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biology: exchange of substances > gas exchange > Flashcards

gas exchange Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is ventilation?

A

breathing

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2
Q

what is the trachea?

A

wind pipe

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3
Q

what is the thoracic cavity?

A

space where the lungs are

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4
Q

explain the human gas exchange system

A

● as you breathe in, air enters trachea

● trachea splits into 2 bronchi

● each bronchus branches off into smaller tubes called bronchioles

● bronchioles end in small air sacs called alveoli

● ribcage, intercostal muscles and diaphragm work together to move air in and out

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5
Q

explain inspiration

A

● external intercostal and diaphragm muscle contract

● causes the ribcage to move upwards and outwards

● diaphragm contracts to flatten

● increasing volume of thoracic cavity

● as volume increases, lung pressure decreases (to below atmospheric pressure)

● air flows down the trachea and into lungs down pressure gradient

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6
Q

what does inspiration require?

A

energy (active)

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7
Q

explain expiration

A

● external intercostal and diaphragm muscles relax

● ribcage moves downward and inwards

● diaphragm becomes curved

● volume of thoracic cavity decreases, causing pressure to increase (to above atmospheric pressure)

● air forced down pressure gradient and out of lungs

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8
Q

what does expiration not require?

A

energy (passive)

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9
Q

explain forced expiration

A

● external intercostal muscles relax

● internal intercostal muscles contract

● pulling ribcage further down and in

● movement of 2 sets of intercostal muscles are antagonising

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10
Q

what are alveoli made from?

A

alveolar epithelium

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11
Q

what is the alveolar epithelium made of?

A

a single layer of thin, flat squamous cells

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12
Q

how does human gaseous exchange happens in the alveoli?

A

● oxygen diffuses out alveoli, across the alveolar epithelium and capillary endothelium

● into haemoglobin in red blood cells

● carbon dioxide diffuses from blood across capillary endothelium and alveolar epithelium and into alveoli and is breathed out

● movement happens down a diffusion gradient

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13
Q

what is the capillary endothelium?

A

type of epithelium that forms the capillary wall

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14
Q

how does human gaseous exchange happens in the alveoli? (simplified)

A

● oxygen - trachea - bronchi - bronchioles - alveoli

● happens down a pressure gradient

● alveoli - diffuse across alveolar epithelium and capillary endothelium - capillary - haemoglobin in blood

● happens down a diffusion gradient

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15
Q

how are alveoli adapted for gas exchange?

A

● short diffusion distance - alveolar epithelium is made of squamous cells (thin exchange surface)

● large surface area - large number of alveoli means there’s a large surface for gas exchange and folds in alveolar epithelium

● steep concentration gradient of O2 and CO2 between alveoli and capillaries

● capillaries give good blood supply

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16
Q

what is fick’s law?

A

surface area x difference in conc / diffusion distance

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17
Q

what is the composition of gases inhaled?

A

● higher conc of O2

● N2 stays the same

● lower conc of CO2

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18
Q

what is the composition of gases exhaled?

A

● lower conc of O2

● N2 stays the same

● higher conc of CO2

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19
Q

what is tidal volume?

A

● tidal volume is the volume of air in each breath

● average 0.4 - 0.5dm^3

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20
Q

what is forced expiratory volume (FEV1)?

A

maximum volume of air that can be breathed out in 1 second

21
Q

what is forced vital capacity (FVC)?

A

maximum volume of air that can be breathed forcefully out after a deep breath

22
Q

what is pulmonary ventilation?

A

● volume of air ventilated by the lungs in 1 minute

● PV (dm^3) = tidal volume x ventilation rate

23
Q

what is ventilation rate?

A

● number of breaths per minute

● average 15

24
Q

how does pulmonary fibrosis slow gas exchange

A

● scar tissue makes alveoli thicker

● reduces elasticity of alveoli

● increases diffusion distance

25
Q

how does TB slow gas exchange

A

● scar tissue makes alveoli thicker

● reduces elasticity of alveoli

● increases diffusion distance

26
Q

how does asthma slow gas exchange

A

● tidal volume reduced

● decreases conc gradient

27
Q

how does lung cancer slow gas exchange

A

● tidal volume reduced

● decreases conc gradient

28
Q

how does emphysema slow gas exchange

A

● reduced elasticity

● prevents exhalation

● decreases conc gradient

29
Q

correlation doesn’t equal

A

causation

30
Q

what is a spiracle

A

● opening in the exoskeleton of insects body

● most of the time closed to avoid water loss

31
Q

what is an insects exoskeleton?

A

● made of chitin

● impermeable to gases

32
Q

explain insect gas exchange system

A

spiracle - tracheal tubes - tracheoles - respiring cells

33
Q

how are insects adapted for gas exchange?

A

● highly branched tracheoles - increases surface area

● tracheoles have thin walls - short diffusion distance

● cells constantly respiring & abdominal pumping (a form of ventilation) - maintains conc gradient

34
Q

how do insects control water loss?

A

● if losing too much water, closes spiracles

● waterproof waxy cuticle and tiny hairs around spiracles - reduce evaporation

35
Q

where does water flow in fish

A

water - mouth - water passes across gills

36
Q

what is the structure of a fish’s gills

A

● gill arch

● gill filaments attached to gill arch

● gill lamellae on the surface of each gill filament

● gill lamellae contain capillaries

37
Q

how are fish adapted for gas exchange?

A

● many gill filaments that are highly branched with lamellae - increases surface area

● ventilation + blood flow + counter current flow - maintains concentration gradient

● lamellae have thin walls(epithelium) - decreases diffusion distance

38
Q

what is counter-current flow?

A

● blood and water flow in opposite directions - through and over the lamellae

● there is a conc gradient maintained along entire lamellae

● O2 conc between water and blood does not reach equilibrium

39
Q

what is the structure of a leaf?

A

● waxy cuticle

● upper epidermis - layer of tightly packed cells

● palisade mesophyll layer - layer of elongated cells containing chloroplasts

● spongy mesophyll layer - layer of cells that contains network of air spaces

● stomata - pores (usually) on underside of the leaf which allows air to enter

● guard cells - pairs of cells that control the opening and closing of stomata

● lower epidermis - layer of tightly packed cells

40
Q

how are leaves dicotyledonous plants adapted to gas exchange

A

● large surface area - main gas exchange surface are mesophyll cells inside leaf

● when guard cells are turgid (full of water), stoma open allowing air to enter leaf
(opposite of turgid is flaccid)

● air spaces within spongy mesophyll layer allows CO2 to rapidly diffuse into cells

● conc gradient maintained - CO2 is quickly used up in photosynthesis by cells containing chloroplasts

● short diffusion distance - thinness of plant tissues and stomata so no active ventilation is required

41
Q

what is the formula for photosynthesis

A

6CO2 + 6H2O –(light)–> C6H12O6 + 6O2

42
Q

what is the formula for aerobic respiration

A

C6H12O6 + 6O2 —> 6CO2 + 6H2O

43
Q

how does H2O enter plant

A

osmoses into roots

44
Q

how do minerals enter plant

A

actively transported into roots

45
Q

how do plants control water loss

A

● day: CO2 and O2 diffuse through stomata. H2O lost through transpiration

● night: closed stomata to stop water loss by transpiration. water can not be used in photosynthesis

● waxy cuticle

46
Q

how are xerophytic plants adapted to reduce transpiration?

A

● waxy cuticle - increases diffusion distance

● spines of cactus - decreases surface area

● rolled leaf - decreases surface area and conc gradient

● stomata sunken In pits - decreases conc gradient

47
Q

what is the singular for stomata?

A

stoma

48
Q

how do you draw scientific drawings?

A

● no shading

● label lines need to be parallel

● label lines need to be on one side

● no hanging lines

● no sketched lines

● draw with sharp pencil

● labels with ruler and with pen

● use key for magnification

● add title

● no arrow heads

biology: exchange of substances (4 decks)

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