3.1 Gas Exchange in mammals Flashcards
How do single-celled organisms gain oxygen?
simple diffusion
What are features of a single-celled organism that will help it take up o2 quickly?
large SA:Vol ratio
short diffusion distance= body surface is cell-surface membrane
converts O2 into ATP for aerobic resp
permeable to gas
What is the relationship of the size of the organism and the SA:VOl ratio?
as the size of the organism increases the SA:VOl ratio decreases
Why are fish less metabollically active than terrestrial mammals?
fish are not endotherms - lower ATP demand
bouyant - less energy to support them needed when stationary
What does the counter-current mechanism mean in fish?
the water and the blood flow in opposite directions across the entire gill length, an equilibrium is not reached
How does a counter-current mechanism increase efficency of gas exchange in fish?
it maintains a conc.grad across the entire gill plate which maximises the saturation of O2 in the blood
What is a spiracle?
the opening of an insect in which air enters their system
What is partial pressure?
the pressure exerted by one gas in a mixture
Why is it an advantage that insects can close their spiracles?
reduces water loss
How does partial pressure of O2 change when the spiracles open?
it increases
How does partial pressure of O2 change when the spiracles closed?
decreases - diffusing into cells
How does partial pressure of CO2 change when the spiracles closed?
increases - waste product from respiration
How does partial pressure of CO2 change when the spiracles open?
decreases
What is the effect of SA:VOL ratio on the rate of diffusion?
as SA:VOL ratio increases the rate of diffusion also increases
What is gas exchange?
gases are exchanged across a membrane by simple diffusion
why is gas exchange important?
O2 exchanged for aerobic respiration to produce ATP
CO2 is removed = it is toxic in high conc
What does SA relate to in gas exchange?
the supply of O2
higher SA = Higher O2 rate
What does volume relate to in gas exchange?
the demand of O2 that respiring cells have
How is a flatworm adapted for gas exchange differently to the earth worm?
has a larger SA:VOL - makes itself thin for a short diffusion pathway
How is a earth worm adapted for gas exchange differently to the flatworm?
its capillaries are close to the skin’s surface = shorter diffusion distance
What properties do all gas exchange surfaces have?
thin = short diffusion distance
large SA:VOL ratio = effective gas exchange
moist = gases dissolve
mechanism for maintaining conc.grad of O2
permeable to gas
What are some metabollic reactions?
respiration
thermoregulation
growth and repair of cells
protein synthesis
What and why are the trachea lined with?
c-shaped rings of cartilage - to provide structual support to prevent collapsing and to provide flexibility
What does the smooth muscle on the trachea do?
contract to reduce air flow
relaxes - widens the airway
What are the trachea and bronchi walls lined with?
ciliated epithelial tissue containing goblet cells
What do the goblet cells do?
secrete mucus to trap dirt and pathogens
sends mucus up into the lumenall area
mucus acts as a barrier on the lining of the airway
What do cilia do in the airway?
wafts mucus up and out of airway towards the mouth so it can be swallowed into the stomach where acid breaks down the mucus
What are the bronchioles?
they branch off the bronchi and lead to the alveoli
they consist of smooth muscle and epithelial cells
What are the alveoli?
the end of the pathway - the site of gas exchange
consist of squamous epithelial tissue and elastic fibres
What does squamous mean?
flattened
What does the waxy exoskeleton help insects?
helps them with protection and water retention
Why is the waxy exoskelenton ineffective for gas exchange?
gases bounce off the surface
Where does gas exchange occur in insects?
the tracheal fluid at the end of the tracheoles
What happens when the insect is active in terms of G.EX?
the muscles draw up the tracheole fluid which provides the muscles with O2
How do air sacs ventilate the insects tracheal system?
can be squeezed by flight muscles to push air in and out
How can flight muscles ventilate the insects tracheal system?
can alter the volume of the insect thorax
How does the amoeba gas exchange surface have a large SA?
large SA:VOL ratio
relatively low metabolic rate = low O2 demand
How does the amoeba gas exchange surface have a short diffusion pathway?
their gas exchange surface is their cell surface membrane
thin = rapid gas exchange
How does the amoeba gas exchange surface maintain a conc grad?
as the cell respires it will convert the O2 into ATP so O2 levels in the cytoplasm remain lower than the external environment
What extra feature of the amoeba is adapted for G.EX?
moist surface so gases can dissolve
How does a flatworm have a large SA for G.EX?
tubular shape is evolved
has a flattened shape = increases SA:VOL ratio
has a low metabolic rate
How are both the worms adapted to maintain a conc grad for G.EX?
The blood flow maintains a diffusion grad by constantly removing O2 and taking it to the cells while removing CO2
How else are flatworms adapted for G.EX?
moist surface for gases to dissolve
How do earthworms have a large SA for G.EX?
evolved a tubular shape
How do earthworms have a short diffusion pathway?
thin surface
short distance between air and capilliaries
How else do earthworms maintain a conc grad for G.EX?
heamoglobin is in a closed circulatory system which increases the efficency of O2 transport = moves O2 away from the skins surface quickly
How do fish have a large SA for G.EX?
gills have highly folded gill filaments
fish have many gill filaments
How do fish have a short diffusion pathway for G.EX?
the gill plates contain blood capillaries
the outer layer of the gill filaments and the capillary walls are 1 cell thick
How do fish maintain a conc.grad for G.EX?
counter-current flow = water and blood flow in opposite directions
How does an insect have a large SA for G.EX?
the tracheoles are branched
How do insects have a short diffusion pathway for G.EX?
the tracheoles are in contact with every tissue in the body
has a large no. of tracheoles
How do insects maintain conc.grad for G.EX?
ventilation of the tracheoles O2 in CO2 out
What is the advantage of having fluid at the end of the tracheoles?
fluid moves out during exercise so faster diffusion through the air to the gas exchange system
How do mammels have a large SA for G.EX?
lots of alveoli which is the site of gas exchange and they are surrounded by a network of capillaries
How do mammals have a short diffusion pathway for G.EX?
capillaries have an endothelial wall
alveoli has a squamous epithelial wall
both are 1 cell thick = short distance between alveoli and capillary
How do mammals maintain a conc grad for G.EX?
capillaries take blood away so blood flows away from the site of G.EX carrying O2
Where do fish get their O2 from?
it is free O2 that is dissolved in water
Why are fish relativly inactive (has a low metabolic rate)?
they are bouyant in water
they are not endotherms
Why are fish respiration rates lower?
less O2 in the water so less respiration takes place and less ATP produced
What type of flow of water do fish have?
unidirectional - in and out at different places
How does water enter the fish for G.EX?
water enters their mouth as they swim and passes over through the gills as they move
What do the gills consist of?
bony gill arches each has two stacks of gill filaments which have lamelle
What do the gill plates consist of?
a network of capillaries
made of single layer of epithelial cells
What is the site of G.EX in fish?
gill plates
How are the gill structures protected?
the operculum
How do fish ventilate their gills?
they coordinate the opening of their opercular vents with closing their buccal cavity (mouth)
What makes up the fish’s mouth?
buccal cavity - empty space in mouth
gills
the opercula cavity
operculum - protects gills
opercular valves
How is the insects body divided?
3 parts:
head
thorax
abdomen
Why don’t insects need to synthesise heamoglobin?
they do not need to transport O2 in the body because the tissues are in direct contact with the G.EX surface
Why are some G.EX surfaces internal?
to reduce water loss
What does the muscle movements in an insect do for G.EX?
ventilation of tracheoles
forces respiratory medium over G.EX surface which maintains a conc.grad
How do the muscles speed up G.EX in insects?
they contract and squeeze the trachea which enables mass movements of air in and out
How does G.EX take place in insects?
- muscles respire by anerobic respiration which produces lactate - soluble and reduces the water potential in muscle cells
- the water moves into cells from the tracheoles by osmosis
- the water at the end of the tracheoles decreases in volume so they draw air in
What are spiracles?
tiny pores that can open and close by valves
where gases enter and leave an insect
What is the tracheal tube lined with in insects?
chitin = structural support and prevents it collapsing under low pressures
How do spiracles reduce water loss?
close valves
How is air drawn into the insect?
into the spiracles because the abdomen expands which lowers the pressure in the thorax so air is drawn in
How is air pushed out of the insect?
air is pushed out of the spiracles because the thoratic spiracles are not open increasing pressure in the thorax
Why shouldn’t the diffusion distance be too large?
the rate of diffusion would be too slow to provide enough O2 to meet the demands of the organism
How do the fluid levels in the tracheoles change during flight?
the fluid levels decrease during flight
What are all the parts of the respiratory system in humans? (mouth to diaphragm)
nasal cavity
pharynx
epiglottis
larynx
oesophagus
trachea - rings of cartilage
ribcage
intercostal muscles
bronchi (left and right bronchus)
heart
lungs
bronchioles
alveoli
pleural membrane
pleural cavity
diaphragm
How are the lungs protected?
the ribcage, sternum and diaphragm
What does tidal ventilation ensure?
ensures the air is constanly being replenished
What is the capillary wall made of?
endothelial cells
What is the alveolus wall made of?
epithelial cells
What is the purpose of the surfactant in the alveoli?
it is a fluid that prevents the alveoli from sticking together and keeps the alveoli open
What is one use of artificial surfactant?
premature babies may need artificial surfactant to inflate their lungs and assist breathing
What is ventilation necessary for?
necessary for the respiratory medium to be in contact with the gas exchange surface
What is the relationship between pressure and volume?
as volume increases, pressure decreases
When does inhalation occur in terms of pressure?
when the thoratic pressure is lower than atmospheric pressure
When does exhalation occur in terms of pressure?
when the thoratic pressure is higher than the atmospheric pressure
How is there rapid diffusion in the alveoli?
rbc are slowed through capillary - more time for diff.
rbc flattened against capill wall - shorter distance
thin walls
large SA of capill and alveoli
ventilation and heart circulates blood, blood flow - conc.grad
What does the nasal cavity do for G.EX in humans?
moistens the air to dissolve
What does the pleural fluid do?
reduces friction of the lungs against the ribs and sternum = provides lubrication
What is the purpose of the bronchi?
has ciliated epithelial cells made up of goblet cells:
produces mucus to trap dirt particles and cilia wafts mucus to the throat
What do the bronchioles do?
muscles allows them to constrict to control the flow of air in and out of the alveoli
What is found between alveoli?
collagen and elastic fibres
What do the elastic fibres allow the alveoli to do?
allows alveoli to strech with air filling them and to spring back when exhaling to expel CO2
What happens in ventilation?
air is constantly moved in and out of the lungs
How is air drawn in during inhalation in terms of pressure?
when the atmospheric pressue is higher than the internal pressure - air is drawn into the lungs
How is air expelled during exhalation in terms of pressure?
the atmospheric pressure is lower than the internal pressure so air is forced out
How does pressure change in the thorax?
due to the movement of muscles = the diagphragm and the intercostal muscles
Which intercostal muscles contaction leads to exhalation?
internal intercostal muscles
Which intercostal muscles contaction leads to inhalation?
the external intercostal muscle
What is the process of inhalation?
diaphragm contracts and flattens
external inter.Costal muscles contract
causes volume to increase and pressure to decrease
air moves down a pressure gradient
What is the process of exhalation?
diaphragm relaxes and returns to dome shape
external inter.costal muscles relax
rib cage moves down and in
volume of thorax decreases
there is no pull applied to outer pleural membrane
pressure in the pleural cavity increases
no pull on the inner pleural membrane so no pull on the lungs surface
aveoli compress
pressure in alveoli increases above atmospheric pressure
air is forced out of the alveoli down a press.grad
What are the advantages of a unidirectional flow of water in fish?
less energy is needed for gas exchange and to push the repiratory medium over G.EX surface
theres a contiuous flow of water
What is the advantage for larger animals of having a specialised system for gas exchange?
larger organisms have a smaller SA:VOL ratio
overcomes long diffusion pathway
What are the environmental conditions that caused gill adaptation in fish gas exchange?
water has a lower partial pressure than oxygen in the air
so the system on the outside of the fish gives a larger SA in contact with water = decreases diffusion distance
water is denser than air
so it supports the gill system
How does SA:VOL link with metabolic rate?
smaller organisms have a larger SA:VOL ratio
more heat lost in smaller organisms per gram of body size
theres a faster rate of respiration which releases heat
Why is oxygen uptake is a measure of metabolic rate in organisms?
oxygen is used in respiration which provides ATP
What are the effects of emphysema of other resp, problems?
less carbon dioxide exhaled
reduced diffusion gradient between blood and alveoli
less movement of carbond dioxide out of blood
What is the pathway taken by an oxygen molecule from an alvelous to the blood?
across the alveolar epithelium
then across the endothelium of the capillary
What are all the adaptations of an insects tracheal system for gas exchange?
Tracheoles have thin walls so short diffusion distance to cells
Highly branched so short diffusion distance to cells
Highly branched so large surface area (for gas exchange)
Tracheae provide tubes full of air so fast diffusion (into insect tissues)
Fluid in the end of the tracheoles that moves out (into tissues) during exercise so faster diffusion through the air to the gas exchange surface
Body can be moved (by muscles) to move air so maintains diffusion / concentration gradient for oxygen / carbon dioxide
