Nervous Control in Humans

Section: Overview of Nervous Control in Humans

  • The nervous system enables humans to react to their surroundings and to coordinate their behaviour.
  • It is made up of two main parts: the central nervous system (CNS) and the peripheral nervous system (PNS).
  • The CNS includes the brain and spinal cord, while the PNS consists of all nerve cells outside of the CNS.

Section: Role of Neurons

  • Nervous control is based on the transmission of nerve impulses along neurons.
  • Neurons, or nerve cells, are specifically adapted to carry these electrical signals around the body.
  • Three types of neurons exist: sensory neurons, relay neurons, and motor neurons.

Section: Steps Involved in a Nervous Reaction

  • The process begins with sensory neurons detecting changes, or stimuli, in the environment.
  • These neurons send signals to the CNS.
  • The CNS interprets these signals and formulates a response.
  • Instructions for this response are sent along motor neurons to an effector (a muscle or gland) which carries out the response.

Section: Understanding Synapses

  • Communication between individual neurons occurs via junctions called synapses.
  • At the synapse, the electrical signal is converted to a chemical one, allowing the nerve impulse to cross the gap.
  • Once the signal reaches the next neuron, it is converted back into an electrical signal.

Section: Voluntary and Involuntary Actions

  • Nervous control can guide both voluntary actions (which are under conscious control) and involuntary actions (those that occur automatically).
  • Voluntary actions are controlled by the somatic nervous system while involuntary actions are controlled by the autonomic nervous system.
  • The ANS has two divisions: the sympathetic and parasympathetic nervous systems. These systems often have opposite effects and allow for fine control of bodily functions.

Section: Nervous Control Key Takeaways

  • The nervous system plays a vital role in coordinating responses based on sensory information.
  • Nerve impulses are carried by neurons and transmitted across synapses.
  • Both voluntary and involuntary actions can be controlled by different divisions of the nervous system.