Exchange and Transport Systems Flashcards
smaller organisms SA:V
higher surface area : volume ratiom
larger organisms SA:V
lower SA : V than smaller organsim’s
volume
width x height x length
surface area
area x no. of faces
if the area for different faces is different make sure you take this into account, check pg 139
surface area measurements
squared
volume measurements
cubed
surface area of a sphere formula
4πr2
volume of cylinder formula
πr2h
volume of a sphere formula
4/3 (πr3)
how do single celled organisms exchange substances?
substances can diffuse directly into/out of the cell across cell surface membrane.
Diffusion rate is quick because of the small distances the substances have to travel –> short diffusion pathway
How do multicellular organisms exchange substances?
they need specialised exchange organs and an efficient system to carry substances to and from their individual cells - THIS IS CALLED MASS TRANSPORT
in multicellular organisms diffusion across outer membrane is too slow because?
- some cells are deep within the body and therefore there is a big distance between them and the outside environment
- larger animals have a low SA:V ratio so it is difficult to exchange enough substances to supply a large volume of animal through a relatively small outer surface
mass transport in humans?
circulatory system - transport of blood which carries glucose hormones antibodies and waste e.g. CO2
mass transport in plants?
transport of water in the xylem and solutes in the phloem
what creates heat?
metabolic activity
why do smaller organisms need a high metabolic rate?
in order to generate enough heat to stay warm, as they have larger SA:V ratios so heat is lost more easily
compact shape –>
less heat loss as they have a small SA:V
not compact shape (sticky out bits) –>
increased heat loss due to a larger SA:V
what impacts heat exchange?
body shape and body size
adaptation of foxes and why?
arctic fox –> small ears and round head to make it more compact in order to reduce its SA:V and thus reduce its heat loss
African bat-eared fox –> large ears more pointed nose to increase SA:V as it is less compact and increase heat loss
European fox –> intermediate to match enviornmental temp
Adaptation to help prevent desert animals with a high SA:V ratio from losing water
some of these animals have kidney structure adaptations so that they produce less urine to compensate
cold region small mammals adaptation in order to support their high metabolic rates?
eat lots of high energy food e.g. seeds and nuts
what do smaller mammals have in order to protect them when it gets cold?
thick layers of fur or they hibernate
larger organisms in hot regions adaptations, e.g. elephant and hippo
beahvioural adaptation for hippos - spend majority of day in water to help them lose heat
Elephants have developed large flat ears which increase their SA allowing them to lose more heat
properties of gas exchange surfaces:
thin - short diffusion pathway
large surface area
what do organisms do in order to increase the rate of diffusion?
they maintain a steep conc grad
single celled organisms - gas exchnage?
simple diffusion already have a relatively large SA and thin so diffusion quick and can take part in metabolic reactions as soon as it is in cell - no need for specialised gas exchange systems
water - o2
lower pO2 in water compared to air so fish need specialised gas exchange system
benefit of lamellae?
good blood supply - lots of blood capillaries and a thin surface layer of cells to speed up diffusion between water and blood
they increase SA further on top of gill filaments
countercurrent system
steep conc grad maintained along the whole length of the lamellae/gill filament/gill/capillary
Oxygen conc is always higher in water than blood
water and blood flow
in OPPOSITE directions
apart from the countercurrent system, what else maintains the steep conc grad?
the normal circulation of the fish as the blood that becomes oxygenated by the gills is replaced with more deoxygenated blood
also, normal ventilation of the fish ensure that more water with a relatively high conc of oxygen is taken in
main gas exchange surface in dicotyledonous plants is?
the surface of the mesophyll cells in the leaf –> they have a large surface area
why would stomata close?
if the leaf is losing too much water
spiracles and stomata are?
pores within the exchange surface of insects and plants
insect gas exchange system
tracheae branch into tracheoles
gases move through spiracles
air moves into tracheae through spiracles and then the air moves into the tracheoles
tracheoles? what do they allow?
thin permeable walls and go to individual cells thus allowing oxygen to diffuse directly into respiring cells
what does the circulatory system of a terrestrial insect not do?
transport oxygen
how do insects move air in and out of the spiracles?
rhythmic abdominal movements
what are tracheoles lined with and why?
lined with thin single layer of cells to minimise diffusion distance
Give ways in which a terrestrial insects gas tracheal system isn adapted for efficient gas exchange?
tracheoles have thin walls SO short diffusion distance
large no. of tracheoles/ highly branched tracheal system SO short diffusion distance to cells
Large no. of tracheoles/hb SO large surface area
Tracheae provide tubes full of air SO fast diffusion
Fluid in the end of the tracheoles that moves out during exercise SO faster diffusion (miss estruch vid) through the air to the gas exchange system
Body can be moved by abdominal muscles to move air SO maintain diffusion gradient for O2/CO2
turgid - limp
guard cells swollen
guard cells limp
reducing water loss in insects:
close spiracles
waxy cuticle layer that is waterproof all over body - red eva
tiny hairs around spiracles - reducing evap
plant gets dehydrated what happens?
guard cells become limp as they lose water which closes the pore
as water enters guard cells it makes them turgid which opens the stomatal pores
xerophytes
specially adapted to reduce water loss as they are found in environments where water loss is a problem
xerophytic adaptations:
sunken stomata –> trap water vapour increases WP outside so reduced evaporation
layer of hairs on the epidermis –> trap water vapour etc.
rolled/curled leaves w/ stomata inside –> protecting from wind as windy conditions increase rate of evap
reduced no. of stomata –> fewer places for water to escape from
thicker waxy waterproof cuticles on leaves and stems –> reduce evaporation
how do windy conditions increase evaporation?
wind blows away water vapour, decreases the WP outside the plant so more water moves out down the WP gradient
inhalation in humans:
diaphragm contracts, external intercostal muscles contract
rib cage up and out
increased volume
decreased pressure in thoracic cavity to below atmospheric pressure
pressure grad
air moves down pressure grad from high to low into the lungs
exhalation in humans:
diaphragm relaxes and external intercostal muscles relax
internal intercostal muscles contract (during forced expiration)
rib cage moves down and in
decreased volume
increased pressure in thoracic cavity above atmospheric pressure
pressure grad created
air moves down pressure grad out of the lungs
human gas exchange system structure?
mouth/nose trachea bronchi bronchioles alveoli
ventilation:
inspiration and expiration
when do internal and external intercostal muscles act as an antagonistic pair?
during forced expiration
alveoli surrounded by?
network of capillaries
where is epithelial tissue usually found?
on exchange surfaces
what is the wall of each alveolus made from?
single layer of thin flat cells called the alveolar epithelium
walls of capillaries are made from?
capillary endothelium
pathway of oxygen from alveoli to capllary?
across alveolar epithelium acorss capillary endothelium
how does ventilation and circulation support a steep conc grad?
air high in oxygen is continually supplied
blood high in oxygen is continually replaced with blood low in oxygen
4 measure of lung function?
tidal volume(vol of air/breath)
ventilation rate (no. of breaths /min)
forced expiratory volume (max vol. air breathed out in 1 sec)
forced vital capacity(max. vol air out after max vol air in)
tuberculosis:
bacteira - immune cells build wall around bacteria in lungs forming tubercles - tissues infected with these die, gas exchange surface damaged –> tidal volume decrease –> results in fibrosis as well –> further reducing tidal volume –> reduced tidal volume so increased ventilation rate (make up for reduced volume in eahc breath so breathe quicker)
fibrosis:
formation of scar tissue in lungs
result of infection or exposure to dust/asbestos
scar tissue thicker and less elastic
SO lungs are less able to expand + can’t hold as much air, reducing tidal volume so FVC reduced (smaller vol of air forcefully breathed out)
reduction in gas exchange rate –> diffusion slower across a thicker scarred membrane
so faster ventilation rate
to get enough air into lungs to oxygenate blood
asthma:
inflamed + irritated airways
smooth muscle lining the bronchioles contracts and large amount of mucus produced
constriction of airways
can’t breathe properly
air flow in and out severely reduced
forced expiratory volume reduced
emphysema:
smoking or long-term exposure to air pollution caused
foreign particles in smoke become trapped in the alveoli
causing inflammation attracting phagocytes which produces an ezyme that breaks down the elastin
less elastic so alveoli stuggle to return to normal shape after inhaling and exhaling
alveolis can’t recoil to expel air - so it remains trapped in alveoli
destruction of alveoli walls
reduces SA of alveoli
rate of gas exchange decreases
increased ventilation rate
lung disease
reduce rate of gas exchange in alveoli
less oxygen able to diffuse down conc grad into blood
body cells receive less oxygen so rate of aerobic resp reduced
less energy released - feel weak and tired
restrictive disease?
FVC severely reduced but FEV1 likely to be high in comparison as restrictive diseases still allow you to breathe out normally ish
when describing a graph, what should you do?
use specific values/numbers from that graph
what can dissecting pins be used for?
used with a wax filled dissection tray to pin a specimen in place during the dissection
ensure all dissecting tools are all…?
sharp, clean and rust-free
sharp to ensure they cut well and you don’t injure yourself
why would you put lungs into a plastic bag when wanting to see them inflate?
to ensure that you stop bacteria inside the lungs from being released into the room
what is the trachea supported by?
C - shaped ring of cartilage
why does lung tissue feel spongy?
due to the air trapped inside the alveoli
what to do after dissections?
dispose of organs separately
wash hands
disinfect work surfaces
