exchange surfaces Flashcards
do small organisms have a big/ small SA: volume ratio?
big SA: volume ratio
how to calculate SA of sphere?
4 x pi x r2
how to calculate volume of sphere?
4/3 x pi x r3
why do multicellular organisms need an exchange surface?
- large diffusion distance between cell and outside environment
-small SA: volume ratio
-higher metabolic rate
how are specialised exchange surfaces adapted?
- large surface area (root hair cells)
- thin (decrease diffusion distance)
-good blood supply
-well ventilated (both of these maintain concentration gradient of O2 and CO2)
pathway of air to lungs?
-trachea
-two bronchi
-bronchioles
-alveoli
5 key features of gaseous exchange system?
- goblet cells
- elastic fibres
- cartilage
- cilia
- smooth muscle
what role and location do goblet cells have?
line the airways, secrete mucus, which trap dust particles and microorganisms, preventing them from reaching alveoli
what role and location does cilia have?
hair like structures on surface of epithelial cells lining the airways
waft mucus to back of throat, away from alveoli, to be swallowed
what role and location do elastic fibres have?
in trachea, bronchi, bronchioles and alveoli
stretch during inhalation, recoil to expel air during exhalation
what is the role and location of smooth muscle?
in walls of trachea, bronchi and bronchioles
control diameter, relax during exercise, making tube wider, so less resistance to airflow
what role and location does cartilage have?
in walls of trachea and bronchi
prevent trachea and bronchi from collapsing under low pressure during inhalation
structure of trachea?
-C shaped cartilage
-smooth muscle
-elastic fibres
-goblet cells
structure of bronchus?
-alternating smooth muscle and cartilage pieces
-elastic fibres
-goblet cells
structure of bronchiole?
-smooth muscle
-elastic fibres
-goblet cells
steps of inspiration?
- external intercostal muscles and diaphragm contract
-ribcage moves up and out, diaphragm flattens
-thorax volume increases, lung pressure decreases
-air flows in to lungs
steps of expiration?
-external intercostal muscles and diaphragm relax
-ribcage moves down and in, diaphragm curves
-thorax volume decreases, air pressure increases (to above atmospheric)
-air forced out of lungs
how is active expiration different to passive?
internal intercostal muscles contract, to pull ribcage down and in
what machine measures breathing?
spirometer
what is tidal volume?
volume of air in each breath
what is viral capacity?
maximum volume of air that can be breathed in or out
what is oxygen uptake?
rate at which a person takes up oxygen
what is expiratory and inspiratory reserve volume?
additional volume of air that can be breathed in/ out after tidal volume
what is residual volume?
volume of air that remains in lungs even after forced expiration (stops lungs collapsing)
how to use a spirometer?
- person breathes into tube connected to oxygen chamber
- lid of chamber moves up and down during breathing
- these movements are recorded by spirometer trace
- soda lime in tubes absorbs CO2
why does volume of gas in chamber decrease over time?
O2 used in body, and CO2 absorbed by soda lime
precautionary steps in spirometer?
- wear nose clip to ensure all air they breathe goes through spirometer)
- use medical grade oxygen
- sterilise mouthpiece
how is oxygen uptake measured on spirometer trace?
decrease in volume of gas in spirometer
slope decrease/time
what adaptation do fish have and why?
gills
because O2 concentration is lower in water than air
gill structure?
- made up of thin plates called gill filaments
-gill filaments covered in gill plates
-each gill is supported by gill arch - lots of blood capillaries and thin surface layer of cells
what is the counter current system?
-blood flows through gill plates in one direction, water over gills in another
-this means that water with high O2 concentration, flows next to blood with lower O2 concentration
(steep concentration gradient, as much O2 diffuses into blood as possible)
ventilation in fish steps?
-fish opens mouth, buccal cavity lowers, pressure decreases, volume increases
-water flows in, mouth closes, pressure increase leads to water pushed out of cavity over gill filaments
-operculum covers gill, forced open by pressure, letting water leave
gas exchange in insects?
-air moves into trachea via spiracles
-O2 travels down concentration gradient to cells
-O2 travels down tracheoles, diffuse from fluid in tracheoles to cells
CO2 does this in opposite direction
ventilation in insects?
- rhythmic abdominal movement to change volume of bodies and move air in and out of spiracles
-wing movement used too
fish dissection?
- push back operculum, remove gills
-cut gill arch to view gill filaments
insect dissection?
-remove piece of exoskeleton
-fill abdomen with saline solution
-thin silvery grey tubes are trachea (colour due to being filled with air)
-view under microscope
