MODULE 7: DRUG ACTING ON AUTONOMIC NERVOUS SYSTEM (PART 1)

Systemic drugs

drugs that act on the different system.

It is a symptomatic treatment according to the clinical signs.

Chemotherapeutic drugs

Drugs used to treat diseases based on the causative agents.

Central nervous system

Components are located in the middle and are protected by bones.

Brain and spinal cord.

Peripheral nervous system

Cranial nerve

Spinal nerve

Somatic nervous system

Autonomic nervous system

Somatic nervous system

Voluntary control

can be controlled by the brain.

Autonomic nervous system

Sustain hemostatic conditions within an organism.

Organized to modulate involuntary activities of the secretory glands, smooth muscles, and visceral organs.

Sympathetic (Fight or flight)

Often referred to as the thoracolumbar outflow because of the anatomic origin.

Sympathetic postganglionic ganglia are long since most sympathetic ganglia are located close proximity to the spinal cord.

Parasympathetic (Rest and digest)

Often referred to as the craniosacral outflow because tracts originate from the midbrain, medulla oblongata, and sacral spinal cord.

It usually effects specific effector system individually.

Adrenal medulla

an extremely important component of the sympathetic nervous system.

Vagus nerve

s the considered to be the most important parasympathetic nerve trunk. Arises from medulla oblongata and send efferent fibers to all thoracic and abdominal viscera from caudal Pharyngeal region to the cranial portions of the large colon.

Preganglionic neurons and postganglionic neurons

Sympathetic and parasympathetic outflow tracts comprise…

Within the central nervous system

The cell body of a preganglionic neuron is located where?

Outside the CNS

The synpase (Junction) of a preganglionic axon with a postganglionic neuronal body occurs where.. — within an autonomic ganglion.

Autonomic ganglia

specialized nodular structures comprising numerous neuronal bodies.

Axon

ganglionic cell passes peripherally and innervates its effector organ or organ substructures.

Neuroeffector junction

The junction of postganglionic axonal terminal with its effector cell.

Neuron

the functional part or the smallest part of the nervous system.

Synapse

Spaces between neurons.

Neurohumoral transmission

Information is communicated from nerve to nerve and to the effector organ by a process termed.

This involves the release from a terminal of a chemical (neurotransmitter substance), which then reacts with specialized receptor areas in the innervated cell.

Acetylcholine and Norepinephrine

2 basic neurotransmitter

Acetylcholine

coming from the parasympathetic or the craniosacral part.

Norepinephrine

Coming from the sympathetic or the thoracolumbar part.

Cholinergic nerves

Nerves that release Ach.

Adrenergic nerves

nerves that release Norepinephrine.

Noradrenergic

used to designate neurons that release Norepinephrine and epinephrine respectively, especially when the CNS is considered.

true

Cholinergic nerve of the sympathetic outflow releases ACH in the preganglionic nerve.

True

Adrenergic nerve releases norepinephrine in the postganglionic nerve.

True

Cholinergic nerve of the Parasympathetic outflow releases ACh in both pre and postganglionic nerve.

Acetylcholine

must bind with the Nicotinic acetylcholine receptor or epinephrine muscarinic (M) acetylcholine receptor.

Excitation

When Ach binds with Nicotinic receptor it will produce — to the organ.

Inhibit and excitation

When Ach binds with muscarinic receptor it will — the organ, but will produce — on GIT

Norepinephrine

Must bind with the Alpha and Beta Norepinephrine receptor.

Inhibition

When Norepinephrine binds with the beta receptor it will — the organ.

A1 (alpha)

located in the dendrites, which receives the message that is why it is post-synaptic synapse, it is found in vascular smooth muscle.

A2 (alpha)

located in the axon, pre-synaptic synapse, found in the brain and periphery.

B1 (beta)

excitation/ stimulate the heart or blood vessel (exception to the rule)

B2 (beta)

Inhibition / dilation of bronchioles in the lungs.

Sympathomimetics/ Adrenergic / Andromimetic

Mimics (copy) the action of the sympathetic nerves which neurotransmitter is norepinephrine but the action will depend to which receptor it will bind (α or β).

Sympatholytic

Drugs that inhibits the action of the sympathetic nerve.

Receptor blocking sympatholytic drug/ Adrenergic blocking (competitive)

Drugs that compete with norepinephrine for the same receptor.

Adrenolytic / neuronal blocking (non competitive)

It cause breakdown of norepinephrine

Parasympathomimetic/Cholinergic/ Cholinomimetics

Mimics (copy) the action of the parasympathetic nerves whose neurotransmitter is Acetylcholine. Receptors are Muscarinic and Nicotinic receptor.

Parasympatholytic

Drugs that inhibits the action of the parasympathetic nerve

Receptor - blocking parasympatholytic drug / cholinergic - blocking (competitive)

Drugs that compete with acetylcholine for the same receptor

Neuronal blocking drugs / Anticholinergic (Non - competitive)

It causes breakdown of acetylcholine

Norepinephrine

came from the adrenal gland, which is normally called adrenaline.

vasoconstriction

cathecolamines causes — to:

Cutaneous blood vessels (Skin)

Mucosal blood vessels (Mucous membranes)

Renal blood vessels (Kidney)

Mesenteric blood vessels (mesentery)

Vasodilation

Cathecolamines causes — in:

Coronary blood vessels.

Vasodilation

Small amounts of epinephrine causes — to skeletal blood vessels.

Propranolol

vasodilation is blocked by —

This is a contraindication of epinephrine.

Vasoconstriction

Large amounts of epinephrine causes the skeletal blood vessel to —

Cathecolamine

They act as Inotropes, which increases the strength of the cardiac muscle contraction (tachycardia) by changing automaticity of the pacemakers.

Halothane and chloroform

This increases the sensitivity of the chart to cardiac rhythm irregularities caused by catecholamines.

Dopamine

Drug of choice to treat Parkinson’s Disease in humans.

True

Dopamine when biotransformed into a - dopa will remain active.

Dopamine as treatment for shock

(hypothermia) shock can cause Cardiovascular Dysfunction and Renal Failure.

Phenoxybenzamine

gives pressor effect on the heart by blocking α receptor

propranolol

gives stimulatory effect by blocking β receptor.

Haloperidol

gives depressor effect in the brain in which it blocks β receptor.

Fenoldopam

Acts on the Dopamine receptor, receptor of vascular bed causing vasodilation.

fenoldopam

It is a treatment for hypotension that will improve perfusion of GIT, renal protection from vasoconstriction.

Dobutamine

An agent the selectively increase cardiac contractility without affecting hearts cardiac rhythmicity and blood pressure.

Dobutamine

treatment for low output cardiac failure.

Non - catecholamine

From natural Catecholamine to synthetic - Starts with ephedrine which is an alkaloid from a plant named Ma Huang from Chinese shrub.

Methamphetamine HCL

is the chemical name of Shabu or “poor man’s cocaine”

B2 - selective bronchodilators

selective because they only bind with β2 receptor of the respiratory system.

It dilates the bronchus.

Phosphodiesterase

An intracellular enzyme Ø It cause breakdown of Cyclic AMP (cAMP).

Aminophylline

It will cause lysis or inhibition of phosphodiesterase. Ø Given together with anti-asthma.