Pharmacology CHAPTER 4 WHAT IS THE DIFFERENCE BETWEEN

Pharmacology CHAPTER 4

WHAT IS THE DIFFERENCE BETWEEN CNS AND PNS?

NERVOUS SYSTEM – A review It is divided into 2 MAJOR categories: 1. THE CENTRAL NERVOUS SYSTEM (CNS) • The brain + the spinal cord – The center of integration and control 2. PERIPHERAL NERVOUS SYSTEM (PNS) • • 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: 2 A. Somatic Nervous System (SNS) (voluntary) 2 B. 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 SANS stimulates the radial smooth muscles, producing an increase in pupil size

If PANS & SANS could talk… ANS PANS & SANS 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

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: SANS – Pre-ganglion fiber is short – Post-ganglion fiber is long • Post-ganglion fibers will terminate at the effector organ or tissue

SANS originate from the thoracic to the lumbar portion of the spinal cord PANS 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 (PANS) § 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?

EPINEPHRINE: IS RELEASED WITH STIMULATION FROM THE ADRENAL MEDULLA AND DISTRIBUTED IN THE BODY VIA THE BLOOD 1. 2. 3. 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?

(SANS) 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