Junior Nervous System &

Patho

DID YOU KNOW?• The human brain is made up of a staggering

15 billion cells with about thousand billion connections between these cells. Yet it weighs less than 3 pounds.

• At three pounds the brain makes up on 2% of the total body weight but consumes 25% of energy of the entire body

• The spinal cord is less than 2 feet long but controls over 2 billion nerve cells.

• The nervous system transmits impulses to the brain at the speed of 180 mph.

• The brain is as soft as butter.

Introduction to Nervous System

• https://www.youtube.com/watch?v=aboVLnsCH44

Student Objectives1. Describe the functions of NS2. List the main divisions of NS3. Define & label neuron4. Differentiate between motor and sensory

neuron5. Identify the parts of brain and spinal cord6. Describe and label functions of the parts

of brain7.Describe and label functions of the spinal

cord8. Identify disorders of the NS.

How many nervous system/s are there?

• One with two subdivisions: CNS PNS

PNS is further divided into autonomic and motor

Central Nervous System• Consists of brain & spinal cord• Located in Dorsal cavity of body• Acts as communication center of

Nervous System• CNS interprets incoming sensory

information & issues instructions from past experience or current conditions

Peripheral Nervous System• Made of nerves outside the CNS• Carries impulses to and from brain• Consists of twelve pairs of cranial

nerves, coming off brain• Also includes 31 pairs of spinal nerves,

coming off spinal cordPNS is further divided into Afferent & Efferent Autonomic Nervous System is also part of PNS

Nerves• 12 cranial• 31 spinal

– 8 cervical– 12 thoracic-5 lumbar-5 sacral-1 coccygeal

Afferent vs. Efferent

Neurons too can be afferent, efferent or association

Afferent = Sensory• Afferent or sensory transmit neurons

impulses from peripheral organs or parts of body to brain.

• So.. it is sensing something and taking that sensation to the brain to be understood in CNS

• Example: Walk into home and smell cookies. Smell goes to brain by way of afferent neurons….stimulation

Efferent = Motor• Efferent or Motor neurons transmit

impulses from the brain back to the body

• So it is taking an impulse that has been understood or interpretated in CNS back out to the body as an action or affect

• Motor means movement or response• Example: Brain has interpreted cookie smell. Now efferent

neurons send signal to walk to get cookie and eat it……response

Autonomic Nervous System• Part of PNS• Causes body action/reactions

automatically with out us thinking about it.

• Helps to control nerve cells to body parts that we don’t control voluntarily, like heart, visceral organs (smooth muscle), & glandular organs

• We are not aware of or cannot control these body functions, thus involuntary

Video• https://www.youtube.com/watch?v=q

Pix_X-9t7E

Neurons vs.Neuroglia=Nerve Tissue

• Neurons: functional nervous cells• Neuroglia: nerve “glue”

Neuroglia• Nerve tissue that support, insulate &

protect delicate neurons in CNS• They glue or hold neurons together• They support neuron, but can not

transmit nerve impulses…NEURONS are the masters.

• Neuroglia however can divide and replenish—a neuron can not divide…thus brain tumors are tumors of the neuroglia or “gliomas”.

Neurons• Neurons is the Nerve Cell• Main job is to transmit messages in

form of nerve impulses from one part of body to another….thus ….communication from brain to body & body to brain

Neuron Structure• Common features of neurons: cell

body with nucleus, cytoplasm & cell membrane.

• Cell body is receiving & sending center• Cytoplasm is different as it has

extensions from cell body called Dendrites and Axons.

• Dendrites & Axons form pathways for nerve impulse to travel from one neuron to another.

Typical Neuron

AXON WITH MYELIN SHEATH

CELL BODY

DENDRITE

Dendrites• Means tree like: look short and

branching• Branching increases surface area to

receive impulses• There job is to carry impulse to cell

body of neuron• A neuron may have many dendrites

Axon• Single projection from Cell Body• There job is to transmit impulse away

from cell body of neuron• Axon is covered is material called

myelin sheath.• Myelin sheath insulates axon and

speeds up impulse along the axon

Nerve Impulse Transmission• Picture your palm as a cell body, your

fingers as dendrites, your arm as the axon to remember Neuron formation.

• Messages move from axon of one neuron to dendrite of another neuron, but these neurons never touch—they communicate over a synapse or space.

• The space between the two neurons is called synaptic gap.

Synapse

Schwann Cells/Myelin Sheath

• Schwann Cells form Myelin to insulate axon, wrapping around axon multiple times

• Myelin Sheath increases speed of nerve impulse, as impulses can jump between myelin sheath on Nodes of Ranuier.

Review Game

• http://msjensen.cehd.umn.edu/webanatomy/nervous/default.html

• Please label the Neuron 2 Short and the Neuron structure short.

Nerve conduction animation• https://www.youtube.com/watch

?v=9euDb4TN3b0• http://outreach.mcb.harvard.edu

/materials.htm

• (locate animation under neurobiology –right side of page)

• https://www.youtube.com/watch?v=Dqf63I_eHTw&t=77s

• https://www.youtube.com/watch?v=OZG8M_ldA1M&t=613s

CHARACTERISTICS OF NEURONS• IRRITABILITY: excitability, to

react when stimulated• CONDUCTIVITIY: ability to

transmit impulse to other neurons, muscles or glands

• Sensory Neurons=Afferent• Motor Neurons=Efferent• Connecting (Association or

Interneurons) Neurons= connect & carry impulse from neuron to neuron

Fun facts about neurons

• Most specialized cell in animals

• Longest cell– blue whale neuron

• 10-30 meters– giraffe axon

• 5 meters– human neuron

• 1-2 metersNervous system allows for 1 millisecond response time

Neurons• Most nerves contain both motor and

sensory fibers.• However; there are a few purely

sensory nerves…..

Neuron transmission terms• Electrochemical=to use both electrical and

chemicals to transmit impulses• Polarized=resting or inactive neuron• Depolarized=activation (loss of polarity or

loss of neg charge)• Action potential=transmission of nerve

impulse; all or none•Repolarized= back to resting, back to

negative•Sodium-Potassium Pump=allows

movement of Na+/K+ in/out of neuron

http://www.unm.edu/~lkravitz/MEDIA2/Action%20Potential.jpg

Action Potential• Axon at rest is polarized= Neg on inside

with K+, Positive on outside with Na.• Nerve impulse causes Sodium gate to

open, rushing in + charges, causing inside of axon to become positively charged or depolarized.

• This continues along axon, as impulse moves. This is action potential

• Once impulse moves, Potassium moves back into cell, back to neg charge. This is repolarization.

• Na+/K+ pump restores back to normal which is polarity

Synapse

Animation of neuron transmission

• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter14/animation__the_nerve_impulse.html

• http://www.brainexplorer.org/neurological_control/Neurological_Neurotransmission.shtml#

Jumping the synaptic gap

• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter14/animation__transmission_across_a_synapse.html ??????

Jumping Synaptic Gap• Chemicals called Neurotransmitters

help to diffuse the nerve impulse across the synaptic gap, triggering a new series of action potential.

• Neurotransmitters names are acetylcholine, dopamine, norepinephrine, serotonin, histamine + 30 more

Cocaine & other drugs

• Scientist believe cocaine causes release of Dopamine and blocks it’s reabsorption.

• Eventually the person makes no Dopmaine of own and is dependent on artificial supplementation with Cocaine.

DA BRAIN--Did you know?• Adult human brain weighs

about 3#.• Brain is the texture of cold

oatmeal.• The brain itself cannot feel

pain The brain is surrounded by loads of tissues, nerves and blood vessels that are plenty receptive to pain.

• 80% of the brain is water.

Meninges

Dura Mater

Arachnoid

Pia Mater

Lumbar Puncture

SPINAL DEFECTSSpinal Bifida

Meningocele

Myelomeningocele

CEREBRAL VENTRICLESLateral Venticles Foramen of

Monroe 3rd Ventricle Cerebral Aqueduct 4th Ventricle

Subarachnoid space Returning to cranial venous supply by arachnoid villi

Hydrocephalus

Shunting

ENCEPHALOCELE

Sagittal, magnetic resonance imaging (MRI) scan through the midline shows brain herniation through the sphenoid into the nasal cavity (arrow).

3 year old with many congenital defects

CEREBROSPINAL FLUID • Made in the

choroid plexus from blood

• Functions for protection, nutrition & waste removal.

http://www.bartleby.com/107/189.html

Brain• Three Parts-

– Cerebrum- Cerebellum

- Brain Stem

Cerebrum

• Convolutuions (gyri)• Sulci (sulcus)

• Fissures

Fissures• Longitudinal – dividing cerebrum into R & L

hemisphere• Transverse – divides cerebrum from cerebellum• Central – located beneath the coronal suture of

skull; divides frontal from parietal lobes• Lateral – situated on side of hemispheres;

divides frontal & temporal lobes( squamous suture)

Parieto-occipital – least obvious, separates occipital lobe from temporal (lambdoidal suture)

Cerebral Lobes

Cerebral Cortex• Not present in Animals. • Cerebral Cortex is what makes us human, as it

provides functions of speech, memory, logic, emotion, consciousness thought, will power and voluntary movement.

• Made of gray matter

Frontal Lobe of Brain• Cortex portion controls voluntary motor

function• Neurons on right control voluntary

movement on the left side of body and vice versa

• Includes areas for speech• CVA in this area affects speech of patient

Parietal Lobe• Comprise Sensory Area from bodies

sensors• Include pain, touch, heat & cold• Differienties distance, shape & size• Provides taste

Occipital Lobe• Located over cerebellum• Houses visual area, controlling

eyesight

Temporal Lobe• Upper part contains Auditory area for

hearing, memory & understanding• Anterior area assists with olfactory

area for smell

Cadaver brain at Rhodes

Corpus Callosum• A very large bundle of nerve fibers

that connects the two hemispheres.• It is deep in the cerebrum and allows

communication between the left and right hemisphere

Basal Ganglia• Islands of gray matter scattered in

the white matter of cerebrum• Function as relay stations in

pathways going to and from the cortex

• Produce Dopamine, which is an inhibitory neurotransmitter.

• What does it inhibit?

Summary of functions of Brain Lobes

• Primary Sensory Area: Parietal• Primary Motor Area: Frontal• Association Areas: help to analyze,

interpret & integrate information—these are scattered throughout the cerebral cortex.

Review• WebAnatomy

http://msjensen.cehd.umn.edu/webanatomy/timed/20.htm

• Use models and sheep brain to identify cerebral & cellebellar structures

Review• WebAnatomy Brain #2 Long (self

test) http://msjensen.cehd.umn.edu/webanatomy/nervous/default.html and Neuron 2 Medium– Use models and sheep brain to identify

cerebral & cellebellar structures

PATHOPHYSIOLOGY

• Parkinson's Disease

• Huntington’s Chorea (Disease)

Parkinsons “Mask Like face”PRE-PARKINSON LATE PARKINSONS

DIENCEPHALON (INTERBRAIN)

• Thalamus• Hypothalamus• Epithalamus

(pineal gland)

The diencephalon is colored reddish-orange

Thalamus• Spherical mass of Gray Matter• Found deep in cerebral hemisphere• Encloses the 3rd ventricle• Is a relay station for sensory

impulses coming from brain stem• All afferent sensory impulses go

through the thalamus, except the Olfactory Nerve

Hypothalamus• Lies below the Thalamus• Eight functions:

– Regulates ANS– Cardiovascular control-Appetite control-Temperature control-Water balance-GI control-Emotional state-Sleep control

Pineal Gland• Pinecone shaped endocrine gland

• Secretes melatonin, which effects our sleep, mood and behavior

Cerebrovascular Accident

05/01/23

CVA TERMS• ANEURYSM• HEMIPLEGIA• HEMIPARESIS• DYSPHASIA• DYSPHAGIA• DIPLOPIA• TIA

CEREBELLUM

05/01/23

Cerebellum• Cauliflower shaped portion of brain

located under Occipital lobe.• Has two hemispheres & convoluted

surface• Also contains gray matter on cortex

and white matter on inner region• Branching arrangement called Arbor

Vitae=tree of life

Cerebellum Functions• Maintenance of balance

• Maintenance of muscle tone

• Coordination of muscle movements

05/01/23

BRAIN STEM

Notice the size of the Thalamus and position of brain stem

Brainstem• Is a three inch long mass of nervous

tissue which forms the upper, club like end of spinal cord.

• Cerebrum would be like a mushroom cap and the brainstem would be the stalk.

• There are 3 parts, Pons, Medulla Oblongata & midbrain.

Pons• Rounded structure located in front of

cerebellum, between midbrain & medulla oblongata.

• Pons means bridge, as it serves as two way conductive pathway for nerve impulses between the cerebrum, cerebellum & other areas of NS.

• Center for Respiratory control of inspiration

• Also helps with breathing & sleep

Medulla Oblongata• Most inferior, between the Pons and SC, &

lies just inside the cranium directly above the foramen magnum.

• Functions=vital visceral activities– Passageway for nerve impulses between

SC & brain– Slows heart rate– Controls rate & depth of respiration– Causes dilation & constriction of BV=BP– Involuntary swallowing, digestion, sleep– Vital Center

Midbrain• Most superior of brainstem &

smallest• Provides conduction pathways to and

from higher and lower centers.• Function also includes reflexes for

vision and hearing…..What would this be?

Hippocampus

• Part of Limbic system

• Lies below lateral ventricles

• Emotional state & memories

Review with brain stem• http://msjensen.cehd.umn.edu/

webanatomy/timed/20.htm

SPINAL CORD• In cross section

gray matter internally and white matter exteriorly

• Spinal nerves (31) emerge laterally from cord

05/01/23

SPINAL CORD

Can you locate the:• Spinal cord?• Spinal nerves?• Cerebellum?• Dura mater?• Medulla Oblongate?

CAUDA EQUINA

SPINAL NERVES

How a Reflex HappensHow a Reflex Happens

CRANIAL NERVESI - Olfactory II - Optic III - Oculomotor IV - Trochlear V - Trigeminal VI - Abducens VII - Facial VIII - Auditory IX - Glossopharyngeal X - Vagus XI - Accessory XII - Hypoglossal

Cranial Nerves (interactive)• http://www.wisc-online.com/objects/

ViewObject.aspx?ID=AP11504

• l

Bell’s Palsy

ANS• Sympathetic

(Fight or Flight)• Parasympathetic(Rest & Digest) or

(Repair & Repose)

PATHOPHYSIOLOGY OF NERVOUS SYSTEM

J.J. NELSON RN, CMA

Neurological Assessment• Assessing the nervous system aids in

diagnosis.• Includes:

• Medical history:• Mental status: (see Glasgow scale on

next slide)• Cranial nerve assessment: with smell,

vision, eye movement, taste, facial muscles, hearing, tongue movements, swallowing

• Muscle Test: muscle strength and tone• Sensory Exam: numbness, tingling, pin

prick exam

Glasgow Coma Scale

There is separate protocol for children

REVIEW• Meningitis• Encephalitis• Spina Bifida,

meningocele, myelomeningocele

• Hydrocephalus• Encephlocele• Parkinson’s Disease• CVA• Bells Palsy

Dementia• Simply describes cluster of S&S:

– Loss of general intellectual capacity– Loss of memory– Loss of judgment– Impairment in cognitive skills e.g.

language

• ALZHEIMER’S is a disease with dementia. This pathology is progressive with unknown etiology

and palliative treatment.

HEAD INJURY

• Cerebral Concussion• Cerebral Contusion • Epidural Hematoma

• Subdural Hematoma

Spinal Cord Injury• A spinal cord injury usually begins with a

sudden, traumatic blow to the spine that fractures or dislocates vertebrae. The damage begins at the moment of injury when displaced bone fragments, disc material, or ligaments bruise or tear into spinal cord tissue.

• Injuries above C3 = death (hyperextension); Other cervical severing =quadriplegia. The lower the injury the lower the paralysis-paresis. The extent of the symptoms depends on the extent of the injury

INTERVERTEBRAL DISK DISEASE

• Degenerative: deterioration of the disk, with associated nerve involvement.

• Trauma: A. B. 

C.

Disc Bulge (A)

Herniated Disc (B)

Disk Rupture (C)

EPILEPSY• Chronic brain disorder

characterized by sudden abnormal intense electrical activity in the brain.

• Etiology idiopathic or traumatic• S&S- many forms of seizures• DX: EEG, CT scan (structural

changes)• TX : anticonvulsants & education• MANY MYTHS

Intracranial Tumors• Benign or malignant• Primary or secondary• S&S vary with area involved. Increased

intracranial pressure results in headache, N&V, vertigo, diplopia, disturbance in balance

• TX: Craniotomy with/without chemotherapy and radiation

Multiple Sclerosis (MS)

• http://www.nationalmssociety.org/about-multiple-sclerosis/what-we-know-about-ms/what-is-ms/index.aspx

CARPAL TUNNEL SYNDROME

Review 13-14• Complete Review WS• Dissect the cow brain and complete

WS• http://msjensen.cehd.umn.edu/

webanatomy/nervous/default.html– Neuron 2 Medium– Brain 2 Medium

Review

1. Dissect the cow brain and draw, record answers #1-#5

2. Label the neuron http://www.enchantedlearning.com/subjects/anatomy/brain/label/neuron.shtml

3. Label the brain: http://www.enchantedlearning.com/subjects/anatomy/brain/label/lateralbrain/label.shtml

4. QUIZ BOWL 12-13 http://msjensen.cehd.umn.edu/webanatomy/game/NervousI.htm