Neurotransmission in the Nervous System Flashcards
What are the 4 main excitatory neurotransmitters used in the CNS?
Glutamate
Noradrenaline
5-HT
Dopamine
What do primary afferents in the CNS release as neurotransmitter?
Glutamate (excitatory)
What are the 2 main inhibitory neurotransmitters used in the CNS?
GABA (main inhibitor in brain)
Glycine (main inhibitor in spinal cord)
Define ‘neuromodulator’
Any of various substances that influence the function of neurons but do not act as neurotransmitters
Describe the characteristics of glutamate as a neurotransmitter
Fast neurotransmission and acts as neuromodulator by acting on G-protein coupled receptors
Give examples of 3 neuromodulators that are not fast neurotransmitters
Co-transmitter neuropeptide substance P, prostaglandin E2 and bradykinin
What mechanisms are involved in the termination of neurotransmitters?
Transmitter breakdown and reuptake using selective transport mechanisms
Provide an example of neurotransmitter breakdown
Acetylcholine esterase (synaptic cleft of NMJ)
Provide an example of neurotransmitter re-uptake
Glutamate is taken up into the pre and post-synaptic terminals and into the adjacent glia, terminating its neurotransmitter action. The transporter uses energy stored in the transmembrane Na+ gradient to take up the glutamate.
In nerve conduction studies, what does an M-wave indicate?
Direct activation of motor units by electrical stimulation
In nerve conduction studies, what does an H-reflex indicate?
Electrical equivalent to stretch reflex (as also stimulated Ia afferents)
In nerve conduction studies, what does an F-wave indicate?
Antidromic motor nerve action potentials bouncing off the a-motor neurones
What abnormalities can be detected with nerve conduction studies?
- Peripheral demyelination
- Lambert-Eaton myasthenic syndrome
- Myasthenia Gravis
- Carpal tunnel entrapment
