exchange surfaces Flashcards
give 2 reasons why a single-celled organism doesn’t need a specialised gas exchange system but a mammal does
they have a large surface area, diffusion is relatively fast
they have a much lower metabolic rate as they are less active, they have a lower demand for oxygen and produce less CO2
give 3 reasons why a multicellular animals have a slow diffusion rate
some cells are deep within the body
larger animals have a low surface area to volume ratio
they have a higher metabolic rate than single cellular organisms
what is the equation for the surface area of a sphere
4 (pi) squared
what is the equation for the volume of a sphere
4/3 pi (radius) cubed
list 3 features which are useful for gas exchange
short diffusion pathway
big concentration gradient
big surface area
why are mammals lungs deep inside the body
if it was too permeable and thin, water would be diffused into the lungs
describe the pathway of the respiratory system
nasal passage
nostrils
trachea
bronchi
bronchioles
alveoli
what are lungs protected by
ribcage
what are muscles called in lungs
intercostal muscles
define metabolic rate
high cell respiration rate to produce ATP fast enough to supply the cells with enough energy to carry out active processes
give 3 ways the nasal capacity is adapted to maximise gas exchange
large surface area
hairy lining to trap dust and bacteria
moist surfaces which increase the humidity of the incoming air reducing evaporation from the exchange surfaces
what is the purpose of goblet cells
secrete mucus which traps microorganisms and bacteria
what is the function of cilia
they move mucus upward towards the throat
what is the function of elastic fibres
they help the process of breathing in and out
they stretch and recoil
what is the purpose of smooth muscle
during exercise the smooth muscle relaxes making tubes wider so there’s less resistance to airflow and air can move in and out of lungs more easily
what is the function of cartilidge
provide support
strong but flexible
stops trachea and bronchiole from collapsing when pressure drops
which part of the lungs have cartilidge
trachea
bronchi
what part of the lungs have smooth muscle
trachea
bronchi
bronchioles
what part of the lungs have elastic fibres
trachea
bronchi
bronchioles
alveoli
what parts of the lungs have goblet cells
trachea
bronchi
bronchioles
why do the smallest bronchioles and alveoli have no smooth muscle and goblet cells
disappears as it is smaller
why do the epithelium not have cilia in the bronchioles and alveoli
they could block the air way
why do smokers often develop long term coughs
destroys cilia hairs
mucus sits there
pathogens are trapped in causing infection and irritation
why does the amount of cartilage reduce as we move from the trachea to the bronchi to the bronchioles
it doesn’t need the support as it is small
why is cartilidge incomplete and a C shape
it would be too rigid
needs flexibility to allow food to be swallowed down the oesphagus which is behind the trachea
give 3 ways the alveoli are adapted for efficient gas exchange
short diffusion pathway (capillaries are close by and the membrane is thin)
good concentration gradient (blood is flowing to take CO2 away and brings O2)
large surface area (millions of alveoli create a large surface area
why is surfactant released by the aveoli into its inner lining
lowers surface tension so they don’t stick together when exhaling
what is inspiration
breathing in
describe the process of inspiration
external intercostal muscles and diaphram contract
ribcage moves up and the diaphram flattens creating an increase in volume for the thorax (where the lungs are)
lung pressure decreases, allowing air to flow into the lungs
why is inspiration an active process
it requires energy
what is expiration
breathing out
describe the process of expiration
external intercostal and diaphram muscles relax
ribcage moves downwards and diaphram becomes curved again
thorax volume decreases and increases in pressure
air is forced out the lungs
describe what happens in forced expiration
the internal intercostal muscles contract to pull the ribcage down and in
what is the calculation of ventilation rate
ventilation rate= breathing rate x tidal volume
what is the typical tidal volume
0.5 dm3
what is tidal volume
volume of air exchanged per breath
what is the intention of a spirometer
to investigate breathing
describe how a spirometer works
person breathes in and out via mouthpiece
when breathing in, they use the oxygen from the chamber and the float decreases
when breathing out, the CO2 is absorbed by soda lime and the flat increases
the float is attached to a pen which writes on a revolving drum recording breathing movements
what is vital capaity
the maximum volume of air that can be breathed in and out in one breath
what are the 2 ways to calculate breathing rate
60/ time for 1 breath
count the peaks in graphs
name 3 safety precautions when using a spirometer
make sure that the soda lime is being used as the person will be breathing in exhaled CO2
make sure the person is healthy
make sure the mouthpiece is sterilised
what difficulties are there in trying to gain oxygen from water rather than air
water is more dense than air so would take more energy to complete
water has a much lower oxygen content than air, so there would be a smaller concentration gradient across the gas exchange surface
how many gills do fish have
4
where are gills found
gill cavity
what is the flap that covers the gill cavity called
operculum
draw a fish gill
(in the back of the booklet)
describe a counter-current system
water with a relatively high oxygen concentration flow next to a blood with a lower concentration of oxygen
why is a counter current system useful
makes a steep concentration gradient
describe the process of ventilation in bony fish
fish opens it mouth
this lowers the floor of the buccal cavity
increases the volume of the buccal cavity
pressure inside the buccal cavity to fall
water is then drawn into the buccal cavity due to pressure gradient
then
fish closes it mouth
floor of buccal cavity is raised
volume inside the buccal cavity falls
pressure inside the buccal cavity increases
water is forced over the gill filaments (where gas exchange happens)
how does the structure of a fish gill have a large surface area
4 gills
each gill is made up of 2 stacks of gill filament
each filament is covered with gill plates (lamellae) which is the site of gas exchange
how does the structure of a fish gill have a short diffusion pathway
capillaries are close to the surface
gill plates are thin
how does the structure of a fish gill have a big concentration gradient
counter-current mechanism
what is 3 things needed for efficient gas exchange
large surface area
steep concentration gradient
short diffusion pathway
what is the purpose of exoskeletons in insects (2 ways)
prevents gas exchange from happening across their body
protection
what type of circulatory system do insects have
open circulatory system
describe the gas exchange structures in insects (in order)
spiracles
trachea
tracheoles
what is the role of chitin in insects
to keep airways open (stop them collapsing)
describe the structure of tracheoles in insects
single elongated cell with no chitin
how does an insect’s gas exchange system have a large surface area
lots of tracheoles in contact with body cells
how does an insect’s gas exchange system have a big concentration gradient
body cells are constantly using oxygen and producing CO2 maintaining a diffusion gradient
how does an insects gas exchange system have a short diffusion pathway
the end of trachea are thin so short distance for diffusion, short distance between air outside insect and body cells
what limits the diffusion of oxygen in insects and how is it overcome
the tracheal fluid limits oxygen getting to the tracheoles near to the cells
if insects’s activity increases, it will repsire aneorbically and produce lactic acid, which lowers the water potential drawing water from the tracheoles in the cells by osmosis, so less fluid is left in the tracheole so an increase in surface area is available for gas exchange
give 3 ways in which larger insects can also ventilate their tracheal system by movements of the body
air sacs can be squeezed by the action of the flight muscles
movements of the wings alter the volume of the thorax
locusts can alter the volume of their abdomen by specialised breathing movements
