nervous system U.4 L.1

  • homeostasis is the tendency of the body to maintain a relatively constant internal environment

  • nervous system :

    • purpose : respond to change, high speed communication system, adjustments vie electrochemical messages or hormones

    • two major divisions : central nervous system, peripheral nervous system

  • central nervous system :

    • nerves of the brain and spinal cord

    • most nervous cells are in CNS, responsible for processing, storage, and retrival of information

    • coordinates incoming and outgoing information

  • peripheral nervous system :

    • nerve cells that extend or reside outside the brain and spinal cord

    • transmits info from sensors to CNS and from CNS to the body

    • information between organs

    • two major divisions : somatic, autonomic

  • PNS - somatic nervous system :

    • controls voluntary movements of skeletal muscle, bones and skin

    • sensory nerves carry information towards CNS

    • motor nerves initiate responses and carry information away from CNS, (1 neuron system (myelinated) (neurotransmitter - acetylcholine (ACh)

  • Autonomic nervous system

    • controls involuntary body acitvities

    • controls internal organs, heart, lungs, intestines, etc..

    • parasympathetic (rest and digest) : involuntary actions under normal actions, ex. stimulates the stomach, slows heart rate

    • sympathetic : (flight or fight) : stress responses, ex. increase heart rate, dilate pupils