Gas Exchange Flashcards

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1
Q

Features of efficient gas exchange

A
  • Large surface area - increases rate of diffusion
  • Thin surface - short diffusion pathway
  • A good blood supply to maintain a steep gradient
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2
Q

How are fish adapted for gas exchange?

A
  • They have gills with multiple gill filaments which have lamallae
  • Blood and water flow in a counter current system. This ensures a steep diffusion gradient so the maximum amount of oxygen is
    diffusing into the deoxygenated blood from the water along the whole length of the gill filament
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3
Q

How are insects adapted for gas exchange?

A
  • Air moves into the trachea through the spiracles
  • Oxygen travels down the concentration gradient
  • Tracheoles have thin, permeable walls
  • They use rhythmic abdominal movements to move air in and out
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4
Q

How are plants adapted for gas exchange?

A
  • Leaves have many stomata to allow gases to enter and leave
  • Stomata also controls water loss, guard cells swell for them to open
  • Short diffusion pathway
  • The surface of the mesophyll cells have a large surface area
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5
Q

How can insects and plants control water loss?

A
  • Insects close their spiracles, they also have a waterproof waxy cuticle and tiny hairs to reduce evaporation
  • Plants stomata open during the day for gas exchange, Water enters making them turgid. When the plant gets dehydrated, guard cells lose water which closes the stomata
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6
Q

Xerophytic adaptations

A
  • Stomata sunk in pits to trap moist air
  • Layer of hairs on epidermis to trap moist air
  • Curled leaves which protect the stomata from the wind
  • Reduced number of stomata, so fewer places for water to leave
  • Waxy, waterproof cuticles to reduce evaporation
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7
Q

Mammalian inspiration

A
  • External intercostal and diaphragm muscles contract
  • This causes the ribcage to move up and out and the diaphragm to flatten which increases the volume of the thoracic cavity
  • The lung pressure decreases
  • Air flows from an area of higher pressure to an area of lower pressure
  • Requires energy
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8
Q

Mammalian expiration

A
  • External intercostal and diaphragm muscles relax
  • Ribcage moves down and in and the diaphragm curves
  • The volume of the thoracic cavity decreased and the air pressure increases
  • Passive process
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9
Q

Gas exchange in the alveoli

A
  • Big surface area due to huge number
  • It is surrounded by a network of capillaries
  • Oxygen diffuses out of alveoli, across alveolar epithelium and capillary endothelium, into the haemoglobin into the blood
  • Carbon dioxide moves out into the alveoli and breathed out
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10
Q

How are alveoli adapted?

A
  • Thin exchange surface - one epithelium cell thick, so a short diffusion pathway
  • A large surface area
  • Constant blood supply due to a large network of capillaries, maintaining a steep concentration gradient between O₂ in the alveoli and O₂ in the blood
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11
Q

Why is there no cartilage at the back of the trachea?

A

So that the oesophagus is not constricted

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12
Q

What is equipment is used to measure gas exchange in the lungs?

A

Spirometer

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13
Q

What is tidal volume?

A

Volume of air in a normal breath

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14
Q

What is ventilation rate?

A

The number of breaths a person takes per minute

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15
Q

What is forced expiratory volume?

A

Maximum volume an individual can expire in one second

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16
Q

What is vital capacity?

A

Maximum volume of air that can be breathed in and out of the lungs

17
Q

What is the equation of Pulmonary ventilation rate(PVR)?

A

PVR = tidal volume x breathing rate

18
Q

What can cause gas exchange problems?

A
  • Decreased surface area
  • Increased diffusion pathway
  • Decreased concentration gradient
19
Q

How does ventilation help maintain a steep concentration gradient?

A

By keeping the O₂ levels in the lungs higher than in the blood

20
Q

What is FEV₁

A

Volume of air forced out of lungs in 1 second

21
Q

How does Pulmonary Tuberculosis affect breathing?

A
  • Cells build walls around the bacteria forming hard lumps called tubercles
  • Infected tissue dies damaging the exchange surface
  • This leads to a decrease in tidal volume and fibrosis which can further decrease tidal volume
  • So less oxygen is taken up in each breath
22
Q

How does fibrosis affect breathing

A
  • Scar tissue forms in the lungs resulting the lung being able to expand normally as scar tissue is thick and less elastic
  • FVC and tidal volume decreases
  • Rate of gaseous exchange decreases
23
Q

How does asthma affect breathing?

A
  • The airways become irritated and inflamed
  • During an attack, the smooth muscle lining the bronchioles contract and produce a large amount of mucus
  • The airways become constricted, air flow is reduced
  • FEV₁ is reduced
24
Q

How does emphysema affect breathing?

A
  • Foreign particles are trapped in the alveoli
  • Causing inflammation which attracts phagocytes that releases an enzyme that breaks down elastin
  • Elastin helps the alveoli to return to their normal shape, so without it it can not recoil to expel air
  • It reduces the SA so gaseous exchange decreases
  • Increased ventilation rate
25
Q

Describe of when a fish moves forward

A
  • Buccal cavity is lowered
  • Water flows in, increasing the volume
  • Buccal cavity raises increasing the pressure
  • Water forced to move over gills out of operculum
26
Q

How does abdominal pumping maintain a steep conc gradient?

A
  • It causes air with high conc of O₂ to move into the tracheal system constantly
  • It keeps a steep conc gradient gradient with CO₂ in cells and CO₂ in the tracheoles
27
Q

How are stomata adapted for gas exchange?

A
  • Have large SA:V ratio
  • Spongy mesophyll have air filled holes
  • Guard cells change shape which controls the size of stomata
28
Q

What measures the rate of transpiration?

A

Potometer

29
Q

Why is the shoot cut under water?

A
  • To stop air bubbles from causing an air lock so water cannot move through the leaf
30
Q

Why is the shoot cut at an angle?

A
  • To increase surface area