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Biology A-Level OCR > Gas exchange in mammals and others > Flashcards

Gas exchange in mammals and others Flashcards

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1
Q

Why do multicellular organisms need exchange surfaces?

A

To maintain the metabolic activity of the organism

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2
Q

What is the volume of a sphere?

A

⁴⁄₃πr³

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3
Q

What is the volume of a circle?

A

πr2

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4
Q

What are the features that most specialised exchange surfaces have in common?

A

Increased surface area, thin layers, good blood supply, ventilation to maintain a good blood supply

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5
Q

How does an increased surface area effect specialised exchange surfaces?

A

Provides more area for exchange and overcomes the limitations of a smaller SA:V of larger organisms

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6
Q

Give an example of a specialised exchange surface with an increased surface area

A

Root hair cells in plants and villi in mammals

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7
Q

How do thin layers effect specialised exchange surfaces?

A

Decreases diffusion distance, therefore increasing the rate of diffusion

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8
Q

Give an example of a specialised exchange surface with thin layers

A

Alveoli in the lungs

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9
Q

How does a good blood supply effect specialised exchange surfaces?

A

Increases the concentration gradient, therefore increasing the rate of diffusion. A good blood supply ensures that substances are being delivered and removed

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10
Q

Give an example of a specialised exchange surface with a good blood supply

A

Alveoli in the lungs and the gills of fish

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11
Q

How does ventilation effect specialised exchange surfaces?

A

Maintains the concentration gradient for gases to make gas exchange more efficient

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12
Q

Give an example of a specialised exchange surface with ventilation

A

Alveoli in the lungs and gills of fish

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13
Q

What are the key structures in the mammalian gas exchange system?

A

Nasal cavity, trachea, bronchus, bronchioles, alveoli

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14
Q

How is the nasal cavity adapted to gas exchange?

A

Large surface area with good blood supply which warms air to body temperature, hairy lining which secretes mucus to trap pathogens and dust to prevent irritation and infection, moist surfaces which increase humidity of incoming air to reduce evaporation from exchange surfaces

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15
Q

How is the trachea adapted to gas exchange?

A

Supported by incomplete c-shaped rings of cartilage to prevent collapse, flexible so food can move down the oesophagus. Also is lined with ciliated epithelium with goblet cells to secrete mucus to prevent infection

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16
Q

What is the effect of smoking on the gas exchange system?

A

The smoke from cigarettes prevents cillia from beating and wafting mucus away from the lungs, therefore causing infection and irritation

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17
Q

How is the bronchus adapted for gas exchange?

A

Similar to trachea but smaller

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18
Q

How are bronchioles adapted to gas exchange?

A

Walls contain no cartilage but smooth muscle, which allows the bronchiole to contract and relax to push air out and allow it in. Also has squamous epithelium that allows gas exchange to occur

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19
Q

How are alveoli adapted to gas exchange?

A

Large surface area, good blood supply (many small capillaries), thin layers (one cell thick), good ventilation

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20
Q

What is ventilation?

A

Inspiration and exhalation; when air is moved in and out of the lungs due to pressure changes in the thorax (chest cavity)

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21
Q

How does ventilation happen in context to the movement of gases?

A

From an area of higher pressure to an area of lower pressure

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22
Q

What muscles are used for inspiration?

A

External intercostals, diaphragm (contract), accessory muscles

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23
Q

What muscles are used for exhalation?

A

Internal intercostals and diaphragm (relax), accessory muscles, passive

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24
Q

What happens in forced exhalation?

A

Abdominal muscles contract to push the diaphragm upwards

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25
Q

How could you measure lung capacity?

A

Peak flow meter, vitalographs, spirometer

26
Q

How do peak flow meters work?

A

Measures rate at which air is expelled from lungs

27
Q

How does a vitalograph work?

A

Same as a peak flow meter but produces a graph of the expelled air produced in 1 second

28
Q

How do spirometers work?

A

Can be used to measure different aspects of lung volume or breathing patterns

29
Q

What are the components of lung volume?

A

Tidal volume, vital capacity, inspiratory reserve volume, expiratory reserve volume, residual volume, total lung capacity

30
Q

What is tidal volume?

A

Volume of air that moves into and out of the lungs with each resting breath, around 500 cm3

31
Q

What is vital capacity?

A

The greatest volume of air that can be expelled from the lungs after taking the deepest possible breath

32
Q

What is inspiratory reserve volume?

A

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

33
Q

What is expiratory reserve volume?

A

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

34
Q

What is residual volume?

A

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

35
Q

What is total lung capacity?

A

The sum of the vital capacity and the residual volume

36
Q

What is the breathing rate?

A

Number of breaths taken per minute

37
Q

What is the equation for ventilation rate?

A

Ventilation rate = tidal volume x breathing rate

38
Q

What are the structures used in insect respiration?

A

Spiracles, trachea, tracheoles

39
Q

Why do insects need spiracles?

A

For gas and water to escape due to their waxy and tough exoskeleton

40
Q

What are spiracles?

A

Openings that lead to airways

41
Q

What are trachea (in insects)?

A

1mm diameter air ways in the system lined with spirals of chitin which prevent collapse

42
Q

What are tracheoles?

A

0.6-0.8 micrometers of smaller branches of trachea. No chitin to allow free exchange of gases, large surface area

43
Q

What is tracheole fluid?

A

Fluid located at the end of the tracheoles

44
Q

How is oxygen transported in insects?

A

Diffusion, then is dissolved into the walls of the trachea and tracheoles

45
Q

What happens to insect respiration during activity?

A

Lactic acid builds up in the tissues and decreases water potential in cells, therefore water leaves the tracheoles by osmosis, therefore tracheole fluid moves towards tissues. Movement of fluid causes increase of surface area of the tracheoles

46
Q

How does mechanical ventilation work in insects?

A

Muscular pumping in the thorax and abdomen change volume in the body, therefore change in pressure in the tracheoles. This causes air to move into the spiracles to even out the pressure

47
Q

How do simple aquatic organisms respire?

A

Can use large surface area compared to their volume for gas exchange by diffusion

48
Q

How do complex aquatic organisms respire?

A

Obtain oxygen through gills, complexity of gill structure correlates with organism’s oxygen requirements

49
Q

What are the component of gills?

A

Operculum, gill lamellae, gill filaments/gill plates, buccal cavity, pharyngeal cavity

50
Q

What is the operculum?

A

Flap that covers the gills

51
Q

What is the gill lamellae?

A

Main site of gaseous exchange in the fish with a rich blood supply and large surface area

52
Q

What are the gill filaments/gill plates?

A

Occur in large stacks and need a flow of water to keep them apart, exposing the large surface area needed for gaseous exchange

53
Q

What is the buccal cavity?

A

Mouth

54
Q

What is the pharyngeal cavity?

A

Throat

55
Q

How is oxygen transported into the blood in fish?

A

Concurrent exchange and parallel exchange

56
Q

How does concurrent exchange occur?

A

When blood and water travel in opposite directions, and so oxygen is delivered to the blood at every point along the gas exchange surface

57
Q

How does parallel exchange occur?

A

When blood and water flow in the same direction and therefore fail to provide a persistent oxygen concentration and therefore can only reach 50% blood saturation

58
Q

How does ventilation in bony fish occur?

A

Inspiration and exhalation

59
Q

Explain inspiration in fish

A

Muscle contraction lowers floor of the pharynx, volume of buccal cavity increases, pressure increases so water enters the mouth. Opercular valves close, pressure decreases in the Opercular cavity, water flows into opercular cavity

60
Q

Explain expiration in fish

A

Buccal cavity contracts. mouth closes, floor of the pharynx is raised, pressure increases and forces water through the gill slits. Therefore opercular cavities contract, pressure increases causing water to be expelled via the operculum

61
Q

What is ram ventilation?

A

When fish swim with their mouths partially open so water continuously flows over the gills for respiration

62
Q

How can gas exchange become more efficient in fish?

A

Larger surface area with many lamellae, steeper concentration gradients with extensive blood supply and the countercurrent mechanism, shorter diffusion pathway with capillaries and lamellae with one cell think walls each

Biology A-Level OCR (26 decks)

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