nervous system and reflex arc

• Nervous system and communication:

  • Large multicellular organisms like humans rely on the nervous system to coordinate behavior and respond to surroundings
  • The nervous system and the endocrine system are the two organ systems responsible for communication within the body
• Structure of a nerve cell:

  • Neurons are adapted to carry electrical impulses from one point to another
  • Neurons are long, thin, and have lots of branch connections at either end to pass messages effectively
• Synapse and communication between nerve cells:

  • Synapse is the connection between nerve cells where chemicals are released to trigger another electrical impulse
  • Electrical impulses travel from one neuron to another through synapses
• Central nervous system (CNS):

  • Made up of the brain and spinal cord
  • Responsible for processing sensory information, making decisions, and sending out orders to the body
  • Receives sensory information from receptors in the body through sensory neurons
• Motor neurons and effectors:

  • Motor neurons carry impulses from the CNS to effectors (muscles or glands)
  • Effectors can be instructed to contract or release hormones based on the impulses received
• Reflex arc:

  • Nerve pathway underlying unconscious reflexes
  • Rapid and automatic responses to stimuli to avoid harm
  • Example: touching a sharp object triggers a reflex arc involving receptor cells, sensory neurons, relay neurons, and motor neurons to move the hand away from the object