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Biology > Topic 3A: Exchange and Transport Systems > Flashcards

Topic 3A: Exchange and Transport Systems Flashcards

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1
Q

How do you calculate SA:V?

A

SA:V = SA / V

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2
Q

Why do organisms need to exchange things with their environment?

A
  • Take in substances –> O2 for respiration , nutrients etc
  • Remove waste products –> CO2, urea etc
  • To remain at a constant temperature –> exchange heat
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3
Q

Do large organisms have a high or low SA:V?

A

low

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4
Q

Do small organisms have a high or low SA:V?

A

high

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5
Q

How does exchange work in single - celled organisms?

A
  • Large SA:V
  • All surface exposed to environment, can exchange enough via surface for whole cell
  • Short diffusion distance = fast diffusion rate
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6
Q

How does exchange work in large, multicellular organisms?

A
  • Small SA:V
  • Too slow diffusion –> some cells deep in the body - large distance
  • Cannot exchange enough substances through relatively small surface for their relatively large volume
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7
Q

What do large multicellular organisms therefore need?

A
  • Exchange organs and mass transport systems to move substances in and out of the organism and supply cells
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8
Q

How does body size affect heat loss from an organism?

A
  • Large volume but small SA = hard to lose heat
  • Small volume but large SA = easier to lose heat
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9
Q

How does shape affect heat loss?

A
  • Compact shape - small SA relative to volume - minimal heat loss
  • Less compact - sticky outy bits - larger SA relative to volume - increases heat loss
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10
Q

How can organisms be adapted for water loss?

A
  • Inc SA:V = inc water loss through surface
  • Kidney structure adaptations to reduce water loss
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11
Q

How are mammals with high metabolic rates adapted?
Esp in cold environments

A
  • Eat lots of high energy foods - e.g. seeds, nuts
  • Thick fur
  • Hibernate
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12
Q

How are large organisms in hot environments adapted?

A
  • Have slow heat loss - low SA:V
  • Large, flat ears - inc SA
  • Spend lots of time in water to lose heat - e.g. hippos
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13
Q

What are features of specialised exchange surfaces?
(5 things)

A
  • Large surface area
  • Thin - short diffusion pathway
  • Selectively permeable
  • Mechanism to move environmental medium (ventilation)
  • Mechanism to move internal medium (blood supply)
    –> both maintain concentration gradient
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14
Q

How are gills structured?

A
  • Gill arches
  • 2 stacks of gill filaments –> inc SA
  • Filaments covered in lamellae - with lots of capillaries
  • Thin layer of cells - quick diffusion
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15
Q

How does water enter and leave fish?

A
  • Water into open mouth with gills closed
  • Mouth closes, gills open - down pressure gradient
  • Water flows over gills and O2 diffuses into blood
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16
Q

How does counter-current flow work?

A
  • Blood and water flow in opposite directions
  • Maintains large concentration gradient
  • Water always ahs much higher O2 concentration
  • Equilibrium is never reached
  • As much O2 as possible taken in from water
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17
Q

How does oxygen enter insects?

A
  • Spiracles = holes in sides
  • O2 moves down concentration gradient towards cells
  • Through trachea then tracheoles - thin permeable walls
  • O2 moves to individual cells directly
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18
Q

How is CO2 removed from insects?

A
  • Moves down concentration gradient out of the insect
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19
Q

What else do insects do to help gas exchange?

A
  • Rhythmic abdominal movements to move air in and out of spiracles
  • When active fluid at ends of tracheoles taken in to inc SA and lower pressure to draw in air
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20
Q

How do insects prevent water loss?

A
  • Can close spiracles
  • Waterproof, waxy cuticle around body
  • Hairs around spiracles to trap water vapour to reduce water potential gradient
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21
Q

How are leaves adapted for gas exchange?

A
  • Most exchange is on mesophyll cells - high SA
  • Gases move in and out via stomata
  • Guard cells open and close stomata
22
Q

How do plant stomata help reduce water loss?

A
  • When guard cells are turgid - stomata open
  • When dehydrated - lose water - flaccid - stomata close
  • Close at night as there can be no photosynthesis so stop water loss at night
23
Q

How do xerophytic plants reduce water loss?

A
  • Sunken stomata - trap water vapour for low water potential gradient
  • Curled leaves - protect from wind which would increase transpiration
  • Hairs on epidermis - trap water vapour for reduced water potential gradient
  • Reduced number of stomata - fewer places for water loss
  • Thicker waxy cuticle - waterproof to reduce evaporation
24
Q

Describe inspiration

A
  • Diaphragm contracts - flattens
  • External intercostal muscles contract - ribcage moves up + out
  • Cavity volume increases, pressure decreases - lower than atmosphere
  • Air moves in down pressure gradient
  • Active process - needs energy
25
Q

Describe expiration

A
  • Diaphragm relaxes - domed
  • External intercostal muscles relax - ribcage moves down + in
  • Cavity volume decreases, pressure increases
  • Air moves out down pressure gradient
  • Passive process
26
Q

How does forced expiration work?

A
  • Internal intercostal muscles contract also
  • Ribcage pulled further down and in
  • Intercostal muscles move antagonistically
27
Q

How are gases exchanged into the blood?

A
  • Out of alveoli
  • Across alveolar epithelium
  • Across capillary endothelium
  • Into haemoglobin in blood
  • Down diffusion gradient (concentration)
  • CO2 moves opposite way
28
Q

How are alveoli adapted for gas exchange?

A
  • Thin exchange surface - alveolar epithelium = 1 cell thick = short diffusion pathway
  • Large SA - millions of alveoli
  • Steep conc gradient - ventilation and blood supply maintain conc gradient
29
Q

What is tidal volume?

A
  • Volume of air in each breath
30
Q

What is ventilation rate?

A
  • Number of breaths per minute
31
Q

What is forced expiratory volume?

A
  • Max volume that can be exhaled in 1 second
32
Q

What is forced vital capacity?

A
  • Max volume possible to forcefully breathe out
33
Q

What is tuberculosis?

A
  • TB bacteria in lungs surrounded by immune system cells
  • Form small hard lumps - tubercles
  • Infected tissue dies - damages exchanage surface
34
Q

What are the consequences of tuberculosis?

A
  • Tidal volume decreases
  • Fibrosis is caused further dec tidal volume
  • Less air can be inhaled - need to breathe faster for enough O2
35
Q

What are symptoms of tuberculosis?

A
  • Cough
  • Coughing blood and mucus
  • Chest pain
  • Shortness of breath
36
Q

What is fibrosis?

A
  • Formation of scar tissue in lungs
  • Due to infection or substances like asbestos
37
Q

What consequences are there to fibrosis?

A
  • Scar tissue - thicker and less elastic - less lung expansion - less air held - reduced tidal volume and FVC
  • Slower diffusion - longer pathway - need more ventilation to get enough O2 into lungs
38
Q

What are symptoms of fibrosis?

A
  • Shortness of breath
  • Dry cough
  • Chest pain
  • Fatigue
  • Weakness
39
Q

What is asthma?

A
  • Inflamed / irritated airways
  • Smooth muscle lining bronchioles contracts
  • Airways constrict
  • Reduced air flow in and out of lungs
  • Less O2 in alveoli and blood
40
Q

What does asthma cause?

A
  • Reduces forced vital capacity
41
Q

What are asthma symptoms?

A
  • Wheezing
  • Tight chest
  • Shortness of breath
42
Q

What is emphysema?

A
  • Caused by smoking / pollution
  • Inflames tissue
  • Attracts phagocytes - enzyme produced which breaks down elastin in alveoli
43
Q

What is caused by emphysema?

A
  • Less stretch and recoil
  • Alveoli walls destroyed - reduced SA
44
Q

What are symptoms of emphysema?

A
  • Shortness of breath
  • Wheezing
45
Q

What are general effects of lung disease?

A
  • Reduced rate of gas exchange in alveoli
  • Less O2 able to diffuse into blood - body cells receive less - reduced rate of aerobic respiration
  • Less energy released - tired and weak
46
Q

What are the stages to dissect lungs?

A
  • Lab coat, clean, sharp, rust-free tools
  • Cut down trachea down gap in C shaped cartilage rings
  • Continue cutting down one bronchi - should see bronchioles
  • Cut off lung piece - spongy from air trapped in alveoli
  • Wash hands and disinfect surfaces
47
Q

How would you inflate lungs?

A
  • Attach rubber tube and inflate with foot / bike pump
  • Deflate on their own due to elastin in alveoli walls
  • Don’t blow down them - could suck in stale air
  • Put lungs in plastic bag at start to stop bacteria in the lungs from being released into the room
48
Q

How would you dissect gills?

A
  • Lab coat
  • Put fish on a board (dissection or cutting)
  • Push back operculum, remove gills with scissors
  • Cut gill arch through bone at top and bottom
  • Observe gill filaments
  • Wash hands and disinfect surfaces
49
Q

How can you dissect insect gas exchange systems?

A
  • Bigger insects better - one humanely killed recently
  • Dissecting pins through legs on dissecting board
  • Cut and remove part of exoskeleton from abdomen
  • Fill abdomen with saline solution with syringe
  • See silvery grey thin tubes - tracheae - filled with air so grey
  • Examine under microscope
  • Should see chitin rings in tracheae walls - support
50
Q

What are ethical issues with dissections?

A
  • Morally wrong to kill animals for dissections –> lots of organs usually from animals already killed for meat
  • Animals for dissection not always raised humanely or killed humanely

Biology (16 decks)

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