Autonomic Nervous System

Autonomic Nervous System

a component of the peripheral nervous system that regulates involuntary physiologic processes

CENTRAL NERVOUS SYSTEM

BRAIN and SPINAL CORD; process, integrate,

store and respond to information from the PNS.

PERIPHERAL NERVOUS SYSTEM

Spinal nerves, Cranial nerves & Ganglia; transmit information to the CNS and receive information

from the CNS

Paralysis

Most common result of injury to spinal cord (nerve damage)

Neurons

nerve cells; Basic elements of the nervous system

Dendrites

branching extensions that conduct nerve impulses toward the cell body

Axon

single branch (most neurons) which conducts

nerve impulses away from the cell body covered

by myelin sheath and neurilemma.

myelin sheath

Protects the axon and allows electrical impulse to transmit quickly and efficiently along the nerve cells

Efferent (motor)

conveys information

from CNS to the muscles/glands (away) (knesis)

Afferent (sensory)

carry information from sensory receptors to the CNS

(towards) (from peripheral region)

Nociceptors

pain sensory receptors

Interneuron

carry and process sensory information.

Multiple sclerosis

Slow response to sensory stimulus causes by damage/inflammation to myelin sheath

Irritability

able to respond to stimuli

Conductivity

able to transmit electrical potential along the axon

Resting Membrane Potential

anions are greater concentration inside

Caused by inhibitory neurotransmitter: Gamma-amino butyric acid (GABA)

Action Potential

cations are greater concentration inside

Caused by excitatory neurotransmitter: Catecholamines, Acetylcholine, Serotonin,

Histamine and Glutamate

Seizure

Prolonged action potential, firing of neurons

Neurotransmission

Transmission of nerve impulses between een neurons or between a neuron and a muscle fiber or other structure.

Neurotransmitter

chemical synthesized, stored and liberated by

neurons.

PRE SYNAPSE

te of the synthesis, storage and release of

neurotransmitters (main site,site of origin)

SYNAPTIC CLEFT

Space between the two neurons/synapse

POST SYNAPSE

majority of the receptors are found in this location. (1,2,3,4 receptors are found here)

also contain metabolizing enzymes. (ex: MAO, Acetylcholinesterase)

Acetylcholinesterase

Has ability to inactivate neurotransmitters

Cerebrum (telencephalon, diencephalon,)

initiation of movement, coordination of movement,

temperature, touch, vision, hearing, judgment, reasoning,problem solving, emotions, and learning.

Cerebellum

receives information from the sensory systems, the spinal cord, and other parts of the brain and then

regulates motor movements.

Brainstem (midbrain, pons, medulla oblongata)

serves a critical role in regulating certain involuntary

actions of the body, including heartbeat and breathing.

White matter

Paler tissue in the spinal cord, mainly consists of myelinated axons; Controls involuntary functions

Grey matter

Darker tissue in the spinal cord, consists of nerve cell bodies (soma) and branching dendrites; Control the senses of the body.

SOMATIC NERVOUS SYSTEM

innervates mostly under voluntary control.

Ex: Skeletal muscles

AUTONOMIC NERVOUS SYSTEM

innervates cardiac muscles, smooth muscles,

vasculature and the exocrine glands that

functions involuntarily.

Ex: Cardiac muscle and Bronchial smooth

muscle

sympathetic nervous system

Erogtropic responses, a.k.a. "ADRENERGIC" system.

Responsible for arousing and adrenaline rush or

"FIGHT or Flight" response

has the property of adjusting in response to stressful situations

Norepinephrine, Epinephrine

Neurotransmitter of sympathetic nervous system

Alpha Beta and Dopamine

Receptors of sympathetic nervous system

Parasympathetic Nervous System

Trophotropic response, a.k.a. "CHOLINERGIC" system produces an opposing effect to sympathetic nervous system "REST and Digest" response.

maintains essential bodily functions and is required for life.

Acetylcholine

Neurotransmitter of parasympathetic nervous system

Muscarinic and Nicotinic

Receptors of parasympathetic nervous system

Enteric Nervous System

a.k.a. "Nervous System of the GIT" system. Innervate (supply nerves to organs) the small intestine.

Organized collection of neurons in the walls of the GIT. Innervated by the myenteric plexus (auerbach plexus) and the submucous plexus (Meissner plexus).

myenteric plexus

controls GI tract motility

Submucosal plexus

lies in the submucosa of the intestinal wall

Substance P, Neuropeptide Y, Vasoactive Intestinal Peptide, ATP. (VANS)

Neurotransmitters of enteric nervous system

Norepinephrine

primary neurotransmitter of postganglionic sympathetic adrenergic nerves.

Synthesized inside nerve axon in the adrenal

medulla and stored within vesicles; released by the nerve when an action potential travels down the nerve.

Tyrosine

precursor of norepinephrine

Sodium (Na+)

facilitates the entry of tyrosine

Tyrosine-DOPA

catalyzed by tyrosine hydroxylase considered as "rate-limiting step" (slowest)

DOPA-Dopamine

catalyzed by dopa decarboxylase Removal of carboxylic acid (COOH) group.

Dopamine-- Norepinephrine

catalyzed by dopamine-b-hydroxylase Addition of (OH) group in C2/ beta carbon.

NE-- Epinephrine

catalyzed by PENMT (Phenyl ethanolamine-N-methyltransferase).

Calcium (Ca+2)

facilitates the release of neurotransmitter (exocytosis)

REUPTAKE

Reuptake of neurotransmitter, Responsible for 70% of inactivation

Facilitated by NET (Norepinephrine transporter)

METABOLISM

Responsible for 30% of inactivation

MAO (Monoamine oxidase/Phase 1 metabolism/oxidation) and COMT (Catechol-O-methyltransferase/Phase 2/methylation)

Vanillylmandelic acid (VMA)

This final product is measured in urine and plasma in

the diagnosis of pheochromocytoma, which can

cause severe hypertension and cardiac arrhythmias.

Metyrosine

inhibits the tyrosine hydroxylase (inhibits rate-limiting steps of norepinephrine)

Reserpine

inhibits the storage of dopamine & other cathecolamines into vesicle

Bretyllium, Guanetidine

inhibits the release of norepinephrine

Cocaine, Tricyclic Antidepressants (TCA`s)

inhibits norepinephrine in the diffusion in the synaptic cleft or in the transportation into the cytoplasm of the

terminal (reuptake)

Latrotoxin

toxin produced by black widow spider that cause explosive release of NE and Ach (can lead to spastic paralysis)

Tyramine,Ephedrine, Amphetamine, Angiotensin II

Release is stimulated by

Acetylcholine

primary neurotransmitter of parasympathetic nervous

system.

Sodium (Na+)

facilitates the entry of choline

Calcium (Ca+2)

facilitates the release of Acetylcholine (exocytosis)

Acetylcholinesterase

metabolize acetylcholine into choline and acetic

acid via phase 1 metabolism (hydrolysis)

Muscarine

occurs through an action on receptors at effector cells. (G-protein linkedreceptors)

Nicotine

occurs at the autonomic ganglia & skeletal muscle neuromuscular junction. (Ionotropic receptors)

M1 receptor

Location: Nerves of the upper GIT (vagus nerve) Cranial #10

Response: Increase acid secretion

M2

Location: Heart (atria)

Response: Decrease heart rate Increase in the duration of AV node conduction delay

M3

Location: Pupil,Bronchial,Intestinal wall & Bladder wall, Intestinal & bladder sphincter Glands (sweat and lacrimal)

Response: Miosis, Bronchoconstriction,Contraction

Relaxation,Increase secretion

Nm

Location: neuromuscula r endplate

Response: Muscle contraction

Nn

Location: CNS Ganglia

Response: Stimulation

Nicotinic receptor

is a transmembrane allosteric protein that mediates transduction of chemoelectric signals throughout the nervous system by opening an intrinsic ionic channel.

Hemicholinium

inhibits choline transportation from the extracellular fluid into the neuron terminal

Vesamicol

inhibits the transportation of Acetylcholine from the cytoplasm into the vesicles

Botulinum Toxin

inhibits the release of Acetylcholine in vesicle (Clostridium botulinum)

Spider venom

promotes release of Acetylcholine

Organophosphates (parathion and malathion)

inhibit acetylcholinesterase.