Winter Test 2 Flashcards
paraplegia
paralysis of lower limbs
quadriplegia
paralysis of all four limbs
hemiplegia
paralysis of one side of the body only
conduction of the spinal cord
bundles of fibers passing information up and down spinal cord, connecting different levels of the trunk with each other and with the brain
locomotion of the spinal cord
central pattern generators are pools of neurons providing control of flexors and extensors that cause alternating movements of the lower limbs
reflexes of the spinal cord
involuntary, stereotyped responses to stimuli
involves brain, spinal cord and peripheral nerves
spinal cord
cylinder of nervous tissue that arises from the brainstem at the foramen magnum of the skull
passes through the vertebral canal
31 pair of spinal nerves
cauda equina
bundle of nerve roots that occupy the vertebral canal from L2 to S5
gray matter
neuron cell bodies with little myelin
site of information processing – synaptic integration
white matter
abundantly myelinated axons
carry signals from one part of the CNS to another
sensory signals travel across three neurons
from origin in receptors to the destination in the sensory areas of the brain
first order neurons
detect stimulus and transmit signal to spinal cord or brainstem
second order neurons
continues to the thalamus at the upper end of the brainstem
third order neurons
carries the signal the rest of the way to the sensory region of the cerebral cortex
anterior ramus
innervates the anterior and lateral skin and muscles of the trunk
gives rise to nerves of the limbs
posterior ramus
innervates the muscles and joints in that region of the spine and the skin of the back
meningeal branch
reenters the vertebral canal and innervates the meninges, vertebrae and spinal ligaments
(reflexes) integrating center
a point of synaptic contact between neurons in the gray matter of the spinal cord or brainstem
determines whether the efferent neurons issue a signal to the muscles
flexor reflex
the quick contraction of flexor muscles resulting in the withdrawal of a limb from an injurious stimulus
polysynaptic reflex arc
pathway in which signals travel over many synapses on their way back to the muscle
crossed extension reflex
the contraction of extensor muscles in the limb opposite of the one that is withdrawn
maintains balance by extending other leg
intersegmental reflex
one in which the input and output occur at different levels (segments) of the spinal cord
cerebrum
83% of brain volume; cerebral hemispheres, gyri and sulci, longitudinal fissure, corpus callosum
cerebrellum
contains 50% of the neurons; second largest brain region,
consists of right and left cerebellar hemispheres connected by vermis
contains half of all brain neurons,
white matter branching pattern is called arbor vitae
brainstem
portion of the brain that remains if the cerebrum and cerebellum are removed; diencephalon, midbrain, pons, and medulla oblongata
corpus callosum
thick nerve bundle at bottom of longitudinal fissure that connects hemispheres
dura mater
outer periosteal – equivalent to periosteum of cranial bones
inner meningeal – continues into vertebral canal and forms dural sac around spinal cord
arachnoid mater
transparent membrane over brain surface
subarachnoid space separates it from pia mater below
subdural space separates it from dura mater above in some places
pia mater
very thin membrane that follows contours of brain, even dipping into sulci
not usually visible without a microscope
lateral ventricles
one in each cerebral hemisphere
interventricular foramen - a tiny pore that connects to third ventricle
third ventricle
single narrow medial space beneath corpus callosum
cerebral aqueduct runs through midbrain and connects third to fourth ventricle
fourth ventricle
small triangular chamber between pons and cerebellum
connects to central canal runs down through spinal cord
ependyma
neuroglia that lines the ventricles and covers choroid plexus
produces cerebrospinal fluid
CSF Circulation
CSF secreted in lateral ventricles flows through intervertebral foramina into third ventricle
then down the cerebral aqueduct into the fourth ventricle
CSF is reabsorbed by arachnoid villi
Functions of CSF
buoyancy, protection, and chemical stability
blood-brain barrier
protects blood capillaries throughout brain tissue
consists of tight junctions between endothelial cells that form the capillary walls
blood-CSF barrier
protects the brain at the choroid plexus
form tight junctions between the ependymal cells
tight junctions are absent from ependymal cells elsewhere
blood barrier system permeability
highly permeable to water, glucose, and lipid-soluble substances such as oxygen, carbon dioxide, alcohol, caffeine, nicotine, and anesthetics
slightly permeable to sodium, potassium, chloride, and the waste products urea and creatinine
midbrain
contains cerebral aqueduct
contains continuations of the medial lemniscus and reticular formation
contains the motor nuclei of two cranial nerves that control eye movements – CN III (oculomotor) and CN IV (trochlear)
tectum
roof-like part of the midbrain
four bulges, the corpora quadrigemina
upper pair, the superior colliculi function in visual attention, tracking moving objects, and some reflexes
lower pair, the inferior colliculi receives signals from the inner ear
cerebral peduncles
two stalks that anchor the cerebrum to the brainstem anterior to the cerebral aqueduct
tegmentum
dominated by the red nucleus
connections go to and from cerebellum
substantia nigra
dark gray to black nucleus pigmented with melanin
motor center that relays inhibitory signals to thalamus & basal nuclei preventing unwanted body movement
cerebral crus
bundle of nerve fibers that connect the cerebrum to the pons
carries corticospinal tracts
reticular formation
loosely organized web of gray matter that runs vertically through all levels of the brainstem
cerebellar peduncles
inferior peduncles – connected to medulla oblongata
most spinal input enters the cerebellum
middle peduncles – connected to the pons
most input from the rest of the brain enters
superior peduncles – connected to the midbrain
carries cerebellar output
Cerebellar Functions
muscle contractions and motor coordination
evaluation of sensory input- comparing textures
timekeeping center
hearing
planning and scheduling tasks
Damage to cerebellum
emotional overreactions and trouble with impulse control
Forebrain
diencephalon: thalamus, hypothalamus, epithalamus
thalamus
plays key role in motor control involved in the memory and emotional functions of the limbic system
hypothalamus
major control center of autonomic nervous system and endocrine system
plays essential roll in homeostatic regulation of all body systems
functions of hypothalamic nuclei
hormone secretion, autonomic effects, thermoregulation, food and water intake, rhythm of sleep and waking, memory, emotional behavior
epithalamus
very small mass of tissue
pineal gland
habenula – relay from the limbic system to the midbrain
function of frontal lobe
voluntary motor functions
motivation, foresight, planning, memory, mood, emotion, social judgment, and aggression
function of parietal lobe
receives and integrates general sensory information, taste and some visual processing
function of temporal lobe
areas for hearing, smell, learning, memory, and some aspects of vision and emotion
insula (functions)
(hidden by other regions)
understanding spoken language, taste and sensory information from visceral receptors
projection tracts
extends vertically between higher and lower brain and spinal cord centers
carries information between cerebrum and rest of the body
commissural tracts
cross from one cerebral hemisphere through bridges called commissures
most pass through corpus callosum
anterior and posterior commissures
enables the two sides of the cerebrum to communicate with each other
association tracts
connect different regions within the same cerebral hemisphere
long association fibers – connect different lobes of a hemisphere
to each other
short association fibers – connect different gyri within a single lobe
stellate cells
have spheroid somas with dendrites projecting in all directions
receive sensory input and process information on a local level
pyramidal cells
tall, and conical, with apex toward the brain surface
a thick dendrite with many branches with small, knobby dendritic spines
include the output neurons of the cerebrum
only neurons that leave the cortex and connect with other parts of the CNS
basal nuclei
masses of cerebral gray matter buried deep in the white matter, lateral to the thalamus
receives input from the substantia nigra of the midbrain and the motor areas of the cortex
send signals back to both these locations
involved in motor control
Stage 1 of sleep
feel drowsy, close our eyes, begin to relax
often feel drifting sensation, easily awakened if stimulated
alpha waves dominate EEG
Stage 2 of sleep
pass into light sleep
EEG declines in frequency but increases in amplitude
exhibits sleep spindles – high spikes resulting from interactions between neurons of the thalamus and cerebral cortex
Stage 3 of sleep
moderate to deep sleep
about 20 minutes after stage 1
theta and delta waves appear
muscles relax and vital signs (body temperature, blood pressure, heart and respiratory rate) fall
Stage 4 of sleep
called slow-wave-sleep (SWS) – EEG dominated by low-frequency, high amplitude delta waves
muscles now very relaxed, vital signs at their lowest, and we become more difficult to awaken
denervation hypersensitivity
exaggerated response of cardiac and smooth muscle if autonomic nerves are severed
visceral reflexes
unconscious, automatic, stereotyped responses to stimulation involving visceral receptors and effectors and somewhat slower responses
Sympathetic Nervous System
thoracolumbar division
short preganglionic and long postganglionic fibers
preganglionic neurosomas in lateral horns
lead to nearby sympathetic chain of ganglia (paravertebral ganglia)
autonomic function of cerebral cortex
anger, fear, anxiety
autonomic function of hypothalamus
major visceral motor control center
nuclei for primitive functions – hunger, thirst, sex
autonomic fuction of midbrain, pons, and medulla oblongata
nuclei for cardiac and vasomotor control, salivation, swallowing, sweating, bladder control, and pupillary changes
enteric nervous system
the nervous system of the digestive tract
does not arise from the brainstem or spinal cord
does innervate smooth muscle and glands
