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Biology - Unit 2 > Adaptations for Gas exchange in animals > Flashcards

Adaptations for Gas exchange in animals Flashcards

1
Q

What 4 things must a respiratory surface be ?

A
  • Thin
  • permeable to gases
  • moist
  • Have a large surface area
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2
Q

How do small unicellular organisms exchange gases ?

A
  • across the cell surface as the surface area to volume ratio is large enough to supply their needs
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3
Q

Amoeba Gas exchange

A

Single cell
-Large surface area
to volume ratio
- A low metabolic
rate means oxygen
demand is low.
- There is a short
diffusion distance
to the middle of the
cell.

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4
Q

Flatworm Gas Exchange

A

Multicellular
- Smaller surface area to volume
ratio
- Flattened body to reduce
diffusion distance so rate of
oxygen diffusion through body
surface meets demand

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5
Q

Earthworm Gas Exchange

A
  • Terrestrial organism
  • Cylindrical = surface area to volume ratio even smaller
    -Body surface still used for
    gas exchange
  • Blood vessels close
    to skin surface and blood has
    haemoglobin ( high affinity for O2)
  • Mucus secreted to moisten
    surface
  • low metabolic rate = reduce oxygen demand
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6
Q

Metabolic Rate

A

The rate of energy expenditure by the body

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7
Q

Why do bony fish require more oxygen ?

A

More active and larger

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8
Q

What is the bony fishes specialised gas exchange surface?

A

The gills

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9
Q

Describe how the gills are specialised for gas exchange

A
  • Have a large surface area due to the gill filaments, these are a specialised respiratory area
  • Water is a dense medium with relatively low oxygen content. This means water must be forced over the gill filaments.
  • Density prevents gills from collapsing
  • Water forced over by ventilating mechanism and flow is one way -unidirectional
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10
Q

Ventilation in bony fish

A
  • Allows water to be passed over gills even when resting
  • Ventilation is achieved by pressure changes in the buccal and opercular cavity
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11
Q

3 stages of ventilation in bony fish

A

STAGE 1 - Mouth opens and the floor of the buccal cavity lowers. Volume increases and pressure decreases. The operculum remains closed. Water pulled into the buccal cavity from outside

STAGE 2 - Mouth closes and buccal cavity contracts raising the floor of the buccal cavity. water is forced across the gills

STAGE 3 - Pressure in the gill cavity increases and forces the operculum open, water leaves via the operculum

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12
Q

What allows efficient diffusion of oxygen in bony fish?

A

The gills have extensive network of capillaries
The blood pigment haemoglobin and a circulatory system carry oxygen throughout the fish

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13
Q

Counter current flow

A

water and blood flow in opposite directions across the gill plates.
- As distance along the gill plate increases the oxygen content of blood also increases. Entire gill plate is used
- Equilibrium is not reached

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14
Q

Parallel flow

A
  • Cartilaginous fish have more inefficient system
  • Water and blood flow in the same direction across the gill plates.
  • The concentration gradient is not maintained
  • Diffusion is not optimal and does not continue across the whole gill plate
  • Equilibrium is reached
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15
Q

What characteristics of the respiratory surfaces in amphibians, reptiles and birds have in common?

A
  • Large surface area = rapid diffusion of respiratory gases
  • Moist surface = facilitate rapid diffusion of gases
  • Short diffusion pathway
  • Circulatory system with blood pigments
  • internal lungs
  • Ventilation mechanism
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16
Q

Amphibian Gas Exchange

A
  • Inactive amphibians uses moist skin for gas exchange.
    -Active use simple lungs these are a pair of hollow sacs. S.A is highly folded
  • Tadpole stage uses gills
17
Q

Reptile Gas Exchange

A
  • Skin is impermeable to gases, not used as a respiratory surface.
  • More efficient lungs than amphibians and gas exchange occurs exclusively here.
  • They are sac like and more complex folds than amphibians
  • Reptiles have ribs, no diaphragm. Ventilation aided by movement of ribs
18
Q

Bird Gas Exchange

A
  • Warm blooded and high respiratory rate
  • Lungs are small and compact, composed of numerous branching air tubes called bronchi.
  • The smallest air tubes, parbronchi, have an extensive blood capillary network- it is here that gas exchange takes place.
    -During flight the action of the wing muscles ventilates the lungs
19
Q

How have insects evolved to reduce water loss ?

A
  • Water evaporates from the body surface
  • Efficient gas exchange requires a thin permeable surface and a large surface area this conflicts with the need to reduce water loss.
  • To reduce it they have evolved a rigid waterproof exoskeleton, covered by a cuticle.
20
Q

How does gas exchange work in an insect?

A
  • Occurs through paired holes called spiracles, running along the side of the body. These can open and close like valves.
  • Allows gas exchange and prevent water loss
  • ## Spiracles lead into a system of branched , chitin lined airtubes called tracheae.
21
Q

End of the tracheae

A

Called tracheoles
Ga exchange takes place at the end of these
- Oxygen passes directly into the cells and it is very rapid

22
Q

How do the spiracles differ in Insects at rest and in flight ?

A
  • Muscle fibres connected to the tracheoles never exceed 20 um in diameter.
  • Fluid levels in the tracheoles decrease during flight, this provides more surface area for gas exchange and further shortens the diffusion pathway.
23
Q

What ventilates the tracheal system in insects?

A

compression and expansion of the abdomen

24
Q

Describe how the abdomen spiracles , thorax spiracles and abdomen shape show how air is drawn into the insect

A
  • As the abdomen expands the thorax spiracles are open and abdomen spiracles are closed. Air enters the tracheal system
  • As the abdomen compresses the thorax spiracles close and the abdominal ones open. Air leaves the tracheal system and expelled via the spiracles in the abdomen
25
Q

Trachea, bronchi, bronchioles and alveoli

A
  • Trachea transports air to bronchi
  • Bronchi transports air to the bronchioles
  • Bronchioles transport air to the alveoli
  • Alveoli are the respiratory surface and site of gaseous exchange
26
Q

Inspiration in humans

A
  • Intercostal muscles contract
  • Raises the ribcage up and out
  • Diaphragm contracts and flattens
  • Volume in thorax increases and pressure decreases
  • Air enters the lungs and they expand
27
Q

Expiration in humans

A
  • Intercostal muscles relax
  • Moves ribcage inwards and downwards
  • Diaphragm relaxes and domes
  • Volume of the thorax decreases but pressure increases
  • Air is forces out the lungs
28
Q

What is the gas exchange surface in mammals

A

The alveoli

29
Q

What do the alveoli have to allow efficient gas exchange

A
  • large surface area
  • moist surface for gases to dissolve
  • Thin walls provide short diffusion pathway
  • Each alveolus is covered in extensive capillary network
30
Q

Composition of air in the lungs (inspired, expired)

A

Oxygen - 21, 16
Carbon Dioxide - 0.04, 4
Nitrogen - 79, 79
Water Vapour- Variable, Saturated

31
Q

Why doesnt nitrogen increase or decrease when expired?

A

It is neither absorbed or used so all that is inhaled gets exhaled

Biology - Unit 2 (6 decks)

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