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Pharmacology
CHAPTER 4
WHAT IS THE DIFFERENCE
BETWEEN CNS AND PNS?
It is divided into 2 MAJOR categories:
•
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
DOES THE PNS CONTAIN
SENORY, MOTOR OR BOTH?
BOTH
THE PNS USE NEURONS THAT ARE
SPECIALIZED TO CONDUCT INFORMATION
FROM ONE PART OF THE BODY TO ANOTHER.
PNS – WHAT DOES THE
SOMATIC NERVOUS SYSTEM
CONTOL?
VOLUNTARY MUSCLE
CONTROLS VOLUNTARY SKELETAL MUSCLE
CONDUCTS SENSORY INFORMATION
FIBERS PASS FROM SPINAL CORD DIRECTLY
TO THE STRIATED MUSCLES
IS THE ANS VOLUNTARY OR
INVOLUNTARY
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
WHAT IS THE FLIGHT AND
FIGHT RESPONSE?
SANS •
•
shocks physiologic
processes into action
during environmental and
internal stress
copes with sudden
emergencies
WHAT IS MYDRIASIS?
DILATED PUPILS
The
stimulates the radial
smooth muscles, producing an
increase in pupil size
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!”
WHAT IS THE SPACE BETWEEN
THE PREGANGIOLIC AND
POSTGANGLIONIC FIBERS?
THE SYNAPSE AREA
The postganglionic neuron
originates in the ganglia and
innervates the effector (or
target) organ or tissue
ARE PREGANGLIONIC
FIBERS LONG OR SHORT?
LONG
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
• 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
originate
from the
thoracic to the
lumbar
portion of the
spinal cord
orginate from
the cranial
nerves and
sacral
segments of
the spinal
cord
Preganglionic
= short
Postganlionic
= long
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
WHAT IS BRADYCARDIA?
DECREASED HEARTRATE
WHAT DRUG IS USED IN
PARKINSONS DISEASE?
COGENTIN
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
WHAT IS USED TO TREAT
MOTION SICKNESS?
SCOPOLAMINE
Scopolamine (CNS
depressant action) is used to
treat motion sickness
WHAT ARE THE
NEUROTRANSMITTERS IN
SANS?
1.
2.
3.
EPINEPHRINE: IS RELEASED WITH STIMULATION
FROM THE ADRENAL MEDULLA AND
DISTRIBUTED IN THE BODY VIA THE BLOOD
NOREPINEPHRINE (NE): MAJOR TRANSMITTER
RELEASED AT THE TERMINAL ENDINGS OF THE
SANS
DOPAMINE: RECEPTORS ARE IMPORTANT IN THE
BRAIN AND SPLANCHNIC AND RENAL
VASCULATURE
WHAT ARE ADRENERGIC
AGENTS USED FOR IN
DENTISTRY?
VASOCONSTRICTION
•
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.
WHAT IS EPINEPHRINE
REVERSAL?
Adrenergic Blocking Agents
α-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