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OCR A Biology > 3.1.1 exchange surfaces > Flashcards

3.1.1 exchange surfaces Flashcards

1
Q

why don’t unicellular organisms need specialised exchange surfaces

A

substances can diffuse across a short diffusion pathway straight into the cell

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2
Q

why do multicellular organisms need specialised exchange surfaces

A

they have a lower SA:V ratio as they are bigger, so need a specialised system for efficient exchange

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3
Q

what are the features needed for efficient gas exchange

A

large SA
thin wall for short diffusion pathway
good blood/gas supply to maintain steep conc. gradient

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4
Q

what is fick’s law

A

(large SA x steep conc. gradient)/short diffusion distance

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5
Q

what are the features of the mammalian gas exchange system

A

trachea
bronchi
bronchioles
alveoli
lungs
ribs
intercostal muscles
diaphragm

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6
Q

what does cartilage do

A

prevents collapse of the trachea, bronchi and lungs during exhalation

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7
Q

what is the trachea and it’s function

A

the ‘windpipe’
made of incomplete rings of cartilage

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8
Q

what are the bronchi

A

extensions of the trachea
narrower and lined with loose tissue and elastic fibres

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9
Q

what are the bronchioles

A

narrower than bronchi
made of smooth tissue

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10
Q

what are the alveoli

A

small air sacs with walls of squamous epithelium
site of ventilation

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11
Q

what do the ribs do

A

protect lungs

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12
Q

what do the intercostal muscles do

A

contract and relax to raise or lower the ribcage

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13
Q

what are the lungs used in

A

inspiration and expiration

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13
Q

what does the diaphragm do

A

contracts and relaxes
separates lungs from abdomen

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14
Q

what does ciliated epithelium do

A

moves mucus along

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15
Q

what do goblet cells do

A

secrete mucus

16
Q

what does smooth muscle do

A

controls diameter and airflow into alveoli

17
Q

what do elastic fibres do

A

stretch in inhalation and recoil in exhalation

18
Q

describe the process of inspiration

A

diaphragm contracts
intercostal muscles contract
ribcage raises
volume of chest cavity increases
pressure in chest cavity decreases below atmospheric pressure
air flows into the lungs down the pressure gradient

19
Q

describe the process of expiration

A

diaphragm relaxes
intercostal muscles relaxes
ribcage lowers
volume of chest cavity decreases
pressure in chest cavity increases above atmospheric pressure
air flows out of the lungs down the pressure gradient

20
Q

what is a bell jar

A

apparatus used to demonstrate the process of inspiration and expiration in mammals
balloons = lungs
glass pipe = trachea
elastic sheet = diaphragm

21
Q

how does ventilation work in the alveoli

A

oxygen rich air is delivered by air and goes into the blood by diffusion across the squamous epithelium and endothelial cells

carbon dioxide is delivered by the blood by diffusion and removed by expiration

22
Q

what is a spirometer

A

apparatus used to measure lung volume

23
Q

what are the components of a spirometer

A

airchamber containing water
soda-lime in a canister to absorb carbon dioxide
mouthpiece

24
Q

how does the spirometer work

A

person breathes in and out so the chamber moves up and down, creating a kymograph

25
Q

what is breathing rate

A

number of breaths per minute

26
Q

what is tidal volume

A

volume of air we breathe in at rest

27
Q

what is vital capacity

A

max volume of air inhaled or exhaled

28
Q

what is expiratory reserve volume

A

volumeof air that can be inhaled on top of tidal volume

29
Q

what is residual volume

A

volume of air always present in lungs

30
Q

how do you calculate pulmonary ventilation

A

tidal volume x ventilation rate

31
Q

what are the components of a bony fish’s gas exchange system

A

mouth
buccal cavity
operculum
gills
gill filaments covered in llamallae
gill arches

32
Q

describe the process of ventilation in fish

A

mouth opens which lowers buccal cavity floor
volume in buccal cavity increases
pressure in buccal cavity decreases
mouth closes which decreases volume in buccal cavity and increases pressure
water flows from buccal cavity to opercular cavity along pressure gradient
pressure builds in the opercular cavity so the operculum opens
water is pushed out of the operculum into the sea
operculum closes

33
Q

describe the process of ventilation in insects

A

spiracles on the sides of the body open, allowing air to enter the tracheae
some air gets stored in air sacs along the tracheae and the rest goes into the trachioles and straight to respiring tissues

34
Q

why aren’t insects bigger

A

more cells = more demand for oxygen
bodies wouldn’t be able to meet oxygen demands with the exchange surfaces they have
mass of exoskeleton would be too high

OCR A Biology (10 decks)

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