Group 2

• Gas exchange


  The process by which organisms require oxygen for metabolism and remove carbon dioxide
• All living organisms obtain energy by metabolizing compounds such as carbohydrates
• Respiration is the process by which organisms require oxygen for metabolism
• Carbon dioxide gas is produced and must be removed from the body of animals
• In plants, carbon dioxide, a waste product of respiration, is needed for photosynthesis
• Animals have to take in oxygen and expel carbon dioxide in order to survive
• Animals


  • Need to take in oxygen and expel carbon dioxide
  • Oxygen and carbon dioxide move by diffusion across moist membranes
  • Breathing is a mechanical process by which oxygen is taken in and carbon dioxide is released
  • The exchange of gases through inhalation and exhalation is called respiration
• Ways in which animals obtain oxygen


  • Through the moist surface directly into the body (e.g. amoeba, flatworm)
  • Through a thin, moist body wall of blood vessels (e.g. earthworm)
  • Through spiracles (opening on the thorax) or a tracheal system to a system of ducts to the tissues (e.g. insects)
  • Through moist lungs surface to blood vessels (e.g. land snail, land vertebrate)
• Respiratory system


  Its function is to exchange oxygen and carbon dioxide between the air and the cells
• Types of gas exchange systems used by animals


  • Skin system
  • Gills system
  • Tracheal system
  • Lung system
• Skin system


  • Animals that live in moist environments like worms and amphibians use their moist body surface to breathe in oxygen
  • Capillaries or tiny vessels lie just below the skin to facilitate gas exchange

  
• Gills system


  • Fish and other aquatic animals use their gills to take up the dissolved oxygen from water
  • Gills are thin tissue filaments that are highly branched and folded
  • Oxygen diffuses across the thin membranes of the gills into the bloodstream, and carbon dioxide leaves through the gills
• Tracheal system


  • Insects, such as grasshoppers and spiders, use their tracheae to facilitate gas exchange
  • Tracheae consist of air tubes called spiracles forming network in the bodies of insects
  • Spiracles connect to the tubular network allowing oxygen to pass into the body and regulate the diffusion of CO2 and water vapor

  
• Lung system


  • A pair of organs divided into small chambers filled with capillaries called lungs are found inside the cavity of land animals such as humans
  • The tube that connects the nose and mouth to the lungs is called trachea
  • Air is inhaled through the nasal cavity, passes through the pharynx and the larynx to the trachea

  
• Plants exchange their gases with the environment in a straightforward way
• Green plants need a supply of carbon dioxide and a means of disposing oxygen for photosynthesis
• Plant leaves


  • Consist of stomata that allow gas exchange between the surrounding air and the photosynthetic cells inside the leaf
  • Stomata regulate CO2 uptake for photosynthesis and are the major avenues for the evaporative loss of water
• Plant roots


  • Take oxygen from the air that is present in between the particles of soil
  • Root hair is in direct contact with the soil, allowing oxygen to diffuse in and carbon dioxide to diffuse out
• Plant stems


  • Have lenticels in the bark that allow gaseous exchange of respiratory gases between air and living cells of the woody stem
• Endocrine system


  A messenger system in an organism comprising feedback loops of hormones that are released by internal glands directly into the circulatory system and that target and regulate distant organs
• Regulation of the endocrine system


  • Maintained by negative feedback mechanisms that work to maintain homeostasis
  • The concentration of hormones, and how they affect other body systems, is controlled in this manner