Autonomic and SomaticNervous System

BrainSpinal Cord

CNS

SomaticNS

PNS

Nervous System

Autonomic NS

Sympathetic

Parasympathetic

Autonomic Nerves: 2 divisions

Sympathetic - thoracolumbar

– exits from thoracic and lumbar regions

Parasympathetic - craniosacral

– exits from cranial and sacral areas

CNS

C

T

L

SSM

Ach - Acetylcholine

Neurotransmitters of the Autonomic Nervous System

NE - Norepinephrine

ACh

muscarinicnicotinic(M)(N)

Cholinergic Receptors

ACh

muscarinicnicotinic(M)(N)

Cholinergic Receptors

NE

1, 2, 1

Adrenergic Receptors

ACh

ACh

ACh

CNS

C

T

L

SSMACh

AChN

N

ACh

MACh

CNS

C

T

L

SSMACh

N

AChNEN

N

ACh

MACh

CNS

C

T

L

SSMACh

NE

N

AChNEN

1

2

1

N

ACh

MACh

CNS

C

T

L

SSMACh

NE

N

AChNEN

ACh

EPIN 1

2

1

N

ACh

MACh

CNS

C

T

L

SACh

NE

SMN

NE

EPI 1, 2, 1, 2

1, 2, 1

Adrenergic Receptors

AChNEN

1

2

1

N

ACh

MACh

CNS

C

T

L

SACh

NESG

AChM

N

ACh

SMN

Differences between autonomic and somatic nerves

Autonomic:

- Synapses located in ganglions outside cerebrospinal axis

- Extensive peripheral plexuses

- Postganglionic nerves are not myelinated

- Some level of spontaneous activity without intact innervation

Somatic:

- Innervates all organs/glands except skeletal muscle

- Innervates only skeletal muscle

- Synapses within CNS

- Does not form peripheral plexuses

- myelinated

- Denervation results in paralysis, atrophy

Differences between functions of the parasympathetic and sympathetic nervous system

Parasympathetic:

- Bradycardia - Salivation increased

- Vasodilator predominance

- Blood pressure reduced

Sympathetic:

- Conservation of energy - Urine output increased

- Respiration reduced

- GI motility and secretions increased - Renal blood flow increased

- Expenditure of energy

- Tachycardia

- Vasoconstrictor predominance

- Blood pressure increased

- Renal blood flow decreased

- Salivation reduced

- Urine output decreased

- Respiration increased

- GI motility and secretions reduced

Opposing actions of the parasympathetic and sympathetic nervous system

Opposing actions of the parasympathetic and sympathetic nervous system

Ach

HRHRHRHR

M

NE

Opposing actions of the parasympathetic and sympathetic nervous system

Opposing actions of the parasympathetic and sympathetic nervous system

Ach

GI motility

M

NE

( )-

Opposing actions of the parasympathetic and sympathetic nervous system

Opposing actions of the parasympathetic and sympathetic nervous system

Opposing actions of the parasympathetic and sympathetic nervous system

Opposing actions of the parasympathetic and sympathetic nervous system

Iris dilator muscle: Sympathetic(mydriasis)

Iris sphincter muscle: Parasympathetic

(miosis)

Ciliary muscle: sole parasympathetic innervation controlling accommodation

Ciliary muscle: sole parasympathetic innervation controlling accommodation

Ciliary muscles: Only parasympathetic

innervation

Relaxation of ciliary muscles causes flattening of the lens for near and far vision focus

Changes during short distance accommodation

A) contraction of ciliary muscles (M3)B)approximation of ciliary muscles to lensC)relaxation of suspensory ligament D)increased curvature of anterior surface of lens (i.e., spherical) for near vision focus.

Synergistic actions of the parasympathetic and sympathetic nervous system

Synergistic actions of the parasympathetic and sympathetic nervous system

5 key steps in neurotransmission

- Synthesis

- Storage

- Release

Neurotransmitter:- Recognition

- Metabolism

PRESYNAPTICPRESYNAPTIC POSTSYNAPTICPOSTSYNAPTIC

NT

Re-uptake 1Re-uptake 1

Metabolic RemovalMetabolic Removal

ActionActionS & S

R

ReceptorBinding

ReceptorBinding

E

SITE EFFECT

EFFECTS OF STIMULATING MUSCARINIC RECEPTORS (SLUDE)

BRONCHOSPASM

BRADYCARDIA

VASODILATION

MIOSIS

INCREASED URINATION

INCREASED GI MOTILITY

INCREASED SALIVATION

INCREASED TEARSLACRIMAL GLANDS

SALIVARY GLANDS

GI TRACT

BLADDER

IRIS

AIRWAYS

VASCULATURE

HEART

SWEAT GLANDS INCREASED SWEATNG

1, 2vasoconstrictionTPR

contractile forceheart rate1

2 vasodilation, TPR

EFFECTS OF STIMULATING ADRENERGIC RECEPTORS

SITE EFFECT

EFFECTS OF STIMULATING ADRENERGIC RECEPTORS

BRONCHORELAXATION (2)

TACHYCARDIA (1)

VASODILATION

MYDRIASIS (2)

DECREASED URINATION (2)

DECREASED GI MOTILITY (2)GI TRACT

BLADDER

IRIS

AIRWAYS

VASCULATURE

HEART

(2)VASOCONSTRICTION

(1, 2)

UTERUS RELAXATION (2)

Dual Innervation

Predominant Tone

Exceptions -

Primarily parasympathetic NS

blood vessels(only sympathetic)

Exceptions - blood vessels (sympathetic)

- sweat glands (sympathetic cholinergic)

Predominate Autonomic Tone

Arterioles Sympathetic (adrenergic)Veins Sympathetic (adrenergic)

Heart Parasympathetic (cholinergic)Iris Parasympathetic (cholinergic)Ciliary muscle Parasympathetic (cholinergic)GI tract Parasympathetic (cholinergic)Urinary bladder Parasympathetic (cholinergic)Salivary glands Parasympathetic (cholinergic)

Sweat glands Sympathetic (cholinergic)

Site Predominate Tone