Pharmacology

Question 1

What are the different type of axons?

Answer 1

Question 2

A delta vs C fibres

Answer 2

Question 3

How are the periphery, spinal cord and brain involved in pain signal?

Answer 3

Periphery → pain signal generation
̶ Nociceptors – free nerve endings
• Noxious stimuli: high threshold
• Polymodal: Mechanical, thermal, chemical
̶ Ad fibres: Sharp / fast / localised / prickly
̶ C fibres: Dull / slow / diffuse / throbbing
• Spinal cord → pain signal transmission
̶ Spinothalamic tract
• Afferents from Ad & C fibres
• Multiple synapses in dorsal horn (1st/2nd order)
• (Lateral/Neo- & Anterior/Paleo- is obsolete)
• Brain → pain signal perception
̶ Thalamus (relay centre)
̶ Cortex
̶ Limbic system

Question 4

What are the different types of nerve tissue?

Answer 4

1. White matter (substantia alba)
   a. White = myelin
   b. Myelinated axon tracts
   c. Outer surface of spinal cord
2. Grey matter (substantia grisea)
   a. Grey = neuronal cell bodies and capillaries
   b. Inner part of spinal cord
   c. Outer surface of cerebrum/cerebellum
3. Black matter (substantia nigra)
   a. Nigro-striatal dopaminergic pathway

Question 5

What is the pharmacology of prostaglandins?

Answer 5

Question 6

What is the physiology of prostaglandins?

Answer 6

Question 7

COX1 vs COX2

Answer 7

Question 8

What is the sequence of events in an action potential?

Answer 8

Depolarisation
1. m gate opens rapidly in response to voltage →
2. m gate open + h gate open = VGNaC open →
3. Na+ influx → further depolarisation (Em = +30 mV)
4. Action potential is propagated

Repolarisation
1. h gate closes slowly in response to SAME voltage →
2. m gate open + h gate closed = VGNaC inactivated →
3. No Na+ current
4. ↑K+ efflux → repolarisation

Reactivation of VGNaC
1. m gate closes rapidly in response to voltage
2. m gate closed + h gate closed = VGNaC closed but
‘reactivating’

Restoration of VGNaC to activatable state
1. h gate opens slowly in response to SAME voltage
2. m gate closed + h gate open = VGNaC closed (‘resting’)

Resting Membrane Potential restored
1. VGNa+ channels closed (‘resting’) and activatable
2. Intra- and extracellular concentrations of Na+ and K+
do not change greatly during the action potential
3. Sodium pump preserves Na+/K+ chemical gradient