9.6

Question 1

what is the effect of nicotine on the NS?

Answer 1

• mimics effect of acetylcholine + binds to acetylcholine specific receptors in PoS membranes
• triggers AP in PoS neurone BUT receptor remains unresponsive to more stimulation fir sine time
• high doses - can be fatal as acetylcholine receptors blocked
  OTHER EFFECTS: raised HR + BP; triggers release of dopamine (neurotransmitter) in brain

Question 2

what is the effect of lidocaine on the NS?

Answer 2

• block VG na channels - prevents production of AP in sensory nerves - SO WILL NOT FEEL PAIN
• used as local anaesthetic

Question 3

what is the effect of cobra venom on the NS?

Answer 3

• binds reversibly to acetylcholine receptors in PoS membranes - prevents transmission of impulses across synapses - muscles not stimulated to contract -> paralysis
• if toxin reaches muscles involved in breathing -> death
• CAN in v low conc - relax muscles of trachea + bronchi in severe asthma attacks - save lives