Gaseous Exchange Flashcards
role of respiratory system
enables gaseous exchange to occur
role of excretory system
responsible for removing metabolic wastes from the blood and to expel them from the organism
e.g. carbon dioxide (expelled through lungs) and nitrogen (through urine)
role of circulatory system
transports gases (oxygen, carbon dioxide, nutrients, waste products, hormones, antibodies)
responsible for maintaining a constant internal environment e.g. ph levels
also removes any toxins or pathogens
responsible for duration of heat
how are gas exchange surfaces adapted to be efficient
thing
large SA
near blood supply
moist
how do fishes increase the surface area:volume ration
have filaments and lamellae in fills. these are very long and thin, maximising the SA
how do mammals increase the surface area:volume ration
the tissue of the gas exchange surfaces folds back on itself.
these folds of the alveoli increase the SA
do insects require a large SA:volume ratio
no
oxygen diffuses straight from the tracheoles into the cells, so the tracheoles reach every cell, but there is no need to have a large surface area:volume ratio at each place where gas exchange occurs
how do fishes keep their gas exchange surface moist
they live in water, and get oxygen from the water, so keeps their gills moist
how do mammals keep their gas exchange surface moist
Mammals have mucus in the trachea keeping it moist, and the whole gas exchange system is internal to keep this moisture in.
how do insects keep their gas exchange surface moist
Insects have water at the ends of their tracheoles for oxgen to dissolve in to diffuse. The gas exchange system is internal to reduce water loss, and the spiracles can open and close to control it, depending on environmental conditions.
do insects, mammals and fishes have a gas exchange system
mammals and fish do
insects don’t
does a bigger insect find it harder or easier for oxygen to get to every cell of diffusion
harder
Insects don’t have a circulatory system. Their tracheoles reach every cell, and they rely on diffusion for oxygen to reach each cell.
are mammals, fishes and insects limited in size?
mammals and fishes are not, because the oxygen is transported by the blood, meaning their sizes are unlimited
insects are limited in size. The bigger the insect, the harder it is for oxygen to get to every cell by diffusion.
how do mammals, fish and insects get their air
mammals and insects get it from the air
fish from the water
why is water hard to ventilate
because it is more vicious than air
why do fish have a more efficient gas exchange system
because water is hard to ventilate as it is more vicious than air, so it’s harder to get the oxygen from the water
describe the direction of flow for a fish
unidirectional
the unidirectional flow is achieved by taking water in through their mouths, then pushing it through the gills and out the operculum.
The water flows through the lamellae in the gills in the opposite direction to the blood. (called the counter-current system and allows for the most efficient diffusion of gases between the water and the blood)
The concentration gradient is maintained the whole way through the gills, because the most oxygenated water meets the most oxygenated blood, and the least oxygenated water meets the least oxygenated blood.
If water and blood flowed in the same direction in a fish, what would happen?
If the water and blood flowed in the same direction, the oxygen concentration of blood and water would equalise at 50% half way through the gills, so not as much oxygen would be absorbed by the blood.
Describe tidal ventilation in insects and mammals
means the air goes in and out the same way.
This means with each breath, not all of the old air makes it out of the body, so not all of the air coming in is new.
Because of this, mammals and insects don’t get the maximum amount of oxygen out of the air.
Transport systems in unicellular organisms
all nutrients needed can be diffused from the external environment over their surface area
Wastes can just be removed from cells by diffusion as well
e.g. can transport oxygen and urea out of bodies by diffusion or osmosis easily
how can wastes in unicellular organisms be removed
Wastes can just be removed from cells by diffusion
in multicellular organisms, do they have a surface area great enough to provide nutrients for all the organisms cells?
no
most of cells inside organisms are too far from the surface of their bodies and diffusion and osmosis are too slow to be relied on
what do the transport systems in multicellular organisms do
carry nutrients to bodies cells
transports food and oxygen
carry wastes away
where does osmosis and diffusion occur in multicellular organisms
diffusion and osmosis would take place between he transport system and the cells
what is an open circulatory system
the more basic type of circulatory system
referred to as open because blood is not contained within an enclosed circuit of vessels.
blood flows from the heart through open-ended vessels and, when it reaches the end of the vessels, it flows directly over the tissues
while the tissues are bathed in blood, gas exchange occurs. Blood then freely flows back into vessels that direct the blood back to the heart
examples of organisms that use an open circulatory system
grasshoppers
clams
snails
what is a closed circulatory system
a closed circulatory system is more structured and controlled
the blood of a closed system always flows inside vessels. These vessels make up the plumbing circuit of the body and can be found throughout the entire body
this plumbing circuit can be broken down into three different types of vessels that transport blood throughout the body: arteries, capillaries and veins.
arteries = responsible for moving blood AWAY from your heart and to your tissues
When blood gets to the tissues it is contained within capillaries
capillaries = very small vessels with thin walls. These thin walls make it possible for gas and waste exchange to occur between your blood and your tissues
the blood then leaves the capillaries and goes into the veins, which bring blood back to your heart
describe stomates and where they are found
located on leaves of plants
they are pores in the leaf which enable the diffusion of gases
present on the upper and lower sides of leaves, but mainly on the lower side
describe the role of stomates
stomates receive the gases needed for photosynthesis (not respiration)
stomates can open and close: when open, gas exchange occurs in the leaf and photosynthesis occurs, but when they close, the rate of photosynthesis slows
how are the stomates controlled
the opening and closing of Stomates is controlled by guard cells
this is dependent on stimuli such as: light, low CO2 levels, an internal clock, water deficiency, and high temperatures
describe lenticels
These are pores on the woody stems of plants.
The gases needed for respiration are diffused through lenticels
Carbon dioxide also diffuses out
describe xylem and its role
Transport water and mineral ions up the plant stem to the leaves
Consists of dead cells, whose cross-walls (connection between cell walls) have been broken away, creating a continuous tube
Xylem also gives strength and rigidity to the plant
describe phloem and its role
Transport the products of photosynthesis (sugars) throughout the whole plant
Made of long columns of ‘sieve tube cells’, which have holes in their cell walls, so that the cytoplasm is mixed and diffusion of sugars occurs
Organic material in the phloem is transported up and down the plant
describe root hair and its role
These structures are on the surface of the roots
They provide a large surface area for water to diffuse into the plant
Water enters the plant via the root hairs and then enters the xylem
describe transpiration
Transpiration is the loss of water from a plant through the stomates in leaves
When stomates are open, gases flow in for photosynthesis. However, at the same time, water is lost by evaporation. This water loss is transpiration
As water is lost, more water flows in through the roots
The constant flow of water from roots, to vascular tissue, to leaves and into the air is called the transpiration stream
Some plants have adaptations to reduce transpiration, such as sunken stomates, small leaves or hairy leaves.
what are radio isotopes
are forms of elements which are radioactive can be used to trace biochemical pathways
how can the pathway of radio isotopes be traced
As the radioactive elements take the same pathway as non-radioactive elements, the pathways can be traced using techniques such as photographic paper
Thallium-201 is used when?
in diagnosing damaged heart muscle.
As it will only accumulate in healthy heart muscle, it will reveal areas that need the be treated
