NERVOUS SYSTEM

• 3 types of neurons:

  • Sensory Neurons
  • Motor Neurons
  • Interneurons
• Sensory Neurons carry impulses from inside and outside the body to the brain and spinal cord
• Interneurons are found within the brain and spinal cord, process incoming impulses, and pass them on to motor neurons
• Motor Neurons carry impulses away from the brain and spinal cord
• Nervous system is composed of nervous tissue, which contains two types of cells:

  • Nerve cells or neurons
  • Supporting cells or neuroglia (glia)
• Nervous system contains millions of neurons that vary in their shape, size, and number of processes
• The junction site of two neurons is called a "synapse or relay". In the synapses, the membranes of adjacent cells are in close apposition (contact, not continuity)
• Nervous system is the major controlling, regulatory & communicating system in the body
• Nervous system is the center of all mental activity including thought, learning, behavior, and memory
• Together with the endocrine system, the nervous system is responsible for regulating and maintaining homeostasis
• Functional Organization has two subdivisions:

  • Sensory or afferent division
  • Motor or efferent division
• Sensory or afferent division consists of nerve fibers that convey impulses from receptors located in various parts of the body to the CNS
• Motor or efferent division consists of nerve fibers that convey impulses from the CNS to the effector organs, muscles, and glands
• Both sensory and motor subdivisions are further divided into:

  • Somatic division
  • Autonomic division
• Somatic division is concerned with skin, skeletal muscles, and joints
• Autonomic division is concerned with the visceral organs
• Structural Organization has two subdivisions:

  • Central Nervous System (CNS)
  • Peripheral Nervous System (PNS)
• Central Nervous System (CNS) consists of Brain & Spinal cord, occupies the dorsal body cavity, and acts as the integrating and command centers
• Peripheral Nervous System (PNS) consists of nerves, ganglia, receptors, and is the part of the nervous system outside the CNS