Synapses

Most important characteristic of synaptic transmission is one way conduction

Explanation :

Ref : Sembulingam 6th edition (Table- 141.3)

Explanation : EPSP is confined only to the synapse. It is a graded potential. It is similar to receptor potential and endplate potential. EPSP has two properties: 1. It is nonpropagated 2. It does not obey all or none law. EPSP is not transmitted into the axon of postsynaptic neuron. However, it causes development of action potential in the axon.
Ref : Sembulingam 6th edition (Page- 783)

Explanation : Acetylcholine is the transmitter substance at the neuromuscular junction and synapse. It is also released by the following nerve endings:
1. Preganglionic parasympathetic nerve
2. Postganglionic parasympathetic nerve
3. Preganglionic sympathetic nerve
4. Postganglionic sympathetic cholinergic nerves:
  i. Nerves supplying eccrine sweat glands
  ii. Sympathetic vasodilator nerves in skeletal muscle
5. Nerves in amacrine cells of retina
6. Many regions of brain.

Ref : Sembulingam 6th edition (Page- 789)

Explanation : Presynaptic inhibition is mediated by axoaxonal synapses. It is prominent in spinal cord. Negative feedback inhibition is the type of synaptic inhibition, which is caused by Renshaw cells in spinal cord. Feedforward synaptic inhibition occurs in cerebellum and it controls the neuronal activity in cerebellum. Inhibition of antagonistic muscles when a group of muscles are activated is called reciprocal inhibition. It is because of reciprocal innervation.
Ref : Sembulingam 6th edition (Page- 783, 784)

Neurotransmitter degrading enzyme locate in synaptic cleft

Explanation :

Ref : Sembulingam 6th edition (Table- 141.1)

Neurotransmitter of Fast pain- Glutamate & Substance P for slow pain.

Pain Initiators
• Glutamate - Central
• Substance P - Central
• Brandykinin - Peripheral
• Prostaglandins - Peripheral
• Aspartate
Pain Inhibitors
• Serotonin
• Endorphins
• Enkephalins
• Dynorphin
• GABA
• Glycine

Glycine has both excitatory and inhibitory effects in the CNS. When it binds to NMDA receptors, it makes them more sensitive to the actions of glutamate. Glycine may spill over from synaptic junctions into the interstitial fluid and in the spinal cord; for example, it may facilitate pain transmission by NMDA receptors in the dorsal horn. However, glycine mediates direct inhibition in the brainstem and spinal cord.

Explanation : Normal duration of synaptic delay is 0.3 to 0.5 millisecond. Synaptic delay is one of the causes for reaction time of reflex activity.
Ref : Sembulingam 6th edition (Page- 785)