Nervous System

• two divisions of the nervous system:

  • central nervous system
  • peripheral nervous system
• brain

  • this organ is the body’s control center
• cerebrum

  • controls voluntary movement, intelligence, memory
  • divided into left and right hemisphere
• frontal lobe

  • reasoning and thought
• parietal lobe

  • integrates sensory information
• temporal lobe

  • auditory information
• occipital lobe

  • visual information
• cerebellum

  • in charge of muscle coordination, muscle tone, posture, balance
• thalamus

  • directs sensory impulses to the cerebrum
• hypothalamus

  • regulates temperature, appetite, water, balance, sleep and blood vessel constriction and dilation; emotions
• midbrain

  • for  eye and auditory reflex
• medulla oblongata

  • connects to the spinal cord
  • “center for respiration”
• spinal cord

  • link between brain and nerves in other parts of the body
  • has 4 regions: cervical, thoracic, lumbar, spinal nerves
• spinal nerves can be afferent or efferent
• afferent

  •  carry information from the

  body to the brain
• efferent

  • carry information from the

  brain to the body
• somatic nervous system

  • carrying motor and sensory information
  • made up of nerves that connect to skin, sensory organs, skeletal muscles
  • responsible for nearly all VOLUNTARY movement
  • processes sensory information from external stimuli
• autonomic nervous system

  • in charge of INVOLUNTARY movements
• sympathetic

  •  revs up the body to defend or escape the threat
• parasympathetic

  • brings body back to normal
• negative feedback mechanism

  • reduces or counteracts the effects of a stimulus to restore balance in the body
  • ensures that conditions like temperature, blood pressure, and blood sugar remain within normal ranges.
• positive feedback mechanism

  • amplifies a response until a specific outcome is achieved
  • though less common, it is essential for processes requiring quick, decisive actions
• neurons

  • strings of special cells that carry information through the nervous system
  • basic functional units of structure of the nervous system
• nerve impulse

  •  information carried by neurons
  • high speed signals that pass along the axons of nerve cells
• sensory neuron

  • carries impulse from sense receptors to the brain or spinal cord
• relay neuron

  •  connects sensory and motor neurons
• motor neurons

  • transmits impulses from the brain or spinal cord to a muscle or gland
• axon

  • the long fiber that carries the nerve impulses
• nerve

  • a bundle of axons
• synapse

  • the connection between adjacent neurons
• neurotransmitter

  • chemical secreted into the gap between neurons at a synapse
• reflex

  • a rapid automatic response to a stimulus
• myelin sheath

  • the covering of fatty material that speeds up the passage of nerve impulses
• axon terminal

  • structure at the end of an axon that produces neurotransmitters to transmit the nerve impulse across the synapse
• dendrite

  • the branching filaments that conduct nerve impulses towards the cell
• sense receptor

  • the sense organ that receives stimuli from within and outside the body
• response

  • reaction to a stimulus by a muscle or gland
• cell body

  • the part of the nerve cell containing the nucleus