3.1 exchange surfaces Flashcards
(59 cards)
why do we need specialised exchange systems
larger organisms there are multiple layers of cells so body surface no longer sufficient
diffusion cannot take place quick enough and supply enough of o2 and nutrients etc.
3 factors that affect the need for exchange systems
size
SA:V
activity level
why does size not matter for exchange in single celled organisms
cytoplasm is close enough to environment (short diffusion pathway) so diffusion can supply enough oxygen and nutrients
why is size an issue for exchange in multi-cellular organisms
there is several layers of cells and oxygen and nutrients have a larger diffusion pathway happens too slowly
describe the SA:V in small and large organisms
small = large SA:V
large = small SA:V
describe the impact of activity levels for the need for specialised exchange systems
lots of metabolic activity = uses energy = need a good supply of nutrients and oxygen
describe features of a good exchange system
good blood supply - maintain conc. gradient
large SA - provides more space for molecules to pass through
thin barrier - permeable, reduce diffusion distance
define breathing rate
number of breaths per minute
define oxygen uptake
volume of oxygen absorbed by lungs in one minute
define tidal volume
volume of air inhaled or exhaled per breath
define vital capacity
maximum volume of air exhaled after a maximum inhalation
what is a spirometer
device used to measure movement of air into and out of lungs
what is a float chamber spirometer
chamber of air floating on a tank of water
what happens to a float chamber spirometer during inspiration and expiration
air drawn out of chamber
lid moves down
air returns to chamber
raises lid
movement recorded by datalogger to produce a trace
describe the purpose of soda lime
absorbs CO2 as its exhaled to allow measurement of oxygen uptake
precautions taken when using spirometers
healthy subject
fresh/functioning soda lime
no air leaks
sterilised mouthpiece
water chamber overfilled
how do you record oxygen uptake by spirometer
breathing in
oxygen absorbed by blood
replaced by CO2
CO2 now absorbed by soda lime
volume of air decreases in chamber
and volume of CO2 released and absorbed by sodalime = volume of oxygen absorbed by blood
calculating vital capacity
Tidal vol. + inspiratory reserve vol. + expiratory reserve vol.
calculating minute ventilation
Breathing rate x tidal volume
calculate total lung volume
Vital capacity + residual volume
the passage of air you breathe in
Nose - Trachea - bronchi - bronchioles - alveoli
What happens during gas exchange in mammals
Oxygen diffuses from air in alveoli into bloodstream
Carbon dioxide diffuses from blood to air in alveoli
How do lungs maintain a concentration gradient
Large SA
Permeable Barrier
Thin barrier - one cell thick, reduce diffusion distance, squamous cells
good blood network
define ventilation
Action of intercostal muscles and diaphragm allowing inhaling air and expiring CO2
