1. Pharmacology PHL 211
Ninth Lecture By Abdelkader Ashour, Ph.D Phone:

2. Regulation of Body Functions, NS & ES
The nervous system has several properties in common with the endocrine system, which is the other major system for control of body function.
These include:
high-level integration in the brain
the ability to influence processes in distant regions of the body
extensive use of negative feedback
both systems use chemicals for the transmission of information
In the nervous system, chemical transmission occurs between nerve cells and between nerve cells and their effector cells
Chemical transmission takes place through the release of small amounts of transmitter substances from the nerve terminals into the synaptic cleft
The transmitter crosses the cleft by diffusion and activates or inhibits the postsynaptic cell by binding to a specialized receptor molecule

3. Organization of The Nervous System
Central Nervous System
“Brain and spinal cord”
Peripheral Nervous System
Autonomic Nervous System
Somatic Nervous System
Afferent Division
Efferent Division
Sympathetic
“thoracolumbar”
Parasympathetic
“craniosacral”

4. Autonomic Nervous System

5. Efferent division of the peripheral nervous system

6. Some anatomic and neurotransmitter features of autonomic and somatic motor nerves

8. How do drugs influence the ANS?
Drugs may mimic or block the effects of the two primary neurotransmitters, Acetylcholine and Norepinephrine/Epinephrine
Drugs that mimic neurotransmitters are referred to as “receptor agonists”
These drugs activate receptors
Drugs that block neurotransmitters are referred to as “receptor antagonists”
These drugs block the endogenous neurotransmitters from activating receptors

9. Classification of drugs affecting the ANS
Parasympathetic nervous system. Drugs may:
Mimic acetylcholine = cholinergic = muscarinic agonists = parasympathomimetic
Block acetylcholine = anticholinergic = muscarinic antagonist = parasympatholytic
Sympathetic nervous system. Drugs may:
Mimic norepinephrine = adrenergic = adrenergic agonist = sympathomimetic
Block norepinephrine = antiadrenergic = adrenergic antagonist = sympatholytic

10. Parasympathetic Nervous System

11. Drugs Acting on the Parasympathetic Nervous System, Responses to parasympathetic activation

12. Parasympathetic Neurons & Synapses
Preganglionic neurons
Long
Synapse with postganglionic neurons at or near organ
Release acetylcholine (ACh) to activate nicotinic receptors on postganglionic neurons
Postganglionic neurons
Short
Synapse on the target organ
Release ACh to activate muscarinic receptors on the target organ
Cholinergic fibers: i.e., act by releasing acetylcholine.
Include:
all preganglionic efferent autonomic fibers
the somatic (non-autonomic) motor fibers to skeletal muscle
most parasympathetic postganglionic and a few sympathetic postganglionic fibers
Parasympathetic Neurons & Synapses

13. Parasympathetic Ganglionic Synapse
Acetylcholinesterase
Ca2+
Na+
ACh a b
Action Potential
Nicotinic
Receptor
Na+
Preganglionic neuron
Postganglionic neuron

14. Acetylcholinesterase
Parasympathetic Organ Synapse
Acetylcholinesterase
Ca2+
Effector
Organ
Na+ K+ G
Action Potential
ACh
Muscarinic
Receptor
Postganglionic neuron