Gas exchange Flashcards

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1
Q

As size of an organism increases what happens to its surface area to volume ratio?

A

It decreases

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2
Q

Describe and explain the five common features of gas exchange surfaces

A

Many folds to increase surface area, thin to give short diffusion distance, permeable so gases can past through, moist so gases can dissolve, a ventilation mechanism/good blood supply to maintain concentration gradient

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3
Q

Name the gas exchange surface of a fish

A

Gill plates (or lamellae)

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4
Q

Name the gas exchange surface of an insect

A

Tracheoles

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5
Q

Name the gas exchange surface of a mammal

A

Alveoli

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6
Q

Name the gas exchange surface of an amphibian

A

Alveoli/skin surface for a frog depending on activity level

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7
Q

Give the advantages of an insect gas exchange system

A

Oxygen diffuses directly to cells, no need to produce haemoglobin, spiracles can be closed to reduce water loss, Hairs in
spiracles to trap moisture

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8
Q

Give the disadvantages of an insect gas exchange system

A

Rate of diffusion limits size and shape of insect, mass of chitin could make it difficult to fly

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9
Q

Why is it difficult to extract oxygen from water?

A

It is dense, viscous and has a low oxgen concentration

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10
Q

Give the advantage of counter current flow in fish gills

A

Maintains concentration gradient across entire gill plate/doesn’t reach equilibrium

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11
Q

Why can’t fish survive out of water?

A

Gill plates stick together due to surface tension, decreasing surface area and increasing diffusion distance for gas exchange.

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12
Q

How do fish breathe in?

A

They open the mouth, close the operculum and lower the floor of the mouth cavity. This increases the volume and decreases pressure.

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13
Q

How do fish breathe out?

A

They close the mouth, open the operculum and raise the floor of the mouth cavity. This decreases volume, increases pressure and pushes water past the gills

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14
Q

Why do terrestrial animals have internal lungs?

A

To minimise heat and water loss

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15
Q

Which cells secrete mucus?

A

Goblet cells

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16
Q

What is the function of ciliated epithelium in the trachea and bronchi?

A

To waft mucus which contains bacteria up to the back of the throat where it can be swallowed

17
Q

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

A

To stretch and recoil

18
Q

What is the function of the cartilage in the trachea?

A

To prevent the trachea from collapsing during inspiration

19
Q

Why is the cartilage in the trachea a C shaped ring rather than a circle?

A

To allow the oesophagus to expand when swallowing

20
Q

What is the function of surfactant?

A

Reduces surface tension to prevent alveoli sticking together when breathing out

21
Q

Which membranes surround the lungs?

A

Pleural membranes

22
Q

How do the ribs and diaphragm cause inhalation?

A

Diaphragm contracts and lowers, external intercostal muscles contract to raise the ribcage. Volume of alveoli increases, pressure decreases below atmospheric. Air is drawn in

23
Q

How are the pleural membranes involved in forced inhalation?

A

External intercostal muscles raising the ribcage pulls out the outer pleural membrane, reduces pressure in the pleural cavity and the inner pleural membrane moves outward. This pulls on the surface of the lungs and causes the alveoli to expand. Volume of alveoli increases, pressure decreases below atmospheric. Air is drawn in

24
Q

How do humans exhale?

A

Diaphram relaxes and moves up into dome shape, external intercostal muscles relax and ribcage lowers. Volume decreases pressure increases.