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Tania Torres-Gomez P.1 Nervous System - Coggle Diagram
Tania Torres-Gomez P.1 Nervous System
functions: nervous system
sensory input
information gathered sensory receptors- internal and external
integration
processing and interpretation sensory input
motor output
activation effector organs (muscles & glands) produces response
master controlling and communicating system of body
central nervous system
Brain and spinal cord of dorsal body cavity
integration and control center interprets sensory input and dictates motor output
Peripheral nervous system
portion nervous system outside CNS
consists nerves extend from brain and spinal cord
spinal nerves
to and from spinal cord
Cranial nerves
to and from brain
PNS
sensory(afferent) division
somatic sensory fibers
convey impulses from skin, skeletal muscles, and joints to CNS
Visceral sensory fibers
convey impulses from visceral organs to CNS
Motor(efferent) division
transmits impulses from CNS- effector organs
muscles & glands
Somatic nervous system
somatic motor nerve fibers conduct impulses from CNS- muscle and conscious control
autonomic nervous system(involuntary)
consists of visceral motor nerve fibers
regulates smooth muscle, cardiac muscle, and glands
two function subdivisions
sympathetic
parasympathetic
Major divisions and Subdivisiones
Peripheral nervous system
PNS provides links from and to world outside our body
consists all neural structures outside brain and spinal cord broken down 4 parts
Sensory receptors
specialized respond environment stimuli activation results graded potentials trigger nerve impulses
awareness stimulus (sensation) and interpretation meaning of stimulus perception occur brain
three ways to classify receptros
type stimulus
mechanoreceptors
respond touch, pressure, vibration, and stretch
thermoreceptors
sensitive in temp.
photoreceptors
respond light energy
chemoreceptors
respond chemicals
nocireceptors
sensitive pain- causing stimuli
body location
Exteroceptors
respond stimuli arising outside body
receptors skin touch, pressure, pain, and temp.
special sense organs
Interoceptors
respond stimuli arising internal visceral and blood vessels
sensitive chemical, tissue stretch and temp.
sometimes discomfort, person unaware of workings
Proprioceptors
respond stretch skeletal muscles, tendons, joints, ligaments, and connective tissue coverings bones and muscles
infoms brain one's movements
structural complexity
transmission lines: nerves and their structure and repair
motor endings and motor activity
Motor Neurons
CNS to muscles and glands
somatic nervous system
controls voluntary movements
autonomic nervous system
controls involuntary responses
Sympathetic Division
moves body activity
"fight-or-flight" system
exercise, excitement, emergency, embarrassment activities
increased heart rate, dry mouth, cold, sweaty skin, dilated pupils
vigorous physical activity
dilates bronchioles, causes liver- release glucose
Parasympathetic division
caniosacral division fibers originate brain steam and sacral regions/ cord
short post ganglionic fibers synapse with effectors
synapse post ganglionic neurons terminal ganglia close- within target organs
long preganglionic fibers extend CNS- target organs
"Rest or Digest"
Sensory Neurons
Sensory organs to CNS
Central Nervous System
brain
receives and processes sensory information, response, stores, memories, generates thoughts and emotions
spinal cord
conducts signals to and from the brain controls reflex activities
Tissues
neuroglia (glial cells)
small cells that surround and wrap delicate neurons
Neurons (nerve cells)
excitable cells that transmit that transmit electrical signals
pia mater
allows blood vessels to pass through and nourish the brain
innermost layer of meninges
covers the brain
arachnoid mater
thin and transparent membrane
barrier and aids in production of cerebrospinal fluid
cover brain and spinal cord
dura mater
surrounds and supports large venous channels
carrying blood from brain toward the heart
extra protective layer
Classification of neurons
sensory neurons
transmit impulses sensory receptors toward CNS
almost all unipolar
cell bodies located ganglia PNS
motor neurons
carry impulses CNS- effectors
multipolar
most cell bodies located CNS (except autonomic neurons)
interneurons
association neurons
lie motor and sensory neurons
shuttle signals CNS pathways
most entirely CNS
Multipolar
three or more processes
1 axon, dendrites
Unipolar
one "T-like" process
two axons
Bipolar
two processes that the cell body seperates
Connective Tissue Coverings
Endoneurium
loose connective tissue encloses axons and their myelin sheaths (schwann cells)
Perneurium
coarse connective tissue bundles fibers- bundles fibers- fascicles
Epineurium
tough fibrous sheath around all fascicles from nerve
Major parts and functions of the brain
cerebrum
largest part of brain, left and right hemispheres
interpreting touch, vision, hearing, speech, reasoning, emotions, learning and control of movement
cerebellum
coordinate muscle movements, maintain posture, and balance
braintstem
relay center connects cerebrum and cerebellum to spinal cord
performs automatic functions breathing, heart rate, body temperature, wake and sleep cycles, digestion, and sneezing
Drugs
Heroine
interferes dopamine transmitter
natural opiates activate receptors that cause release
pain signals, stress response, and emotional attachment are affected
Ectasy
interferes with serotin transmitters
Transporter is altered , does its job in reverse
affects mood, sleep, perception of appetite
Marijuana
interferes dopamine neurotransmitter
Anadamide receptors turn off release, dopamine is then released, and dopamine is allowed to go in the synapse
can lead to to short term memory, movement is slowed, person feels relaxed and calm
Methaphetamine
interferes dopamine neurotransmitter
meth enters dopamine vesicles that forces dopamine molecules to leave, caused transporters to work in reverse
feel pleasure and exhilaration
Alcohol
drug interferes GABA, and excitary neurotransmitter
double seductive punch is entered, interacts with GABA receptors
affects person's memory formation, decision making, and impulse control
Cocaine
dopamine neurotransmitters are interfered
cocaine blocks transmitters
affects voluntary movements which can lead to person to be unable to stay still
LSD
Seratonin neurotransmitters are interfered with
reacts to different receptors, it has sensory effects
might feel wakefulness and evoking a startle response to unexpected stimulus
Opiods
Heroin
taken with pill, injecting, snorting, or smoking
pain reliever
drug found in opium poppy, opioid receptors are activated which are in the brain, spinal cord, and other organs, which is involved with plain and pleasure- wanting to take opiods again
Inhalents
solvents, aerosol sprays, gases
inhaling
chemical vapors
Vapors from toxic substances, chemicals are absorbed through the lungs into the bloodstream that reaches the brain and other organs. Causes irreversible physical and mental damage
MDMA
3,4 - methylendioxy methamphetamine, ecstasy
swallowing or snorting
synthetic
drug that alters mood and perception. Dopamine produces increased heart rate and blood pressure
Nicotine
Cigarettes, e-cigarettes, cigars, snuff, pipe, and chewing tobacco, nicotine gum, patches
smoking, inhaling, vaping, patch, chewing or dipping
stimulant
increases the blood pressure, heart rate, and blood flow, arteries narrow, arterial walls hardens which can lead to heart attacks
Psychedelics
Psilocy, mushrooms, peyote cactus, LSD (lysergic acid diemylamide)
swallowing, snorting, injecting, or smoking
Dissociative Drug
ketamine, PCP, Dextromethorphan
psycleclic
cause visual and auditory distortions and a sense of floating
autonomic nervous system
motor neurons
innervate smooth, cardiac muscles, and glands
adjustments ensure optimal support body activities
blood- areas need it and adjusts heart rate, blood pressure, and digestive process
operate subconscious control
involuntary nervous system or general visceral motor system
Preganglionic fibers
release ACh
Postganglionic fibers
release norepinephrine/ ACh effectors effect either stimulatory depending type receptors
parasympathetic division
promotes maintenance functions conserves energy
sympathetic division
movement of body during activity
dual innervation
all visceral organs served both divisions, cause opposite effects
neurotransmitters
acetylcholine
chief neurotransmitter of parasympathetic nervous system, part of ANS contracts smooth muscles, dilates blood vessels, increases bodily secretions, and slows heart rate
norepinephrine
increases heart rate, blood pumping to heart, increases blood pressure, and helps break down fat and increase blood sugar levels to provide more energy to body
control
under control CNS centers in
brain stem, spinal cord, hypothalamus, and cerebral cortex
hypothalamus main integrative center of ANS activity
cerebral input may modify ANS- subconsciously
hypothalamus
integration of ANS
Brain stem
regulates pupil size, heart, blood pressure, airflow, salivation
Spinal cord
reflexes urination, defecation, erection, and ejaculation
Disorders
Hypertension (high blood pressure)
overactive sympathetic vascoconstrictor response to stress
heart work harder, and artery walls are subject to increase wear and tear
can be treated adrenergic receptor- blocking drugs
Raynaud's disease
painful, exaggerated vasoconstriction in fingers and toes
digits turn pale, cyanotic
treated with vasodilators
Autonomic dysreflexia
life- threatening, uncontrolled activation autonomic neurons in quadriplegics and people with spinal cord injuries above T6
blood pressure skyrockets, increased risk of stroke
Cranial nerves
12 pairs
two attach forebrain, rest brain stem
most mixed nerves, two pairs purely sensory
each # (I-XII) and named rostral (frontal) - caudal (back)
I: olfactory nerves
sensory nerves
fibers synapse olfactory bulb
pathway terminates primary olfactory cortex
purely sensory (olfactory) function
II: Optic Nerve
arise retinas, brain tract pass through optic canals converge and partially cross over optic chiasma
optic tracts- thalamus, synapse
optic radiation fibers run occipital (visual) cortex
purely sensory (visual) function
III: Oculomotor nerves
fibers extend ventral mid brain- superior fissures 4-6 extrinsic eye muscles
function raining- eyelid directing eyeball constricting iris (parasympathetic) and controlling lens shape
IV: Trochlear nerves
fibers dorsal mid brain or via superior fissures- innervate superior oblique muscle
primarily motor nerve directs eye
V: Trigeminal nerves
largest cranial nerves; fibers extend pons- face
three divisions
ophthalmic (V1) passes- superior fissure
maxillary (V2) passes through foramen rotundum
mandibular (V3) passes- foramen ovale
convey sensory impulses various areas face (V1 and V2)
supply motor fibers (V3)- mastication
VI: Abducens nerves
fibers interior pons- via superior
primarly motor- innervating lateral rectus muscle
VII: Facial nerves
fibers pons travel- internal acoustic and stylomastoid foramina lateral aspect face
chief motor nerves face with five major branches
motor functions facial expressions, parasympathetic impulses lacrimal and salivary glands
motor functions facial expression, parasympathetic impulses lacrimal and salivary glands
sensory function (taste) anterior two-thirds tongue
VIII: Vestibulocochlear nerves
afferent fibers hearing receptors (cochlear division) and equilibrium receptors (vestibular division) pass inner ear- internal acoustic and enter brain stem pons- medulla border
IX: Glossopharymgeal nerves
fibers medulla0 skull jugular foramen and run - throat
motor functions: innervate parts tongue and pharynx swallowing and provide parasympathetic fibers parotid salivary glands
sensory functions" fibers conducts taste and general sensory impulses from pharynx and posterior tongue impulses carotid
chemo receptors and baroreceptors
X: Vagus nerves
only cranial nerves extend to head and neck region
fibers medulla exit jugular foremen
most motor fibers parasympathetic fibers help regulate activities heart, lungs, and abdominal viscera
sensory fibers carry impulses thoracic and abdominal viscera, baroreceptors, chemoreceptors, and taste buds posterior tongue and pharynx
XI: Accessory Nerves
formed ventral rootlets C1- C3 region of spinal cord
rootlets pass eranium via each formen magnum
acessory nerves exit via jugular foramina- innervate trapezius and sternocleidmastoid muscles
formerly spinal acessory nerve
XII: Hypoglassal nerves
fibers medulla skull via hypoglossal canal
innervate extrinsic and intrinsic muscles tongue contribute swallowing and speech
Major parts and functions of the spinal cord
spinal cord enclosed vertebral column
begins foramen magnum
ends L1 or L2 vertebra
Functions
provides two way communication to and from brain & body
major reflex center
reflexes initiated and completed at spinal cord
Epidural space
cushion of fat and network of veins in space vertebrae and spinal dura mater
CSF fills subarachnoid arachnoid and pia maters
spinal cord terminates in cone-shapes structure conus medullaris
Filum terminale extends to coccyx
fibrous extension of conus covered with pia maters
anchors spinal cord
Denticulate ligaments
extensions of pia mater that secure cord to dura mater
cervical and lumbar elargements
areas where nerves servicing upper and lower limbs arise from spinal cord
spinal nerves
part of PNS
attach to spinal cord 31 paired roots
each spinal cord segment designated paired spinal nerves arise from it
Cervical and lumbosacral enlargements
nerves serving upper and lower limbs emerge here
Cauda equina
collection nerve roots at inferior end of vertebral canal
ventral (anterior) median fissure
dorsal (posterior) median sulcus
Reflex arc
visceral relfex arc
receptor, sensory neuron, integration center, motor neuron and effector
2 consecutive neurons motor pathway
afferents fibers visceral
sensory neurons
effectors smooth muscle
cardiac muscle and glands rather than muscles
exsvisceral reflex
reflexes empty rectum and bladder
three neuron reflex arcs exist walls gastrointestinal tract
involve enteric nervous system made up sensory neurons, interneurons, and motor neurons
Receptor
site stimulus action
Sensory neuron
transmits afferent impulses- CNS
3.Integration center:
monosynaptic/ polysympatic region CNS
Motor neuron
conducts efferent impulses integration center- effector organ
Effector:
muscle fiber/gland cell responds efferent impulses contraction/secreting
Reflexes classified functionally
somatic reflex
activate skeletal muscle
autonomic (visceral) reflexes
activate visceral effectors smooth/ cardiac muscle glands
spinal nerves
31 pairs
mixed nerves named point of issue- spinal cord
supply all body parts except head and part of neck
8 pairs cervical nerves (C1-C8)
12 pairs thoracic nerves (T1-T12)
5 pairs lumbar nerves (L1-L5)
1 pair tiny coccygeal nerves (C0)
5 pairs of sacral nerves (S1-S5)
each spinal nerve is connected to spinal cord via two roots
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 ganaglia that conduct impulses from peripheral receptors
roots are branched medially as rootlets that join laterally to form spinal nerve
dermatones
area of skin innervated- cutaneous branches of single spinal nerve
all spinal nerves except C1 participate
extent spinal cord injuries ascertained- affected dermatomes
most overlap so destruction of single spinal nerve will not cause complete numbness
Action potential and the nerve Impulse
Action potential
Principal way neurons send signals
long distance neural communication
occur only muscle cells and axons of neurons
brief reversal membrane potential - voltage 100mv
Action potentials do not decay distance as graded potentials do
in neurons- nerve impulse
involves opening specific voltage-gated channels
generating
Resting State: All gated Na+ and K+ channels are closed
only leakage channels Na+ and K+ are open
maintains resting membrane potential
Depolarization: Na+ channels open
depolarizing local currents open voltage- gated Na+ channels & Na+ rushes into cell
Na+ influx causes more depolarization opens more Na+ channels
threshold positive feedback causes opening all Na+ channels
results large action potential
membrane polarity jumps - +30mv
Repolarization: Na+ channels are inactivating and K+ channels open
Na+ channel inactivation gates close
membrane to Na+ declines to resting state
AP spike stops rising
voltage-gated K+ channels open
K+ exits cell down in electrochemical gradient
membrane returns to resting membrane potential
Hyperpolarization
Some K+ channels remain open, and Na+ channels reset
Some K+ channels remain open, allowing excessive K+ efflux
inside of membrane more negative than resting state
Causes hyperpolarization of the membrane (slight dip below resting voltage
propagation
allows AP- transmitted from origin down entire axon length toward terminals
initiated AP is self-propagating
nonmyelinated axons each successive segment of membrane depolarizes, then repolarizes
propagation in nonmyelinated axons differ
Na+ channels closer to AP origin are still inactivated, no new AP generated
AP occurs only in a forward direction
Refractory period
neuron cannot trigger another AP
voltage-gated Na+ channels are open, neuron cannot respond to another stimulus
Conduction velocity
APs occur only axons, not other cell areas
AP conduction velocities axons vary widely
continuous conduction
slow conduction occurs nonmyelinated axons
Saltatory conduction
occurs only in myelinated axons and is about 30 times faster
myelin sheaths insulate & prevent leakage of charge
voltage--gated Na+ channels located myelin sheath and AP generated
electrical signals appear to jump rapidly
Neurotransmitters
language of nervous system
50/ +
most neurons make two or more neurotransmitters
can exert several influences
released at different stimulation frequencies
classified
chemical structure
Acetylcholine (ACh)
released at neuromuscular junction
ANS neurons and some CNS neurons use it
synthesized from acetic acid and choline enzyme choline acetyltransferase
degraded enzyme acetylcholinesterase (ACHE)
Amines
Catecholamines
dopamine
norepinephrine (NE), and epinephrine made from amino acid tyrosine
Indolamines
Serotonin
made from amino acid tryptophan
Histamine
made form amino acids histidine
all widely used in brain
ANS motor neurons some use it
Imbalances associated wtih mental illness
amino acids
make up all protein
Peptides (neuropeptides)
stings of amino acids have diverse functions
endorphins
beta endorphin, dynorphin, and enkephalins, act natural opiates reduce pain perception
Purines
monomers of nucleic acids that have an effect in both CNS & PNS
Gases and lipids
Biogenic
Catecholamines
dopamine- norepinephrine (NE), and epinephrine- amino acid tyrosine
function
effects
neurotransmitters effects can be excitatory (depolarizing) / (hyperpolarizing)
determined receptor
actions
direct action
neurotransmitter directly to and opens ion channels
indirect action
neurotransmitter acts through intracellular second messengers
Disorders associated with nervous system
Raynaud's disease
painful, exaggerated vasoconstriction fingers and toes
autonomic dysreflexia
life-threatening, uncontrolled activation autonomic neurons quadriplegics and people spinal cord injuries, blood pressure increases, risk for stroke
Autonomic neuropathy damage
autonomic nerves common complication diabetes
Phantom Limb pain
instense pain limb
Multiple Sclerosis (MS) autoimmune disease
myelin sheaths CNS destroyed immune system
hypertension
high blood pressure
overactive sympathetic vasoconstrictor response
stress