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Amy Gonzalez Period 5 The Nervous System - Coggle Diagram
Amy Gonzalez
Period 5
The Nervous System
Compare & Contrast the Autonomic Nervous System
Autonomic Nervous System
: consists of motor neurons that innervate smooth muscles, cardiac muscle, and glands
Pathway uses a two-neuron chain
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
Sympathetic Divison
: mobilizes body during activity
Reffered to as "fight-or-flight" system
Parasynaptic Division
: promotes maintenance functions, conserves energy
Reffered to as "rest-and-digest" system
Somatic Nervous System
Innervates skeletal muscles
All motor neurons release acetylcholine
-Effect is always stimulatory
Cranial Nerves
(IV) Trochlear Nerves
Primarily motor nerve that directs eyeball
(V) Trigeminal Nerves
Largest cranial nerves; supplies motor fibers for mastication
(III) Occulomotor Nerves
Function in raising eyelid, directing eyeball, constricting iris, and controlling lens shape
(VI) Abducens Nerves
Primarily a motor, innervating lateral rectus muscle
(II) Optic Nerves
Purely sensory visual function; arise from retinas
(VII) Facial Nerves
Chief motor nerves of face; facial expression, parasympatheic impulses, to lacrimal and salivary glands; taste
(I) Olfactory Nerves
Sensory nerves of smell; pathway terminates in primary olfactory cortex
(VIII) Vestibuloclear Nerves
Afferent fibers from hearing receptors and equilibrium; formerly auditory nerve
(IX) Glossopharyngeal Nerves
Innervate part of tounge and pharynx for swallowing and contribute to salivary glands; fibers conduct taste
(X) Vagus Nerves
Only cranial nerves that extend beyond head and neck region; help regulate heart, lungs, and abdominal viscera
(XI) Accessory Nerves
Formerly spinal accessory nerve
(XII) Hypoglossal Nerves
Innervate tounge muscles for speech and swallowing
Major Parts and Functions of the Brain
Cerebellum
: Located dorsal to pons and medulla
Purkinje Fibers
: Originate in cortex, synapse, with cerebellum
Arbor Vitae
: White matter in shape of a tree
Brain Stem
Pons
Medulla Oblongata
Midbrain
Cerebrum
Cerebral Hemispheres
: Left and right sections of the brain
Sulci
: shallow grooves
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
Gyri
: ridges (bumps on brain)
FIssures
: deep grooves
Longitudinal Fissure
: Seperates both hemispheres
Transverse Fissure
: Seperates cerebrum and cerebellum
Diencephalon
Thalamus
Hypothalamus
Epithalamus
Cerebral Cortex
: Site of conscious mind; 40% of mass of brain
Motor Areas
:control voluntary movement
-Located in frontal lobe
-Controls voluntary movement
Premotor Cortex
-Helps plan movements
-The "pre" to a movement
Broca’s Area
Responsible for motor speech and voluntary motor activities
Primary Motor Cortex
-In precentral gyrus of frontal lobe
-
Somatotopy
: all muscles of body can be mapped to area on primary motor
Sensory Areas
: conscious awareness of sensation
Association Areas
: integrate diverse information
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
Major Divisions and Subdivisions of the Nervous System
Central Nervous System:
Consists of the brain the the spinal cord; Integrative and control centers
Sensory (afferent) Division:
Somatic and visceral sensory nerve fibers; conducts impulses from receptors to the CNS
Peripheral Nervous System:
Consists of the cranial and spinal nerves; Communication lines between the CNS and the rest of the body
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
Neurotransmitters
Chemical Structure
Indolamines
: widely used in brain; play roles in emotional behaviors and biological clock
Seratonin: made from amino acid tryptophan
Histamine: made from amino acid histadine
Amino Acids
: make up all proteins; proven neurotransmoitters
Catecholamines
Dopamine
: made from amino acid, tyrosine
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
Function
Effects
Actions
Drugs of Abuse
Methamphetamine
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
Alcohol
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
Marijuana
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
Cocaine
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
Ecstasy
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
Effects of Mood:
Elevates mood and has addictive properties due to interaction with reward pathway
LSD
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
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:
Heroin mimics natural opiates and binds to opiate receptors which turns off dopamine inhibition
Reflex Arc
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)
Disorders/Diseases
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
Major Parts and Functions of the Spinal Cord
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
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
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 Cord Trauma
Paralysis
: caused by damage to ventral roots or ventral horn cells; leads to motor function loss
Flaccid
Spastic
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
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
Tissues
Neuroglia
(glial cells):
Small cells that surround and wrap delicate neurons
Neuroglia of the PNS
Satellite Cells
-Surround neuron cell bodies in PNS
-Similar in function to astrocytes
Schwann Cells
-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
Neuroglia of the CNS
Astrocytes
-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
Microglial Cells
-Small, ovoid cells with thorny processes
-Migrate towards injured neurons
-Ability to transform to phagocytize microorganisms
Oligodendrocytes
-Branched cells
-Wrap CNS nerve fibers, which form myelin sheaths in thicker nerve fibers
Ependymal Cells
-Range in shape
-May be ciliated
-Line central cavities of brain and spinal column
-Form premeable barrier
Neurons
(nerve cells):
Excitable cells that transmit electrical signals
Neuron Cell Body
: Known as the perikaryon or soma
-Synthesizes proteins, membranes, and chemicals
-Rough ER
-Most are located in CNS
Nuclei
: clusters of neuron cell bodies in CNS
Ganglia
: clusters of neuron cell bodies in PNS
Neuron Processes
: Arm-like processes that extend from cell body
-CNS has both neuron cell bodies and their processes
-PNS has only neuron processes
Tracts
: bundles of processes in CNS
Nerves
: Bundles of processes in PNS
Structure of Motor Neuron
Axon
-Each neuron has one axon
-Size varies
Axon Hillok
: where axon begins
Nerve Fibers
: long axons
Axon Terminal
: distal endings
Axolemma
: neuron cell membrane
Myelin Sheath
: Protects and insulates axon
-Increases speed of nerve impulse
Myelination in PNS
: Formed by Schwann cells
Myelin Sheath Gaps
: Gaps between adjacent Schwann cells
Nonmyelinated Fibers
: Thin fibers not wrapped in myeline
Myelination in CNS
: Formed by processes of oligodendrocytes
White Matter
: Regions of brain and spinal cord with dense collections of myelinated fibers
Gray Matter
: Mostly neuron cell bodies and nonmyelinated fibers
Dendrites
-Diffusely branched processes
-Contain some organelles as in cell body
-Receive input region of neuron
-Convey incoming messages
-Contain dendritic spines
Connective Tissue Coverings
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
Classification of Neurons
Bipolar
: Two processes (rare)
Unipolar
: One T-like process (pseudounipolar)
Multipolar
: Three or more processes (most common)
Major Functions of the Nervous System
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
Action Potential & the Nerve Impulse
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
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
Graded Potentials
: incoming signals operating over short distances
Spinal Nerves
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