necessary life functions, survival needs, homeostasis, and feedback mechanisms

necessary life functions

• maintain boundaries

• movement

  • locomotion

  • movement of substances

• responsiveness

  • ability to sense changes and react

• digestion 

• breakdown and absorption of nutrients

• metabolism– chemical reactions within the body

  • break down complex molecules into smaller ones

  • build larger molecules from smaller ones

  • produces energy

  • regulated by hormones

• excretion

  • eliminates waste from metabolic reactions

  • wastes may be removed in urine or feces

• reproduction

  • occurs on cellular level or organismal level

  • produces future generation

• growth 

  • increases cell size and number of cells

survival needs

• nutrients 

  • chemicals for energy and cell building

  • includes carbohydrates, proteins, lipids, vitamins, and minerals

• oxygen

  • required for chemical reactions

• water

  • 60 to 80 percent of body weight

  • most abundant chemical in the human body

  • provides for metabolic reactions

  • helps stabilize body temperature

• stable body temperature

  • 37°C (98.6°F)

• atmospheric pressure

  • must be appropriate for gas exchange

homeostasis

• homeostasis– maintenance of a stable internal environment

  • a dynamic state of equilibrium, balance

  • necessary for normal body functioning and to sustain life

  • if the balance is maintained, the person is healthy and everything is functioning properly

• homeostatic imbalance

  • a disturbance in homeostasis resulting in disease

    • dis-ease; without ease

      • imbalance of acids, bases, enzymes, immune system cause people to get sick

maintaining homeostasis

• control center

  • determines set point

  • analyzes information

  • determines appropriate response

• effector

  • provides a means for response to the stimulus

feedback mechanisms

• negative feedback

  • includes most homeostatic control mechanisms

  • shuts off the original stimulus, or reduces its intensity

    • turns off, decreases when in excess

  • works like a household thermostat

    • ex.) in your stomach, when the stomach acid gets to a certain level, it’s going to trigger and shut off acid production if/when there’s no food to digest

• positive feedback

  • increases the original stimulus to push the variable farther

    • turns on, increases when there’s not enough 

  • in the body, this only occurs in blood clotting and during the birth of a baby