exchange surfaces and breathing Flashcards
(45 cards)
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
