The maximum volume of air which can be breathed in over and above normal inhalation.

73
Q

What is expiratory reserve volume?

A

The maximum volume of air which can be forced out of the lungs over and above the normal tidal volume of air breathed out.

74
Q

What is the residual volume?

A

The volume of air that is left in the lungs after having exhaled as hard as possible.

75
Q

Why can residual volume not be directly measured?

A

It is not possible to exhale all of the air out of the lungs (without death) otherwise the lungs would stick together and collapse because the air prevents the water in the lungs sticking the walls together.

76
Q

What is total lung capacity?

A

The sum of the vital capacity and the residual volume, the total potential amount of air in the lungs at any one time.

77
Q

Why can’t total lung capacity be measured?

A

Because residual volume can’t be measured.

78
Q

How is the circulation system of insects different?

A

They have an open circulatory system in which body fluid acts as blood and tissue fluid.

79
Q

Describe the structure of the insects gas exchange system

A
  • Air enters the tracheal system through pores called spiracles, each segment of the insect apart from the head as a pair of spiracles.
  • The air is transported through tracheae which divide into tracheoles. The ends of the tracheoles are open and filled with tracheal fluid.
  • The tracheal fluid moves around the body and causes the exchange of gases. Gas exchange occurs between air in the tracheole and tracheal fluid. Some exchange occurs across the thin walls of the tracheoles.
  • Oxygen diffuses down the concentration gradient from the air into the body cells. Carbon dioxide diffuses down the concentration gradient from body cells to the air.
80
Q

Describe how the expansion and contraction of air sacs aid ventilation in insects.

A

Sections of the tracheal system have flexible walls which contract and expand changing tracheal volume of the thorax. Repetitive expansion and contraction of the air sacs ventilates the tracheal system.

81
Q

How do wing movements aid ventilation in insects?

A

Wing movements change the volume of the thorax so air is forced in and out of the thorax with pressure changes. As the volume of the thorax decreases, the pressure increases and air is pushed out of the tracheal system. When the thoracic volume increases, the pressure decreases and air is pulled into the tracheal system.

82
Q

How have some insects developed ventilation further?

A

Through the use of specialised breathing systems and the coordinated opening and closing of spiracles. An example is locusts.

  • As the volume of the abdomen increases, the spiracles at the front of the body open and air enters the tracheal system.
  • As the volume of the abdomen decreases, the spiracles at the rear end of the body open and air exits the tracheal system.
  • This is ventilation by rhythmic abdominal movements and is a type of mechanical ventilation.
83
Q

Why do insects have an open circulatory system and a separate tracheal system?

A
  • Insects have a tough exoskeleton so no gas exchange can take place.
  • Insects have no blood pigments to carry the oxygen in the blood.
  • Circulation is slow so even if the insects had the blood pigments gas exchange in the circulatory system would be inefficient.
84
Q

How are spiracles adapted to prevent water loss through them?

A

Spiracles can open and close by sphincters but are closed most of the time to prevent water loss.

85
Q

What keeps the tracheoles open in insects?

A

Chitin, it acts as cartilage does in the human gas exchange system - holding the tracheoles open and preventing them from collapsing.

86
Q

How is tracheal fluid an adaptation for gas exchange in insects?

A

Many insects are active so require a good oxygen supply. Tracheal fluid can be withdrawn from the ends of the tracheoles into body fluid. This increases the surface area of the tracheole wall exposed to air. Therefore more oxygen can be absorbed when active.

87
Q

How many pairs of gills do fish typically have?

A

5 pairs of gills

88
Q

What bony plate covers the gills?

A

The operculum plate

89
Q

Describe the structure of the gill

A

Each gill consists of two rows of gill filaments (primary lamellae) attached to a bony arch. The surface of the thin filaments is folded into many secondary lamellae (gill plates).

90
Q

How does the structure of the gill make it efficient for gas exchange?

A
  • Large exchange surface area

- The capillaries carry blood close to the exchange surface

91
Q

What is the counter current flow system

A

Water flows over the lamellae in the opposite direction to blood flow through the capillaries.

92
Q

How does ventilation occur in bony fish?

A

Water is drawn into the mouth and forced out over the gills, increasing gas exchange

93
Q

What are the gill lamellae?

A

The gill lamellae project at right angles from the filaments and their function is to increase the surface area of the gills.

94
Q

What is the function of the bony gill arch?

A

To support the structure of the gills

95
Q

What is an alternate name for the primary lamellae?

A

gill filaments

96
Q

What is an alternate name for the secondary lamellae?

A

gill plates

97
Q

What is the efferent blood vessel?

A

A blood capillary close to the surface of the secondary lamellae which carries the blood leaving the gills in the opposite direction to the incoming water, maintaining a steep concentration gradient.

98
Q

What is the afferent blood vessel?

A

The blood capillary close to the surface of the secondary lamellae which brings blood into the system.

99
Q

What is the main site of gas exchange in the fish?

A

The gill lamellae due to the rich blood supply and the large surface area

100
Q

Why do the gill filaments have a large surface area?

A

Because the flow of water keeps them apart and increases surface area

101
Q

Describe the process of inspiration in fish.

A
  • The buccal cavity opens and the the floor of the cavity is lowered, increasing the volume of the buccal cavity so the pressure decreases.
  • Water moves into the buccal cavity due to the low pressure.
  • The operculum valve shuts and the operculum cavity containing the gills expands/increases in volume so the pressure in the operculum cavity decreases.
  • The floor of the buccal cavity moves up so pressure increases and water moves from the buccal cavity over the gills.
102
Q

Why is the counter current flow system an adaptation for gas exchange in fish?

A
  • It results in blood always coming into contact with water with a higher dissolved oxygen concentration.
  • The diffusion gradient of oxygen is therefore maintained along the entire length of the gill structure, facilitating maximum possible gas exchange across the gill lamellae.
103
Q

How can cigarette smoke affect the gas exchange system?

A

Cigarette smoke stops the cilia on the ciliated epithelium cells lining the trachea and other structures from beating, this prevents mucus and microorganisms from being removed/destroyed.

104
Q

What are elastic fibres composed of?

A

Elastin

105
Q

What is the breathing rate?

A

the number of breaths taken per minute

106
Q

What is the ventilation rate?

A

The total volume of air inhaled in one minute

107
Q

what is the equation for ventilation rate?

A

ventilation rate = tidal volume x breathing rate (per minute)

108
Q

What is it called when other fish rely on movement to ventilate their gills?

A

ram ventilation

109
Q

Describe the process of expiration in fish.

A

-The mouth closes, the operculum opens and the sides of the opercular cavity move inwards.

-

110
Q

What is parallel flow?

A

In parallel flow the concentration gradient will level out when blood and water are both 50% saturated with oxygen. Therefore diffusion stops when the blood is only 50% saturated with oxygen.

A Level Biology (8 decks)

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