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Biology component 3 > adaptations for gas exchange > Flashcards

adaptations for gas exchange Flashcards

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1
Q

parallel flow

A

blood and water flow in the same direction at the gill lamallae maintinging the conentration graident for oxygen to diffuse into the blood only up to the point where its concentration in the blood and water is equal

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2
Q

What gases do organisms exchange and where

A
  • oxygen and carbon dioxide with the atmosphere
  • via a gas exchang surface
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3
Q

Describe why an organism may need a specialised gas exchange surface due to its surface area to volume ratio

A
  • when an organism doubles in size its volume (therfore oxygen requirements) is cubed butsurface area is only squared
  • therefore as organism increaes in size a specialised gas exchange surface is required to increase the area available
  • this also increases area available for water loss they will be a balance between exchanging gases and water loss in terretrial organisms
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4
Q

What are the general characteritics of a gas exchange surface

A
  • large surface area to volume ration
  • moist to allow gases to dissolve
  • thin to provide a short diffusion distance
  • permeable to gases
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5
Q

Describe gas exchange in unicellular organisms

A
  • in single celled organisms eg amoeba the surface area is large enough to meet the needs of the organism
  • thherefore materials can be exchanged directly across its thin and permeable cell surface membrane
  • as the cytoplasm is constantly moving the concentration graidient is always maintained
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6
Q

Describe gas exchange in multicellular organisms

A
  • in larger organisms the surface area to volume ratio decreases so diffusion acros the body surface is insuffiecient to meet the needs of the organism
  • adaptations have evolved becoming more specialised the larger the organism
  • where animals and very active and therefore have a higher metabolic rate their oxygen requirements cannot be supplied by the body surface alone
  • therfore a specialised gas exchange surface with a ventrilation mechanism ensures that the concentration gradient is maintained across the respiratory surface
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7
Q

What is one consequence of a gas exchange surface in terretrial animals and how is this overcome

A
  • maintaining a moist respiratory surface
  • water loss
  • minimised by havning an internal gas exchange surface called lungs
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8
Q

Describe adaptations of a flatworm regarding gas exchange

A
  • flattened body to reduce the diffusion distance between the surface and the cells inside and to increase the overall surface area
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9
Q

Describe adaptations of a earthworm regarding gas exchange

A
  • secretes mucus to maintain a moist surface and has a well developed capillary network under the skin
  • has a low metabolic rate to reduce oxygen requirements
  • has a network of blood vessels and blood containing haemoglobin for the transport of oxygen cos is transported largely in the blood plasma
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10
Q

Describe adaptations of a amphibians regarding gas exchange

A
  • moist and permeable skin with a well developed capillary network beneath the surface
  • have lungs that are used when more active
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11
Q

Describe adaptations of reptiles regarding gas exchange

A
  • have internal lungs like amphibians but these are more complex and have a larger surface area
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12
Q

Describe adaptations of birds regarding gas exchange

A
  • flight generates a very high metabolic rate and hence the oxygen requirement
  • to meet this bird have an efficient ventialtion mechanism to increase concentration gradient across the lung surface
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13
Q

Describe the gas exchange surface in fish

A
  • fish have a developed specialised intrernal gas exchange surface called gills that are made up of numerous gill filaments containing gill lamellae at right angles to the filaments
  • greatly increase the surface area for the exchange of oxygen and carbon dioxide
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14
Q

Describe gas exchange in cartliengous fish eg shark

A
  • blood and water flow in same direction over the gill
  • gas exchange only posible over part of the gill filament surface as an equilibrium is reached which prevents further diffusion and reduce the oxygen that can be absrobed into the blood
  • ventilation mechanism in cartiligenous gish is basic they can swim open their mouth allowing water to pass over the gills
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15
Q

counter current flow

A

blood and water flow in oppposite directions at the gill lamellae maintianing the concentration gradient and therfore oxygen diffusion into the blood along their entire length

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16
Q

Describe gas exchange in bony fish eg salmon

A
  • counter current flow
  • blood and water flow in opposite directions
  • diffusion maintained along the entire length of the gill filamet as there is always a higher concentration of oxygen in the water than in the blood it meets
  • results in a higher oxygen absorption as an equilibrium is not reached
  • more advanced ventilation mechanism than in cartilengous fish
17
Q

What is the operculum

A

bony fish have an internal bony skeleton and flap covering the gills called the operculum

18
Q

Describe the ventilation mechanism in bony fish for water intake

A
  • mouth opens
  • floor of buccal cavity lower
  • opercular valve is closed
  • volume decreaes and pressure drops
  • water rushes in
19
Q

Describe the ventrilation mechanism in bony fish for water expulsion

A
  • mouth closed
  • floor of buccal cavity rises
  • opercular valve opens
  • volume decreases pressure increases
  • water forced out over gills
20
Q

Describe the human respiratory system

A
  • the trachea which is supported by 20 incomplete catilaginous rings branches into two bronchi each entering a lung
  • bronchi branch into finer tubes called bronchioles
  • finally ending in alveoli where gas exchange takes place
21
Q

Describe the ventilation mechanicsm for inspiration

A
  • active process
  • external intercostal muscles contract moving ribs up and out which pulls the outer pleural membrane outwards
  • diaphragm contracts and flattens
  • reducing pressure in the pleural cavity and the innter pleural membrane moves outwards
  • pulls on the surface of the lungs causes alveoli to expand
  • alveolar pressure decreaes to below atmospheric pressure so air is draw in
22
Q

Describe the ventilation mechanism in expiration

A
  • passive
  • external intercostal muscles relax so ribs move downwards and inwards allowing the outer pleural membrane to move inward
  • diaphragm relaxes and moves upwards
  • this increases pressure in the pleural cavity and the innter pleural membrane moves inwards
  • this pushes on the surface of the lungs causes the alveoli to contract
  • alveolar pressure increases to above atmospheric pressure so air is forced out
23
Q

Describe adaptations of the alveoli

A
  • very large surface area
  • very thin walls
  • surrounded by capillaries so short diffusion distance and good blood supply
  • moist lining
  • permeable to gases
  • collaged and elastic fibres aloow expansion and recoil
24
Q

Describe how gas exchange occurs in the alveoli and why it doesn’t collapse

A
  • a branch of the pulmonary artery brings deoxygenated blood to ther alveoli and a branch of the pulmonary vein carries oxygenated blood from the alveoli back to the heart
  • alevoli produces a surfactant which lowers the suface tension preventing the alveoli from collapsing and sticking together and allows gases to dissolve
25
Q

Describe gas exchange in insects

A
  • insects have a branched chitin lined system of tracheae with openings called spiracles
  • chitin is arranged into rings allows the tracheae to expand and contract and act like bellows drawing air in and out of the insects body
  • spiracles whcih are found in pairs on segments of the thorax and abdomen can close during inactivity and the presence of chitin help to reduce water loss
  • tracheole tubes come into direct contact with every tissue supplying oxygen and removing carbon dioxide no need for haemoglobin
  • end of tibes are filled with fluid allow gases to dissolve
  • muscles in thorax and abdomen contract/relax causing rythmical movements that ventriate the tracheole tubes maintaining a concentration gradient
26
Q

transpiration

A

the evaporation of water vapour from the leaves or other above ground parts of the plant out through the stomata into the atmosphere

27
Q

Describe gas exchange in plants

A
  • plants require oxygen for respiration and carbon dioxide for photosynthesis these gaes are obtained via diffusion throught the leaf
  • to reduce water lo plants have a waxy cuticle which covers the surface of leaf preventing the diffusion of gases
  • plants have pores called stomata found on the underide of most leaves that can open during the day to allow gas exchange and close at night or during drought conditions to reduce water loss
28
Q

How is the size of the stomata controlled and why

A
  • reduce water los via transpiration by the guard cells that surround it
29
Q

Describe the stomatal opening mechanism

A
  • guard cells photosynthesis producing ATP
  • energy released from ATP is used to activley transport potassium ions into guard cells
  • triggers starch (insoluble) to be converted to malate ions (soluble)
  • water potential of guard cell is lowered so water enters the cell via osmosis
  • guard cells expand and outer wall stretches more than the inner wall because it is thinner creates a poer between two guard cells
  • reverse happens at night
30
Q

Describe adaptation of the leaf for gas exchange

A
  • leaves are thin and flat providing a large surface area to capture light and for gas exchange
  • leaves have many pores called stomata allow exchange of gases
  • spongy mesophyll cells are surrounded by air spaces that allow gases to diffuse

Biology component 3 (7 decks)

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