AHS-102 Chapter 12 Part 1

functions of the nervous system

coordinates and controls body functions; receives sensory input, makes decisions based on that input, and orders appropriate body responses

primary structures of the nervous system

brain, spinal cord, and nerves

alges/o

sense of pain (cf)

astr/o

star (cf)

centr/o

center (cf)

cerebell/o

cerebellum (cf)

cerebr/o

cerebrum

clon/o

rapid contracting and relaxing (cf)

concuss/o

to shake violently (cf)

dur/o

dura mater (cf)

encephal/o

brain (cf)

esthesi/o

feeling, sensation (cf)

gli/o

glue (cf)

medull/o

medulla oblongata (cf)

mening/o, meningi/o

meninges (cf)

ment/o

mind (cf)

myel/o

spinal cord (cf)

neur/o

nerve (cf)

peripher/o

away from the center (cf)

poli/o

gray matter (cf)

pont/o

pons (cf)

radicul/o

nerve root (cf)

thalam/o

thalamus (cf)

thec/o

sheath, meninges (cf)

tom/o

to cut (cf)

ton/o

tone (cf)

ventricul/o

ventricle (cf)

-paresis

weakness (s)

-phasia

speech (s)

-taxia

muscle coordination (s)

Central Nervous System (CNS)

brain and spinal cord; sensory info comes in for processing; motor messages exit with commands for muscles and glands

Peripheral Nervous System (PNS)

cranial nerves and spinal nerves; sensory nerves carry messages into CNS; motor nerves carry commands away from CNS

2 types of nervous cells

neurons and neuroglia

3 parts of neurons:

dendrites, nerve cell body, axon

Dendrites

highly branched projections that receive impulses

nerve cell body

contains the nucleus and other organelles of the cell

axon

projection from the cell body that conducts the impulse toward its destination

the axon of one neuron meets meets a dendrite of the next at the \________

synapse

synaptic cleft

between two neurons; electrical impulses cannot directly pass

neuroglial cells

some produce myelin (insulation for the axon)

gray matter

unsheathed cell bodies and dendrites

white matter

myelinated nerve fibers

3 meninges...

...encase and protect CNS

brain

one of largest organs; coordinates body activities

4 sections of brain

cerebrum, cerebellum, diencephalon, brainstem

cerebrum

largest section and upper portion; processes thought, judgment, memory, problem solving, and language

cerebral cortex

outer layer; folds of gray matter

gyri

elevated portions

sulci

fissures between gyri

four lobes

frontal, parietal, occipital, temporal

frontal lobes

anterior; control motor function, personality, and speech

parietal lobes

superior; interpret nerve impulses and language

occipital lobes

posterior; control vision

temporal lobes

lateral; control hearing and smell

diencephalon contains:

thalamus and hypothalamus

thalamus

gray matter; relays impulses from the eyes, ears, and skin to the cerebrum; controls pain perception

hypothalamus

below thalamus; controls temp, appetite, sleep, sexual desire, and emotion; controls automatic nervous system, cardiovascular system, digestive system, and pituitary gland

cerebellum

2 largest portion of brain; located under posterior part of cerebrum; coordinates voluntary body movements and maintains balance and equilibrium; refines muscular movements

3 components of brainstems

midbrain, pons, medulla oblongata

Midbrain

pathway for impulses between the brain and spinal cord

pons

connects the cerebellum to the rest of the brain

medulla oblongata

connects brain to spinal cord; controls centers for respiration, heart rate, temp, and blood pressure; site where nerve tracts cross

four interconnected ventricles

one in each hemisphere, one in the thalamus, one in front of the cerebellum; contain cerebrospinal fluid (CSF)

cerebrospinal fluid (CSF)

contained in ventricles; provides shock and motion protection to the brain and spinal cord; flows down center of spinal cord

spinal cord

pathway for impulses traveling to and from the brain; column of nervous tissue extending from the medulla oblongata to second lumbar vertebra; vertebral column

inner portion of spinal cord

made of cell bodies and dendrites; gray matter

outer portion of spinal cord

myelinated white matter

Ascending tracts of the spinal cord

carry sensory info up to the brain

descending tracts

carry motor commands down from brain to peripheral nerve

meninges

3 layers of connective tissue membranes surrounding the brain and spinal cord

dura mater

tough, fibrous, outermost sac

subdural space

space between dura mater and arachnoid mater

arachnoid layer

middle layer, web-like

subarachnoid space

between arachnoid mater and pia mater

pia mater

applied directly to the brain and spinal cord surface

cranial nerves

arise from the brain, typically the medulla oblongata

spinal nerves

split off of the spinal cord, with one pair of nerves between each pair of vertebrae

nerve root

point where nerve is attached to CNS

afferent neurons (sensory neurons)

carry info from a receptor to the CNS

efferent neurons (motor neurons)

carry info from CNS to muscles glands

autonomic nervous system (ANS)

controls involuntary or unconscious body functions; affects smooth muscle function in viscera and vessels; affects activity of cardiac muscle; affects activity of the glands; divided in sympathetic and parasympathetic branches

sympathetic branch

"fight or flight"; active in times of stress and crisis; increases heart rate, dilates airways, increases blood pressure, inhibits digestion, and stimulates production of adrenaline

parasympathetic branch

"rest and digest"; counterbalance to sympathetic branch; causes heart rate to slow, lowers blood pressure, stimulates return of digestion

somatic nerves

serves the skin and skeletal muscles; involved with conscious and voluntary activities

absence seizure

epileptic seizure characterized by loss of awareness and absence of activity

focal seizure

seizure in only one limb or body part

palsy

temporary or permanent loss of the ability to control movement

syncope

fainting

Alzheimer's disease (AD)

disorder characterized by dementia, progressive disorientation, apathy, and loss of memory

cerebral palsy (CP)

brain damage resulting from a defect, trauma, infection, or lack of oxygen before, during, or shortly after birth

cerebrovascular accident (CVA)

infarct due to loss of blood supply to the brain; commonly called a stroke

Chronic Traumatic Encephalopathy (CTE)

characterized by blows to the head that result in progressive degeneration of brain tissue

Shaken Baby Syndrome (SBS)

caused by violent shaking; symptoms include subdural hematoma, brain swelling, and retinal bleeding

Transient Ischemic Attack (TIA)

temporary interference with blood supply to brain; may lead to a CVA

amyotrophic lateral sclerosis (ALS)

condition of degeneration of motor neurons of the spinal cord; also called Lou Gehrig's disease

spinal cord injury (SCI)

damage to spinal cord due to trauma; cord may be bruised (temporary) or severed (permanent)

Reye's syndrome

combination of acute encephalopathy and organ damage; follows viral infection; also associated with aspirin

Bell's Palsy

One-sided facial paralysis due to inflammation of the facial nerve, probably viral in nature. The patient cannot control salivation, tearing of the eyes, or expression, but most will eventually recover.

Guillain-Barre syndrome

loss of myelin sheath from nerves; may be autoimmune; begins in the legs and progresses up toward the trunk

Multiple Sclerosis (MS)

inflammatory disease of the CNS; causes weakness and numbness due to loss of myelin sheath from nerves; plaques appear