nervous system Flashcards
protection of brain
skull-> bone that encloses the brain
meninges-> membrane that covers and protects the CNS
CSF-> watery cushion that protects CNS from trauma
BBB-> prevents foreign substance from entering the CNS
CSF formation
formed via choroid plexus located in pia matter
choroid plexus hangs from each ventricle
arachnoid villi allows for CSF resorption
ependymal cells use ion pumps to control comp. of CSF and help cleanse CSF by removing wastes
order of CSF flow
ventricles-> median and lateral apertures-> subarachnoid space-> arachnoid villi
theta waves
common in children
Ex: distracted child
cerebellum
allows for smooth, coordinated movements
maintains balance and posture
all fibers are ipsilateral (superior, middle, inferior)
contains arbor vitae-> treelike pattern of white matter
connected by vermis
beta waves
awake and alert
Ex: studying
REM
skeletal muscles except ocular muscles and diaphragm are actively inhibited
dreaming occurs
NREM
delta waves-> deep sleep, arousal is difficult, nightmares may occur in stages 3 and 4
alpha waves-> relaxation occurs and arousal is easy in stage 1
STM
temporary holding of info
Ex: phone numbers
involves hippocampus and surrounding temporal lobes
LTM
has limitless capacity
involves hippocampus and surrounding temporal lobes
limbic system
emotional or affective brain
puts emotional responses to odors
amygdaloid body-> anger, fear, danger response; plays role in memory
cingulate gyrus-> resolves mental conflicts; plays role in body language
recticular formation
maintains consciousness and alertness
filters out repetitive, familiar, or weak stimuli
helps control coarse limb movements
regulate visceral motor functions (vasomotor, cardiac, and respiratory centers)
gyri
ridges
sulci
shallow grooves
fissures
deep grooves
Ex: longitudinal and transverse fissures
cerebral cortex
made up of gray matter
white matter is deep to it
basal nuclei is deep to white matter
frontal lobe
primary motor cortex
premotor cortex
broca’s cortex
frontal eye fields
prefrontal cortext
parietal lobe
primary somatosensory cortex
somatosensory association cortex
vestibular cortex
insula
vestibular cortex
gustatory cortex
visceral sensory area
temporal lobe
primary olfactory cortex
posterior association areas
involved in understanding written and spoken language-> wernicke’s area (temporal lobe)
prefrontal cortex
involved w/ intellect, cognition, recall, and personality
contain working memory needed for abstract ideas, judgement, reasoning, persistence, and planning
aka anterior association area
diencephalon
thalamus
hypothalamus
epithalamus
thalamus
sensation
motor activities
cortical arousal
learning and memory
hypothalamus
controls ANS and physical responses to emotions
hunger
thirst
water balance
satiety
body temp.
sleep-wake cycles
endocrine cycles
epithalamus
secretes melatonin via pineal gland
brainstem
midbrain
pons
medulla oblongata
midbrain
pain suppression
visual and auditory relay stations
contains periaqueductal gray matter, corpora quadrigemina, substantia nigra, and red nucleus
pons
maintains normal rhythm of breathing (pneumotaxic center)
medulla oblongata
cardiac and respiratory centers
substanstia nigra
produces dopamine
corpora quadrigemina
superior colliculi-> visual reflex centers
inferior colliculi-. auditory reflex centers
commissures
fibers that connect gray matter between the two cerebral hemispheres
the ventral posterolateral nuclei are located in the
diencephalon
association fibers
communicate between gyri in the same hemisphere
corpus callosum
connect the two hemispheres and allow communication and the sharing of info
projection fibers
connect hemispheres with lower brain or spinal cord
subcortical nuclei (basal nuclei/ganglia)
caudate nucleus
putamen
globus pallidus
functions of basal nuclei/ganglia
influence muscle movements
role in cognition and emotion
suprachiasmatic nucleus
biological clock
in hypothalamus
superior cerebellar peduncles
connects cerebellum to midbrain
middle cerebellar peduncles
connects pons to cerebellum
inferior cerebellar peduncles
connects medulla to cerebellum
procedural memory
dopamine from substantia nigra is necessary
LTP
glutamate binds to NMDA receptors, opening Ca2+ channels in postsynaptic terminals
cauda equina
collection of nerve roots at inferior end of vertebral column
ventral and dorsal median fissure/sulcus
lengthwise grooves that partially divide cord into right and left halves
gray commissure
connects masses of gray matter
encloses central canal
funiculi
white columns divided into dorsal, lateral, and ventral parts
conus medullaris
terminal end of spinal cord
white matter
ascending
descending
transverse
filum terminale
extends to coccyx
anchors spinal cord
fibrous extension of conus covered w/ pia matter
dorsal root (spinal) ganglia
cell bodies of sensory neurons
lateral horns
sympathetic neurons
only in thoracic and superior lumbar regions
ventral horns
motor neurons
descending
dorsal root
sensory neurons
ascending
dorsal horns
interneurons
both sensory and motor
ascending tracts
sensory
spinocerebellar
spinothalamic
dorsal columns
descending tracts
motor
pyramidal (corticospinal)
extrapyramidal
first order neurons
synapses at the medulla oblongata
carries afferent impulse from proprioception and sends them into spinal cord
second-order neurons
carries afferent impulse via the spinal cord
synapses at the thalamus
third-order neuron
carries afferent impulse via the thalamus
synapses at the cerebral cortex (sensory cortex-> parietal lobe)
epidural space
cushion of fat and network of veins in the space b/w vertebrae and spinal dura matter
reticulospinal tracts
maintains balance and posture
rubrospinal tracts
controls flexor muscles
upper motor neurons
pyramidal cells in primary motor cortex
lower motor neurons
ventral horn motor neurons
innervate skeletal muscles
direct pathways
pyramidal tracts (corticospinal)
synapse w/ interneurons/ventral horn motor neurons
descend w/o synapsing
fast/fine skilled movements
indirect pathways
all others
includes brainstem motor nuclei
complex and multisynaptic
spinothalamic
temp
pain
pressure
light touch
dorsal column
proprioception
deep pressure
vibration
composed of fasciculus cunelus and fasciculus gracilis (in spinal cord and medial lemniscus)-> medulla to thalamus
aka medial lemniscal pathways
second order neurons
spinocerebellar
proprioception
second order neurons
pyramidal (corticospinal)
skeletal muscle tone
voluntary muscle movement
extrapyramidal
skeletal muscle activity
balance and posture
transverse tracts
from one side to other (commissural fibers)
subdural space
b/w dura (outer) and arachnoid (middle) mater
subarachnoid space
b/w arachnoid (middle) and pia (inner) mater
central canal
carries CSF
cervical enlargement
nerves that supply to the upper limbs
sensory receptors
specialized to respond to change in environment
activation results in graded potentials that trigger nerve impulses
sensory adaptation
change in sensitivity in presence of constant stimuli
receptor membranes become less responsive
receptor potentials decline in frequency or stop
mechanoreceptors
both extero and interoceptor
respond to touch, vibration, and stretch
thermoreceptor
nonencapsulated
respond to temp
photoreceptor
respond to light
chemoreceptor
interoceptor
respond to chemicals
nociceptor
contain vanilloid receptors
exteroceptor
nonencapsulated
respond to pain
proprioceptors
respond to stretch in areas of the skeletal and muscular system
inform brain of one’s movements
other nonencapsulated dendritic endings
tactile (merkel) discs-> fine touch
hair follicle receptors-> fine touch
encapsulated dendritic endings
all other mechanoreceptors
tactile (meissner’s) corpuscles= discriminative touch
lamellar (pacinian) corpuscles= deep pressure and vibration
bulbous corpuscles (contain ruffini endings)= deep continuous pressure
muscle spindles, tendon organs, and joint kinesthetic receptors
phasic receptors
fast adapting
signal beginning or end of stimulus
respond to pressure, touch, and smell
tonic receptors
adapt slowly or not at all
are nociceptors or most proprioceptors
nerve regeneration
only PNS fibers are able to regenerate
CNS fiber never regenerate (oligodendrocytes bear growth inhibiting proteins and astrocytes form scat tissue containing chondroitin sulfate)
monosynaptic reflex
provides direct communication b/w sensory and motor neurons innervating muscle
Ex: knee-jerk reflex (stretch reflex)->shortening/contracting
polysynaptic reflex
utlilizes interneurons which pass signals b//w sensory and motor neurons (multiple synaptic connections)-> motor neuron, spinal cord, axon, muscle, sensory axons, etc.
Ex: withdrawl, tendon (lengthening/relaxation), and crossed extensor reflex
ipsilateral reflex
withdrawl and knee-jerk reflex
contralateral
crossed extensor reflex
ascending pathways
circuit level sensory integration
precommand areas of the brain
basal nuclei and cerebellum
highest level of hierarchy or motor control
spinal nerves
31 total
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
rami communicates
joins ventral rami in thoracic region
autonomic pathways
cervical plexus and neck
formed by ventral rami (C1-C5)
phrenic nerve controls diaphragm (C3-C5)
brachial plexus and upper limbs
formed by ventral rami (C5-C8 and T1)
median nerve
innervates skin
flexor muscles in anterior forearm pronate
thumb opposition muscles
damage can cause carpal tunnel
usually damaged through suicide attempts
ulnar nerve
supplies flexor muscles of anterior forearm
most intrinsic hand muscles
skin of medial aspect of hand
wrist/finger flexion
“funny bone”
radial nerve
innervates essentially all extensor muscles, supinators, and posterior skin of limb
anterolateral thorax and abdominal wall
form intercostal nerves that supply intercostal muscles, muscle and skin of anterolateral thorax, and most of the abdominal wall
lumbar plexus
L1-L4
innervates thigh, abdominal wall, and psoas muscle
contains femoral nerve (quads, sartorius, iliacus)
sacral plexus
L4-S4
serves the buttock, lower limb, pelvic structures, and perineum
contains sciatic nerve (hamstrings and adductor magnus)-> longest and thickest nerve of body/combo. of common fibular and tibial nerve
dermatome
area of skin innervated by cutaneous branches single spinal nerve (except C1)
assessed extend of spinal cord injuries ascertained by affected dermatomes
somatic reflexes
activate skeletal muscle
autonomic reflexes
activate visceral effectors (smooth or cardiac muscle of glands)
spinal somatic reflexes
integration center in spinal cord
effectors are skeletal muscle
muscle spindles
3-10 intrafusal muscle fibers wrapped in CT capsule
assesses length of muscle
tendon organs
assesses amount of tension in muscle
effector fibers
extrafusal muscle fibers
alpha
intrafusal muscle fibers
noncontractile
anulospiral endings (primary)= stimulated by rate and degree of stretch
flower spray endings (secondary)= respond to stretch
gamma
gamma efferent fibers
maintain spindle sensitivity
contractile end regions innervated
alpha-gamma coactivation maintains tension and sensitivity of spindle during muscle contraction
stretch receptors
hypoactive= can indicate peripheral nerve damage or ventral horn injury (diabetes)
hyperactive= can indicate lesions of corticospinal tract (stroke)
reciprocal activation
contracting muscle relaxes
antagonist contracts
superficial reflexes
elicited by gentle cutaneous stimulation
plantar reflex (L4-S2)
abdominal reflex (T8-T12)
babinski’s sign
damage to motor cortex or corticospinal tracts
crossed extensor reflex
stepping barefoot on broken glass
flexor (withdrawl) reflex
finger stick for blood test
perceptual detection
ability to detect a stimulus (requires summation of impulses)
magnitude estimation
intensity coded in frequency or impulses
spatial discrimination
identifying site or pattern of stimulus (2-point discrimination test)
referred pain
pain from one body region perceived from diff region
Ex: left arm pain during heart attack
feature abstraction
identification of more complex aspects and several stimulus properties
quality discrimination
ability to identify submodalities of sensation (sweet or sour tastes)
pattern recognition
recognition of familiar or significant patterns in stimuli (melody in piece of music)
somatic NS
cell body in CNS
thick
myelinated
contain group A fibers
release Ach
stimulatory
ANS
2-neuron chain
preganglionic neuron (CNS)= thin, lightly myelinated
postganglionic (PNS)= in automatic ganglion, nonmyelinated, extends to effector organ
preganglionic fibers release Ach
postganglionic fibers release NE or Ach
stimulatory or inhibitory
dual innervation
all visceral organs served by both divisions, but cause opp. effects
adrenal medulla
secrete NE and epinephrine into blood
modified sympathetic ganglion
cholinergic receptor
bind Ach
nicotinic= stimulatory, causes depolarization, found on SKM cells
muscarinic= inhibitory or excitatory, found on all effector cells
adrenergic receptor
releases NE
autonomic dysreflexia
uncontrolled activation of autonomic neurons in quadriplegics and those w/ spinal cord injuries above T6
increases BP
is life-threatening
hypertension
higher than normal BP
overactive sympathetic vasoconstriction response to stress
treated w/ adrenergic receptor-blocking drugs (alpha and beta blockers)
raynaud’s disease
exaggerated vasocontriction in fingers and toes
pale, cyanotic, painful
treated w/ vasodilators
atrophine
anticholinergic= blocks muscarinic Ach receptors
prevents salivation during surgery and dialates pupils
neostigmine
inhibits Ach-esterase= breakdown of Ach
treats myasthenia gravis
parasympathetic division
long preganglionic fibers and short post ganglionic fibers
controlled by cranial nerves 3, 7, 9, and 10 (majority of target organs controlled by vagus nerve)
short-lived
highly localized
Ach destroyed by Ach-esterase
sympathetic division
preganglionic neurons in T1-L2 (form lateral horns of spinal cord)
pass through white rami communicantes and enter sympathetic trunk (chain or paravertebral) ganglia
responsible for ejaculation and body temp. regulation
long-lasting
widespread
NE inactivated more slowly than Ach
NE and epinephrine hormones from adrenal medulla prolong effects
a1 adrenergic receptors
on most blood vessels
vasocontriction
increases BP
B1 adrenergic receptors
found on heart, liver, kidneys
increases HR, CO, and BP
release renin from kidneys
B2 adrenergic receptors
found on airways and blood vessels going to heart
opens of airways and blood vessels (broncho and vasodilation)
B3 adrenergic receptors
found on adipose tissue
lipolysis
a2 adrenergic receptors
found on presynaptic autonomic neurons
initiates neg. feedback system
inhibits further NE release
beta agonists
dilate lung bronchioles
attach to B2 receptors
OTCs
stimulate a-adrengenic receptors
S.L.U.D.G.E
salivation
lacrimation
urination
defecation
GI tract motility
erection
(for PNS)
the gray rami communicantes contain
postganglionic sympathetic fibers
nicotinic receptors
found in adrenal medulla, skeletal muscle, autonomic ganglia
not found in heart
fucntions of hypothalamus
main integration center of ANS
visceral responses to emotion
the hypothalamus controls the autonomic regions of the brain stem and spinal cord via the
reticular formation
the parasympathetic division and the sympathetic division share control w/ the sympathetic over
heart, respiratory system, salivary glands
but not blood vessels
autonomic ganglia
contain only motor neurons
sympathetic tone
aka vasomotor tone
keeps blood vessels in continual state or partial constriction
alpha-blockers interfere w/ vasomotor fibers (used to treat hypertension)
left hemisphere
speech
comprehension
arithmetic
writing
right hemisphere
creativity
spatial ability
artistic and musical skills
cranial nerves in the midbrain
occulomotor
trochlear
cranial nerves in the pons
trigeminal
abducens
facial
vestibulocochlear
cranial nerves in the medulla
glossopharyngeal
vagus
hypoglossal
accessory