NERVOUS SYSTEMNERVOUS SYSTEM

CENTRAL NERVOUS SYSTEM (CNS)Brain

Spinal Cord

PERIPHERAL NERVOUS SYSTEM

Cranial & Spinal Nerves

Somatic -- supplies the skeletal muscles & skin

Autonomic Nervous System (ANS)

1. Sympathetic Nervous System

2. Parasympathetic Nervous System

-- supplies smooth muscles, cardiac, & glands

NEURON-- structural unit of the nervous system

-- conducts impulse towards the cell body

-- contains the nucleus

-- conducts impulses awayfrom the cell body

Dendrites

Cell Body

Axon

Nervous tissue contain cells called Neuroglial (glial)-- supply nutrients-- cleans up debris-- assist in the production

Cerebrospinal fluid

Schwann Cell

-- is that part of the Schwann cell thatcontains the nucleus & allows forregeneration of the nerve

-- type of neuroglial cell found outsidethe CNS & forms the Myelin Sheatha connective tissue that binds nervefibers together

Neurilemma Sheath

Nodes of Ranvier

Synapse or Synaptic Cleft

-- junction between theAxon of one neuron &the Dendrite of another

-- are bare spots where myelin is not present

The Myelin sheath acts as an insulator& speeds up nerve transmission

to the next & further increase speed oftransmission

-- allows impulse to “jump” from one node

TYPES OF NEURONSTYPES OF NEURONS

MOTOR

(EFFERENT)

SENSORY(AFFERENT)

send impulses to the brain & spinal cord

send impulses away from the brain & spinal cord

found only in the CNS & can be sensory or motor

INTERNEURON

--the more complex the required action, thegreater the number of interneurons involved

NEUROTRANSMITTERSNEUROTRANSMITTERS

Epinephrine

Norepinephrineproduced by the Adrenal Medulla

Dopamine -- found only in the brain & helps regulatebody movement & facial expression

-- Serotonin -- Histamine

-- GABA -- Endorphins

-- Prostaglandin

-- Glutamate

Others:

-- are certain chemicals releases from the axon ofone neuron that changes the permeability of

allow Sodium into the cellthe cell membrane of the receiving neuron to

Acetylcholine -- released at the neuromuscularjunction

SPINAL CORDSPINAL CORD-- contains 31 pairs of spinal nerves

1. It is a pathway for conductingimpulses to and from the brain& spinal cord

2. It is an area of reflex activitySpinal Tracts are nerve fibers in the cord

-- Ascending Tracts -- carriessensory impulses

-- Descending Tracts -- carriesmotor impulses

-- consists of gray & white matter

-- found in the columns of whitematter

Spinal Roots

-- Each spinal nerve is attached to the cord by2 roots or horns located in the gray matter

Ventral Root -- carries motor signals

Dorsal Root -- carries sensory signals

-- these roots are combined in the spinalnerve as it leaves the vertebral columnmaking all spinal nerves Mixed Nerves-- Areas where roots combine:Cervical -- serves muscles & skin of neck & diaphragm

(Phrenic Nerve)Brachial -- serves muscles & skin of the arms & hands

(Radial Nerve)Lumbosacral -- serves muscles & skin of lower abdomen,

genitalia, legs & feet (Sciatic Nerve)

CEREBRUM-- contains 2 hemispheres ( right & left)

Frontallobe

ThalamusHypothalamus

Pituitary

Corpuscallosum

Parietallobe

Temporallobe

Occipitallobe

Cerebellum

Pons

Medullaoblongata

MidbrainThird

ventricle

Lateralventricle

Fourthventricle

Thalamus & Hypothalamus together is called the Diencephalon

FUNCTIONS OF THEHYPOTHALAMUS

1. Body Temperature

2. Some emotions, such as fear & pleasure

4. Control of the Pituitary gland

5. Water balance

6. Appetite

7. Sleep

8. Center for mind over body phenomena

3. Control of the AutonomicNervous System

Link between nervous & endocrine systems

Cerebral CortexCerebral Cortex (Cerebrum)

-- area of brain responsible for consciousness& functions in intelligence

Major Functions

1. Sensory perception

2. Voluntary control of movement

3. Language

4. Personality Traits

5. Sophisticated mental events

a. Thinking

b. Memory

c. Decision making

d. Creativity

e. Self-consciousness

--tissues of the brain are convolutedGyri

Sulci

Lobes of the BrainLobes of the Brain

-- thought association-- judgement-- discrimination-- control of skeletal muscles

Frontal Lobe

(damage to this area causes APHASIA)

-- understanding speech & usingspeech to express thoughts & feelings

-- sensory area for pain, touch, & temperature

Parietal Lobe

-- Broca center located in the left hemisphere

-- sensory area for hearing& smelling

Temporal Lobe

-- interpreting what we see,hear, and smell

Occipital Lobe

-- responsible for vision

-- combining visual images

-- These areas when stimulated or depressed willresult in certain expected symptoms

BRAIN STEMBRAIN STEM

-- connects cerebellum, brain stem, spinal cord & cerebrum

-- acts as a relay center forsight, hearing, & feeling

-- helps to regulate breathing along with the Medulla

-- reflex center concerned with head movement in response to visual & auditory stimuli

Midbrain

Pons

-- also acts as connection for the cerebrum &spinal cord

-- is a relay center & containsmany vital functions:

Medulla Oblongata

1. Respiratory Center-- regulates rate, depth, &

rhythm of respiration-- sensitive to decreased O2, increased

CO2, & change in pH

2. Cardiac Center-- regulates rate & force of the heart beat

3. Vasomotor Center-- contracts or dilates blood vessels to regulate

blood pressure

-- also contains cough, vomiting, & swallowing centers

-- may affect hiccups

-- area where nerve fibers shiftso that right side of braincontrol left side of body& visa versa

-- Reticular Activating System (RAS)area between the Pons & Medullaresponsible for keeping us awake

-- aids in the co-ordinationof voluntary muscles

-- aids in muscle tone, so that all muscle fibersare slightly tensed

CEREBELLUMCEREBELLUM

-- helps maintain balance by receivinginformation from the inner ear

-- it integrates impulses received from the cerebrum(Frontal Lobe)

CEREBROVASCULAR ACCIDENT (CVA)

-- a disorder of the blood system to the cerebrumresulting in death of tissue

-- also called a Stroke

-- may be due to a blood clot or broken blood vessel

-- area of dead tissue is called an Infarct

ISCHEMIA

-- a deficiency of bloodto a body part

Transient Ischemic Attack(TIA)

Central Nervous System is protected by:

1. Skull & vertebrae

2. Meninges

-- thickest & toughestlayer

-- contains sinuses tocollect venous blood

-- middle web-like covering-- cerebrospinal fluid flows

in the web-like spaces

-- thin delicate layer that follows the contourof the brain & spinal cord

B. Arachnoid membrane

C. Pia Mater

A. Dura Mater

Cerebrospinal FluidCerebrospinal Fluid

-- occupies the spaces between the middle layer of the meninges

-- it cushions & nourishesthe brain & spinal cord

-- it is obtained from thecirculatory system

Pathway: Lateral ventricle Foramen of Munro

Third ventricle Aqueduct of Sylvius

Fourth ventricle into the subarachnoid space

around the brain & spinal cord & returned tothe circulatory system

-- it is formed by the ChoroidPlexuses (capillaries in thewalls of the ventricles)

CRANIAL NERVESCRANIAL NERVESOn Old Olympus, Towering Tops, A Fin Visiting

Germany Viewed Some Hops

II. Optic Sight Sensory

III. Oculomotor Controls eye muscles Motor

IV. Trochlear Supplies one eye muscle Motor

V. Trigeminal Deals with pain, touch, &temperature of the faceSupplies muscles for chewing

Both

I. Olfactory Smell Sensory

BothDeals with facial expressiontaste, salivary & lacrimalglands

VII. Facial

VI. Abducen MotorSupplies one eye muscle

VIII. Vestibulocochlear SensoryHearing & balance

IX. Glossopharyngeal

muscles for swallowing

Supplies tongue, parotid gland, &

Both

X. Vagus BothSupplies thoracic &abdominal organsand digestive glands-- when stimulated

can drop the heart rate

XI. Spinal Accessory Supplies musclesof neck & back

XII. Hypoglossal MotorAllows for tonguemovement

Motor

AUTONOMIC NERVOUS SYSTEMAUTONOMIC NERVOUS SYSTEM (ANS)-- part of the Peripheral Nervous System-- supplies smooth muscles, cardiac muscles, & glands-- functions to maintain homeostasis and is

concerned with involuntary functions

--begins inthe thoracic region &

Sympathetic Parasympathetic

-- begins in thecranial area& in thelower sacral area

extends tothe 2ndlumbarspinal nerve

Function of the Sympathetic & Function of the Sympathetic & Parasympathetic Nervous SystemsParasympathetic Nervous Systems

-- Sympathetic nervous system stimulates whilethe Parasympathetic inhibits the activity of a given organ

-- acceleration versus slowing down

-- parasympathetic system is concerned withrestorative process

-- sympathetic system is involved with energyexpenditure

FUNCTIONS OF THE AUTONOMIC NERVOUSFUNCTIONS OF THE AUTONOMIC NERVOUS SYSTEMSYSTEM

SYMPATHETIC RESPONSE ORGAN PARASYMPATHETIC RESPONSE

Increase rate HEART Decrease rate (to normal)

Dilate BRONCHIOLES Constrict (to normal) (Smooth muscle)

Pupils dilate IRIS Pupils constrict (to normal)

Decrease secretion SALIVARY GLANDS Increase secretion (to normal)

Decrease peristalsis STOMACH & INTESTINES Increase peristalsis for (Smooth muscle) normal digestion

Decrease secretion STOMACH & INTESTINES Increase secretion for (Glands) normal digestion

Contracts to prevent INTERNAL ANAL Relaxes to permit defecation defecation SPHINCTER

Relaxes to prevent URINARY BLADDER Contracts for normal urination urination

Fight or Flight SyndromeFight or Flight Syndrome-- what happens to our body when under stress; whether frightened or angry

-- increases heart rate,dilates pupils

respiratory rate,& inhibits digestive

& urinary tract

-- Most organs receive both Sympathetic &Parasympathetic stimulation

-- Like the gas pedal and a brake on a car