topic 8 exchange and transport Flashcards
why can single celled organisms diffuse directly in/out the cell membrane
large surface area compared to their volume
why CAN’T multicellular organisms diffuse directly in and out across the cell membrane
smaller surface area to volume ratio
difficult to exchange enough substances
what’s the job of the lungs?
transfer oxygen to the blood and remove waste (carbon dioxide) from it
how do the lungs exchange gases
happens in the alveoli
blood arriving at the alveoli has lots of CO2, little O2.
O2 diffuses out of the air in the alveoli (where concentration of O2 is high) and into the blood (where it is low)
CO2 diffuses in the opposite direction to be breathed out.
the membranes are partially permeable.
how is the alveoli adapted to exchange gases?
moist lining to dissolve gases
good blood supply to maintain concentration gradient of O2 and CO2
very thin walls - short diffusion distance
rate of diffusion depends on three main things. what is it.
distance
concentration difference
surface area
what’s fick’s law equation?
rate of diffusion ∝ surface area * concentration difference / thickness of membrane
(∝ means ‘is proportional to’)
fick’s law explained
rate of diffusion will DOUBLE if:
surface area or the difference in concentration doubles
OR
if the thickness of the membrane HALVES
what is respiration
process of transferring energy from the breakdown of organic compounds (like glucose) into energy
aerobic respiration equation
glucose + oxygen -> carbon dioxide + water
C6H12O6 + 6O2 -> 6CO2 + 6H2O
what’s anaerobic respiration
respiration with NO OXYGEN
anaerobic respiration in humans
less efficient due to less energy being transferred
glucose is only partially broken down, and lactic acid is produced
equation for anaerobic respiration in ANIMALS
glucose -> lactic acid
anaerobic respiration in PLANTS
plants can respire without oxygen, but they produce ethanol instead of lactic acid
word equation for anaerobic respiration in plants
glucose -> ethanol + carbon dioxide
red blood cells are also known as
erythrocytes
adaptions of a red blood cell
biconcave disc shape to give a large surface area for absorbing oxygen
no nucleus for more room to carry oxygen
has haemoglobin to bind to oxygen to release oxygen into cells
name two different types of white blood cells
phagocytes and lymphocytes
what do phagocytes do
engulf unwelcome microorganisms
what do lymphocytes do
produce antibodies against microorganisms
adaptations of a white blood cell
can multiply to fight infection off
irregular shape to squeeze out of blood vessels to travel to the infection
lymphocytes have a large nucleus to help them receive signals from the brain
what does plasma carry
red blood cells
white blood cells
platelets
urea
carbon dioxide
hormones
proteins
antibodies and antitoxins
what are the three types of blood vessels
arteries - away from heart
capillaries - exchange of materials
veins - to heart
what are arteries like
thick layers of muscle to make them strong and elastic fibres to allow them to stretch and spring back
the walls are strong and elastic because the blood pumps blood out at a high pressure
