Nervous tissue

• Dendrites - send impulses to cell body
• Myelin sheath insulates the axon so that impulses don't get lost and they can travel quicker
• Nissl bodies manufacture neurotransmitters
• Motor Neuron:

  • Efferent neuron
  • multipolar - has many processes branching off cell body
  • Carries impulse from CNS to effectors

  A) dendrites

  B) Nissl bodies

  C) schwann cell

  D) node of ranvier

  E) axon

  F) terminal branches

  
• Sensory Neuron:

  • afferent
  • unipolar - only 1 process
  • impulse goes from the receptor to the CNS

  A) axon

  B) dendron

  C) schwann cell

  D) Nissl bodies

  E) terminal branches

  
• Interneuron:

  • connects spinal motor and sensory neurons, it transfers signals and communicates making complex circuits
  • multipolar
  • relay
• Synapse: microscopic gap or junction between neurons
• Impulse across a synapse:

  1. Impulse travels down presynaptic nerve
  2. impulse triggers the release of neurotransmitters from synaptic vesicles into synapse
  3. neurotransmitters diffuse across synapse and bind on the receptors of the post synaptic neuron's dendrites
  4. neurotransmitters are either inhibitory (calm down) or excitatory - this triggers a nerve response in the post synaptic neuron
  5. excess neurotransmitters diffuse out of synapse or are taken in by the presynaptic nerve
• Structure of a nerve:

  A) epineurium

  B) perineurium

  C) neuron

  D) endoneurium

  E) blood vessels

  
• Glial cells:

  • helper cells, they support the neurons
  • involved in nutrition and maintenance of nerve cells
• Schwann cell (glial cell):

  • makes up the myelin sheath
• Microglial cells:

  • eliminates microbes and dead cells
• Astrocyte:

  • glial cell that clears excess neurotransmitters and maintains synapses
• Ependymal cells:

  • glial cells that control the production of cerebrospinal fluid