Central Nervous System Flashcards
dura mater
*outer layer of meninges
*dense connective tissue
*forms internal periosteum of the skull
arachnoid mater
*middle layer of meninges
*spreads across the brain and spinal cord
*does not dip into their grooves
*thin strands extend to pia mater
pia mater
*delicate inner layer
*contains many nerves and blood vessels
*attached to the brain and spinal cord
*follows grooves/depressions
subarachnoid space
*space between the arachnoid mater and pia mater
*contains clear, watery cerebrospinal fluid (CSF)
meninges
protective membrane surrounds brain and spinal cord
ventricles
interconnected cavities within two cerebral hemispheres of the brain and the stem
choroid plexus
secreats cerebrospinal fluid
Cerebrospinal fluid
*surrounds brain and spinal cord
*protects from jarring forces
*maintains stable ionic concentration
*provides pathway to the blood and waste
brain
*largest and most complex part of nervous system
*responsible for sensation, perceptions, motor commands, higher mental functions
4 regions of brain
*cerebral hemispheres
*diencephalon
*brain stem
*cerebellum
cerebrum
*the largest part of the mature brain
*consists of two hemispheres
corpus callosum
deep nerve fibers
convolutions (gyri”s)
ridges in the surface of the cerebrum separated by sulcus
sulcus
shallow grooves/folds
longitudinal fissure
separates the two hemispheres
transverse fissure
separates the cerebrum from the cerebellum
insula (island of reil)
*5th lobe of the brain
*lies deep within the brain
lobes of the brain
frontal, parietal, temporal, occipital, insula
cerebral cortex (pt 1)
*thin layer of gray matter
*constitutes the outer portion of the cerebrum
*contains almost 75% of all neuron cell bodies of the nervous system
white matter
*lies under cerebral cortex
*makes up most of the cerebrum
*contains myelinated axons
function of cerebrum
higher brain function, memory, reasoning, intelligence & personality
function of frontal lobe
*concentration, planning, problem solving, judgement of behavior
*right hemisphere controls left side of brain & vice-versa
broca’s area controls need for speech-only left hemisphere.
function of parietal lobe
*sensory, provides sensation of temp, touch, pressure and pain
*responsible for understanding speech, using words to express thoughts
function of temporal lobe
sensory area responsible for hearing
area responsible for remembering visual scenes, music & complex patterns
function of occipital lobe
*sensory responsible for vision
* area combines visual imaging with other sensory experiences
function of insula lobe
thought to serve as a crossroads for translating sensory information
hemisphere Dominance
*dominant hemisphere will control motor cortex
*controls speech, writing, reading, verbal, analytical and computational skills
*non-dominant controls nonverbal tasks, motor tasks, understanding and interpretating musical and visual patterns, emotions & intuitive thought
short-term memory
*closed neuronal circuit
*when impulse flow ceases, memory does also, unless it enters long term memory
long-term memory
*changes structure or function of neurons by enhancing synaptic transmission
*requires enough synapses to encode the memory
*pattern of synapses to remain unchanged
diencephalon
*nerve tissue that connects cerebral hemispheres and brainstem
*surrounds third ventricle and is composed of gray matter
thalamus
*gateway for sensory impulses heading to cerebral cortex
*receives all sensory impulses
*channels impulses to appropriate part of cerebral cortex for interpretation
hypothalamus
*maintains homeostasis by regulating visceral activities
*hunger, thirst, sleep etc.
*links nervous system and endocrine system
*pituitary gland secretions
epithalamus
*forms roof of third ventricle
pineal gland
*secretes melatonin
*along with hypothalamus it regulates sleep-wake cycle
brain stem
connects the brain to the spinal cord
midbrain
*between diencephalons and pons
*contains bundles of fibers that join the lower part of spinal cord with higher part of brain
*contains cerebral aqueduct taht connects third and fourth ventricles
*contains corpora quadrigemina
corpora quadrigemina
center for visual and auditory reflexes
pons
*rounded bulge on underside of brainstem between midbrain and medulla oblongata
*relays impulses between medulla oblongata and cerebrum
*also relays impulses from cerebrum to cerebellum
*contains respiratory control center with controls rate and depth of breathing
medulla oblongata
*enlarged continuation of spinal cord
*conducts ascending and descending impulses between brain and spinal cord
*contains reflex centers (cardiac center, vasomotor center, respiratory center)
cardiac center
reflex center that increases or decreases heartbeat
vasomotor center
reflex center that controls diameter of blood vessels
respiratory center
reflex center that regulates rhythm, rate and depth of breathing
reticular formation
*complex network of fibers and small areas of gray matter that runs throughout medulla oblongata, pons and midbrain
*filters incoming sensory information
*arouses cerebral cortex into state of wakefulness
types of sleep
slow wave (non-REM sleep)
REM sleep
rapid eye movement (REM) sleep
*paradoxical sleep
*some areas of brain are active
*eyes seen rapidly moving/hear and resp rate irregular
*dreaming occurs
non-rapid eye movement (non-REM) sleep
*decreased activity of reticular formation
*restful and dreamless sleep
*reduces blood pressure and resp rate
*3 stages ranging from lite to heavy
cerebellum
*large mass of tissue below occipital lobes
*composed mainly of white matter (arbor vitae) and thin layer of gray matter (cerebellar cortex)
*integrates sensory information concerning position of body parts and coordinates skeletal muscle activity
*movement, balance, posture
blood brain barrier
*helps maintain stable environment in brain
*tight junction ensures substances pass thru endothelial cells
*substances move thru simple diffusion and specific transport mechanisms
*contains enzymes that destroy certain chemicals that would activate brain neurons
spinal cord
*nerve column that extends from brain into the vertebral canal
*extends from foramen magnum of the skull down to the 1st and 2nd lumbar vertebrae
cervical enlargment
supply nerves to the upper limbs
lumbar enlargment
supply nerves to the lower limbs
conus medullaris
inferior to lumbar enlargment, tapering of spinal cord
cauda equina
axons from both motor and sensory neurons extend from lumbar and sacral levels of spinal column
filum terminale
connective tissue that anchors the spinal cord to the surface of the coccyx
anterior median fissure & posterior median sulcus
two grooves divide it into right and left halves
core of spinal cord
*consists of gray matter surrounded by white matter
*gray matter looks like a butterfly
white matter divisions of spinal cord
ventral funiculi
dorsal funiculi
lateral funiculi
grey matter divisions of spinal cord
*upper wings- dorsal horns
*lower wings- ventral horns
*wings connect- gray commissure
tracts that conudct sensory impulses to the brain
ascending tracts
fasciculus gracilis &
fasciculus cuneatus
*part of ascending tract
*located along posterior funiculi
*senses touch, pressure and body movments from skin, muscle, tendons and joints
spinothalamic tract
*part of ascending tract
*located along lateral and anterior funiculi
*senses pain, temperature, touch and pressure from various body regions
spinocerebellar tract
*part of ascending tract
*located along lateral funiculi
*coordination of muscle movements from muscles of lower limbs and trunk of cerebellum
tracts that conduct sensory impulses from the brain to muscles or glands
descending tracts
corticospinal tract
*part of descending tract
*located along lateral and anterior funiculi
*voluntary movement from brain to skeletal muscles
reticulospinal tract
*part of descending tract
*located along lateral and anterior funiculi
*maintenance of muscle tone and the activity of sweat glands
rubrospinal tract
*part of descending tract
*located along lateral funiculi
*muscle coordination and the maintenance of posture
reflexes
automatic, subconscious response to changes outside or inside the body
reflex classifications
somatic reflexes- activate skeletal muscle
autonomic (visceral) reflexes- activate visceral effectors
relfex arc
nerve pathway that forms structural and functional bases for a reflex
receptor
site of stimulus action
sensory neuron
transmits afferent impulses to CNS
integration center
monosynaptic or polysynaptic region within CNS
motor neuron
conducts efferent impulses
effector
muscle fiber or gland cell that responds to efferent impulses by contracting or secreting
types of reflexes
stretch reflex
tendon reflex
withdraw reflex
crossed-extensor reflex
stretch (knee-jerk) reflex
*myotatic reflex
*muscle contraction in response to stretching a muscle
tendon reflex
withdraw reflex
pain message sent to spinal cord via sensory receptors
crossed-extensor reflex
*when pain reflex withdraws the hurt limb, contralateral extensors are stimulated to contract
*allows body to support the shift in weight