Amy Gonzalez
Period 5
The Nervous System

Compare & Contrast the Autonomic Nervous System

Cranial Nerves

Major Parts and Functions of the Brain

Major Divisions and Subdivisions of the Nervous System

Neurotransmitters

Drugs of Abuse

Reflex Arc

Disorders/Diseases

Major Parts and Functions of the Spinal Cord

Tissues

Connective Tissue Coverings

Classification of Neurons

Major Functions of the Nervous System

Action Potential & the Nerve Impulse

Spinal Nerves

Methamphetamine

Alcohol

Marijuana

Cocaine

Ecstasy

LSD

Heroin

Effects on Mood: Acts as a painkiller due to its effects with body's natural opiates

Neurotransmitters Affected: Inhibitory and dopamine

How it is Affected: Mimics seratonin and travels along seratonin transporters; ecstasy alters the transporter and has it work in reverse; the cell then become overstimulated from excess

Neurotransmitters Affected: Seratonin

Neurotransmitters Affected: Inhibitory and dopamine

How it is Affected: THC is active chemical in marijuana and it mimics anandamide; leads to inhibition turning off and dopamine to squirt into the synapse

Effects of Mood: It is a relaxant so it slows down movements and removes unnecessary short term memories

How it is Affected: Mimics dopamine and enters the dopamine vesicles while forcing dopamine molecules out of it; excess dopamine makes transporters work in reverse and pump it to the synapse binds to receptor and overstimulates the cell

Effects on Mood: Makes person feel exhilerated feel intense pleasure

Neurotransmitters Affected: Dopamine

How it is Affected: Interacts with GABA receptors and makes them more inhibitory; binds to glutamate receptors and blocks glutamate from exciting the cell

Effects of Mood: Affects decision-making and impulse control

Neurotransmitters Affected: GABA inhibitory and glutamate

Neurotransmitters Affected: Dopamine

How it is Affected: Blocks dopamine transporters which traps dopamine in the synaptic cleft; the cell is overstimulated from constant binding

Effects of Mood: Makes person unable to stay still due to interaction with part of the brain that controls voluntary movements

Neurotransmitters Affected: Seratonin

How it is Affected: LSD resembles seratonin and binds to seratonin receptors; it may inhibit or excite the two types of receptors

Effects on Mood: Affects the LC which is responsible for feeling wakeful and evokes a startle response to unexpected stimulus

How it is Affected:Heroin mimics natural opiates and binds to opiate receptors which turns off dopamine inhibition

Effects of Mood: Elevates mood and has addictive properties due to interaction with reward pathway

Integration: Processing and interpretation of sensory input

Motor Output: Activation of effector organs (muscles and glands) produces a response

Sensory Input: Information gathered by sensory receptors about internal and external changes

Central Nervous System: Consists of the brain the the spinal cord; Integrative and control centers

Peripheral Nervous System: Consists of the cranial and spinal nerves; Communication lines between the CNS and the rest of the body

Sensory (afferent) Division: Somatic and visceral sensory nerve fibers; conducts impulses from receptors to the CNS

Motor (efferent) Division: Motor nerve fibers; Conducts impulses from the CNS to effectors (muscles and glands)

Somatic Nervous System: Somatic (voluntary) motor nerve fibers; conducts impulses from the CNS to skeletal muscles

Autonomic Nervous System: Visceral (involuntary) motor nerve fibers; Conducts impulses from the CNS to cardiac muscle, smooth muscle, and glands

Sympathetic Division: Mobilizes body systems during activity

Parasympatheic Division: Conserves energy; promotes house-keeping functions during rest

Components:
1.) Receptor: site of stimulus
2.)Sensory Neuron: transmits afferent impulses to CNS
3.) Integration Center: either monosynaptic or polysynaptic region within CNS
4.) Motor Neuron: conducts efferent impulses from integration center to effector organ
5.) Effector: muscle fiber or gland cell that responds to efferent impulses by contracting or secreting

Somatic Reflexes: Activate skeletal muscle

Autonomic (visceral) Reflexes: Activate visceral effectors (smooth or cardiac muscle or glands)

Alzheimer's Disease: A form of dementia with age
Causes or Risk Factors: Heredity; Family history; Age over 60
Symptoms: Memory loss; Confusion and disorientation; Mood changes
Treatment Options: Uncurable; Medication; Removing behavior triggers

Spinal Cord Injury: Damage to the spinal cord
Causes or Risk Factors: Direct injury or disease; Assault, fall, accident; Weakened vertebral column
Symptoms: Weakness; Loss of feeling below
Treatment Options: Completely severed spinal cord cannot be cured; Surgery

Meningitis: Infection in the meninges surrounding the brain
Causes or Risk Factors: Bacteria or viral infection; Drug allergies; Fungi or parasites
Symptoms: Nausea and vomiting; Sensitivity to light; Fever and chills

Multiple Scelerosis: Autoimmune disease that damages the myelin sheath
Causes or Risk Factors: Cause not well understood; Hereditary; Family history

Austism: Brain disorder that makes it difficult to communicate
Causes or Risk Factors: Cause is not well understood; Family history; Hereditary
Symptoms: Delay in learning to talk; Repeated behaviors; Anxiety
Treatment Options:Medication; Coping skills; Specialized therapy

Cerebrovasuclar Accident: Occurs when blood flow to a portion of the brain is halted
Causes or Risk Factors: Certain types are hereditary; Blood vessel is clogged by plaque or blood clot
Symptoms: Severe headache; Change in hearing,taste,touch, or vision; Change in alertness
Treatment Options: Hospitalization; Blood clot=clot busting drugs; Blood thinners

Neuroglia(glial cells):
Small cells that surround and wrap delicate neurons

Neurons(nerve cells):
Excitable cells that transmit electrical signals

Neuroglia of the PNS

Neuroglia of the CNS

Astrocytes

Microglial Cells

Oligodendrocytes

Ependymal Cells

-Most abundant
-Cling to neurons, synaptic endings, and capillaries
-Support neurons
-Guide migration of young neurons
-Control chemical environment
-Respond to nerve impulses and neurotransmitters

-Small, ovoid cells with thorny processes
-Migrate towards injured neurons
-Ability to transform to phagocytize microorganisms

-Branched cells
-Wrap CNS nerve fibers, which form myelin sheaths in thicker nerve fibers

-Range in shape
-May be ciliated
-Line central cavities of brain and spinal column
-Form premeable barrier

Satellite Cells

Schwann Cells

-Surround neuron cell bodies in PNS
-Similar in function to astrocytes

-Surround ALL peripheral nerve fibers and form myelin sheaths in thicker nerve fiber
-Similar in function to oligodendrocytes
-Vital to regeneration of peripheral nerve fibers

Neuron Cell Body: Known as the perikaryon or soma
-Synthesizes proteins, membranes, and chemicals
-Rough ER
-Most are located in CNS

Neuron Processes: Arm-like processes that extend from cell body
-CNS has both neuron cell bodies and their processes
-PNS has only neuron processes

Structure of Motor Neuron

Nuclei: clusters of neuron cell bodies in CNS

Ganglia: clusters of neuron cell bodies in PNS

Tracts: bundles of processes in CNS

Nerves: Bundles of processes in PNS

Axon

Myelin Sheath: Protects and insulates axon
-Increases speed of nerve impulse

Dendrites

-Diffusely branched processes
-Contain some organelles as in cell body
-Receive input region of neuron
-Convey incoming messages
-Contain dendritic spines

-Each neuron has one axon
-Size varies

Myelination in PNS: Formed by Schwann cells

Axon Hillok: where axon begins

Nerve Fibers: long axons

Axon Terminal: distal endings

Axolemma: neuron cell membrane

Myelination in CNS: Formed by processes of oligodendrocytes

Myelin Sheath Gaps: Gaps between adjacent Schwann cells

Nonmyelinated Fibers: Thin fibers not wrapped in myeline

White Matter: Regions of brain and spinal cord with dense collections of myelinated fibers

Gray Matter: Mostly neuron cell bodies and nonmyelinated fibers

Bipolar: Two processes (rare)

Unipolar: One T-like process (pseudounipolar)

Multipolar: Three or more processes (most common)

Meninges:
-Cover and protect CNS
-Protect blood vessels and enclose sinuses
-Contain CSF

Dura Mater:
-Strongest meninx
-Outermost layer

Arachnoid Mater:
-Middle layer with web-like extensions
-Seperated from dura mater by subdural space
-Subarachnoid space contains CSF and largest blood vessels of the brain

Pia Mater:
-Thinnest
-Delicate layer that clings tightly to the brain
-Contains many tiny vessels that feed the brain

Cerebellum: Located dorsal to pons and medulla

Brain Stem

Cerebrum

Pons

Medulla Oblongata

Midbrain

Ventricles:
-Filled with CSF
-Lined by ependymal cells

Fourth Ventricle

Lateral Ventricle

Third Ventricle

Cerebral Aqueduct: Path in which third and fourth ventricle are connected

Cerebral Hemispheres: Left and right sections of the brain

Diencephalon

Sulci: shallow grooves

Gyri: ridges (bumps on brain)

FIssures: deep grooves

Longitudinal Fissure: Seperates both hemispheres

Transverse Fissure: Seperates cerebrum and cerebellum

Central Sulcus: Seperates precentral gyrus of frontal lobe and postcentral cyrus of parietal lobe

Parietio-occipital Sulcus: Seperates occipital and parietal lobes

Lateral Sulcus: outlines temporal lobes

Cerebral Cortex: Site of conscious mind; 40% of mass of brain

Thalamus

Hypothalamus

Epithalamus

Motor Areas:control voluntary movement
-Located in frontal lobe
-Controls voluntary movement

Sensory Areas: conscious awareness of sensation

Association Areas: integrate diverse information

Premotor Cortex

Broca’s Area

-Helps plan movements
-The "pre" to a movement

Primary Motor Cortex

-In precentral gyrus of frontal lobe
-Somatotopy: all muscles of body can be mapped to area on primary motor

Responsible for motor speech and voluntary motor activities

Purkinje Fibers: Originate in cortex, synapse, with cerebellum

Arbor Vitae: White matter in shape of a tree

Spinal Cord: enclosed in vertebral column
-begins in foramen magnus
-ends at L1 or L2
-Provides two-way communication to and from brain and body
-Protected by bone, meninges, and CSF

Cervical and Lumbar Enlargements: Areas where nerves servicing upper and lower limbs arise from spinal cord

Spinal Nerves:
-Part of PNS
-Attach to spinal cord by 31 paired roots

Epidural Space: Cushion of fat and network of veins in space between vertebrae and spinal dura mater
-CSF. fills space
-Spinal cord terminates in cone-shapes structure called conus medullaris

Spinal Roots

Dorsal Horns: interneurons that receive somatic and viscerak sensory input

Ventral Horns: some interneurons;l somatic motor neurons

Lateral Horns: (only in thoracic and superior lumbar regions) sympathetic neurons

Ventral Roots: bundle of motor neuron axons that exit the spinal cord

Dorsal Roots: sensory input to cord

Dorsal Root (spinal) Ganglia: cell bodies of sensory neurons

Spinal Cord Trauma

Paralysis: caused by damage to ventral roots or ventral horn cells; leads to motor function loss

Paraplegia: transection between T1 and L1

Paresthesias: caused by damage to dorsal roots or sensory tracts; leads to sensory function loss

Quadriplegia: transection in cervical region

Spinal Shock: transient period of functional loss caudal to lesion

Flaccid

Spastic

Amyotrophic Lateral Sclerosis: also called Lou Gehrig's disease
-Destruction of ventral horn motor neurons and fibers of pyramidal tract

Neuronal Pathways

Somatotopy: precise spatial relationship in CNS correspond to spatial relationship in body

Symmetry: pathways are paired symmetrically (left and right)

Relay: consist of chain of two or three neurons

Decussation: most pathways cross from one side of CNS to another at some point

Action Potentials: long-distance signals of axons
-Principle way neurons send signals
-Occur only in muscle cells and oxons of neurons
-Do not decay over distance
-Involves opening of specific voltage-gated channels

Graded Potentials: incoming signals operating over short distances

Generating and Action Potential

2.)Depolarization: Na+ channels open
-Na+ influx causes more depolarization, which opens more channels

3.)Repolarization: Na+ channels are inactivating and K+ channels open
-Membrane permeability to Na+ declines to resting state
-Ap spike stops rising
-K+ exits cell down its electrochemical gradient

1.)Resting State: All gated Na+ and K+ channels are closed
-Maintains the resting memerane potential

4.) Hyperpolarization: Some K+ channels remain open, and Na+ channels reset

Autonomic Nervous System: consists of motor neurons that innervate smooth muscles, cardiac muscle, and glands

Somatic Nervous System

Pathway uses a two-neuron chain

Innervates skeletal muscles

Preganglionic Neuron: cell body in CNS with thin, lightly myelinated prganglionix axon extending to ganglion

Postganglionic Neuron: cell body synapses with preganglionic axon in autonomic ganglion with nonmyelinated postganglionic axon that extends to effector organ

All motor neurons release acetylcholine
-Effect is always stimulatory

Sympathetic Divison: mobilizes body during activity

Parasynaptic Division: promotes maintenance functions, conserves energy

Reffered to as "fight-or-flight" system

Reffered to as "rest-and-digest" system

Chemical Structure

Function

Effects

Actions

Indolamines: widely used in brain; play roles in emotional behaviors and biological clock

Amino Acids: make up all proteins; proven neurotransmoitters

Catecholamines

Peptides: strings of amino acids that have diverse functions

Acetylcholine: First identified; released at neuromuscular junctions

Purines: monomers of nucleic acids that have an effect in both CNS and PNS

Endocannabinnoids: act at same receptors as THC; neurotransmitters exhibit great diversity of fucntions

Dopamine: made from amino acid, tyrosine

Seratonin: made from amino acid tryptophan

Histamine: made from amino acid histadine

Sensory (afferent) Nerves:impulses only towards CNS

Motor (efferent) Nerves:Impulses only away from CNS

Mixed Nerves: contain both sensory and motor fibers; travel both to and from CNS

(IV) Trochlear Nerves

(V) Trigeminal Nerves

(III) Occulomotor Nerves

(VI) Abducens Nerves

(II) Optic Nerves

(VII) Facial Nerves

(I) Olfactory Nerves

(VIII) Vestibuloclear Nerves

(IX) Glossopharyngeal Nerves

(X) Vagus Nerves

(XI) Accessory Nerves

(XII) Hypoglossal Nerves

Sensory nerves of smell; pathway terminates in primary olfactory cortex

Purely sensory visual function; arise from retinas

Function in raising eyelid, directing eyeball, constricting iris, and controlling lens shape

Primarily motor nerve that directs eyeball

Largest cranial nerves; supplies motor fibers for mastication

Primarily a motor, innervating lateral rectus muscle

Chief motor nerves of face; facial expression, parasympatheic impulses, to lacrimal and salivary glands; taste

Afferent fibers from hearing receptors and equilibrium; formerly auditory nerve

Innervate part of tounge and pharynx for swallowing and contribute to salivary glands; fibers conduct taste

Only cranial nerves that extend beyond head and neck region; help regulate heart, lungs, and abdominal viscera

Formerly spinal accessory nerve

Innervate tounge muscles for speech and swallowing