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