The Nervous System

• 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. 

• Brain
• Spinal Cord

• location:
•   cranial nerves
•   spinal nerves
• function:
•   sensory-- afferent
•   motor-- efferent
•     autonomic-- involuntary
•     somatic-- voluntary
•   interneuron
•     connect sensory and motor
•     found only in spinal cord

• Parts
•   cell body
•   fibers
•     denrites
•     axxons

• white fatty substance
• surrounds axons
• segmented

• Forms Myelin
• outside the CNS-- PNS

• outer cell membrane of schwann cell
• essential role in regeneration
• found in PNS

• interruption in myelin sheath
• indentations between adjacent schwann cells

• connective tissue
• supporting cells
• glioma-- common brain tumor

• star shaped cells
• anchor small blood vessels to neurons
• From blood brain barrier
•   separates blood tissue and nervous tissue
• protects brain

carry on phagocytosis in inflammed brain tissue

• form myelin sheaths on axons in CNS
•   no schwann cells
•   regenerration is impossible

• nerve-- PNS
•  
• Tract- CNS

• composed of myelinated fibers
• nerves or tracts

• cell bodies
•   ganglia- group of cell bodies
• unmyelinated fibers- axons and dendrites
• forms H core of spinal cord

surrond individual fibers

surrounds a group of nerve fibers- fascicle

surround entire nerve

• 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

• 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

• receptor- detects change or stimulus and generates impulse
• sensory neuron
• central nervous system
•   synapse
•   interneuron
•   synapse
• motor neuron
• synapse
• effector

• 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

self propagating wave of elctrical disturbance that travels along the surface of a neuron membrane

• excitation
•   adequate stimulus
•   increased permeability of neuron membrane
•   inward movement of positive sodium ions
•   negative charge outside stimulated point- beginning of the nerve impulse

impulses move faster on myelinated membranes

• allow for transmission of signals from one neuron to the next
• pre-synaptic neuron to the post synaptic neuron

• presynaptic neuron- synaptic knob-axon
•   vesicles
•   neurotransmitters
• synaptic cleft
• post synaptic neuron- dendrite

• synaptic knob
•   knob at the end of the terminal branch of presynaptic neuron
•     vesicles
•     neurotransmitters

• space
•   pre synaptic neuron
•   post synaptic neuron

• plasma membrane
• protein molecules
•   act as receptors
• initiate impule in post synaptic neuron by increasing permeability to positive ions

• CHEMICALs by which neurons communicate
• assist, stimulate, or inhibit post synaptic neurons

• 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

• Brain
• Spinal Cord

• brain stem
• diecncephalon
•   thalmus
•   hypothalmus
• cerebellum
• cerebrum

• above large hole in occipital bone
• foramen magnum

• medulla oblongata
• pons
•   bridge
•   reflex center for some cranial nerves
• midbrain

white matter with some gray matter

• vital centers- medulla oblongata 
•   cardiac
•   respiratory
•   vaso motor- diameter of blood vessels`

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

motor tracts cross

• thalmus
• hypothalmus

below thalmus

• posterior pituitary gland and pit stalk
• Gray matter!

• 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

• Food and Water intake
•   hunger and satiety centers
•   osmoreceptors
• sleep and waking
•   circadian rhythm

• pleasure
• pain
• anger
• fear
• sex drive
• sexual response-- orgasim

• above hypothalmus
• dumb bell shaped mass
• extends from r to l cerebral hemispheres

gray matter

• relays impulses to the cerebral cortex from the sense organs
• associates sensations with emotions- integrates sensory impulses
• suppresses unimportant sensations

second larges part of human brain

• outer layer- gray
• inner- white matter

• proprioception
•   awarness of posture and movement changes
•   production of normal movements
•   controls  muscle tone, equilibrium and posture
• Voluntary movements

• uppermost part of brain
• responsible for higher brain functions
•   inpulses are received and analyzed
• Largest portion of brain

• outer layer- cerebral cortex- gray matter
• inner- white matter and gray matter- basal ganglia
• convolutions or gyri ridges
• sulci- groves
• longtudinal fissure
•   deepest sulcus

• 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

• names for bones that lie over them
• work together but influence particular catergories of function

• voluntary skeletal movements
• broca's speech center

processes sensory data

• perception and interpretation of sound
• wernicke;s area- comprehending language
• olfactory area

• visual center
• interpret visual communication

communication centers are located in the frontal, temporal, and occipital lobes. together these allow us to speak, read, and understand

• higher mental functions- thinking
• conscious memory
• emotion, sensations
• voluntary movements
• vision, hearing, speech

• protected by spinal colum
• extends from occipital bone to first lumbar vertebrae
• protected by veterbrae

• 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

• spinal cord reflexes
• carry signals to brain
•   ascending 
•   sensory tracts
• carry signals away from brain
•   descending
•   motor tracts

• 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

• subarachnoid space. 
• bt L3 or L4 or L4 and L5

• injected above dura
• L3 and L4 or L4 and L5

meningitis- inflammation of the covering

spinal cord starts at L1

• 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

• 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

• spinal fluid wasn't circulating and accumulate in skull. severe brain damage. head swells. 
• Shunt may be used to reroute fluid into peritoneal area.

• 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

• 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

• PNS
• arise from brain
• connect brain with neck and structures in thorax and abdomen

• motor
• sensory
• both- mixed

• lowers heart rate when stimulated
• can be stimulated by enemas, digital rectal exams, disimpaction, etc... 

• assess eye movements and pupillary response
• assess increase intra-cranal pressure

• cervical- 8
• thoracic- 12
• lumbar- 5
• sacral- 5
• coccygeal- 1

7 cervical verterbrae and 8 cervical nerves- line up

• 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

• conduct sensory info 
• conduct motor impulses

• group of intersecting branches
• cervical
• brachial
• lumbosacral
• pudendal

skin surface area supplied by a single spinal nerve

• sensory- afferent
• motor-efferent

carry nerve impulses from receptors or sense organs towareds the CNS 

• somatch nervous system
• autonomic nervous system

• 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

• automatic function
• effectors-
•   cardiac muscle
•   smooth muscle
•     hollow organs
•     blood vessels
•   glandular epitheileal tissue
• conduction pathway
•   two neuron relay- various interruptions
•   synapse

• structure
•   pre ganglionic autonomic neuron
•     carries info fromCNS
• autonomic ganglion
• synapse (in ganglion)- bt 2 nerves
• post ganglionic neuron to effector

• sympathetic
• para sympathetic

• Structure- cranioscaral
•   preganglionic axons- long
•   ganglia are far from spinal cord
•   postganglionic axons-short
• effector- one organ

• general housekeeping
• rest and digest
• maintain normal function (heart, breathing, peristalsis, urination)

• thoracolumbar
•   preganglionic axons- short
•   chain of sympathetic ganglion in front of and at each side of the spinal colum
• Effectors
•   widespread
•   affect several organs

• fight or fligh
•   controls visceral effectors during times of strenuous exercise or strong emotion-- anger, fear. 

• 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

• parasympathetic neurotransmitters
•   released by cholinergic fibers
•   target- cholinergic recepters
• example
•   acetlycholine
•   most abuntant

• 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

• Dry mouth
• Urinary retention
• Constipation
• Blurred vision
• Confusion
• Tachycardia
• Increasing intraocular pressure

• uses
•   control hypertension'
•   control arrythmias
• side effects
•   hypotension
•   bradycardia
•   bronchoconstriction

Propranolol- Inderal 

• 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