3.1.1 - exchange surfaces Flashcards
what is an exchange surface
a surface on/inside an organism over which exchange of gases, nutrients and waste can take place
what is a mass transport system
a system by which large quantities of exchanged materials can be moved around the body to the cells that need them
why is simple diffusion not good for multicellular organisms
diffusion pathway is too long + too many substrates get used up as they move to the centre cells
what is metabolic activity
the sum of all the reactions in a cell/body
does a large organism have a big or small SA:V
small
does a small organism have a big or small SA:V
big
what are the features of an efficient gas exchange
large SA:V
short diffusion distance
good blood supply
what maintains a large SA:V in an exchange surface
- Small alveoli (100-300 micrometres)
- small but there are lots that increase the SA of the lungs
- surfactant producing cells
- surfactant - substance reducing cohesive forces of a liquid (phospholipid)
- coats the internal surface of alveoli to reduce cohesive forces between water molecules. These forces may make alveoli collapse - reducing SA
what maintains a short diffusion distance in an exchange surface
- alveolus and capillary walls are 1 cell thick
- barrier is only 2 cells thick which is less than 1 micrometre
- alveolar walls made of squamous epithelial cells
- flattened so thin barrier
- capillaries are in close contact with alveolus wall
- decreased diffusion distance
- capillaries are so narrow that red blood cells are squeezed against the capillary wall
- rbcs are very close to the air in the alveoli and have a very short diffusion distance
what maintains a good blood supply distance in an exchange surface
- blood system transports CO2 from tissue to lung
- higher conc of CO2 in the blood than alveoli so it can diffuse into the alveoli for exhalation
- blood transports O2 from lungs
- lower conc of O2 in blood than alveoli so it can diffuse into the blood
what is inhalation
getting air into the lungs
what happens to volume during inhalation
diaphragm flattens / moves down
external IM contract
internal IM relax
ribs move up and out
volume inside chest (thorax) increases
what happens to pressure during inhalation
pressure decreases
what happens to the movement of air during inhalation
air rushes into the lungs
what is exhalation
getting air out of the lungs
what happens to volume during exhalation
diaphragm relaxes and moves up
external IM relax
internal IM contract
ribs move down and in
volume inside chest (thorax) decreases
what happen to pressure during exhalation
pressure increases
what happens to the movement of air during exhalation
air rushes out of the lungs
why do we say the diaphragm contracts and relaxes
it is made out of muscle
what does a spirometer do
measures lung volume
why does the spirometer have a disposable mouthpiece
prevents infection between patients
why is a noseclip worn when using a spirometer
prevents air entering/escaping through the nose
why does a spirometer have soda-lime
absorbs CO2 so it doesn’t go into the chamber
why does the lid of the spirometer go up and down
happens when you breathe in and out
why does the patient have to be healthy and free from asthma when using a spirometer
more safe and the transfer of disease between patients is less likely
why should the soda-lime in a spirometer be fresh and functioning
so that is absorbs the CO2 and it doesn’t go into the chamber
why should there be no leaks in the spirometer
air can escape and results won’t be accurate
why should the spirometer mouthpiece be sterilised
reduced transfer of disease
why shouldn’t the water chamber in a spirometer be overfilled
so that the person doesn’t inhale water
what is the tidal volume
the volume of air inhaled or exhaled in one normal breath - usually at rest
what is the volume breathed in or out at tidal volume
~0.5dm3
what is the inspiratory reserve volume
additional air that can be inhaled with maximum effort above normal breath
what is expiratory reserve volume
additional air that can be exhaled with maximum effort above normal breath
what is the vital capactiy
max volume of air that can be moved by the lungs in 1 breath ( measured by taking a deep breath)
how do you find the vital capacity
inspiratory reserve volume + expiratory reserve volume + tidal volume
what is the approximate volume of the vital capacity
~2.5-5.0 dm3
what is the residual volume
volume of air that remains in the lungs even after forced exhalation
where does the residual volume air stay
remains in the airways and in the alveoli
what is the approximate volume of the residual volume
~1.5 dm3
what is total lung capacity
total amount of air held in the lungs
how do you calculate the total lung capacity
vital capacity + residual volume
what do the airways consist of
trachea, bronchi and bronchioles
what must the airways be like
- large enough to allow sufficient airflow without obstruction
- supported to prevent collapse when air pressure is low
- flexible to allow movement
where is the ciliated epithelium located
trachea bronchi and bronchioles
what kind of cells are in the ciliated epithelium and what do they do
goblet cells which release mucus to trap pathogens
what kind of shape is the ciliated epithelium
columnar
what do the cilia in the ciliated epithelium do
move/waft mucus at the top of the airways where it is swallowed
where is smooth muscle located
in the trachea, bronchi and bronchioles
what does the smooth muscle do
can contract and narrow the lumen of the airways which restricts airflow to and from the alveoli
why is it good if the smooth muscle contracts
important if harmful substances are in the air for example it is involuntary in an allergic reaction
where is elastic fibres found
trachea, bronchi, bronchioles and alveoli
what do elastic fibres do
- works with smooth muscle
- when muscle contracts, elastic fibres are deformed/stretched. When muscle relaxes, elastic fibres recoil to original shape + size
where is cartilage found
trachea, bronchi and some large bronchioles
what does cartilage do
supports the airway to prevent collapse
what kind of cartilage is in the trachea
c - shaped which allows for flexibility and space for food to pass down the oesophagus
hat kind of cartilage is in the bronchi
fragmented
what is the terminal bronchiole
the part of the bronchioles that is close to the alveoli. It has an increased SA and no cartilage
is alveoli part of the airways
no
what does the alveolar tissue contain
elastic fibres that stretch during inhalation but recoil to push out air during exhalation
where is the squamous epithelium found
in alveoli
what does squamous mean
flattened
why is it good that squamous epithelial cells are flattened
reduce diffusion distance
where are capillaries found in the lungs
trachea, bronchi, bronchioles, alveoli
how do you measure the breathing rate from a trace
count the number of breaths taken per min on the trace by counting either the peaks or the troughs.
how do you measure the tidal volume from a trace
draw 2 lines on the trace, one above and one below the tidal volume peak and trough. Measure between lines of 3-4 peaks and take an average
what is the pulmonary breathing rate
total volume of air breathed in a minute
how to calculate the pulmonary breathing rate from a trace
tidal volume x breathing rate
how do you calculate the vital capacity from a trace
measure the height of the vital capacity
how to find the oxygen consumption from a trace
look how much the line has fallen in 1 min (look at 1 of the 2 lines) and divide by 60 to find oxygen consumption per second.
how many times denser is water than air
1000x
how many times more viscous is water than air
100x
does water have a higher or lower O2 content than air
lower
describe the inspiration of a bony fish
- mouth opens (operculum is closed)
- buccal cavity floor is lowered
- this increases the volume and decreases the pressure of the buccal cavity compared to outside
- water rushes into the mouth down a pressure gradient
- buccal cavity floor is raised AND opercular cavity expands
- the pressure inside the buccal cavity is now higher than in the opercular cavity
- water moves from the buccal cavity over the gills into the opercular cavity
describe the expiration of a bony fish
- mouth closes AND the operculum opens
- the sides of the opercular cavity move inwards, increasing the pressure
- water rushes out of the fish through the operculum
how do bony fish maintain a good blood supply
has a counter current exchange system
what do gill rakers do
they act like a sieve and prevent harmful grit and debris from passing over the gill filaments
what is the purpose of a gill arch
provides structural support and keeps rows from sticking together
roughly what is the size of gill lamellae
around 5 micrometers
why is it good that the gill lamellae are very thin
maintains a short diffusion distance between capillaries
what kind of exchange system does a fish have
counter current
what does a counter current exchange system mean
- blood is always adjacent to the water which has a higher O2 concentration and therefore oxygen continuously diffuses into the blood and an equilibrium is never reached
- even when water has little O2, it still has more than the blood and maintains a concentration gradient (constant rate of diffusion)
what are the features of an insect gas exchange
spiracle, tracheae, tracheole, tracheal fluid
what does the spiracle do
- allows gases in and out
- open when active (O2 in and Co2 out)
- most close when at rest (less H2O loss)
what does the tracheae do
carries air into the body
what is the tracheae lined with and what does it do
lined with chitin which provides support and is impermeable to gas
what happens in the tracheoles
there is no chitin lining so gas exchange can take place
what does the tracheal fluid do
limits O2 penetration into the tracheoles
a little bit can dissolve into fluid that is enough to sustain the insect at rest
what happens in the exchange system when the insect is active
- tracheal fluid is initially low which decreases the O2 in muscle cells
- activity begins
- muscle cells have to anaerobically respire
- increased lactic acid in cells
- decreased water potential of cells
- water/tracheal fluid moves from the tracheoles into muscle cells vio osmosis down a water potential gradient
- increased SA of tracheoles so more O2 can go in
- there is an increased O2 in tracheoles that diffuses into muscle cells
- aerobic respiration releases energy for activity
- CO2 can diffuse from the cells into the tracheoles and out of the spiracles
