Excitable Tissue

Question 1

NMDA receptor activation

Answer 1

• both voltage and ligand (glutamate and aspartate) gated
• the pore of the NMDA receptor is blocked by Mg2+ if Em is more negative than -70
• this Mg2+ block is removed if Em becomes less negative than -70
• binding of either glutamate or aspartate is required to open the channel (only occurs when Em is less negative than -70)

Question 2

NMDA blockers

Answer 2

• phencyclidine (PCP)

- ketamine = dissociative anesthetic

Question 3

NMDA receptor function

Answer 3

• non-selective cation channel (Na+, K+ and Ca2+)
• opening this channel results in depolarization
• involved in pain and memory
  1. Memory: involved in long-term potentiation of cells = memory formation
  2. pain: transmission and perception of pain