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what does the nervous system control?
- all body cells and systems
- communication, control, and integration
- Homeostatis is possible only if this system is working properly
- transmits info rapidly by means of nerve impulse conducted from one body area to another.
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Central Nervous system divisions
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Peripheral Nervous System Divisions
- location:
- cranial nerves
- spinal nerves
- function:
- sensory-- afferent
- motor-- efferent
- autonomic-- involuntary
- somatic-- voluntary
- interneuron
- connect sensory and motor
- found only in spinal cord
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cell of the nervous system- Neurons
- Parts
- cell body
- fibers
- denrites
- axxons

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myelin sheath
- white fatty substance
- surrounds axons
- segmented

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Schwann cells
- Forms Myelin
- outside the CNS-- PNS
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Neurilemma
- outer cell membrane of schwann cell
- essential role in regeneration
- found in PNS
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Node of Ranvier
- interruption in myelin sheath
- indentations between adjacent schwann cells
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Neuroglia
- connective tissue
- supporting cells
- glioma-- common brain tumor
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Astrocytes
- star shaped cells
- anchor small blood vessels to neurons
- From blood brain barrier
- separates blood tissue and nervous tissue
- protects brain
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microglia
carry on phagocytosis in inflammed brain tissue
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Oligondendroglia
- form myelin sheaths on axons in CNS
- no schwann cells
- regenerration is impossible
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White matter
- composed of myelinated fibers
- nerves or tracts
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Gray matter
- cell bodies
- ganglia- group of cell bodies
- unmyelinated fibers- axons and dendrites
- forms H core of spinal cord
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endoneurium- nerve covering
surrond individual fibers
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perineurium- nerve covering
surrounds a group of nerve fibers- fascicle
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epineurium
surround entire nerve
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Reflex Arcs- Spinal reflexes
- involuntary responses
- does not involve brain
- receptor- detects change or stimulus and generates impule
- sensory neuron-- afferent
- interneuron (3 neuron arch only)
- motor neuron- efferent
- effector
- Involves
- contaction of muscle
- secretion of a gland
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2 Neuron Arc
- receptor
- dendrite of sensory neuron
- cell body- posterior(dorsal) root ganglion
- axon of sensory neuron
- cell body of motor neuron
- axon of motor neuron- anterior(ventral) root
- synapse
- effector- muscle or gland
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3 neuron arc- withdraw reflex to avoid injury
- receptor- detects change or stimulus and generates impulse
- sensory neuron
- central nervous system
- synapse
- interneuron
- synapse
- motor neuron
- synapse
- effector
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3 neuron arc pathway
- receptor
- dendrite of sensory neuron
- cell body- posterior (dorsal) root ganglion
- axon of sensory neuron
- synapse
- interneuron
- synapse
- dendrite of motor neuron
- cell body of motor neuron
- axon of motor neuron- anterior(ventral) root
- synapse
- effector muscle or gland
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nerve impulse
self propagating wave of elctrical disturbance that travels along the surface of a neuron membrane
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nerve impulses- mechanism
- excitation
- adequate stimulus
- increased permeability of neuron membrane
- inward movement of positive sodium ions
- negative charge outside stimulated point- beginning of the nerve impulse
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saltatory conduction
impulses move faster on myelinated membranes
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synapse
- allow for transmission of signals from one neuron to the next
- pre-synaptic neuron to the post synaptic neuron
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synapse- structures
- presynaptic neuron- synaptic knob-axon
- vesicles
- neurotransmitters
- synaptic cleft
- post synaptic neuron- dendrite
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presynaptic neuron
- synaptic knob
- knob at the end of the terminal branch of presynaptic neuron
- vesicles
- neurotransmitters
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synaptic cleft
- space
- pre synaptic neuron
- post synaptic neuron
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post synaptic neuron
- plasma membrane
- protein molecules
- act as receptors
- initiate impule in post synaptic neuron by increasing permeability to positive ions
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neurotransmitters
- CHEMICALs by which neurons communicate
- assist, stimulate, or inhibit post synaptic neurons
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neuro-transmitters types
- acetlycholine*
- catecholamines*
- norepinephrine, epinephrine
- dopamine
- inhibit movement
- affects emotional response
- as a drug- effect similar to epinephrine and norephinephrine
- serotonin
- brain
- attention
- emotion
- regulates sleep and wake cycles
- intestine
- stimulates smooth muscle to contract
- vasoconstrictor
- Neuroactive peptides- inhibit pain
- endorphins
- enkephalins
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Brain
- brain stem
- diecncephalon
- thalmus
- hypothalmus
- cerebellum
- cerebrum
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Brain Stem location
- above large hole in occipital bone
- foramen magnum
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brain stem- parts
- medulla oblongata
- pons
- bridge
- reflex center for some cranial nerves
- midbrain
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brain stem structure
white matter with some gray matter
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brain stem function
- vital centers- medulla oblongata
- cardiac
- respiratory
- vaso motor- diameter of blood vessels`
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2 way conduction path for Brain stem
sensory tracts- conduct sensory impulses to higher portion of brain
- motor tracts- conduct impulses from the higher parts of the brain to the spinal cord
- decussation of the pyramids-- morot tracts cross
- R brain controls l side of body
- L brain controls r side of body
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decussation of the pyramids-
motor tracts cross
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hypothalmus- location
below thalmus
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structure of hypothalmus
- posterior pituitary gland and pit stalk
- Gray matter!
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Function of hypothalmus
- controls autonomic nervous system
- indirectly controls all int organs
- coordination between voluntary and autonomic functions
- controls hormone secretion
- imp link between endocrine and nervous system
- relationship with pit gland
- regulates water balance-- maintains homeostasis
- manf ADH
- maintains body temp
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hypothalmus
- Food and Water intake
- hunger and satiety centers
- osmoreceptors
- sleep and waking
- circadian rhythm
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behavioral responses associated with emotion
- pleasure
- pain
- anger
- fear
- sex drive
- sexual response-- orgasim
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Thalmus location
- above hypothalmus
- dumb bell shaped mass
- extends from r to l cerebral hemispheres
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thalmus structure
gray matter
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thalmus function
- relays impulses to the cerebral cortex from the sense organs
- associates sensations with emotions- integrates sensory impulses
- suppresses unimportant sensations
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cerebellum
second larges part of human brain
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structure of cerebellum
- outer layer- gray
- inner- white matter
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functions of cerebellum
- proprioception
- awarness of posture and movement changes
- production of normal movements
- controls muscle tone, equilibrium and posture
- Voluntary movements
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cerebrum
- uppermost part of brain
- responsible for higher brain functions
- inpulses are received and analyzed
- Largest portion of brain
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structure of cerebrum
- outer layer- cerebral cortex- gray matter
- inner- white matter and gray matter- basal ganglia
- convolutions or gyri ridges
- sulci- groves
- longtudinal fissure
- deepest sulcus
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divisions of cerebrum
- hemispheres divided by long fissures
- R Hem- controls movement of L side of body
- music and emotion
- L Hem-
- movement R side of body
- lang, analytical skills, and logic
- Corpus Callosum
- connects L and R hem
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cerebrum lobes
- names for bones that lie over them
- work together but influence particular catergories of function
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Frontal Lobe- motor lobe
- voluntary skeletal movements
- broca's speech center
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parietal lobe- sensory
processes sensory data
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temporal lobe- auditory area
- perception and interpretation of sound
- wernicke;s area- comprehending language
- olfactory area
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occipital lobe
- visual center
- interpret visual communication
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NOTE
communication centers are located in the frontal, temporal, and occipital lobes. together these allow us to speak, read, and understand
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cerebrum function
- higher mental functions- thinking
- conscious memory
- emotion, sensations
- voluntary movements
- vision, hearing, speech
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spinal cord
- protected by spinal colum
- extends from occipital bone to first lumbar vertebrae
- protected by veterbrae
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spinal cord structure
- Core- Gray Matter (H shaped)
- posterior (dorsal) horn
- carries sensory info
- anterior (ventral) horn
- carries motor info
- contains cell bodies of motor neuron
- Exterior- White matter- myelinated nerve fibers- tracts
- ascending- sensory- afferent
- descending-motor- efferent
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spinal cord functions
- spinal cord reflexes
- carry signals to brain
- ascending
- sensory tracts
- carry signals away from brain
- descending
- motor tracts
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Central Nervous system coverings and fluids
- Coverings-
- cranial bones
- vertebrae
- cerebral and spinal meninges
- dura mater- outermost
- arachnoid
- subdural space- potential space bt arachnoid and dura
- subarac space- space bt arach and pia mater
- Pia mater- innermost
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spinal injection
- subarachnoid space.
- bt L3 or L4 or L4 and L5
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epidural
- injected above dura
- L3 and L4 or L4 and L5
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clinical condion of spinal cord
meningitis- inflammation of the covering
spinal cord starts at L1
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cerebro spinal fluid location
- subarach space
- central canal
- cerebra ventricles-- 4
- L and R lateral
- ant horn
- post horn
- inf horn
- third ventricle
- fourth ventricle
- bt brain and spinal cord
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cerebrospinal fluid Formation
- formed through plasma
- filtered thru
- choroid plexus
- network of capillaries
- found in 3rd and 4th ventricle
- blood brain barrier- prevents certain sub from entering the brain
- Charateristics
- glucose and protein
- lacks RBC and WBC
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Hydrocephalus- Water baby
- spinal fluid wasn't circulating and accumulate in skull. severe brain damage. head swells.
- Shunt may be used to reroute fluid into peritoneal area.
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PNS classification
- Cranial Nerves- 12 pairs
- Spinal nerves- 31 pairs
- attaches to spinal cord by 2 short roots
- doral root- dorsal ganglion
- ventral root
- mixed nerves
- sensory fibers- dorsal
- motor fibers- ventral
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divisions of PNS
- sensory- afferent system
- carries info from receptor to CNS
- motor- efferent
- carries info from cns to effectors
- divisions
- somatic nervous system
- autonomic
- sympathetic NS
- Parasympathetic NS
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Cranial Nerves location
- PNS
- arise from brain
- connect brain with neck and structures in thorax and abdomen
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Vagus Nerve- cranial nerve
- lowers heart rate when stimulated
- can be stimulated by enemas, digital rectal exams, disimpaction, etc...
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Cranial nerves III, IV, VI
- assess eye movements and pupillary response
- assess increase intra-cranal pressure
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Spinal nerves- 31 pairs
- cervical- 8
- thoracic- 12
- lumbar- 5
- sacral- 5
- coccygeal- 1
7 cervical verterbrae and 8 cervical nerves- line up
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structure of spinal nerve
- sensory nerves
- dendrite of sensory nerve
- dorsal root ganglion- enlarged part of the dorsal root that contains the cell bodies of the sensory neurons
- dorsal root- connects nerve to spinal cord
- Motor nerves
- cell bodies of motor nerves are located in the gray matter of the spinal cord
- ventral root- leaves spinal cord
- axxon of motor nerve- info leaves
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Spinal Nerve Functions
- conduct sensory info
- conduct motor impulses
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plexus
- group of intersecting branches
- cervical
- brachial
- lumbosacral
- pudendal
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dermatome
skin surface area supplied by a single spinal nerve
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divisions of spinal nerves
- sensory- afferent
- motor-efferent
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sensory- afferent
carry nerve impulses from receptors or sense organs towareds the CNS
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Motor- efferent
- somatch nervous system
- autonomic nervous system
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somactic nervous system- function
- voluntary action
- effector- skeletal muscles
- conduction pathway
- single neuron(axon)
- impulses carried from CNS to effector without interbening synapse
- long axon from spinal cord to effector
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Autonomic nervous system function
- automatic function
- effectors-
- cardiac muscle
- smooth muscle
- hollow organs
- blood vessels
- glandular epitheileal tissue
- conduction pathway
- two neuron relay- various interruptions
- synapse
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autonomic nervous system
- structure
- pre ganglionic autonomic neuron
- carries info fromCNS
- autonomic ganglion
- synapse (in ganglion)- bt 2 nerves
- post ganglionic neuron to effector
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Autonomic nervous systems
- sympathetic
- para sympathetic
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Parasympathetic nervous system structure
- Structure- cranioscaral
- preganglionic axons- long
- ganglia are far from spinal cord
- postganglionic axons-short
- effector- one organ
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Parasym Function
- general housekeeping
- rest and digest
- maintain normal function (heart, breathing, peristalsis, urination)
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Sympathetic nervous system structure
- thoracolumbar
- preganglionic axons- short
- chain of sympathetic ganglion in front of and at each side of the spinal colum
- Effectors
- widespread
- affect several organs
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Sympathetic Function
- fight or fligh
- controls visceral effectors during times of strenuous exercise or strong emotion-- anger, fear.
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relationship to homeostatsis
- visceral effectors are double innervated
- parasymphathetic function
- sympathetic funciton
- bodies autonomic functions can be maintained or quickly restored
- stimuli from the hypo and the limbic system(emotional brain) influence autonomic function
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Autonomic neurotransmitters- cholinergic
- parasympathetic neurotransmitters
- released by cholinergic fibers
- target- cholinergic recepters
- example
- acetlycholine
- most abuntant
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autonomic neurotransmtters- adrenergic- sympathomimetic
- sympathetic neurotransmitters- catecholamines
- released by adrenergic fibers
- target- adrenerdic receptors
- examples
- epinephrine- adrenalin- stimulate heart-rate, force of contraction.
- relax bronchi- cardiac stimulation, bronchodilation
- norepinephrine- vasocontricter increase bp, cns stimulation
- dopamine
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Anticholinergic side effects:
- Dry mouth
- Urinary retention
- Constipation
- Blurred vision
- Confusion
- Tachycardia
- Increasing intraocular pressure
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Adrenergic blockers- beta blockers
- uses
- control hypertension'
- control arrythmias
- side effects
- hypotension
- bradycardia
- bronchoconstriction
Propranolol- Inderal
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how to Remember Cranial nerves
- 1 OLFACTORY ON
- II OPTIC OLD
- III OCULOMOTOR OLYMPUS
- IV TROCHLEAR TOWERING
- V TRIGEMINAL TOP
- VI ABDUCENS A
- VII FACIAL FRIENDLY
- VIII VESTIBULOCOCHLEAR VIKING
- IX GLOSSOPHARYNGEAL GREW
- X VAGUS VINES
- XI ACCESSORY AND
- XII HYPOGLOSSAL HOPS
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