Nutrition and Gas exchange

• Nutrition and gas exchange in plants and animals
• Autotrophs


  Organisms that can produce their own food
• Heterotrophs

  Organisms that cannot produce their own food and must consume other organisms
• Nutrient


  Any material necessary for an organism's growth and maintenance
• Nutritional requirements of plants

  • Water
  • Carbon dioxide
  • Essential nutrients (macronutrients and micronutrients)
• Macronutrients


  • Sulfur (S)
  • Phosphorus (P)
  • Oxygen (O)
  • Calcium (Ca)
  • Potassium (K)
  • Nitrogen (N)
  • Magnesium (Mg)
  • Hydrogen (H)
  • Carbon (C)
• Micronutrients


  • Molybdenum (Mo)
  • Iron (Fe)
  • Cobalt (Co)
  • Manganese (Mn)
  • Zinc (Zn)
  • Boron (B)
  • Chlorine (Cl)
• Symplast route


  Absorption of water and minerals through plasmodesmata

  
• Apoplast route


  Absorption of water and minerals along cell walls

  
• Mycorrhizae


  Mutualistic interaction between a young root and a fungus
• Mycorrhizae


  • The fungus collects sugars and nitrogen-containing compounds from root cells
  • The plant can get some scarce minerals that the fungus can better absorb from the soil

  
• Root hairs


  Slender extensions of specialized epidermal cells that significantly increase the surface area available for absorption
• Root nodules


  Localized swellings in plant roots where bacterial cells symbiotically reside with the plant
• Root nodules


  • The bacteria help fix nitrogen in the plant, and the bacteria may use some organic compounds created by the plant
• Nutritional adaptations by plants

  • Symbiosis of plants and soil microbes
  • Symbiosis of plants and fungi
  • Parasitism
  • Predation
• Calorie


  A unit of energy that indicates how much energy is found in a given amount of food
• Carbohydrates


  Serve as a significant energy source for the cells in the body, usually obtained from grains, cereals, bread, vegetables, and fruits
• Proteins

  Can also be used as a source of energy, but the body primarily uses them as building materials for cell structures, hormones, enzymes, bones, and muscle parts
• Fats

  Used to produce steroid hormones, cell membranes, and other cell structures; also used to insulate nervous tissue and act as a source of energy
• Essential nutrients


  • Essential amino acids
  • Essential fatty acids
  • Vitamins
  • Trace elements or minerals
• Phagocytosis


  Pseudopod formation in Amoeba, for example, involves the engulfment of organic fragments of large particles
• Pinocytosis


  Small vesicles originating from the plasma membrane are used by a cell to absorb extracellular fluid
• Receptor-mediated endocytosis


  Relies on membrane receptor recognition of specific solutes, which are then taken up by the cell via receptor-coated pits
• Gas exchange is the environmental absorption of molecular Oxygen and the discharge to the atmosphere of carbon dioxide
• Gas exchange is often referred to as respiration or respiratory exchange, but it is not confused with cellular respiration
• Oxygen is essential in tissues to carry out aerobic cellular respiration, and ATP will be extracted from nutrients
• To keep the physiological pH of tissues from being too acidic, carbon dioxide must be released. However, in plants, the carbon dioxide emitted as a by-product of cellular respiration can be reabsorbed for the Photosynthesis process
• Respiratory organ/surface


  The portion of an animal's body that exchanges gases with the atmosphere. It must be moist, wide enough, and safe from desiccation to allow for gas exchange
• Respiratory systems


  • Rely on the diffusion of gases down pressure gradients
  • It is possible to calculate partial pressures for each gas in the atmosphere
  • According to Fick's Law, the amount of gas diffusion through a membrane is proportional to the surface area and the partial pressure difference between the two sides and inversely proportional to the membrane's thickness
• Surface-to-volume ratio


  • As an animal grows, the surface area increases at a lesser rate than its volume, making the diffusion of gases into the interior more difficult
  • Flatworms, for example, must have a body design that holds internal cells close to the surface or a mechanism to transfer gases inward
• Ventilation


  The respiratory medium's movement (air or water) over the respiratory surface
• Ventilation in bony fish and humans

  • Bony fish moves the gill covers (operculum) for water carrying Oxygen to flow across the gill
  • Humans move the thorax muscles to expand and contract the chest cavity and move air in and out of the lungs
• Structures for gas exchange in plants

  • Stomata found in leaves
  • Stems' lenticels
  • Aerial root hairs
  • Lateral roots of mangroves or pneumatophores
• Respiratory organs/surfaces in invertebrates

  • Cell membrane/cell surface
  • Integumentary exchange
  • External gills
  • Tracheal system
• Respiratory organs/surfaces in vertebrates


  • External gills
  • Internal gills
  • Lungs
• Lungs


  • Are internal respiratory surfaces shaped like a cavity or sac
  • Lungs have a gaseous exchange membrane
  • Lungs need a circulatory system to carry gases to the rest of the body
  • Bulk flow transports air into and out of the lungs
  • In the inner respiratory surfaces of the lungs, gases diffuse
  • The diffusion of dissolved gases through lung capillaries is allowed by pulmonary circulation
  • Oxygen diffuses for body tissues starting from blood —› interstitial fluid —› cells; the pathway of carbon dioxide is in reverse
  • Both lungs obtain deoxygenated blood from the heart and return oxygenated blood