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CHAPTER 4
Pharmacology
WHAT IS THE DIFFERENCE BETWEEN CNS AND PNS?
• The brain + the spinal cord– The center of integration and control
• The nervous system outside of the brain and spinal cord
• Consists of:– 12 Cranial nerves
» Carry info to and from the brain– 31 Spinal nerves
» Carry info to and from the spinal cord• 2 divisions:
2A. Somatic Nervous System (SNS) (voluntary)2B. AUTONOMIC NERVOUS SYSTEM (ANS) (involuntary)
--> *SANS & **PANS
NERVOUS SYSTEM – A reviewIt is divided into 2 MAJOR categories:
1.THE CENTRAL NERVOUS SYSTEM (CNS)
2. PERIPHERAL NERVOUS SYSTEM (PNS)
DOES THE PNS CONTAIN SENORY, MOTOR OR BOTH?
THE PNS USE NEURONS THAT ARE SPECIALIZED TO CONDUCT INFORMATION
FROM ONE PART OF THE BODY TO ANOTHER.
BOTH
PNS – WHAT DOES THE SOMATIC NERVOUS SYSTEM CONTOL?
CONTROLS VOLUNTARY SKELETAL MUSCLECONDUCTS SENSORY INFORMATION
FIBERS PASS FROM SPINAL CORD DIRECTLY TO THE STRIATED MUSCLES
VOLUNTARY MUSCLE
IS THE ANS VOLUNTARY OR INVOLUNTARY
THE ANS FUNCTIONS AS AN AUTOMATIC MODULATING SYSTEM FOR MANY BODILY
FUNCTIONS.
IT IS THE PART OF PNS CONSISTING OF MOTOR NEURONS THAT CONTROL
INTERNAL ORGANS.
IT CONTROLS THE BODY’S ACTIVITIES THAT YOU DON’T THINK ABOUT:
INVOLUNTARY
INVOLUNTARY
WHAT IS THE FLIGHT AND FIGHT RESPONSE?
• shocks physiologic processes into action during environmental and internal stress
• copes with sudden emergencies
SANS -
WHAT IS MYDRIASIS?
DILATED PUPILS
The SANS stimulates the radial smooth muscles, producing an increase in pupil size
If PANS & SANS could talk…
The afferent (sensory) fibers say: “Hey…What’s happening?”
The central integrating areas exclaim: “Let’s coordinate all this info! Hey what
did you find out?” While, the efferent (peripheral) motor PREGANGLIONIC & POSTGANGLIONIC
fibers could respond like: “Begin sweating! Heart begin palpitating!”
ANS PANS
& SANS
WHAT IS THE SPACE BETWEEN THE PREGANGIOLIC AND
POSTGANGLIONIC FIBERS?
The postganglionic neuron originates in the ganglia and
innervates the effector (or target) organ or tissue
THE SYNAPSE AREA
ARE PREGANGLIONIC FIBERS LONG OR SHORT?
PREGANGLIONIC FIBERS OF THE PANS ARE RELATIVELY LONG AND EXTEND NEAR
TO OR INTO THE INNERVATED ORGAN, WHICH LEADS TO A DISCRETE RESPONSE
POSTGANGLIONIC FIBERS, ORIGINATING IN GANGLIA (GANGLION/SYNAPSE) , ARE
USUALLY SHORT AND TERMINATE ON THE INNERVATED TISSUE
LONG
Let’s talk about SANS • NOTE: there is a difference in the
length on the preganglionic fibers in the SANS vs the PANS
• In the SANS it is OPPOSITE:–Pre-ganglion fiber is short–Post-ganglion fiber is long
• Post-ganglion fibers will terminate at the effector organ or tissue
ANS SANS
SANS originate from the
thoracic to the lumbar
portion of the spinal cord
Preganglionic = short
Postganlionic = long
PANS orginate from
the cranial nerves and
sacral segments of
the spinal cord
Preganglionic = long
Postganlionic = short
WHAT ARE PARASYMPATHOMIMETIC
AGENTS?
1. Cholinergic (parasympathomimetic) agents Classified as either direct or indirect
acting agents.Direct acting drugs act directly on
the parasympathetic receptors (Eg. Pilocarpine acts on Nicotinic).
Indirect acting drugs either cause release of neurotransmitter which then goes to the receptor site OR they inhibit the enzyme cholinesterase (EG: Sarin (nerve gas) HAS no therapeutic use; it was used on a subway in Japan to poison riders) Table 4-3, p.39
(PANS)
WHAT IS BRADYCARDIA?
DECREASED HEARTRATE
WHAT DRUG IS USED IN PARKINSONS DISEASE?
An anticholinergic drug such as benztropine (Cogentin) reduce the tremors and rigidity associated with Parkinson and drug-induced Parkinson disease
used occasionally in combination with levodopa
COGENTIN
WHAT IS USED TO TREAT MOTION SICKNESS?
Scopolamine (CNS depressant action) is used to treat motion sickness
SCOPOLAMINE
WHAT ARE THE NEUROTRANSMITTERS IN SANS?
1. EPINEPHRINE: IS RELEASED WITH STIMULATION FROM THE ADRENAL MEDULLA
AND DISTRIBUTED IN THE BODY VIA THE BLOOD
2. NOREPINEPHRINE (NE) : MAJOR TRANSMITTER RELEASED AT THE TERMINAL ENDINGS OF THE
SANS
3. DOPAMINE: RECEPTORS ARE IMPORTANT IN THE BRAIN AND SPLANCHNIC AND RENAL
VASCULATURE
WHAT ARE ADRENERGIC AGENTS USED FOR IN DENTISTRY?
• Used in dentistry for their vasoconstrictive actions (hemostasis) on blood vessels.
• Added to local anesthetics to prolong the action of the LA, to reduce the risk for systemic toxicity, and to help to create a dry field.
VASOCONSTRICTION
WHAT IS EPINEPHRINE REVERSAL?
(SANS)
Adrenergic Blocking Agents
Clients pretreated with α-adrenergic blocking agents and then given epinephrine
exhibit a predominance of beta effects (vasodilation), which lowers BP
This is called EPINEPHRINE REVERSAL because BP goes down rather than up
α-adrenergic blocking agents