homeostasis

• Characteristics of living things

  • Growth
  • Reproduction
  • Responsiveness
  • Movement
  • Metabolism
• Growth


  Increase in cell number and size and increase in body size
• Reproduction


  Production of new cells and organisms
• Responsiveness


  Reaction to a change inside or outside of the body
• Movement


  Change in body position or location; motion of internal organs
• Metabolism


  The sum of all chemical reactions in a living system: Energy and nutrient cycling
• Respiration


  Acquiring energy. Most organisms do it by taking in oxygen and giving off carbon dioxide
• Digestion


  Breaking down food into usable nutrients for absorption into the blood
• Circulation


  Moving chemicals and cells through the body fluids
• Excretion


  Removing waste products
• Water


  The most abundant chemical in all living systems, required for many metabolic processes and provides the environment in which most of them take place, carries substances within the organism and is important in regulating body temperature
• Intracellular fluid


  Water inside the cells, along with substances dissolved in it
• Extracellular fluid


  Outside of the cells, including the interstitial fluid (tissue fluid) and the liquid portion of the blood (plasma)
• Chemicals readily exchanged between living systems and the environment

  • Water
  • Carbon dioxide
  • Oxygen
• Food/Nutrients


  Brought in to living systems
• Waste chemicals


  Eliminated from living systems
• Heat


  A form of energy
• The degree of heat present


  Partly determines the rate at which metabolic reactions occur
• Temperature


  A measure of the degree of heat
• Pressure


  An application of force to something
• Atmospheric pressure


  • The force on the outside of the body due to the weight of air above it
• Atmospheric pressure


  • Important in breathing
• Hydrostatic pressure


  The pressure a liquid exerts due to the weight of water above it
• Organisms living underwater


  • Subjected to hydrostatic pressure
• Blood pressure


  A form of hydrostatic pressure that forces blood to flow through blood vessels
• Blood pressure


  • Produced by heart action
• intrecellular & extracellular

  A)

  B)

  C)

  
• Homeostasis


  The body's ability to keep its internal conditions stable, such that its cells can survive
• All cells, whether as part of a tissue, an organ, or an organ system, make some specific contribution to homeostasis
• Unicellular organisms

  Single-celled organisms
• Most of Earth's residents are unicellular
• Bacteria


  The most ancient and abundant unicellular organisms, whose cells do not have membrane-bound organelles
• Amoeba

  • Some unicellular organisms have organelles that are as complex as our own
  • It survives and reproduces as long as its lake or pond environment is of a tolerable temperature and composition
  • It can obtain food
  • It has a limited ability to move and depends upon the conditions in its lake or pond environment to stay alive
• Adult humans are composed of over 30 trillion cells that maintain their own environment—our bodies
• Our cells, as parts of organs and organ systems, interact in ways that keep this internal environment relatively constant, despite an ever-changing outside environment
• Homeostasis


  The process of maintaining a relatively constant internal environment despite changes in the external environment
• Homeostasis is so important that it requires most of our metabolic energy
• Interstitial fluid

  The fluid that bathes cells in the body
• The interstitial fluid is in equilibrium with the composition of the blood plasma, so both contribute to the internal environment
• A simple blood test can provide important information about what is going on in the body's internal environment