Pharmacology PHL 211 Ninth Lecture By Abdelkader Ashour, Ph.D. Phone: 4677212 Email:...
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Pharmacology PHL 211 Ninth Lecture By Abdelkader Ashour, Ph.D. Phone: 4677212 Email: [email protected]
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Transcript of Pharmacology PHL 211 Ninth Lecture By Abdelkader Ashour, Ph.D. Phone: 4677212 Email:...
Pharmacology PHL 211
Ninth Lecture
By
Abdelkader Ashour, Ph.D. Phone: 4677212 Email: [email protected]
Regulation of Body Functions, NS & ES
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
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
Organization of The Nervous System
Central Nervous System
“Brain and spinal cord”
Peripheral Nervous System
Somatic Nervous SystemAutonomic Nervous System
Sympathetic
“thoracolumbar”
Parasympathetic
“craniosacral”
Efferent DivisionAfferent Division
Autonomic Nervous System
Efferent division of the peripheral nervous system
Some anatomic and neurotransmitter features of autonomic and somatic motor nerves
• 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
How do drugs influence 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
Classification of drugs affecting the ANS
Parasympathetic Nervous System
Drugs Acting on the
Parasympathetic Nervous System,
Responses to parasympathetic
activation
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
Action Potential
Na+
Ca 2+
ACh
Acetylcholinesterase
Na+
Preganglionic neuron Postganglionic neuron
NicotinicReceptor
Parasympathetic Ganglionic Synapse
Action Potential
Ca 2+
Na+
ACh
Acetylcholinesterase
K+
G
EffectorOrgan
Postganglionic neuron
MuscarinicReceptor
Parasympathetic Organ Synapse
