exchange surfaces and breathing Flashcards
how are the lungs adapted for exchange
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
what is the mechanism behind breathing in
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
what is the mechanism behind breathing out
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
what is Boyle’s Law?
as pressure increases, volume decreases
what happens during forced exhale
requires more energy as abdominal muscles contract as well
further decrease volume, all intercostal muscles contract (interior and exterior)
describe the trachea
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
describe the bronchi (bronchus)
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
describe the bronchioles (in reference to the bronchi)
similar to bronchi but have no cartilage
some gas exchange at the end
describe the alveoli
one layer of squamous epithelial cells, elastic fibres
large surface area to volume ratio
smallest diameter of the tissues
what is a tissue plan?
labelled diagram showing sections of tissue, no individual cells labelled or shown
what are the different tissues in the lungs
in order of decreasing diameter
trachea
bronchi
bronchioles
alveoli
what equations for calculating surface area to volume ratio do you need to know?
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)
define vital capacity
the maximum volume of air that can be exhaled OR inhaled in one breath
define tidal volume
the volume of air that is inhaled OR exhales in one breath at resting (usually an average)
define residual volume
the volume of air left in the lungs after hardest possible exhalation (vital capacity + residual volume = total lung capacity)
define oxygen uptake
the rate of oxygen consumption in dm^3/min
define breathing rate
the number of breaths per unit of time
define ventilation rate
the total volume of air inhaled in one minute
what are the ways of measuring lung capacity
- peak flow meters
- vitalograph - advanced peak flow meter
- spirometers
describe how a peak flow meter works
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
describe the difference between a peak flow meter and a vitalograph
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
describe how a spirometer works
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
why does the spirometer trace decrease in height over time
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
how can you use a spirometer to work out the total volume of Oxygen used?
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
what is the function of the pleural membrane and where is it found?
thin layers that reduce friction between the lungs and the inside of the chest wall during breathing
what is the function of the nasal cavity
warms and filters the air as it enters the body
what features does the nasal cavity have
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
Why is it important for the person using a spirometer to wear a nose clip
Maintain a closed system - validity
State one chemical used in a spirometer that absorbs carbon dioxide
Soda lime - sodium hydroxide
How do you calculate the breathing rate from a spirometer trace
Number of breaths/ time x 60 to get breaths per minute
How do you work out the rate of oxygen consumption from a spirometer trace
Measure the change in the ‘trough’ (bottom) of the waves between 0seconds and 60 seconds to get volume of oxygen per minute
What is the function of elastic fibres in the gas exchange system
Contract when breathing in to prevent bursting, relax when breathing out to push air out of the lungs
State one way in which a steep concentration gradient is maintained in the lungs
Capillaries form a dense network which moves blood continuously, removing oxygenated blood, high in CO2, to maintain the concentration gradient
Why does the gaseous exchange system surface need to be well ventilated
Maintain a concentration gradient - increasing the rate at which O2 diffuses into the blood
describe the process of ventilation in bony fish
- fish mouth opens and lowers floor of buccal cavity,
- volume of buccal cavity increases and pressure decreases - water enters mouth
- fish closes mouth, floor of buccal cavity rises, volume decreases, pressure increases - forcing water out of gill filaments
- operculum forced open and water leaves the gills
define operculum in fish
why is it important
gill covering, made of bone (strong resistance)
important as it allows water pressure to build and only opens when the fish’s mouth closes
describe how the gills of fish are adapted for gas exchange
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
describe the counter current system in fish and why it’s important
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
describe the process of gas exchange in insects
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
how are the tracheoles in insects adapted for gas exchange
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
when dissecting an insect, what is the first important thing to mention
that the insect was humanely killed!!
State the function of the smooth muscle fibres in the bronchus
To constrict the bronchus - control flow of air
State the function of the elastic fibres in alveoli
Recoil/ expel air/ prevent bursting
Suggest how the diameter of the bronchioles might become reduced in someone with asthma
Contraction of smooth muscle - involuntary
Extra mucus production - blocked
Inflammation - swelling/ oedema
Explain why is it difficult to expel air from the lungs if the bronchioles reduce in diameter
Reduced diameter means increased resistance to air flow / friction
Additional force is required to exhale
