Nervous System (book & ppt)

• peripheral nervous system consist of all nervous tissue outside the CNS, including nerves and ganglia
• The sensory division of the PNS conducts action potentials from sensory receptors
• The neuron that transmit action potentials from the periphery to the CNS called sensory neurons
• The motor division of the PNS conducts action potential from CNS to effector organs
• The neurons that transmit action potentials from the CNS toward the periphery called motor neurons
• Skeletal muscle is voluntarily controlled

  Cardiac and smooth muscle is involuntary controlled
• Somatic Nervous System transmit action potentials from the CNS to Skeletal muscle
• Autonomic nervous system transmits action potentials from the CNS to cardiac muscle, smooth muscle and gland.
• The enteric nervous system is a unique part of the peripheral nervous system
• the enteric nervous system can function without input from the CNS or other parts of the PNS
• Two types of cell that make up nervous system

  1. neurons
  2. glial cell
• neurons receive, stimuli, conduct action potentials to other neurons or effector organs.
• cell body contains a single nucleus
• axon is a single long cell process extending from the neuron cell body
• the area where the axon leaves the neuron cell body is called the axon hillock
• axon remain branch and unbranched to form collateral axon
• multipolar neurons have many dendrites and a single axon
• bipolar neurons have one dendrite and one axon
• pseudo-unipolar neurons have a single process extending from the cell body
• Dendrites are shorts, often highly branching cytoplasmic extensions that are tapered from their base
• Glial cells also known as neuroglia
• glial cells are the supportive cells of the CNS and PNS, meaning this cells do not conduct action potentials.
• Glial cells enhance neuron function and maintain normal conditions within nervous tissue
• Astrocytes serve as the major supporting cells in the CNS
• Ependymal cells line the fluid-filled cavities within the CNS; epithelial like
• Microglia act as immune cells of the CNS; small mobile cells
• Oligodendrocytes provide an insulating material that surrounds axons
• Schwann cells provide insulating material around axons
• Satellite cells are found around the cell bodies of certain neurons of the PNS
• Schwann cell- single cells surrounding axons

  Satellite cell- single cells surrounding cell bodies
• Nervous system is a group of tissues composed of highly specialized cells possessing in the characteristics of excitability and conductivity
• Peripheral Nervous System:

  1. Cranial nerves : 12 pairs
  2. Spinal nerves : 31 pairs
  3. autonomic nervous system
• Somatic efferent innervating somatic structure like skeletal muscles
• visceral efferent are involuntary structures like smooth muscle, cardiac muscles and glands
• Neurons is the active conducting elements
• Neuroglia is the supporting elements
• Neuron is the basic unit of NS which conducts electrical impulses from one part of the body to another
• Dendrites transmit impulses toward the cell body
• Axon is conducting impulses away from the cell body
• Synapse is point of connection between neurons