ObjectivesObjectives

Describe the structure of the brain, spinal Describe the structure of the brain, spinal cord, and nerves.cord, and nerves.

Analyze the function of the nervous Analyze the function of the nervous system.system.

Identify characteristics and treatments of Identify characteristics and treatments of common nervous system disorders.common nervous system disorders.

Central Nervous SystemCentral Nervous System

Communication and coordination system Communication and coordination system of the bodyof the body

Seat of intellect and reasoning.Seat of intellect and reasoning. Consists of the brain, spinal cord, and Consists of the brain, spinal cord, and

nerves.nerves.

NEURON-Nerve cell

-Transmits a message from one cell to another

-Has a nucleus, cytoplasm, and cell membrane

MASS OF NEURONSMASS OF NEURONS

Dendrites

Processes that carry impulse to cell body.

May be one or more of theses projections.

Axon

Carries impulses away from the cell body

Single long arm of a neuron.

NERVE IMPULSE

A STIMULUS creates an IMPULSE. The impulse travels into the neuron on the dendrite's) and out on the axon. At the end of the axon, a NEUROTRANSMITTER is released that carries the impulse across the SYNAPSE, to the next dendrite.

SYNAPSE

A space between neurons, messages go from one cell to another.

ASSOCIATIVE NEURONS (INTERNEURONS)

Carry impulses from sensory neurons to motor neurons.

MOTOR NEURONS

(EFFERENT)

Carry messages from brain and spinal cord to muscles and glands.

SENSORY NEURONS (AFFERENT)

Emerge from the skin or sense organs. Carry impulses to spinal cord and brain.

NEUROGLIA

Cells that insulate, support and protect the neurons, nerve glue.

AUTONOMIC NERVOUS SYSTEMAUTONOMIC NERVOUS SYSTEM

This includes This includes peripheral nerves peripheral nerves and ganglia, and ganglia, supplies heart supplies heart muscle, smooth muscle, smooth muscle and muscle and secretory glands, secretory glands, involuntary actioninvoluntary action

CENTRAL NERVOUS CENTRAL NERVOUS SYSTEMSYSTEM

The The brain and brain and spinal cordspinal cord

Peripheral Nervous System

Cranial nerves Cranial nerves and spinal and spinal nervesnerves

The BrainThe Brain 3lb mass of soft nervous tissue

100 billion neurons

Protected by skull, 3 membranes called meninges, and cerebrospinal fluid

Adequate blood supply is needed, brain tissue will die in 4-8mins with O2

Divided into 4 major parts: cerebrum, diencephalon, cerebellum, brain stem

Coverings of the Brain Coverings of the Brain (MENINGES)(MENINGES)

DURA MATER- outer brain covering, lines inside of skull, tough dense fibrous connective tissue

SUBARACHNOID SPACESUBARACHNOID SPACE

A space between arachnoid and pia mater, filled with CEREBROSPINAL FLUID.

Cerebrospinal Fluid!!!Cerebrospinal Fluid!!!

CEREBROSPINAL CEREBROSPINAL FLUIDFLUID-- acts as a acts as a liquid shock absorber liquid shock absorber and source of and source of nutrients for the brainnutrients for the brain

Choroids plexusChoroids plexus helps helps in the formation of in the formation of cerebrospinal fluid. cerebrospinal fluid.

PIA MATERPIA MATER

Covers the Covers the brain’s surface, brain’s surface, comprised of comprised of blood vessels blood vessels held together held together by connective by connective tissuetissue

Innermost layer Innermost layer of the of the meninges.meninges.

ARACHNOIDARACHNOID

Middle layer, Middle layer, resembles fine resembles fine cobweb.cobweb.

SUBDURAL SPACESUBDURAL SPACE

Between Between the dura the dura and and arachnoid.arachnoid.

Ventricles of the BrainVentricles of the Brain

Brain Brain contains four cavities filled with cerebrospinal fluid called CEREBRAL VENTRICLES.

LUMBAR PUNTURE

Removal pf CSF from spinal canal, needle puncture between 3rd and 4th lumbar vertebrae.

BLOOD-BRAIN BARRIER-BLOOD-BRAIN BARRIER-

Choroid plexus capillaries prevent substance (like drugs) from penetrating brain tissue – this makes infections, like meningitis, difficult to cure.

CEREBROSPINAL FLUIDCEREBROSPINAL FLUID Forms inside

ventricles of the brain.

Serves as a liquid shock absorber

CHOROID PLEXUSCHOROID PLEXUS

Network of blood vessels lining the ventricles which helps in the formation of cerebrospinal fluid.

CEREBRUMCEREBRUM Largest part of the brain

Maintains consciousness, mental processing and normal speech.

Divided into R and L

hemispheres by deep groove.

Divided into four lobes – FRONTAL, PARIETAL, OCCIPITAL and TEMPORAL

CEREBRUM cont..CEREBRUM cont..

SULCI- fissure or grooves separating cerebral convolutions

CONVULTIONSCONVULTIONS

EElevated folds on the levated folds on the surface of the surface of the cerebrum, they cerebrum, they increase the surface increase the surface area of the brain.area of the brain.

CEREBRAL FUNTION: CEREBRAL FUNTION: Conscious thought, Conscious thought, judgment, memory, reasoning,and will power.judgment, memory, reasoning,and will power.

DIENCEPHALON Located between

cerebrum and midbrain

Composed of THALAMUS and HYPOTHALAMUS

Vital functions of the hypothalamus:

1. Autonomic nervous control

2. Temperature control

3. Appetite control

4. Emotional state

5. Sleep control

BRAIN STEMBRAIN STEM Made up of PONS, MEDULLA and

MIDBRAIN Pathway ascending and

descending tracts Pons – in front of cerebellum,

between midbrain and medulla – contains center that controls respiration

Midbrain – vision and hearing Medulla oblongata – bulb-shaped

structure between pons and spinal cord, inside the cranium above foramen magnum.

Responsible for: 1. Heart rate 2. Blood pressure

CEREBELLUMCEREBELLUM Located behind the pons

and below the cerebrum Second largest part of

the brain. Composed of two

hemispheres Controls all body

functions related to skeletal muscles, including:

o Balanceo Muscle toneo Coordination of muscle

movements

Begins at foramen magnum and continues down to 2nd lumbar vertebrae

White and soft, in spinal canal

Surrounded by cerebrospinal fluid

FUNCTIONS AS:1. Reflex center2. Conduction pathway to

and from the brain

SPINAL CORDSPINAL CORD

Peripheral Nervous SystemPeripheral Nervous System All of the nerves of the body

and ganglia

NERVES Bundle of the nerve fibers

enclosed by connective tissue

Sensory nerves carry impulses to brain and spinal cord

Motor nerves carry impulses to muscles or glands

Mixed nerves contain both sensory and motor fibers.

Cranial NervesCranial Nerves12 pairs12 pairs

Begin in the brainBegin in the brain

Designated by number and nameDesignated by number and name

SPINAL NERVESSPINAL NERVES

Originate at spinal Originate at spinal cord and go through cord and go through openings in openings in vertebraevertebrae

31 pairs of spinal 31 pairs of spinal nervesnerves

All are mixed nervesAll are mixed nerves Named in relation to Named in relation to

their location on the their location on the spinal cordspinal cord

REFLEXREFLEX Unconscious and involuntaryUnconscious and involuntary In a simple In a simple reflex, only a sensory reflex, only a sensory

nerve and motor nerve involved – nerve and motor nerve involved – example “knee-jerk” reflexexample “knee-jerk” reflex

AUTONOMIC NERVOUS SYSTEMAUTONOMIC NERVOUS SYSTEM

Regulates Regulates activities of activities of visceral visceral organs such organs such as the heart.as the heart.

Not subject Not subject to conscious to conscious controlcontrol

SYMPATHETIC NERVOUS SYSTEM

The The “fight or flight”“fight or flight” system- when the system- when the body perceives body perceives danger, SNS sends danger, SNS sends message to adrenal message to adrenal medulla to secrete medulla to secrete adrenaline- adrenaline- heartbeat increases.heartbeat increases.

Disorders of the Nervous SystemDisorders of the Nervous SystemEPILEPSYEPILEPSY Seizure disorder of the brain,Seizure disorder of the brain,

characterized by recurring characterized by recurring and excessive discharge from and excessive discharge from neuronsneurons

Seizures believed to be result Seizures believed to be result of spontaneous, of spontaneous, uncontrolled uncontrolled electrical activity of neuronselectrical activity of neurons

Cause – UncertainCause – Uncertain Victim may have Victim may have

hallucinations and seizureshallucinations and seizures Grand mal – severe, Grand mal – severe,

convulsive seizureconvulsive seizure Petit mal - milderPetit mal - milder

MENINGITIS MENINGITIS

Inflammation of the Inflammation of the lining of the brain and lining of the brain and spinal cordspinal cord

May be bacterial or May be bacterial or viralSymptoms- viralSymptoms- headache, fever and headache, fever and stiff neckstiff neck

In severe form, may In severe form, may lead to paralysis, coma lead to paralysis, coma and deathand death

If bacterial, may be If bacterial, may be treated with antibioticstreated with antibiotics

Disorders Cont.Disorders Cont.ENCEPHALITISENCEPHALITIS• Inflammation of the brainInflammation of the brain• Cause- virus or chemical. Cause- virus or chemical.

Symps- fever, lethargy, Symps- fever, lethargy, extreme weakness, visual extreme weakness, visual disturbances.disturbances.

CEREBRAL PALSYCEREBRAL PALSY• Disturbance in voluntary Disturbance in voluntary

muscular action due to brain muscular action due to brain damage.damage.

• May be due to birth injury or May be due to birth injury or abnormal brain developmentabnormal brain development

• Spastic Quadriplegia- spastic Spastic Quadriplegia- spastic paralysis in all four limbs.paralysis in all four limbs.

• Symps- head rolling, grimacing, Symps- head rolling, grimacing, difficult speech and swallowingdifficult speech and swallowing

• No impairments of intellect.No impairments of intellect.

Disorders Cont.Disorders Cont.POLIOMYELITISPOLIOMYELITIS• Disease of nerve pathways of spinal cord- causing paralysisDisease of nerve pathways of spinal cord- causing paralysis• Almost eliminated in USA (vaccine)Almost eliminated in USA (vaccine)HYDROCEPHALUS (pictured below)HYDROCEPHALUS (pictured below)• Increased volume of cerebrospinal fluid within ventricles of the brain.Increased volume of cerebrospinal fluid within ventricles of the brain.• Usually, blockage in 3Usually, blockage in 3rdrd and 4 and 4thth ventricle ventricle• Enlargement of the head, usually noticed at birth.Enlargement of the head, usually noticed at birth.• Bypass or shunt performed to relieve pressure.Bypass or shunt performed to relieve pressure.DEMENTIADEMENTIA• Loss of 2 areas of complex behavior, such as languages, memory, visual and spatial Loss of 2 areas of complex behavior, such as languages, memory, visual and spatial

abilities, or judgementabilities, or judgement• Interferes with person’s daily life.Interferes with person’s daily life.

Disorders (cont.)Disorders (cont.)ALZHEIMER’S DISEASEALZHEIMER’S DISEASE Progressive disease that begins with Progressive disease that begins with problems remembering problems remembering (Aphasia)(Aphasia) Nerve endings in cortex of brain degenerate and block signals Nerve endings in cortex of brain degenerate and block signals

that pass between nerve cellsthat pass between nerve cells Abnormal fibers build up creating tanglesAbnormal fibers build up creating tangles Cause – UnknownCause – Unknown 11stst stage (2-4 yrs) involves confusion, short-term memory loss, stage (2-4 yrs) involves confusion, short-term memory loss,

anxiety, poor judgmentanxiety, poor judgment 22ndnd stage (2-10 yrs) increase in memory loss, logic problems, stage (2-10 yrs) increase in memory loss, logic problems,

and loss of social skillsand loss of social skills 33rdrd stage (1-3 yrs) inability to recognize oneself, weight loss, stage (1-3 yrs) inability to recognize oneself, weight loss,

seizures, mood swings and aphasiaseizures, mood swings and aphasia

PARALYSIS- PARALYSIS- loss of power of motion or sensationloss of power of motion or sensationHEMIPLEGIA- HEMIPLEGIA- paralysis on one side of the bodyparalysis on one side of the body

PARKINSON’S DISEASEPARKINSON’S DISEASE• Symps- tremors, Symps- tremors,

shuffling gait, pill-rolling, shuffling gait, pill-rolling, and muscular rigidity.and muscular rigidity.

• Decrease in Decrease in neurotransmiter neurotransmiter dopaminedopamine

• RX- L-dopa and other RX- L-dopa and other drugs to treat symptoms.drugs to treat symptoms.

MULTIPLE SCLEROSIS (MS)MULTIPLE SCLEROSIS (MS)

• Chronic inflammatory disease of Chronic inflammatory disease of CNSCNS

• Immune cells attack myelin Immune cells attack myelin sheath of axon-myelin sheath sheath of axon-myelin sheath destroyed, leaving scar tissue on destroyed, leaving scar tissue on nerve cells.nerve cells.

• Transmission of nerve impulses Transmission of nerve impulses blocked.blocked.

• Cause- UNKNOWNCause- UNKNOWN• Symps- weakness of Symps- weakness of

extremities, numbness, double extremities, numbness, double vision, nystagmus, speech vision, nystagmus, speech problems, loss of coordination, problems, loss of coordination, possible paalysis.possible paalysis.

• Typically stikes young adults Typically stikes young adults age 20-40, mostly womenage 20-40, mostly women

• Rx- Avonex- slows progressionRx- Avonex- slows progression

Cerebral Vascular AccidentCerebral Vascular Accident Stroke or CVAStroke or CVA Interruption of blood and O2 to the brainInterruption of blood and O2 to the brain Tissue deathTissue death Third leading cause of death in USAThird leading cause of death in USA

Risk FactorsRisk Factors SmokingSmoking HypertensionHypertension Heart diseaseHeart disease Family historyFamily historyCauses of CVACauses of CVA 90% caused by blood clots90% caused by blood clots Clots lodge in carotid arteries, blocking the flow of blood to the brainClots lodge in carotid arteries, blocking the flow of blood to the brain 10% caused by ruptured blood vessels in the brain10% caused by ruptured blood vessels in the brain

SYMPTOMSSYMPTOMS Hemiplegia on the opposite side of the bodyHemiplegia on the opposite side of the body Sudden, severe headacheSudden, severe headache DizzinessDizziness Sudden loss of vision in one eyeSudden loss of vision in one eye AphasiaAphasia DysphasiaDysphasia ComaComa Possible deathPossible deathTREATMENTTREATMENT1.1. Get to the hospital immediately!!Get to the hospital immediately!!2.2. CT done to determine etiologyCT done to determine etiology3.3. If a clot, treatment aimed at dissolving clotIf a clot, treatment aimed at dissolving clotPREVENTIONPREVENTIONIf TIAs- one aspirin a dayIf TIAs- one aspirin a dayStop smokingStop smokingExercise and lose weightExercise and lose weightControl hypertensionControl hypertension