Nervous System Test

Oligodendrocytes

wrap around the nerve fibers; form myelin sheaths in CNS

Microalgia

spiderlike; resident macrophages/phagocytes

Schwann cells

individual cells form myelin sheaths in PNS; protection and cushioning

Astrocytes

star shaped; brace and anchor neurons; support blood-brain barrier

ependymal cells

ciliated to circulate cerebral spinal fluid in the brain and spinal cord

Axon terminal

releases neurotransmitters

dendrite

conducts electrical currents towards cell body

Myelin sheath

increases the speed of impulse transmission

nodes of ranvier

separations between myelin sheath toward Schwann cells

cell body

location of the nucleus

axon

generally, conducts impulses away from the cell body

“gray matter”

axon terminals, cell body, dendrtied, unmyelinated axons

“white matter”

myelinated neurons (white comes from fat of myelin)

What is the protective role of the reflex arc?

to protect the body from harm automatically

nerve pathway arc

stimulus —> sensory recepor —> afferent/sensory neuron —> associative neuron/integration center —> efferent/motor neuron -> effector

Afferent/sensory neuron

carries response to CNS

Associative/inter neuron

“decision maker”, connects afferent and efferent neuron

effector

muscle or gland that is stimulated into action

efferent/motor neuron

carries response into effector

neurotransmitter

chemical messengers, communicate information across synapses

dopamine

control brain’s reward and pleasure centers, regulates movement and emotion

acetycholine

excites skeletal muscles, inhibits cardiac muscle

serotonin

regulation of mood, appetite, and sleep, serves as vasoconstrictor

synapse

small gap separating neurons

Action potential events

1. “message” from receptor triggers action potential (electric impulse) in presynaptic neuron

2. Action potential reaches axon terminal of presynaptic neuron

3. Action potential triggers vesicles to move axon/neuron membrane

4. Vesicle membrane fuses with axon/neuron membrane releasing neurotransmitters

5. Neurotransmitter molecules diffuse across the synaptic cleft

6. Neurotransmitter binds to receptor on polysynaptic side of synapse

7. Neurotransmitter triggers an action potential in the polysynaptic cell

8. “message” continues along presynaptic neuron toward CNS

Polarized

electrical condition of the plasma membrane of a resting neuron

repolarization

period during which potassium ions diffuse out of the neuron

NA-K pump

process by which ATP is used to move NA+ out of the cell and K+ back into the cell, restoring the resting conditions of the neuron

depolarization

state in which the resting potential is reversed as sodium ions rush into the neuron

sodium

chief positive intracellular ion in a resting neuron

action potential

transmission of the depolarization wave along the neuron’s membrane

peripheral

all nerves except brain and spinal cord, Serves as communication lines, linking all parts of the body to the CNS

autonomic

also called the involuntary nervous system

somatic

Controls voluntary activities such as the activation of skeletal muscles

central

Interprets incoming information and issues orders

cerebellum

lies on top of the pons, behind the brain stem; involved in the coordination of motor as well as balance

brain stem

located between spinal cord and brain; controls many vital autonomic

medulla oblongata

Contains autonomic centers, which regulate blood pressure and

respiratory rhythm, as well as coughing and sneezing centers

pons

Midbrain area that is largely fiber tracts; bulges anteriorly

hypothalamus

Part of the limbic system; site of regulation of water balance and body temperature

cerebellum

Responsible for the regulation of posture and coordination of skeletal muscle movement

meninges

membranes around the spinal cord

What is the function of the meninges?

to protect the CNS

what is CSF fluid?

watery fluid circulating around the brain and spinal cord

function of CSF

to cushion the brain and spinal cord

The meninges form a sac in the lumbar region of the spinal cord from which cerebrospinal fluid can be withdrawn without damage to the spinal cord. What is this procedure called?

spinal tap

EEG

records electrical activity of brain via electrodes affixed to scalp

MRI

Uses magnetic field and pulses of radio wave energy; may see problems not seen with other imaging methods

CT

Uses x-rays to create cross-sectional pictures of body

Cerebral edema

after head injury, retention of water by brain

spinal cord injury

Damage to vertebrae may cause this peripheral system injury

concussion

Slight and transient brain injury

contusion

Traumatic injury that destroys brain tissue

blink

corneal reflex

both irises constrict

papillary light reflex

one iris constricts

contralateral reflex

lower leg jerks forward

patellar reflex

toex flex forward and move closer together

plantar reflex

toes/foot jerk down

achille’s heel

uvula moves forward

gag reflex

plantar reflex procedure

drawing a blunt instrument across the ball of the foot and down the outer edge of the sole

contralateral procedure

shining a light in one eye but checking the other eye for a reaction

pupillary reflex

shining a light in one eye while the other is covered

achille’s heel

striking the tendon above the heel while the foot is dorsi-flexed

patellar reflex

striking the tendon just below the knee cap

corneal reflex

touching the cornea of the eye with a wisp of cotton

gag reflex

touching the pharyngeal walls near the uvula

olfactory neuron

a sensory neuron responsible for the sense of smell

gustatory hairs

microvilli on tatse cells that etect dissolved substances in the mouth

papillae

small bumps on the tongue that contain taste buds

taste pores

openings on taste buds through which gustatory hairs detect chemicals

retina

light sensitive layer at the back of the eye that contains photoreceptor cells

cornea

the clear, dome-shaped surface at the front of the eye that focuses light

lens

a transparent, flexible structure in the eye that focuses light onto the retina

aqueos humor

A clear fluid in the front chamber of the eye that nourishes it and maintains pressure

vitreous humor

A gel-like substance inside the eye that helps maintain its shape.

Optic Nerve

the nerve that carries visual information from the retina to the brain

iris

the colored part of the eye that controls the size of the pupil

pupil

the adjustable opening in the iris that regulates light entering the eye

nerve receptors

Specialized cells that detect changes in the environment (e.g., light, sound, pressure).

Cochlea

A spiral-shaped structure in the inner ear that converts sound vibrations into neural signals.

Tympanic Membrane

the eardrum; vibrates in response to sound waves.

Auditory Canal

The passage leading from the outer ear to the eardrum

Outer ear

he external part of the ear that collects sound.

Vestibulocochlear Nerve

The cranial nerve responsible for hearing and balance.

Eustachian Tube

A tube connecting the middle ear to the throat, equalizing pressure.

Nodes of Ranvier

gaps in the myelin sheath where action potentials are generated.

stem cell treatment

the use of stem cells to regenerate or repair damaged neural tissue, showing promise for treating conditions like spinal cord injuries and multiple sclerosis