1. Drugs of the Peripheral Nervous System

2. The Nervous System Review

3. Organization of the Nervous System
Central nervous system (CNS)
Brain and spinal cord
Peripheral nervous system (PNS)
Neurons outside the CNS
Sensory division
Afferent fibers transmit impulses from receptors to CNS
Motor division
Efferent fibers transmit impulses from CNS to effector organs

4. Relationship between motor and sensory fibers of the PNS and the CNS

5. Autonomic Nervous System
Sympathetic
Fight or flight, stress
Excitatory effects elicited by norepinephrine activating beta receptors
Inhibitory effects elicited by activation of alpha receptors

6. Parasympathetic Rest and digest
Digestive system activated, heart rate inhibited, blood vessels dilated
Vagus nerve primarily responsible for activating parasympathetic responses

7. Fig. 8.39

8. Autonomic Neurotransmission
Two neurons
Presynaptic and postsynaptic
Presynaptic from the brain to autonomic ganglia
Acetylcholine released from prenaptic neuron across synapse to activate postsynaptic neuron
Postsynaptic neurons release norepinephrine (sympathetic) or acetylcholine (parasympathic) at the effector organ

10. The Synapse
Fig. 8.13

11. Neurotransmitters --packaged in synaptic vesicles.
Nerve endings of the ANS secrete:
Acetylcholine (ACh)--Cholinergic neuron
Parasympathetic effector
Norepinephrine (NE)--Adrenergic neuron
Sympathetic effector

12. If stimulatory, Na+ channels will open
Neurotransmitters diffuse across the synaptic cleft and bind to receptor on the post-synaptic membrane
This can cause membrane channels (Na+, K+, or Cl-) to open or close depending on the neurotransmitter
If stimulatory, Na+ channels will open
If inhibitory, K+ or Cl- channels will open
Cell becomes more negative, hyperpolarized

13. Catecholamines Norepinephrine and epinephrine
Norepinephrine primarily neurotransmitter
Epinephrine primarily hormone
Primarily concerned with sympathetic transmission
Released at synaptic cleft and bind to alpha or beta receptors

14. Acetylcholine Responsible for all parasympathetic neurotransmission
Binds to mucarinic receptors at the end organ

15. Ganglionic transmission
Transmits both parasympathetic and sympathetic preganglionic signals to nicotinic receptors (Nn)
All ganglionic transmission is cholinergic (acetylcholine)
Drugs that block ganglionic transmission block either parasympathetic or sympathetic depending on which is active
This is a paradox many have a problem grasping

16. Fig. 8.39

17. Neuromuscular transmission
Somatic motor neurons release acetylcholine at neuromuscular junction
Acetycholine diffuses across synapse and binds to muscular nicotinic receptors (Nm) causing sodium influx

18. The Neuromuscular Junction

19. Central Neurotransmission
Acetylcholine the primary neurotransmitter in the brain
Works by interaction with muscarinic receptors

20. Neurotransmitter degradation
Neurotransmitters which fail to bind to a post-synaptic receptor are
degraded by enzymes (acetylcholinersterase)
Taken up into the presynapse and recycled
Diffuse out of the synapse

21. Receptors 2 types of cholinergic receptors: Nicotinic Muscarinic
Preganglionic sympathetic and parasympathetic (Nn)
Also neuromuscular somatic motor (Nm)
Muscarinic
parasympathetic
2 types of adrenergic receptors:
Alpha
Generally inhibitory
Beta
Generally excitatory

22. Neurotransmission Enhancers
Receptor agonists
Compound which bind to the receptor and activate
Can be cholinergic or adrenergic
Agents which induce neurotransmitter release
Stimulate release of neurotransmitter in absence of signal (or reduced signal)
Inhibitors of neurotransmitter degradation
Inhibit acetylcholinersterase

23. Neurotransmission Inhibitors
Presynaptic nerve blockerss
Receptor antagonists
Bind to receptor and prevent activation
Ganglion blockers