gas exchange

SURFACES (reliant on effective diffusion)

gets oxygen in to the mitochondria and carbon dioxide out

RESPIRATION

moist

large surface area

short diffusion distance (thin membrane)

high concentration gradient

MAMMALS

  1. nose hairs to filter (mouth doesnt filter)
  1. trachea windpipe connecting air from nose/mouth to lungs
  1. mammal will inhale and oxygen will travel to left and right bronchi. the bronchus will then divert into smaller tubes known as bronchioles
  1. oxygen will then travel to alveolar ducts and then will meet a cluster of grapelike structured known as alveoli (structural adaptation)

ecological niche

occurs in the mitochondira

cellular process that produces an organism's energy

the movement of oxygen from the outside environment to the cells within tissues, and the removal of carbon dioxide

co2 released during exhaling, if it doesn't get removed, it can cause toxic build up in blood

no gas exchange = no oxygen to reach mitochondria, hence no respiration

larger surface area provides more space for this diffusion to occur per unit of time

gases need to dissolve in a thin film of moisture on the exchange surface (for effective diffusion) . allows oxygen and carbon dioxide molecules to dissolve and move across the surface, speeding up gas exchange.

allows for faster and more efficient diffusion of gases. rapid movement ensures that the exchange of gases an occur quickly enough to meet the organism's metabolic demands.

so that gases can get in and out of the cells quicker and more efficiently. gases don't have to travel far to move between the external environment and the internal tissues of an organism.

mammals are large + active

need efficient gas exchange system - cannot rely on diffusion alone to transport oxygen to all cells

gas exchange surfaces: lungs and a system of blood vessels

ring shaped cartilage to prevent it from collapsing

the branching out of these tubes maximises surface area for optimised gas exchange

hence more opportunities for oxygen to diffuse in and carbon dioxide to diffuse out

thin walled sacs where the exchange exchange of oxygen and co2 between the air take place in the bloodstream

there are millions of alveoli in the lungs, so combined surface area will maximise gas exchange efficiency

alveoli are coated by a chemical substance known as surfactant which keeps the gas exchange surface moist. this prevents the system from collapsing when the mammal undergoes ventilation (a behavioural adaptation that allows an animal to intake deep breaths to diffuse larger amounts of oxygen)

these thin-walled sacs provide a short diffusion distance due to its thin membrane. reduces diffusion distance from the air carrying oxygen and haemoglobin. the alveoli are enveloped bycapillaries

haemoglobin is a red pigment found in red blood cells (found in the capillaries) it is a physiological adaptation that readily binds to oxygen in the lungs and transports it efficiently throughout the body. it amplifies the ability of the body to carry huge amounts of oxygen

ventilation is a behavioural adaptation in which the bear iis able to take deep breaths to allow for diffusion of large volumes of oxygen for optimised gas exchange.
when the bear undergoes strenuous activity such as swimming and hunting, it is more efficient to ventilate in order to meet its high energy demands. therefore, when ventilation occurs it ensures a continuous flow of oxygen throughout the body. this hightens the concentration gradient of oxygen in the alveoli and lowers the concentration gradient of carbon dioxide.

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FISH

fish live in water

  • water is dense and viscous which makes it harder for the fish to ventilate as it resists flow. this means that the salmon will require more energy to ventilate to meet its metabolic demands
  • water is 800x more dense than air and contains only 2-3% of oxygen concentration
    this means that to breathe in its aquatic environment, fish will need to extract oxygen from the air constantly. this hwoever is very energy demanding requiring the salmon to have an efficient gas exchange system
  • salmon must also migrate and hunt for prey, which will require strenuous swimming, making them active and needing large amounts of energy.

the fish gas exchange surface is in the gills where because of the gills, fish can extract up to 80% of oxygen from the water

surface area
gills have gill filaments supported by a bony arch. these contain many tiny thin folds called lamellae which maximise the surface area as they project from the gill arch. this increases the space allowing more diffusion to occur between oxygen and the bloodstream, this then increases the rate of gas exchange

short diffusion distance
the thin folds of the lamallae are also enveloped by thin capillaries. these thin membranes shorten the travel distance between the gases in and out of the blood stream. this means diffusion is faster and increases the rate of gas exchange. furthermore, the salmon's red blood cells contains haemoglobin which bind to oxygen and allow the fish to have the ability to cary large amounts of oxygen to the entire body

moist
the salmon's gas exchange system is external and due to its aquatic habitat/ecological niche, the fish's gas exchange system is always moist. therefore, no special adaptation is required to keep its ge surface moist for diffusion and ge

favourable concentration gradient:
the fish ventilates through its buccal cavity. however, due to the fish' having a unidirectional flow for its ventilation system, when the buccal cavity is open water enters through, however, when it is closed, water is forced out the fish through the gills. therefore, for gas exchange to adapt to the water's density, the fish will need a unique system to maximise their oxygen concentration intake.

this is done through the counter-current exchange system. water that flows through the gills for oxygen to be extracted will move in the opposite direction to the bloodstream's flow in the capillaries. when fresh water filled with oxygen comes in, the oxygen will diffuse into the bloodstream due to the different in concentration (because of their opposite direction flow). therefore, water that flows in through the lamallae will lose some of the oxygen concentration to the blood. so that oxygen that comes in water decreases in concentration towards the end. this maintains a favourable concentration gradient and maximises gas exchange. this ensures that the fish's gas exchange is efficient enough to meet its high energy demands from migration and hunting despite the density and viscocity of water.

INSECTS

terrestial, active

  • colonies + queen = constant hunting for food/prey
  • pollinators
  • need rapid and continous flow of oxygen for flight muscles

oxygen content higher in air

  • faster diffusion, easier ventilation
  • good because bees are small in size and rely solely on diffusion to transport oxygen to respiring cells
  • bees do not have lungs or any circulaorty systems that use haemoglobin to carry oxygen to all the cells
  • bees also do not have a vessel for oxygen transport making their gas exchange system inefficient
  • run risk for drying out cus of constant evaporation on land
  • therefore they need efficient gas exchange system to meet metabolic needs. they do this through special adaptations

REQUIREMENTS

pathways

  • bees can rely solely on diffusion, no lungs so oxygen diffuses through a tracheal system
  • oxygen enters and co2 exits the bee's body through tiny holes on the sides of its thorax and abdomen called spiracles.
  • spiracles lead to tiny tubes called trachea which divert into smaller tubes called tracheoles
  • tracheoles lead directly to the respiratory tissues of the bees
  • small fluid at end of tracheoles which allow the gasses to dissolve through in order to diffuse into and out of the bee's cells

SURFACE AREA

  • air travels down the trachea. these trachea branch out extensively, forming a network of tubes that penetrate their respiratory tissues
  • this branching out maximises the surface area of the gas exhange surface

SHORT DIFFUSION DISTANCE

  • tracheoles end directly to the respiratory cells
  • no transport system is required for oxygen as a result so it saves space, weight energy
  • less energy is required to diffuse oxygen due to its short distacne which makes diffusion ocur faster, increasing gas exchange efficiency
  • tracheols are also thin, providing short membrain

MOIST

  • bees run the risk of drying out their respiratory systems on land
    • if they aren't excreting at all, water loss can occur
    • to maintain moisture in ge surface, bees can control the opening and closing of their spiracles using muscle contractions (a behavioural adaptation)
    • t his is crucial during the day/drought conditions as it ensures diffusion can occur successfully.
    • small amount of fluid at the end of tracheoles also keep the surface moist for gasses to dissolve and diffuse in and out of respiratory system
    • tracheole walls are also moist which allow oxygen to dissolve through surrounding fluid for optimised diffusion and hence, increased rate of gas exchange

HCG

  • bees have air sacs which can be controlled/relaxed for continuous air flow in the trachea, maximising the bee's oxygen intake for strenuous activity.
  • this increases ventilation and maintains a steep concentration gradient
  • as a result oxygen concentration is higher in the incoming air, allowing for rapid movement of oxygen into the bee's respiratory system.