SEKOLAH TINGGI ILMU KESEHATAN KOTA SUKABUMI

Program Study S1 Keperawatan

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NERVOUS SYSTEM

PERIPHERAL NERVOUS SYTEM

CENTRAL NERVOUS SYETM

MOTOR

DIVISION

SENSORY

DIVISION

AUTONOMIC

SYSTEM

SOMATIC

SYSTEM

Sympathetic

Parasympathetic

Organization of Nervous System

BRAIN SPINAL

CORD

PERIPHERAL NERVOUS SYSTEM (PNS)

Sensory neuron Motor neuron

Somatic motor neuron

Autonomic motor neuron

Innervate smooth muscle, cardiac muscle, and gland

Innervate skeletal muscle

Anatomical diff …

Spinal cord

Spinal cord

Somatic motor neuron

Preganglionic neuron

Postganglionic neuron

Skeletal muscle

Effector organ e.g. smooth muscle, heart, or gland

Autonomic ganglion

Somatic motor neuron

Autonomic motor neuron

ORGANIZATION OF SNS AND ANS

PERIPHERAL …….

Anterior horn

Lateral horn

1. CONTRASTING THE SOMATIC AND THE AUTONOMIC NERVEOUS SYSTEMS

Anatomical differences between Somatic Nervous System and Autonomic Nervous Syatem

Somatic Nervous System

Autonomic Nervous System

Cell body in CNS

Cell body (Ganglion) out of CNS

Effectors

Preganglionic neuron

Postganglionic neuron

Somatic neuron

Functional differences between Somatic Nervous System and Autonomic Nervous System

Somatic Nervous System Autonomic Nervous System

1. Conscious2. Always excitatory

1. Unconscious2. Excitatory and inhibitory (during

meal ANS stimulate the stomach activities, during exercise inhibit)

Summarizes of differences…………

Comparison of the Somatic and Autonomic Nervous Systems

Feature SNS ANS

Target tissues Skeletal muscle Smooth, cardiac muscle, and glands

Regulation Controls all conscious and unconscious movement of skeletal muscle

Unconscious regulation, although influenced by conscious mental function

Response to stimulation Skeletal muscle contract Target tissues are stimulated or inhibited

Neuron arrangement One neuron extends from the CNS to skeletal muscle

Two neuron in series, the preganglioni from CNS to ganglion, postganglion from ganglion to effectors

Neuron cell body location

Neuron cell bodies are in motor nuclei of the cranial nerves and in the ventral horn of the spinal cord

Pregangiolonic neuron cell bodies are in autonomic nuclei of the cranial nerves and in the lateral part of the spinal cord; postganglionic neuron cell bodies are in the autonomic ganglia

Continued …………

Comparison of the Somatic and Autonomic Nervous Systems

Feature SNS ANS

Number of synapses One synapse between the somatic motor neuron and the skeletal muscle

Two synapses; first in autonomic ganglia; second is at the target tissues

Axon sheaths Myelinated Preganglionic are myelinated; postganglionic are unmyelinated

Neurotransmitter substances

Acetylcholine Acetylcholine is released by preganglionic neurons; either acetylcholine and norepinephrine is released by postganglionic neurons

Receptor molecules Receptor molecules for acetylcholine are nicotinic

In autonomic ganglia, receptor molecules for acetylcholine are nicotinic; in target tissues, receptor for acetylcholine are muscarinic, for norepinephrine are α or β - adrenergic

Organization of somatic and autonomic nervous syetem ……

2. ANATOMY OF THE AUTONOMIS NERVOUS SYSTEM

ANS

SYMPATHETIC PARASYMPATHETIC

ENTERIC NERVOUS SYSTEM

Complex network of neuron cell bodies and axons within the wall of digestive tract that composed of sympathetic and parasympathetic

SYMPATHETIC DIVISION

1. Neuron cell bodies located in the lateral horn spinal cord gray matter between T1 and L2 segments called thoracolumbar division

2. The preganglionic neuron project to autonomic ganglia (sympathetic chain ganglia = paravertebral ganglia) on either side of vertebral column behind the parietal pleural

3. The sympathetic chain extends into cervical and sacral regions but only ganglia from T1 – L2 that receive preganglionic axons. The cervical and sacral regions is associated with the nearly every pair of spinal nerves

4. The cervical ganglia fuse during fetal development only two or three pairs exist in the adult

5. The preganglionic neuron are small and myelinated

6. The short connection between spinal nerve and a ganglion called white ramus communicants

SYMPATHETIC DIVISION

Preganglionic neuron cell bodies in the lateral horn between T1-S2 Thoracolumbar divison

Sympathetic chain ganglia = paravertebral ganglia

THE ROUTES TAKEN BY SYMPATHETIC AXONS

THE ROUTES TAKEN BY SYMPATHETIC AXONS……….

PARASYMPATHETIC DIVISION

The cell bodies are within the brainstem and sacral region

Craniosacral division

III

VII

IX

X

Comparison of the Sympathetic and Parasympathetic Division

Feature Sympathetic division Parasympathetic division

Location of preganglionic cell Bodies

Lateral horns of spinal cord gray matter (T1 – L2)

Brainstem and lateral parts of spinal gray matter (S2 – S4)

Outflow from the CNS Spinal nervesSympathetic nervesSplanchnic nerves

Cranial nervesPelvic nerves

Ganglia The chain along spinal cord for spinal and sympathetic nerves; collateral ganglia for splanchnic nerves

Terminal ganglia near or on effector organ

Number of postganglionic neurons for each preganglionic neuron

Many (much divergence) Few (less divergence)

Relative length of neuron Short preganglionicLong postganglionic

Long preganglionicShort postganglionic

ENTERIC NERVOUS SYSTEM

1. Consist of nerve plexuses within the wall of the digestive tract

2. The plexuses have contributions from three sources:

a. Sensory neurons that connect the digestive tract to the CNS

b. ANS motor neurons that connect the CNS to the digestive tract

c. Enteric neurons, which are confined to the enteric plexus

3. The CNS is capable of monitoring the digestive tract through sensory neurons and controlling its smooth muscle and gland through ANS motor neurons

TYPE OF ENTERIC NEURON

1. Enteric sensory neurons, detect chemical composition and wall stretching.

2. Enteric motor neurons, stimulate or inhibit smooth muscle contraction and gland secretion

3. Enteric interneurons, connect sensory and motor neurons to each other.

THE DISTRIBUTION OF AUTONOMIC NERVE FIBERS

1. Sympathetic division

a. Sympathetic axons from ganglia to target tissues pass through spinal, sympathetic, and splanchnic nerves, head and neck nerve plexuses, thoracic nerve plexuses, and abdominopelvic nerve plexuses

b. Sympathetic and splanchnic nerves join autonomic nerve plexus, complex, interconnected neural network formed by neurons of sympathetic and parasympathetic division. They are named according to organs they supply (cardiac plexus) or to blood vessels along which they are found (thoracic aortic plexus).

2. Parasympathetic division

a. Parasympathetic outflow is through cranial nerve (III, VII, IX, X), and plexuses (vagus and thoracic nerve plexuses, abdominal nerve plexuses, and plevic nerve and pelvic nerve plexuses

SENSORY NEURONS IN AUTONOMIC PLEXUSES

a. Not strictly part of autonomic nervous system

b. Some are part of reflex arcs regulating organ activities.

c. Transmit pain and pressure sensations from organ to CNS

d. The cell bodies of these sensory neuron are found in the dorsal root ganglia and in certain cranial nerve (which are swelling on nerves close to their attachment to the brain)

3. PHYSIOLOGY OF THE ANS

Neurotransmitters

Sympathetic Parasympathetic

Acetylcholine

Norepinephrine

Ganglion

Preganglion (cholinergic)

Postganglion (adrenergic)

Postganglion (Cholinergic)

Receptors

Cholinergic receptor(binds to acetylcholine)

Adrenergic receptor(binds to norepinephrine)

Nicotinic Bind to nicotin (tobacco

alkaloid)Muscarinic

Bind to muscarine (alkaloid poisonous mushroom)

Alpha receptor

α1 stimulatory response

α2 inhibitory response

Beta receptor

β1 various response

β2 various response

Nicotine does not bind the muscarinic receptor

Muscarine does not bind to nicotinic receptor

Actylcholine binds other the nicotinic or muscarinic receptor

Location of ANS receptors

Sympathetic division

Most target tissues have adrenergic receptors

Sympathetic division

Some target tissues have muscarinic receptor

Sweat gland

Parasympathetic division

Effects and receptor types of sympathetic and parasympathetic division on various tissues

Organ Sympathetic effects and receptor types Parasympathetic effects and receptors types

Adipose tissue Fat breakdown release of fatty acids (α2 and β1) None

Arrector pili muscle Contrastion (α1) None

Blood (platelets) Increase coagulation None

Blood vessels (arterioles):Digestive organHeartKidneysLungsSkeletal muscleSkinBlood vessels (veins)

Constriction (α1)

Dilatation (β2), constriction (α1)

Constriction (α1 & 2); dilatation (β1&2)

Dilatation (β2); constriction (α1)

Dilatation (β2); constriction (α1)

Constriction (α1 & 2)

Constriction (α1 & 2); dilataion (β2)

NoneNoneNoneNoneNoneNone

Effects ………………continue

Organ Sympathetic effects and receptor types Parasympathetic effects and receptors types

EyeCiliary musclePupil

Relaxation for far vision (β2)

Dilated (α1)

Constriction for near vision (m)Constricted (m)

Gallbladder Relaxation (β2) Constriction (m)

GlandsAdrenalGastricLacrimalPancreas

Salivary

Sweat• Apocrine• Merocrine

Release of epinephrine & norepinephrin (n)

Decrease gastric secretion (α2)

Slight tear production (α)

Decrease insulin secretion (α2)

Decrease exocrine secretion (α)

Blood vessel constriction; produce thick and viscous saliva

Thick, organic secretion (m)Watery sweat from most of the skin (m); sweat from palms and soles (α1)

NoneIncrease gastric secretion (m)Increase tear secretion (m)Increase insulin secretion (m)Increase exocrine secretion (m)Blood vessels dilation ; produce thin and copious saliva (m)

NoneNone

Continue ………….

Organ Sympathetic effects and receptor types Parasympathetic effects and receptors types

Heart Increases rate and force of contraction (β2 & β2) Decreases rate (m)

Liver Glucose released into blood (α1 & β2) None

Lungs Dilates air passageways (β2) Constricts airpassageways (m)

Metabolism Increases up to 100% (α & β) None

Sex organs Ejacutaion (α1); erection Erection (m)

Skeletal muscle Breakdown glycogen to glucose (β2) None

Stomach and intestines•Wall•Sphincter

Decreases tone (α1, α2 & β2)

Increases tone (α1)

Increases motility (m)Decreases tone (m)

Urinary baldder•Wall (detrusor)•Neck of bladder•Internal urinary spihincter

None

Contraction (α1)

Contraction (α1)

Contraction (m)Relaxation (m)Relaxation (m)

4. REGULATION OF THE ANS

1. To maintain homeostasis, the structures innervated by ANS are regulated through the autonomic reflexes

2. Input come from cerebrum, hypothalamus, and other area as conscious thoughts and actions, emotions, and other CNS activities

a. Parasympathetic reflex

b. Sympathetic reflex

c. Influence of higher part of the brain on autonomic functions

Thought and emotion influence ANS through hypothalamus

ANS integrating center that interact with cerebrum, limbic system, brainstem, spinal cord; also regulate the body temperatureANS reflex centers for controlling pupil size, accommodation, tear production, salivation, coughing, swallowing, digestive activities, blood vessels diameter, and respiration

ANS reflex centers for regulating defecation, urination, penile and clitoral erection, and ejaculation

Functions at rest versus activity

Sympathetic division influences under active or stress condition referred to “flight – or fight response”

Parasympathetic division influences under resting condition

During exercise

1. Increases heart rate and force of contraction; increase blood pressure and movement

2. Oxygen, nutrient consumption, waste product are increased

3. Blood flow into tissue increase; reduces blood flow into tissues not involve in exercise by vasoconstriction making blood more available for the exercising tissues

4. Dilatation of air passageway

5. Increases the availability of energy sources. Muscle and liver stimulated to break down glycogen into glucose

6. Exercising muscle generate heat, body temperature increase

7. The activity of organs not essential for exercise decrease