Fundamentals of the Nervous System and Nervous Tissue

Question 1

What are the functional characteristics of the AXON?

Answer 1

1. conducting region
2. generates nerve impulses
3. transmits impulses along axolemma (neuron cell membrane) to axon terminal
4. neurotransmitters release into extracellular space
5. communicates w/ many diff. neurons at same time
6. lacks rough ER, golgi apparatus

Question 2

What is the myelin sheath?

Answer 2

1. segmented sheath around most long or large-diameter axons
2. formed by Schwann cells (PNS)
3. myelin: whitish, lipid protein

Question 3

What are myelin sheath gaps?

Answer 3

• gaps b/w adjacent Schwann cells
• sites where axon collaterals can emerge
• “nodes of Ranvier”

Question 4

Describe myelin sheaths in the CNS.

Answer 4

1. multiple, flat processes of oligodendrocytes, not whole cells
2. can wrap up to 60 axons at once
3. myelin sheath gap present
4. thinnest fibers are unmyelinated

Question 5

What are multipolar neurons?

Answer 5

• 3 or more processes
  
  • 1 axon, others dendrites
  • most common, major neuron in CNS

Question 6

What are bipolar neurons?

Answer 6

• 2 processes
  
  • 1 axon + 1 dendrite
  • rare

Question 7

What are unipolar neurons?

Answer 7

• 1 process
  
  • extends from cell
  • forms central, peripheral processes
  • together >> axon

Question 8

What are the functional classifications of neurons?

Answer 8

1. sensory
   
   • 2. motor
   • 3. interneurons
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