Exchange Surfaces

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    Created by
    Khads <3

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    Cards (91)

    • What are the six factors affecting the rate of simple diffusion?
      + temperature
      + concentration gradient
      + surface area of membrane (SA: V)
      + distance of the diffusion path (thickness of exchange surface)
      + size of particle
      + chemical nature of particle
    • How does the Planarian flatworm get its oxygen and nutrients?
      + relies solely on diffusion from surrounding environment for oxygen and nutrients
    • How is diffusion different in a flatworm compared to a gorilla?
      + flatworm surface creates a short diffusion distance so oxygen can diffuse though and reach all cells
      + gorilla has too many layers of cells i.e. diffusion path too deep
      + oxygen would be used by outer layers and not reach those deep inside
    • Which organisms need an exchange surface?
      organisms with more than two layers of cells as diffusion would be too slow to meet needs
    • What is an exchange surface?
      a specialised area that is adapted to make it easier for molecules to cross from one side of surface to other
    • Which factors affect the need for an exchange surface?
      + number of layers of cells
      + size (i.e. greater than two layers of cells thick)
      + SA: V
      + level of activity
    • How does SA: V affect the need of an exchange surface?
      + the larger SA: V of an organism, the easier exchange of substances by diffusion
      + multicellular organisms have small SA: V so require specialised exchange systems
    • How does the level of activity affect the need for an exchange surface?
      + to move, animals must release energy from food by aerobic respiration using oxygen
      + more active on animal, greater need for good supply of oxygen and nutrients
      + greater need for good transport system (exchange surface)
    • What are the reasons for exchange systems?
      + large multicellular organisms have small SA:V
      + cells in centre of organism would not receive any materials if multicellular organisms only relied on diffusion
      + high metabolic rate in multicellular ogranism (especially if generating body heat
      + need to exchange lots of materials quickly
    • What are the features of good exchange surfaces?
      + large SA
      + short diffusion distance (thin)
      + maintain a steep concentration gradient (e.g. good blood supply)
    • How does a large surface area make an exchange surface good?
      + provides more space for molecules to pass through
      + if the walls of the alveoli have broken down, this reduces O2 absorption and causes breathlessness (emphysema)
    • How does a short diffusion distance make an exchange surface good?
      + thin, permeable barrier reduces diffusion distance
      + improves efficiency e.g. one cell thick in alveolus
    • What are the barriers to oxygen and carbon dioxide in the alveolus?
      alveolar membrane and capillary membrane
    • How is there a steep concentration gradient in the alveoli?
      + large capillary network surrounding alveoli
      + give good blood supply i.e continuous flow
      + brings fresh O2 and removes CO2 to maintain a steep concentration gradient
      + good ventilation also increases the efficiency of the lungs
    • How are fish gills good exchange surfaces?
      + large SA
      + short diffusion distance (thin)
      + good blood supply/ large network of capillaries to maintain a steep concentration gradient
      + well-ventilated as fresh water will constantly pass over them
    • What is the gas exchange surface and transport system in mammals?
      + alveoli and capillaries as a gas exchange surface
      + transport system is blood
    • Which structure allows locusts to obtain oxygen?
      pores along the thorax and abdomen, from which air enters and exits called spiracles
    • Why do insects have a gas exchange system?
      + insects have evolved a system
      + deliver oxygen directly to respiring cells
      + remove carbon dioxide in the same way
    • Why would condensation form on a glass jar when an insect is placed in a closed jar?
      + condensation forms on a glass jr as fireflies carry out gas exchange
      + insects need to maximised gas exchange efficiency while minimising water loss
    • How is the trachea adapted for gas exchange in an insect?
      + spiracles open into trachea
      + trachea shape maintained by reinforcing spirals of chitin
      + little gas exchange occurs here
      + carry air into the body
      + trachea: ~ 1 mm diameter
    • How is are tracheoles adapted for gas exchange in an insect?
      + trachea branch into narrower tracheoles: ~ 0.6-0.8 micrometers diameter
      + each tracheole is a fully permeable elongated cell (no chitin)
      + extends between respiring cells
      + end is fluid-filled
    • Why are the numerous tiny tracheoles important in insects?
      provide a very large SA for gas exchange
    • How is air supplied directly to respiring tissues in insects?
      + air moves along tracheal system by diffusion
      + oxygen dissolves in moisture in tracheal wall
      + diffuses into respiring cells
      + tracheole fluid in tracheole prevents diffusion
    • How is a concentration gradient maintained in the insect gas exchange system?
      + diffusion in tracheal system driven by concentration gradients
      + cellular repsiration reduces the concentration of oxygen
      + increases the concentration of carbon dioxide at the end of tracheoles
      + creates a concentration gradient
      + oxygen diffuses from atmosphere towards cells
      + carbon dioxide diffuses from cells towards the atmosphere
    • Which tracheoles does gas exchange occur in?
      tracheoles that are air filled
    • How does the insect gas exchange system adapt to increases in activity?
      + when insects are most active, muscle cells produce lactate through anaerobic respiration
      + lactate lowers the water potential of muscle cells, so water moves from tracheoles to muscle cells by osmosis
      + this decreases the volume of liquid in tracheoles
      + draws air further into them
      + increases the rate of diffusion and allows insects to obtain oxygen more rapidly
    • How does the volume of tracheal fluid change in resting tissue?
      + more tracheal fluid and less air in tracheole
      + decrease in the surface area of tracheole air in contact with respiring cells
      + less oxygen absorbed
    • How does the volume of tracheal fluid change in active tissue?
      + less tracheal fluid and more air in tracheole
      + increases the surface area of tracheole air in contact with respiring cells
      + more oxygen is absorbed
    • How is gas exchange in insects controlled?
      by the opening and closing of spiracles
    • What must be done to meet the energy demand of active animals?
      + for active animals with greater energy demand
      + alternative methods used to increase levels of gas exchange
    • What is the mechanical ventilation of the tracheal system?
      + alternative method to increase levels of gaseous exchange
      + insects use rhythmic abdominal movements (abdominal pumping)
      + change volume of bodies and pressure in tracheae and tracheoles
      + draw in one end of body and force out from other - mass transport
    • What is the ventilation of sacs in insects as an alternative method to increase gaseous exchange?
      + collapsible air sacs (enlarged tracheae)
      + act as air reservoirs
      + increase amount of air movement through tracheal system
      + thorax and abdomen move to inflate and deflate them
    • What is the thorax?
      the chest region of insect
    • What is the abdomen?
      the furthest region from the head of an insect
    • What is the trachea of an insect?
      larger tubes transporting air from the spiracle towards respring tissue
    • What is the tracheal fluid in an insect?
      reduces the surface area for gas exchange in tracheoles
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