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Kayla Lay P2 Nervous System - Coggle Diagram
Kayla Lay P2 Nervous System
Neurotransmitters
Peptides (neuropeptides)
string of amino acids that have diverse functions
endorphins: beta endorphin, dynorphin, and enkephalins: act as natural opiates; reduce pain perception
Purines
monomers of nucleic acids that have an effect in both CNS and PNS
Amino acids
make up all proteins: therefore, it's difficult to prove which are neurotransmitters
Gases and lipids
Biogenic amines
catecholamines
dopamine, norepinephrine, and epinephrine
indolamines
serotonin: made from the amino acid tryptophan
histamine: made from the amino acid histidine
all widely used in the brain: play roles in emotional behaviors and biological clock
Endocannabinoids
act as same receptors as TCH (active ingredient in marijuana
Acetylcholine
released at neuromuscular junction
used by many ANS neurons and some CNS neurons
synthesized from acetic acid and choline by enzyme choline acetyltransferase
degraded by enzyme acetylcholinesterase
classification
Effects: excitatory (depolarizing) versus inhibitory (hyperpolarizing)
effect determined by receptor to which it binds
Actions: direct (neurotransmitter binds directly to and opens ion channels) versus indirect (neurotransmitter acts through intracellular second messenger)
Disorder/diseases
damage to primary motor complex
paralysis occurs on opposite side of body from damage
muscle strength or ability to preform discrete individual movement is not impaired; only movement control is lost
other premotor neurons can be reprogrammed to take over skill of damaged neurons
damage to primary visual cortex
functional blindness
by contrast, individuals w/ a damaged visual association area can see, but they do not comprehend what they are looking at
hypothalamus disturbances
severe body wasting
obesity
sleep disturbances
dehydration
emotional imbalances
Epileptic seizure
not associated w/ intellectual impairments
occurs in 1% of pop; genetic factor play a role, but brain injuries, stroke, infections, or tumors can also be causes
may lose consciousness, fall stiffly, and have uncontrollable jerking
control includes anticonvulsive drugs, vagus nerve stimulator or deep brain stimulator implantations that deliver pulses to vagus nerve or directly to brain to stabilize brain activity
torrent of electrical discharges by groups of neurons; prevent any other messages from getting through
Meningitis
inflammation of the meninges
may spread to CNS, which would lead to inflammation of the brain (encephalitis)
usually diagnosed by observing microbes in a sample of CSF obtained via lumbar puncture
Hydrocephalus
obstruction blocks CSF circulation or drainage, result in increased pressure
in newborns, skull bones are unfused so increased pressure causes head to enlarge
in adults, rigidity of the skull keeps pressure within, potentially leading to brain damage (can compress blood vessels and crush soft nervous tissue)
Alzheimer's disease
memory loss, short attention span, disorientation, eventual lang loss, irritability, moodiness, confusion, hallucinations
plaques of beta-amyloid peptides form in brain
progressive degenerative disease of brain that results in dementia (key proteins appear misfolded and malfunction)
neurofibrillary tangles inside neurons interfere w/ transport mechanisms, eventually killing neuron
as brain cells die, brain shrinks
Anencephaly
cerebrum and parts of brain stem never develop b/c neural fold fails to fuse
child is vegetative; death occurs soon after birth
Spina bifida
incomplete formation of vertebral arches; typically involves lumbosacral region
laminae and spinous processes are missing on at least one vertebre
US incidence dropped w/ recommendations for supplementation
spina bifida occulata: least serious, involves only one or few missing vertebrae and usu causes no neural probs; sacral dimple or patch of pair may indicate hint at underlying omally
more severe situation if meninges protrude through dorsal spinal (form saclike cyst called meningocele) (portion of spinal cord and nerve roots protrude inside it's called myelomenigocele) (child may have hydrocephalus, paralysis, and bowler and bladder dysf
most caused by lack of folic acid
Autonomic neuropathy
damage to autonomic nerves that is common complication of diabetes mellitus
early signs include sexual dysfunction
other frequent symptoms: dizziness, urinary incontinence, sluggish eye pupil, impaired sweating
best way to prevent is maintain good blood glucose levels
Parkinson's disease
degeneration of dopamine; releasing neurons of substantia nigra
basal nuclei deprived of dopamine become overactive, result in tremor at rest
cause unknown; theories: mitochondrial abnormalities or protein degration pathway
treatment includes L-dopa, deep brain stimulation, gene theory
Paralysis
caused by damage to ventral roots or ventral horn cells
lead to motor function loss
Huntington's disease
fatal hereditary disorder caused by accumulation of protein huntingtin in brain cells (degeneration of basal nuclei and cerebral cortex)
initial symptoms include wild, jerky "flapping" movements
later marked by mental disorientation (usually fatal within 15 yrs of onset
treated w/ drugs that block dopamine effects
Paresthesias
caused by damage to dorsal roots or sensory tracts
lead to sensory function loss
Cerebral palsy
neuromuscular disability involving poorly controlled or paralyzed voluntary muscles
due to brain damage, possibly from lack of oxygen during birth
spasticity, speech difficulties, motor impairments can be seen
some patients have seizures, are intellectually impaired, and/or deaf
visual impairment common
long lasting or intense pain, such as limp amputation
lead to hyperalgesia, chronic pain, and phatom limb pain
NMDA receptors are activated by long-lasting or intense pain
Phantom limb pain: pain felt in limb that has been amputated
now use as epidural anesthesia during surgery to reduce phantom pain
Multiple sclerosis
an autoimmune disease that affects primarily young adults
myelin sheaths in CNS are destroyed when immune system attack myelin (myelin hardened lesions called scleroses) (impulse conduction slows and ceases)
symptoms: visual disturbances, weakness, loss muscular control, speech disturbances, incontinence
treatment: drugs that modify immune system activity
may not be able to prevent, but maintaining high blood levels of vitamin D may reduce risk develp
Autonomic dysreflexia
life threatening, uncontrolled activation of autonomic neurons in quadriplegics and people w/ spinal cord injuries above T6
blood pressure skyrockets, posing increased risk for stroke
Raynaud's disease
painful, exaggerated vasoconstriction in fingers and toes
digits turn pale, then cyanotic
treated w/ vasodilators
Hypertension (high blood pressure)
heart must work harder, and artery walls are subjected to increased wear and tear
can be treated w/ adrenergic receptor-blocking drugs
overactive sympathetic vasoconstrictor response to stress
Autism
brain disorder that makes it difficult to communicate
Cerebrovascular accident (stroke)
occurs when blood flow to a portion of the brain is halted
Reflex arc
Integration Center
either monosynaptic or polysynaptic region within CNS
Motor neuron
conducts efferent impulses from integration center to effect or organ
Sensory neuron
transmits afferent impulses to CNS
Receptor
site of stimulus action
Effector
muscle fiber or gland cell that responds to efferent impulses by contracting or secreting
Compare and contrast autonomic nervous system
ANS motor neurons
make adjustments to ensure optimal support for body activities
operate via subconscious control
innervate smooth muscles, cardiac muscles, and glands
two divisions
Parasympathetic divison
promotes maintenance functions, conserves energy
role
keeps body energy use low as possible, even while carrying out maintenance activities (directs digestion, diuresis, defecation)
rest and digest system
blood pressure, heart rate, and respiratory rates are low; gastrointestinal tract activity is high; pupils constricted
also called craniosacral division
long preganglionic fibers extend from CNS almost to target organs
synapse w/ postganglionic neurons in terminal gangia that close or within target organ; short postganglionic fibers synapse w/ effectors
ACh neurotransmitter
Sympathetic divison
mobilizes body during activity
role
fight or flight system
exercise, excitement, emergency, embarrassment activates sympathetic system
increased heart rate, dry mouth, cold and sweaty skin, dilated pupils
during vigorous phy activity: shunts blood to skeletal muscles and heart; dilates bronchioles; causes liver to release glucose
also called thoracolumbar division
preganglionic neurons are in spinal cord seg T1-L2
form lateral horns of spinal cord
sympathetic more complex and innervates more organs than parasympathethic
some structures innervated only by sympathetic: sweat glands, arrector pili muscle of hair follicle, smooth muscles of all blood vessels
short preganglionic fibers, long postganglionic fibers
NE neurotransmitter
Dual innervation: all visceral organs served by both divisions, but divisions cause opp effects; dynamic antagonism
action potentials continually fire down axons of both divisions, producing a dynamic antagonistic interaction
works to precisely control visceral activity
one division usually predominates, but in a few cases, divisions have cooperative effects
both ANS divisions are partially active, resulting in a basal sympathetic and parasympathetic tone
Drugs of Abuse
Heroine
interfere: inhibitory neurotransmitter; dopamine neurotransmitter
affect neurotransmitters: mimics natural opiates and binds to opiate receptors; turn off dopamine inhibition; dopamine flood synapse
affect mood/action: immediate feelings of sedation and well being; pain, stress, and emotional attachment diminished
Ecstasy
interfere: serotonin neurotransmitter
affect neurotransmitter: mimics serotonin and is taken up by serotonin transporters; transporter becomes confused and start transporting serotonin out; excessive serotonin trapped in synaptic cleft, overstimulating cell
affect mood/action: affects mood, sleep, perception and appetite; indirectly interacts w/ reward pathways; addictive properties
Marijuana
affect neurotransmitter: mimics anandamine and binds to cannabinoid receptors; inhibition turned off and dopamine squirt into synapse
affect mood/action: remove unnecessary short term memories; slow down movement, feel relaxed and calm
interfere: inhibitory neurotransmitter; dopamine neurotransmitter
Alcohol
interfere: GABA inhibitory neurotransmitter; glutamate neurotransmitter
affect neurotransmitter: interacts w/ GABA receptors to make then more inhibitory; binds to glutamate receptors, prevent exit
affect mood/action: double sedative punch; affect memory formation, decision making, and impulse control
Cocaine
interfere: dopamine neurotransmitter
affect neurotransmitter: blocks transporters, leaving dopamine trapped in synaptic cleft; dopamine binds again and again to receptors, stimulating cell
affect mood/action: concentrates reward pathways; control voluntary movement; fidget and unable to stay still
Methamphetamine
affect neurotransmitter: mimics dopamine and taken into cell; enters dopamine vesicles, forcing dopamine molecules out; transports work in reverse; overstimulate cell from trapped excessive dopamine
affect mood/action: feel intense pleasure and exhilaration
interfere: dopamine neurotransmitters
LSD
affect neurotransmitter: chemically resembles serotonin and elicits its effect by binding to serotonin receotor; may inhibit receptors and excite them; excite locus coruleus; single neuron may branch to diff sensory areas of brain
affect mood/action: complex sensory effects; feelings of wakefulness and evoke a startle response to unexpected stimulus
interfere: serotonin neurotransmitters
Action Potential and the Nerve Impulse
principal way neurons send signals; long distance neural communication
Depolarization: Na+ channels open
depolarizing local currents open voltage-gated Na+ channels, and Na+ rushes into cell
Na+ influx causes more depolarization, which opens more Na+ channels
at threshold, positive feedback opens all Na+ channels
large action potential spike; membrane polarity jumps to +30 mV
Repolarization: Na+ channels are inactivating, and K+ channels open
Na+ channel inactovation gates close
membrane preambility to Na+ declines to rest state; AP spike stops rising
voltage-gated K+ channels open
K+ exits cell down its electrochem gradient
membrane returns to resting membrane potential
Resting state : all gated Na+ and K+ channels are closed
only leakage channels for Na+ and K+ are open
maintains resting membrane potential
Hyperpolarization: some K+ channels remain open, and Na+ channels rest
slight dip below resting voltage
Na+ channels also begin to rest
some K+ channels remain open, allow excessive K+ efflux
inside membrane more negative than in resting state
Threshold and All-or-None Phenomenon
not all depolarization events produce APs
for axon to fire, depolarization much reach threshold voltage to trigger AP
AP either happens completely, or does not happen at all
Propagation of an AP
allows AP to be transmitted from origin down entire axon length toward terminals
nonmyelinated axons- each successive segment of membrane depolarizes, then reploarizes; myelinated axons differ
no new AP is generated because Na+ channels closer to AP origin inactivated
Refractory Period
time in which neuron cannot trigger another AP; voltage-gated Na+ channels are open, so neuron cannot respond to other stimulus
Conduction Velocity
APs occur only in axons, not other cell areas
Continuous conduction: slow conduction that occurs in nonmyelinated axons
Saltatory conduction: occurs only in myelinated axons and is about 30 times faster
Major parts and functions of the spinal cord
structure
Ventral (anterior) median fissure
Dorsal (posterior) medican sulcus
Gray matter
Gray commisure: bridge of gray matter that connects masses of gray matter on either side (encloses central canal)
Ventral roots: bundle of motor neuron axons that exit the spinal cord
Lateral horns (only in thoracic and superior lumbar regions): sympathetic neurons
Dorsal root (spinal) ganglia: cell bodies of sensory
Ventral horns: some interneurons; somatic motor neurons
Dorsal roots: sensory input to cord
Dorsal horns: interneurons that receive somatic and visceral sensory input
spinal nerves: formed by fusion of dorsal and ventral roots
divided into four groups
visceral sensory
visceral autonomic motor
somatic motor
somatic sensory
White matter
myelinated and nonmyelinated nerve fibers allow communication between parts of spinal cord, and spinal cord and brain
divided into three white columns
lateral
ventral (anterior)
dorsal (posterior)
three directions
descending
ascending
transverse
Central canal
runs length of cord (filled w/ CSF)
functions
provides two way communication to and from brain and body
major reflex center: reflexes are initiated and completed at spinal cord
Cranial nerves
VII: Facial nerves
Chief motor nerves of face w/ five major branches; motor functions include facial express, parasympathetic impulses to lacrimal and salivary glands
sensory function (taste) from anterior two-thirds of tongue
fibers from pons travel through internal acoustic meatuses and emerge through stylomastoid foramina to lateral aspect of face
V: Trigeminal nerves
largest cranial nerves; fibers extend from pons to face
three divisions: ophthalmic, maxillary, mandibular
convey sensory impulses from various areas of face; supply motor fibers for mastication
VIII: Vestibulocochlear
afferent fibers from hearing receptors and equilibrium receptors pass from inner ear through internal acoustic meatuses and enter brain; stem at pons-medulla boarder
mostly sensory function; small motor component for adjustment of sensitivity of receptors
formerly auditory nerve
IV: Trochlear nerves
fibers from dorsal midbrain enter orbits via superior orbital fissures to innervate superior oblique muscle
primarily motor nerve that directs eyeball
IX: Glossopharyngeal nerves
motor functions: innervate part of tongue and pharynx for swallowing and provide parasympathetic fibers to parotid salivary glands
sensory functions: fibers conduct taste and general sensory impulses from pharynx and posterior tongue, impulses from carotid chemoreceptors and baroreceptors
fibers from medulla leave skull via jugular foramen and run to throat
III: Oculomotor nerves
fibers extend from ventral midbrain through superior orbital fissures to four of six entrinsic eye muscles
function in raising eyelid, directing eyeball, constricting iris, and controlling lens shape
X: Vagus nerves
only cranial nerves that extend beyond head and neck region; fibers from medulla exit skull via jugular foramen
most motor fibers parasympathetic fibers that help reg activities of heart, lungs, and abdominal viscera;
sensory fibers carry impulses from thoracic and abdominal viscera, baroreceptors, chemoreceptors, and taste buds of posterior tongue and pharynx
II: Optic nerves
optic tracts continue to thalamus where synapse; optic radiation fibers run to occipital cortex
purely sensory (visual) function
arise from retinas; really a brain tract; pass through optic canals, converge, and partially cross over at optic chiasma
XII: Hypoglossal nerves
fibers from medulla exit skull via hypoglossal canal
innervate extrinsic and intrinsic muscles of tongue that contribute to swallowing and speech
I: Olfactory nerves
sensory nerves of smell
fibers synapse in olfactory bulbs; pathway terminates in primary olfactory cortex
purely sensory (olfactory) function
XI: Accessory nerves
accessory nerves exit skull via jugular foreamina to innervate trapezius and sternocleidomastoid muscles
formerly spinal accessory nerve
formed from ventral rootlets from C1 to C5 region of spinal cord; rootlets pass into cranium via each foramen magnum
VI: Abducens nerves
fibers from inferior pons enter orbits via superior orbital fissure
primarily a motor, innervating lateral rectus muscle
Spinal nerves
5 pairs of lumbar nerves (L1-L5)
5 pairs of sacral nerves (S1-S5)
12 pairs of thoracic nerves (T1-T12)
1 pair of thin coccygeal nerves (C0)
8 pairs of cervical nerves (C1-C8)
connected via
Ventral roots: contain motor (efferent) fibers from ventral horn motor neurons that innervate skeletal muscles
Dorsal roots: contain sensory (afferent) fibers from sensory neurons in dorsal root ganglia that conduct impulses from peripheral repeaters
Major divisions and subdivisions
Central nervous system (CNS)
brain and spinal cord of dorsal body cavity; integration and control center: interprets sensory input and dictates motor output
Peripheral nervous system (PNS)
portion of nervous system outside CNS; consists mainly of nerves that extend from brain and spinal cord
sensory (afferent) division
Visceral sensory fibers: covey impulses from visceral organs to CNS
Somatic sensory fibers: convey impulses from skin, skeletal muscles, and joints to CNS
motor (efferent) division
transmits impulses from CNS to effector organs- muscles and glands
Somatic nervous system
somatic motor nerve fibers conduct impulses from CNS to skeletal muscle; conscious control of skeletal muscles
Autonomic nervous system
consists of visceral motor nerve fibers; regulates smooth muscle, cardiac muscle, and glands
Sympathetic
Parasympathetic
Major functions
master of controlling and communicating system of body
cells communicate via electrical and chemical signals; rapid and specific, almost immediate reponses
three overlapping functions
Sensory input
info gathered by sensory receptors about internal and external changes
Integration
processing and interpretation of sensory input
Motor output
activation of effector organs (muscles and glands) produces a response
Major parts and functions of the brain
Parietal: top of head
sensory of touch
Temporal: above ears
auditory; hearing
Frontal: behind forehead
judgement and making plans
Occipital: behind head
vision
Right hemisphere
visual-spatial skills, intuition, emotion, artistic, and muscle skills
Short-term: temp. holding of info
Long-term: has limitless capacity
Left hemishpere
controls language, math, and logic
Wernicke's area: understanding spoken and written words
Broca's area: involved in speech production
Cerebellum: rear of brainstem
processing sensory input and coordinating movement output and balance, nonverbal learning and memory; arbor vitae
brainstem
Midbrain: between diencephalon and pons
vision, hearing, motor control, sleep/wake, arousal, temp reg.
Pons: between midbrain and medulla
coordinates facial movements, hearing and balance
Medulla Oblongata: blends into spinal cord at foramen magnum
regulate your breathing, heart rhythms, blood pressure and swallowing.
exterior
Central sulcus: separates frontal from parietal lobe
Longitudinal fissure: separates left and right cerebrum
Sulci: grooves
Transverse fissure: separates occipiatal lobe and cerebellum
Gyri: ridges
Pineal gland
helps regulate circadian rhythm
Mammillary body
recollective memory
ventricles
Fourth ventricle
protect the human brain from trauma; help form central canal
Lateral ventricle
CSF provides cushioning for the brain while also helping to circulate nutrients and remove waste
Third ventricle
sends messages to and receives messages from the lateral ventricle
Corpora Quadrigemina
controls position of head and eyes in response to visual, auditory, and somatic stimuli; transmits auditory signals
fornix
cognition and episodic memory recall
Corpus callosum
ensures both sides of the brain can communicate and send signals to each other
Hypothalamus
keep body in homeostasis
Thalamus
body's information relay station
Cerebral cortex
associated with higher level processes such as consciousness, thought, emotion, reasoning, language, and memory
White matter
conduct, process, and send nerve signals up and down the spinal cord
Cerebral Peduncle
assist in refining motor movements, learning new motor skills, and converting proprioceptive info
Classification of neurons
structural classification- grouped by number of processes
Bipolar
two processes (1 axon, 1 dendrite)
rare (ex: retina and olfactory mucosa)
Multipolar
three or more processes (1 axon, others dendrites)
most common and major neuron type in CNS
Unipolar
one T-like process (2 axons)
also called psuedounipolar
functional classification- grouped by direction in which nerve impulse travels relative to CNS
Sensory
almost all are unipolar
cell bodies located in ganglia in PNS
transmit impulses from sensory receptors toward CNS
Motor
carry impulses from CNS to effectors
multipolar
most cell bodies located in CNS (except some autonomic neurons)
Internuerons
shuttle signals through CNS pathways
most are entirely within CNS
lie between motor and sensory neurons
99% body neurons are interneurons
also called association neurons
Tissues
Neuroglia (glial cells): small cells that surround and wrap delicate neurons
Neuroglia of the PNS
Satellite cells
surround neuron cell bodies in PNS
function similar to astrocytes of CNS
Schwann cells (neurolemmocytes)
surround all peripheral nerve fibers and form myelin sheaths in thicker nerve fibers
vital to regeneration of damaged peripheral nerve fibers
similar function as oligodendrocytes
Neuroglia of the CNS
Oligodendrocytes
processes wrap CNS nerve fibers, forming insulating myelin sheaths in thicker nerve fibers
branched cells
Astrocytes
most abundant, versatile, and highly branched
functions: support and brace neurons; role in exchange between capillaries and neurons; guide migration of young neurons; control chem env around neurons; respond to nerve impulses and neurotransmitters; influence neural function; and participate in info processing in brain
cling to neurons, synaptic endings, and capillaries
Ependymal cells
form permeable barrier between cerebrospinal fluid in cavities and tissue fluid bathing CNS cells
line central cavities of the brain and spinal column
range in shape from squamous to columnar
may be ciliated (cilia beat to circulate CSF)
Microglial cells
small, ovoid cells w/ thorny processes that touch and monitor neurons
can transform to phagocytize microorganisms and neural debris
migrate toward injured neurons
Neurons (nerve cells): excitable cells that transmit electrical signals
structural units of nervous system
all have cell body and one or more processes
special characteristics: extreme longevity (last a person's lifetime); amitotic w/ few exceptions; high metabolic rate: requires continuous supply of oxygen and glucose
large, highly specialized cells that conduct impulses
neuron cell body
also called perikgryon or soma
biosynthetic center of neuron
synthesizes proteins, membranes, chemicals; rough ER
contain nucleus w/ nucleolus; some contain pigments
plasma membrane is part of receptor region (receive input)
cell body in CNS
nuclei: clusters of neuron cell bodies in CNS
ganglia: clusters of neuron cell bodies in PNS
neuron processes
Dendrites
short, tapering, diffusely branched processes
receptive (input) region
convey incoming messages toward cell bodies as graded potentials
Axon
one neuron start at axon hillock
either short or absent, or almost entire length of cell (nerve fibers)
distal endings called axon terminals or terminal boutons
branch profusely at end (terminus)
conducting region
carries on many convos w/ dif neurons at same time; movements occur towards and away from cell body
generates nerve impulses and transmits them along axolemma to axon terminal
nerves: bundles of neuron processes in PNS
Myelin sheath
composed on myelin, a whitish, protein-lipid substance
function: protect and electrically insulate axon; increase speed of nerve impulse transmission
nonmyelinated fibers: do not contain sheath (conduct impulses more slowly)
myelinated fibers: segmented sheath surrounds most long or large diameter axons
tracts: bundles of neuron processes in CNS
Connective Tissue Coverings
CNS
meninges: cover and protect, protect blood vessels and encloses venous sinuses
Arachnoid mater: middle layer with spiderweb-like extensions
separated from dura mater by subdural space
subarachnoid space contains CSF and kargest blood vessels of brain
Pia mater: delicate CT that clings tightly to brain, following every convolution
Dura mater: strongest menix
PNS
Endoneurium: loose CT that encloses axons and their myelin sheath
Perineurium: coarse CT that bundes fibers into fasicles
Epineurium: tough fibrous sheath around all fascicles to form nerve