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biology > exchange surfaces and breathing > Flashcards

exchange surfaces and breathing Flashcards

1
Q

how are the lungs adapted for exchange

A

large surface area to volume ratio - alveoli allow for more points of contact with the gas particles increasing diffusion rate

moisture - surfacant allows gases to dissolve and stops alveoli sticking together

permeable - to O2 and CO2 (can diffuse across membranes)

thin barrier - alveolar walls are one epithelial squamous cell thick - short diffusion pathway

concentration gradient - maintained by blood flow and ventilation

alveoli are in close proximity to capillaries - short diffusion distance

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2
Q

what is the mechanism behind breathing in

A

chest expands, diaphragm contracts (moves down)
gases move from a high to low pressure,
intercostal muscle - exterior contracts, internal relaxes, moving ribs up and outwards
inspiration - intrapulmonary volume increases as diaphragm contracts, reducing pressure in the lungs

interpulmonary pressure falls below atmospheric pressure - air moves in

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3
Q

what is the mechanism behind breathing out

A

expiration, diaphragm relaxes and moves up
external intercostal muscle relaxes and internal contracts, moving ribs down and inwards
reducing interpulmonary volume, increasing pressure above atmospheric
air moves out of the lungs

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4
Q

what is Boyle’s Law?

A

as pressure increases, volume decreases

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5
Q

what happens during forced exhale

A

requires more energy as abdominal muscles contract as well
further decrease volume, all intercostal muscles contract (interior and exterior)

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6
Q

describe the trachea

A

c shaped rings of cartilage - prevent collapse and bursting of trachea during pressure changes

ciliated cells - moves mucus
goblet cells - secretes mucus
smooth muscle - allows constriction of the trachea
elastic fibres - allows the trachea to return to its normal shape when relaxed and expand with pressure

largest diameter of the lung tissues
no gas exchange occurs yet

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7
Q

describe the bronchi (bronchus)

A

ciliated cells - moves mucus
goblet cells - secrete mucus
smooth muscle - allows constriction
elastic fibres - allows recoiling and expansion

cartilage arranged in blocks
smaller diameter than trachea
no gas exchange occurs yet

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8
Q

describe the bronchioles (in reference to the bronchi)

A

similar to bronchi but have no cartilage
some gas exchange at the end

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9
Q

describe the alveoli

A

one layer of squamous epithelial cells, elastic fibres
large surface area to volume ratio
smallest diameter of the tissues

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10
Q

what is a tissue plan?

A

labelled diagram showing sections of tissue, no individual cells labelled or shown

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11
Q

what are the different tissues in the lungs
in order of decreasing diameter

A

trachea
bronchi
bronchioles
alveoli

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12
Q

what equations for calculating surface area to volume ratio do you need to know?

A

SA and circumference of a circle (Pi r^2 and 2Pi r)
SA and Volume of a cuboid (4base x height +2 x width x height) and (base x width x height)

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13
Q

define vital capacity

A

the maximum volume of air that can be exhaled OR inhaled in one breath

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14
Q

define tidal volume

A

the volume of air that is inhaled OR exhales in one breath at resting (usually an average)

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15
Q

define residual volume

A

the volume of air left in the lungs after hardest possible exhalation (vital capacity + residual volume = total lung capacity)

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16
Q

define oxygen uptake

A

the rate of oxygen consumption in dm^3/min

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17
Q

define breathing rate

A

the number of breaths per unit of time

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18
Q

define ventilation rate

A

the total volume of air inhaled in one minute

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19
Q

what are the ways of measuring lung capacity

A
  1. peak flow meters
  2. vitalograph - advanced peak flow meter
  3. spirometers
20
Q

describe how a peak flow meter works

A

you exhale into the mouthpiece and the volume of air you expel creates a pressure in the tube which pushes the barrier upwards.
the peak flow meter then calculates the time at which it took to get the barrier to that point, calculating your lung capacity

21
Q

describe the difference between a peak flow meter and a vitalograph

A

vitalograph are more advanced and record a graph of the volume of air breathed out and how quickly
vitalographs are mainly used to measure tidal volume whereas peak flow meters are used to measure vital capacity

22
Q

describe how a spirometer works

A

you exhale into a mouth piece which takes the air to a soda-lime CO2 absorber.
the oxygen and nitrogen that remains is moved into an air chamber, filled with water
the increase in volume of air in the chamber causes the lid to be pushed upwards. on the lid is a counter balance to counteract the mass of the lid.
as the lid is pushed upwards, the pen attached to the lid is moved up and draws a line upwards on rotating graph paper.
when you inhale, the volume of gases in the air chamber decreases so the pen is moved down

23
Q

why does the spirometer trace decrease in height over time

A

because you remove the oxygen by inhaling, but the carbon dioxide is not replaced as it is absorbed. therefore the total volume in the air chamber decreases

24
Q

how can you use a spirometer to work out the total volume of Oxygen used?

A

the difference in position on the graph paper from the trough (bottom) of inhale one and the trough of the last inhale
= total volume of CO2 used up, giving the total volume of O2 used

25
Q

what is the function of the pleural membrane and where is it found?

A

thin layers that reduce friction between the lungs and the inside of the chest wall during breathing

26
Q

what is the function of the nasal cavity

A

warms and filters the air as it enters the body

27
Q

what features does the nasal cavity have

A

large surface area with good blood supply - warms the air to body temperature

hairy lining which secretes mucus to trap dust and bacteria, protecting delicate lung tissue

moist surfaces - increase the humidity of the incoming air, reducing evaporation from the exchange surfaces

28
Q

Why is it important for the person using a spirometer to wear a nose clip

A

Maintain a closed system - validity

29
Q

State one chemical used in a spirometer that absorbs carbon dioxide

A

Soda lime - sodium hydroxide

30
Q

How do you calculate the breathing rate from a spirometer trace

A

Number of breaths/ time x 60 to get breaths per minute

31
Q

How do you work out the rate of oxygen consumption from a spirometer trace

A

Measure the change in the ‘trough’ (bottom) of the waves between 0seconds and 60 seconds to get volume of oxygen per minute

32
Q

What is the function of elastic fibres in the gas exchange system

A

Contract when breathing in to prevent bursting, relax when breathing out to push air out of the lungs

33
Q

State one way in which a steep concentration gradient is maintained in the lungs

A

Capillaries form a dense network which moves blood continuously, removing oxygenated blood, high in CO2, to maintain the concentration gradient

34
Q

Why does the gaseous exchange system surface need to be well ventilated

A

Maintain a concentration gradient - increasing the rate at which O2 diffuses into the blood

35
Q

describe the process of ventilation in bony fish

A
  1. fish mouth opens and lowers floor of buccal cavity,
  2. volume of buccal cavity increases and pressure decreases - water enters mouth
  3. fish closes mouth, floor of buccal cavity rises, volume decreases, pressure increases - forcing water out of gill filaments
  4. operculum forced open and water leaves the gills
36
Q

define operculum in fish
why is it important

A

gill covering, made of bone (strong resistance)
important as it allows water pressure to build and only opens when the fish’s mouth closes

37
Q

describe how the gills of fish are adapted for gas exchange

A

gill filaments & plates provide a large surface area
the tip of adjacent gill filaments overlap, slows down movement of water over gills by increasing resistance - more time for gas exchange
lots of capillaries surround maintaining a steep concentration gradient
thin surface layer - short diffusion distance

38
Q

describe the counter current system in fish and why it’s important

A

blood flows through the gills in an opposite direction to the flow of water which maintains a steep concentration gradient
water always diffuses into the blood

39
Q

describe the process of gas exchange in insects

A

air moves into spiracles, then into the tracheae - covered in rings of chitin so no gas exchange occurs yet

tracheae branch off into smaller tracheoles - with thin permeable walls

O2 diffuses from air - spiracles - tracheae - tracheoles - cells

CO2 diffuses the opposite way
insects use rhythmic abdominal movements + wing movements to move air in and out of spiracles

40
Q

how are the tracheoles in insects adapted for gas exchange

A

do not have a layer of chitin - thin permeable walls

contain a fluid, insects can withdraw the fluid when active to provide a larger surface area in the tracheoles for gas exchange

41
Q

when dissecting an insect, what is the first important thing to mention

A

that the insect was humanely killed!!

42
Q

State the function of the smooth muscle fibres in the bronchus

A

To constrict the bronchus - control flow of air

43
Q

State the function of the elastic fibres in alveoli

A

Recoil/ expel air/ prevent bursting

44
Q

Suggest how the diameter of the bronchioles might become reduced in someone with asthma

A

Contraction of smooth muscle - involuntary
Extra mucus production - blocked
Inflammation - swelling/ oedema

45
Q

Explain why is it difficult to expel air from the lungs if the bronchioles reduce in diameter

A

Reduced diameter means increased resistance to air flow / friction
Additional force is required to exhale

biology (14 decks)

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