M2, T2: Cells of the Nervous System

Question 1

Neurons

(Function, structure)

Answer 1

• Send and receive messages in either a chemical (i.e. neurotransmitter) or electrical (i.e. action potential) form
• Consists of:
  
  • Cell body or soma → where nucleus & organelles are located
  • Dendrites → recives signals from other neurons or sensory receptors
  • Axon → carries nerve impulse towards another structure
  • Myelin sheath → insulates neuron to speed up neural impulse

Question 2

Glial cells

Answer 2

• Nourish, protect and physically support neurons
  1. Schwann cells
  2. Oligodendrocytes
  3. Astrocytes
  4. Ependymal cells

Question 3

Structural classifications of neurons

Answer 3

• Multipolar → >2 processes extending from the soma
• Bipolar → 2 processes extending from the soma
• Pseudounipolar → Looks like 1 process, but there are 2 extending from the soma

Question 4

Functional classifications of neurons

(In the spinal cord)

Answer 4

• Sensory (aff.) neurons
  * Action potential travels towards CNS
  * Mostly pseudounipolar; some bipolar
• Motor (eff.) neurons
  * Action potential travels away from PNS
  * All multipolar
• Interneurons:
  * Only in CNS
  * All multipolar
  * Process incoming information from sensory neurons

M(otor) = m(ultipolar)

Question 6

Myelin sheath

Answer 6

• Made my oligodendrocytes and Schwann cells

Question 7

Sensory receptors

Answer 7

• 3 main types:
  
  • Encapsulated endings
  • Free ‘nerve’ endings (bare dendrites)
  • Specialised receptor cells

Question 8

Nerve

Answer 8

• Organ
• Close to none in CNS
• Comprises the axons and myelin sheaths of multiple neurons, connective tissue sheaths (bind the axons together), blood vessels (supplies these cells/tissues)