coordination and response

• Sensory receptors detect changes in the environment or within the body, such as temperature, pressure, pain, taste, smell, light, sound, and touch.
• Nervous system is responsible for communication within the body
• Structure of a nerve cell:

  • Neurons are long, thin, and have branch connections at both ends
  • Adapted to carry electrical impulses from one point to another
• Synapse is the connection between nerve cells where chemicals are released to trigger another electrical impulse
• Central nervous system (CNS) consists of the brain and spinal cord

  • CNS processes sensory information, makes decisions, and sends out orders to the body
  • Receives sensory information from sensory neurons
• Sensory neurons carry information from receptors in the body to the CNS
• Motor neurons carry impulses from the CNS to effectors (muscles or glands) for response
• Reflex arc is a nerve pathway underlying unconscious reflexes

  • Rapid and automatic responses to stimuli to avoid harm
  • Example: touching a sharp object triggers a reflex arc to move the hand away
• Reflex arc steps:

  • Stimuli (e.g., touching a sharp object) detected by receptor cells
  • Sensory neuron carries impulse to the spinal cord (part of the CNS)
  • Relay neuron in the spinal cord transfers impulse to a motor neuron
  • Motor neuron carries impulse to an effector (e.g., muscle) for a response
• A synapse is a gap between two neurons
• Neurotransmitters are chemicals that are released across the synapse
• Neurotransmitters diffuse across the synapse from a high to low concentration