127172 nervous-system

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NERVOUS SYSTEMNERVOUS SYSTEM

NERVOUS SYSTEMNERVOUS SYSTEM

FUNCTIONSFUNCTIONS

1. CONTROL1. CONTROL

2. COMMUNICATION2. COMMUNICATION

3. COORDINATION3. COORDINATION

NERVOUS SYSTEMNERVOUS SYSTEM

Types of Cells:Types of Cells:1. NEURON - structural & functional 1. NEURON - structural & functional

unit unit

Parts: Cell Body ; Dendrites ; Parts: Cell Body ; Dendrites ; AxonAxon

MYELIN SHEATH - lipid MYELIN SHEATH - lipid protein complex covering axons protein complex covering axons

- - increases velocity of impulse increases velocity of impulse conductionconduction

SYNAPSE - neuronal SYNAPSE - neuronal connectionsconnections

NERVOUS SYSTEMNERVOUS SYSTEM

Types of Cells:Types of Cells:2. NEUROGLIA - 5x more abundant than neurons2. NEUROGLIA - 5x more abundant than neurons

- non-neuronal & non-excitable- non-neuronal & non-excitableFunctions: SupportFunctions: Support

InsulationInsulationNutritionNutrition

Types: CNS - Oligodendroglia, Astrocytes, Types: CNS - Oligodendroglia, Astrocytes, Ependymal Cells, MicrogliaEpendymal Cells, Microglia

PNS - Satellite Cells, Neurolemma (Schwann PNS - Satellite Cells, Neurolemma (Schwann Cells)Cells)

NERVOUS SYSTEMNERVOUS SYSTEM

I. ANATOMICAL DIVISIONSI. ANATOMICAL DIVISIONS

1. CENTRAL NERVOUS SYSTEM1. CENTRAL NERVOUS SYSTEM

Components: Components:

a) Nucleus - collection of nerve cell bodiesa) Nucleus - collection of nerve cell bodies

b) Tract - bundle of nerve fibers (axons)b) Tract - bundle of nerve fibers (axons)

Layers: Layers:

a) Gray Matter - made up of nerve cell bodiesa) Gray Matter - made up of nerve cell bodies

b) White Matter - made up of connecting fiber tract systemb) White Matter - made up of connecting fiber tract system

CENTRAL NERVOUS SYSTEMCENTRAL NERVOUS SYSTEM

Parts: Brain & Spinal CordParts: Brain & Spinal Cord

Coverings: (Meninges)Coverings: (Meninges)1. PIA MATER1. PIA MATER - innermost covering- innermost covering

2. ARACHNOID MATER2. ARACHNOID MATER - most vascular- most vascular

3. DURA MATER3. DURA MATER - outermost & thickest covering- outermost & thickest covering

CEREBROSPINAL FLUIDCEREBROSPINAL FLUID

CENTRAL NERVOUS SYSTEMCENTRAL NERVOUS SYSTEM

A. BRAINA. BRAIN

- 75% water, gelatin-like consistency- 75% water, gelatin-like consistency

- supported & protected by bony cranium- supported & protected by bony cranium

- suspended in CerebroSpinal Fluid (CSF)- suspended in CerebroSpinal Fluid (CSF)

Parts:Parts:

1. CEREBRUM1. CEREBRUM

2. CEREBELLUM2. CEREBELLUM

3. BRAINSTEM – Medulla Oblongata, Pons & Midbrain3. BRAINSTEM – Medulla Oblongata, Pons & Midbrain

CENTRAL NERVOUS SYSTEMCENTRAL NERVOUS SYSTEM

B. SPINAL CORDB. SPINAL CORD- about 45 cms (18 ins) from foramen magnum to L1- about 45 cms (18 ins) from foramen magnum to L1

- supported & protected by the vertebral column- supported & protected by the vertebral column

- suspended in CSF- suspended in CSF

Parts:Parts:

1. Conus Terminalis (Medullaris)1. Conus Terminalis (Medullaris)

2. Filum Terminale2. Filum Terminale

3. Cauda Equina3. Cauda Equina

NERVOUS SYSTEMNERVOUS SYSTEM

2.2. PERIPHERAL NERVOUS SYSTEMPERIPHERAL NERVOUS SYSTEM

Parts: Cranial & Spinal NervesParts: Cranial & Spinal Nerves

Components of a Peripheral Nerve Fiber:Components of a Peripheral Nerve Fiber:

1. Axon1. Axon

2. Neurolemmal Sheath2. Neurolemmal Sheath

3. Endoneurial Connective Tissue Sheath3. Endoneurial Connective Tissue Sheath

PERIPHERAL NERVOUS SYSTEMPERIPHERAL NERVOUS SYSTEM

Types of Nerve FibersTypes of Nerve Fibers

1. 1. Myelinated Nerve FibersMyelinated Nerve Fibers

- continuous series of Schwann Cells- continuous series of Schwann Cells

2. 2. Unmyelinated Nerve FibersUnmyelinated Nerve Fibers

- enclosed as a group by neurolemmal sheath- enclosed as a group by neurolemmal sheath

- cutaneous nerve- cutaneous nerve

PERIPHERAL NERVOUS SYSTEMPERIPHERAL NERVOUS SYSTEM

Connective Tissue Coverings:Connective Tissue Coverings:1. ENDONEURIUM1. ENDONEURIUM

- delicate sheath around - delicate sheath around neurolemmal cells & axonneurolemmal cells & axon

2. PERINEURIUM2. PERINEURIUM- encloses a bundle of nerve - encloses a bundle of nerve

fibers (Fascicle)fibers (Fascicle)

3. EPINEURIUM3. EPINEURIUM- thick loose connective - thick loose connective

tissue that encloses nerve bundlestissue that encloses nerve bundles- outermost covering of a - outermost covering of a

peripheral nerveperipheral nerve

PERIPHERAL NERVOUS SYSTEMPERIPHERAL NERVOUS SYSTEM

1. CRANIAL NERVES (12 Pairs)1. CRANIAL NERVES (12 Pairs)

I - OlfactoryI - Olfactory VII - FacialVII - Facial

II - OpticII - Optic VIII - VestibuloCochlearVIII - VestibuloCochlear

III - OculomotorIII - Oculomotor IX - IX - GlossopharyngealGlossopharyngeal

IV - TrochlearIV - Trochlear X - VagusX - Vagus

V - TrigeminalV - Trigeminal XI - Spinal AccessoryXI - Spinal Accessory

VI - AbducensVI - Abducens XII - HypoglossalXII - Hypoglossal

PERIPHERAL NERVOUS SYSTEMPERIPHERAL NERVOUS SYSTEM

2. SPINAL NERVES (31 Pairs)2. SPINAL NERVES (31 Pairs)

Cervical = 8 pairsCervical = 8 pairs

Thoracic = 12 pairsThoracic = 12 pairs

Lumbar = 5 pairsLumbar = 5 pairs

Sacral = 5 pairsSacral = 5 pairs

Coccygeal = 1 pairCoccygeal = 1 pair

PERIPHERAL NERVOUS SYSTEMPERIPHERAL NERVOUS SYSTEM

3. GANGLIA3. GANGLIA

4. PLEXUSES4. PLEXUSES

A. Upper Limb – Cervical & Brachial PlexusA. Upper Limb – Cervical & Brachial Plexus

B. Lower Limb - Lumbar & Sacral PlexusB. Lower Limb - Lumbar & Sacral Plexus

PERIPHERAL NERVOUS SYSTEMPERIPHERAL NERVOUS SYSTEM

General Structure of a Spinal NerveGeneral Structure of a Spinal Nerve

Anterior Root = Efferent Fibers (Motor)Anterior Root = Efferent Fibers (Motor)

Posterior Root = Afferent Fibers (Sensory)Posterior Root = Afferent Fibers (Sensory)

Anterior Ramus = Muscles & Skin of Anterolateral wall &Anterior Ramus = Muscles & Skin of Anterolateral wall & extremities extremities

Posterior Ramus = Muscles & Skin of Posterior wallPosterior Ramus = Muscles & Skin of Posterior wall

Meningeal Branch = supply vertebra & spinal cordMeningeal Branch = supply vertebra & spinal cord

NERVOUS SYSTEMNERVOUS SYSTEM

Functional Divisions:Functional Divisions:

1. SOMATIC NERVOUS SYSTEM (VOLUNTARY)1. SOMATIC NERVOUS SYSTEM (VOLUNTARY)a. General Somatic Afferent Division (Sensory)a. General Somatic Afferent Division (Sensory)b. General Somatic Efferent Division (Motor)b. General Somatic Efferent Division (Motor)

** found both in CNS & PNS** found both in CNS & PNS ** innervates all parts of the body (motor & sensory)** innervates all parts of the body (motor & sensory)

EXCEPT visceral organsEXCEPT visceral organs smooth musclessmooth muscles glandsglands

NERVOUS SYSTEMNERVOUS SYSTEM

2. VISCERAL NERVOUS SYSTEM (Involuntary)2. VISCERAL NERVOUS SYSTEM (Involuntary)

2.a. General Visceral Afferent Division (Sensory)2.a. General Visceral Afferent Division (Sensory) - provides info on body’s internal environment- provides info on body’s internal environment - transmits visceral pain (hunger, spasms, ischemia,- transmits visceral pain (hunger, spasms, ischemia,

distension & chemical irritations)distension & chemical irritations)

NERVOUS SYSTEMNERVOUS SYSTEM

2.b. General Visceral Efferent Division (Motor)2.b. General Visceral Efferent Division (Motor) (AUTONOMIC NERVOUS SYSTEM)(AUTONOMIC NERVOUS SYSTEM)

- innervates smooth muscles, cardiac muscle & glands- innervates smooth muscles, cardiac muscle & glands- regulates visceral functions- regulates visceral functions- uses both Norepinephrine & Acetylcholine as- uses both Norepinephrine & Acetylcholine as

neurotransmittersneurotransmitters

NERVOUS SYSTEMNERVOUS SYSTEM

Divisions of the Autonomic Nervous SystemDivisions of the Autonomic Nervous System1. SYMPATHETIC DIVISION (Excitatory)1. SYMPATHETIC DIVISION (Excitatory)

2. PARASYMPATHETIC DIVISION (Inhibitory)2. PARASYMPATHETIC DIVISION (Inhibitory)

NERVOUS SYSTEMNERVOUS SYSTEM

AUTONOMIC NERVOUS SYSTEMAUTONOMIC NERVOUS SYSTEM1. SYMPATHETIC DIVISION (Excitatory)1. SYMPATHETIC DIVISION (Excitatory)

Function: prepares the body for emergenciesFunction: prepares the body for emergencies - increases the heart rate- increases the heart rate

- vasoconstriction- vasoconstriction - elevates the blood pressure- elevates the blood pressure

1.a. Efferent Fibers1.a. Efferent Fibers a) Terminate in Gangliaa) Terminate in Ganglia

- smooth muscles of bld vessel walls- smooth muscles of bld vessel walls- sweat glands- sweat glands- arrector pili muscles of skin- arrector pili muscles of skin

b) Splanchnic Nervesb) Splanchnic Nerves- smooth muscles & glands of the viscera - smooth muscles & glands of the viscera

NERVOUS SYSTEMNERVOUS SYSTEM

ANS – Sympathetic DivisionANS – Sympathetic Division

1.a. Efferent Fibers1.a. Efferent Fibers a) Terminate in Gangliaa) Terminate in Ganglia

- smooth muscles of bld vessel walls- smooth muscles of bld vessel walls- sweat glands- sweat glands- arrector pili muscles of skin- arrector pili muscles of skin

b) Splanchnic Nervesb) Splanchnic Nerves- smooth muscles & glands of the viscera - smooth muscles & glands of the viscera

NERVOUS SYSTEMNERVOUS SYSTEM

AUTONOMIC NERVOUS SYSTEMAUTONOMIC NERVOUS SYSTEM

Sympathetic Trunk Ganglia DistributionSympathetic Trunk Ganglia Distribution

3 cervical3 cervical 5 lumbar5 lumbar

12 thoracic12 thoracic 5 pelvis5 pelvis

1.b. Afferent Fibers1.b. Afferent Fibers

- form the afferent component of a local reflex arc- form the afferent component of a local reflex arc

NERVOUS SYSTEMNERVOUS SYSTEM

AUTONOMIC NERVOUS SYSTEMAUTONOMIC NERVOUS SYSTEM2. Parasympathetic Division (Inhibitory)2. Parasympathetic Division (Inhibitory)

Function: anabolic / hemostatic (energy conserving)Function: anabolic / hemostatic (energy conserving) - slows the heart rate- slows the heart rate

- increases peristalsis of the intestines- increases peristalsis of the intestines- increases glandular secretions- increases glandular secretions- relaxes body sphincters- relaxes body sphincters

NERVOUS SYSTEMNERVOUS SYSTEM

ANS - Parasympathetic DivisionANS - Parasympathetic Division

2.a. Efferent Fibers – Preganglionic both Cranial & Sacral Segments2.a. Efferent Fibers – Preganglionic both Cranial & Sacral SegmentsCranial Segment – Ciliary, Pterygopalatine, SubmandibularCranial Segment – Ciliary, Pterygopalatine, Submandibular

Otic GangliaOtic GangliaSacral Segment – Pelvic PlexusSacral Segment – Pelvic Plexus

2.b. Afferent Fibers - activated by sensations of stretch & ischemia2.b. Afferent Fibers - activated by sensations of stretch & ischemia - travel alongside the somatic afferent fibers- travel alongside the somatic afferent fibers

PERIPHERAL NERVOUS SYSTEMPERIPHERAL NERVOUS SYSTEM

Components of a Typical Spinal NerveComponents of a Typical Spinal Nerve

A. SOMATIC FIBERSA. SOMATIC FIBERSGENERAL SOMATIC AFFERENTGENERAL SOMATIC AFFERENT (Sensory) (Sensory) - extroceptive sensation (pain, temp, touch & pressure)- extroceptive sensation (pain, temp, touch & pressure) - propioceptive sensation (joint position, tension on tendon- propioceptive sensation (joint position, tension on tendon

& muscles)& muscles)

GENERAL SOMATIC EFFERENTGENERAL SOMATIC EFFERENT (Motor) (Motor) - skeletal muscles (voluntary)- skeletal muscles (voluntary)

PERIPHERAL NERVOUS SYSTEMPERIPHERAL NERVOUS SYSTEM

B. VISCERAL FIBERSB. VISCERAL FIBERS

GENERAL VISCERAL AFFERENTGENERAL VISCERAL AFFERENT (Sensory) (Sensory)

- reflex/pain sensation from mucus membranes, glands- reflex/pain sensation from mucus membranes, glands

& blood vessels& blood vessels

GENERAL VISCERAL EFFERENTGENERAL VISCERAL EFFERENT (Motor) (Motor)

- smooth muscles & glandular tissues- smooth muscles & glandular tissues

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