Nervous System. Flashcards
CNS consists of
brain and spinal cord.
PNS consists of
cranial and spinal nerves; peripheral components of ANS.
Synapse:
structural and functional junction between two neurons.
Two types of synapses:
electrical and chemical.
Electrical synapse:
an action potential moves from neuron to neuron directly by allowing electrical current to flow between neurons.
Chemical synapse:
an action potential reaches the end of the axon (presynaptic terminal) then it causes release of a chemical substance (neurotransmitter) from tiny vesicles with the axon terminal.
Neurotransmitters are:
excitatory or inhibitory.
Excitatory neurotransmitters:
they cause an increase in Na+ permeability at the postsynaptic cell membrane, increasing a likelihood of an action potential; acetylcholine, norepinephrine, serotonin, dopamine, glutamate, and histamine.
Inhibitory neurotransmitters:
they cause an increase in permeability of K+ and Cl- ions, decreasing the likelihood than an action potential will be generated; gamma-aminobutyric acid (GABA) and glycine.
Spinal cord consists of:
white and gray matter.
White matter:
surrounds the gray matter; contains the axons of the ascending sensory and the descending motor fibers.
Gray matter:
contains the cell bodies of voluntary motor neurons and preganglionic autonomic motor neurons, as well as cell bodies of association neurons.
Brain is divided into:
cerebrum, brainstem, and cerebellum.
Ventricles:
supporting structure located within the CNS; the ventricles are four fluid-filled cavities with the brain that connect with one another and with the spinal canal.
CSF:
circulates within the subarachnoid space that surrounds the brain, brainstem and spinal cord; provides cushioning for the brain and spinal cord allows fluid shifts from the cranial cavity to the spinal cavity and carries nutrients.
PNS consists of:
spinal and cranial nerves, associated ganglia, and portion of the ANS.
SNS:
located in T1-L2; increases the rate and force of the heart contraction, dilates bronchi and bronchioles of the lungs.
PNS (parasympathetic):
located in the brainstem and in the sacral spinal segments (S2 through S4); decreases the rate and force, constricts the bronchioles and bronchi.
CN I:
olfactory; smell, testing sensory.
Test CN I:
identify odor; vials of scents.
CN II:
optic; visual acuity and visual fields.
Test CN II:
use snellen or rosenbaum chart; test peripheral by standing in front of pt and wiggle fingers.
CN III:
olculomotor; eye movement and pupil response.
Test CN III:
look at movement of the eyes; 6 cardinal fields of gaze; shape, response to light, accommodation; cover/uncover test.
CN IV:
trochlear; movement of the eyes, motor.
Test IV:
look at movement of the eyes; 6 cardinal fields of gaze; shape, response to light, accommodation; cover/uncover test.
CN V:
trigeminal; corneal reflex, jaw, face sensation; motor and sensory.
Test CN V:
evaluate sharp, dull and light touch sensations on cheek, and chin areas. Test corneal reflex.
CN VI:
abducens; eye movements; motor.
Test CN VI:
look at movement of the eyes: six cardinal fields of gaze, pupil size (pen light), look at shape, response to the light, and accommodation, and opening of the eyelids; perform cover/uncover test.
CN VII:
facial; facial expressions; motor and sensory.
Test CN VII:
motor: observe pt performing a series of facial expressions (clench teeth, squeeze eyes shut, smile); sensory: touch (cotton on skin).
CN VIII:
acoustic; hearing and balance; sensory.
Test CN VIII:
hearing function: whisper or watch test; vestibular function: romberg test.
CN IX:
glossopharngeal; taste, gag, swallowing; motor and sensory.
Test CN IX:
watch patient swallow, gag, and taste test.
CN X:
vagus; gag reflex; sensory and motor.
Test CN X:
say “ah;” observe movement of the soft palate and uvula for symmetry.
CN XI:
spinal accessory; shoulder shrug; motor.
Test CN XI:
assess symmetrical shoulder shrug.
CN XII:
hypoglossal; tongue movement, motor.
Test CN XII:
test tongue strength and movement.
Neuron:
basic functional unit of the brain.
Neuron is made of:
cell body - clusters are call centers; dendrite - synapses for receiving messages; axon - carries impulses away from cell body.
Cerebrum:
comprised of the frontal, parietal, temporal, and occipital lobes.
Frontal lobe:
conceptualization, abstraction, motor ability, judgment, and ability to write words.
Pre-frontal cortex:
ability to plan, reason, concentrate, and adjust behavior.
Pre-motor cortex:
coordinates series of movement or intricate, complex movements.
Broca’s:
infero-lateral portion of frontal lobe; ability to speak.
Parietal:
integrating and coordinating center for perception and interpretation of sensory information; involved in sensations of pain and touch, spatial orientation, and speech.
Motor cortex:
sends instructions to muscles to cause voluntary movements.
Temporal:
memory storage; integration of auditory stimuli.
Wernicke’s:
posterior portion of superior temporal convolution - reception and understanding of language.
Occipital:
visual center; understanding of written material.
Diencephalon is made of:
thalamus, epithalamus, subthalamus, and hypothalamus.
Brainstem is made of:
midbrain, pons, and medulla.
Midbrain:
origin of righting and postural reflex.
Pons:
connects medulla, midbrain, and cerebrum; controls rhythm of respiration.
Medulla:
connects central canal to spinal cord; vital center for cardiac, respirations, swallowing, gag, and cough.
Cerebellum:
controls fine movement, balance, and position sense; keeps body oriented in space and maintaining truncal equilibrium, controlling antigravity muscles, checking or halting voluntary movements.
Decorticate:
(towards core) arms flexed, wrist and fingers flexed, adduction of upper extremities, extension of the lower extremity, feet are plantar, can be unilateral or bilateral.
Decerebrate:
poor prognosis – everything is hyperextended except hands; injury is at the level of the brain stem.
Meninges:
connective tissue that covers the brain and spinal cord.
CSF:
150 mls; 15-25 in each lateral ventricle; circulates within the subarachnoid space that surrounds the brain, brainstem and spinal cord.
CSF description:
clear, colorless, SG of 1.007, minimum WBC, no RBC.
CSF function:
cushion, support, nutrition, removes metabolites, empties into venous system through jugular veins
Circle of Willis:
allows a continuous blood supply because of the communication between the arteries.
Upper motor neuron lesions:
motor cortex, internal capsule, and other structures of the brain; loss of voluntary control, increased muscle tone or spasticity, no muscle atrophy, hyperactive and abnormal reflexes.
Lower motor neuron lesions:
between muscle and spinal cord (may involve spinal nerves); loss of voluntary control, decreased muscle tone, flaccid muscle paralysis with atrophy, absent or decreased reflexes.
Neuro assessment:
mental status, intellectual function, thought content, emotional status, perception, motor ability, language ability, motor strength, cranial nerve exam; assess muscle strength, balance and coordination, deep tendon reflexes, and sensory system.
