conducts efferent impulses from integration center to effect or organ

muscle fiber or gland cell that responds to efferent impulses by contracting or secreting

Pia mater: delicate CT that clings tightly to brain, following every convolution

subarachnoid space contains CSF and kargest blood vessels of brain

Endoneurium: loose CT that encloses axons and their myelin sheath

Epineurium: tough fibrous sheath around all fascicles to form nerve

master of controlling and communicating system of body

cells communicate via electrical and chemical signals; rapid and specific, almost immediate reponses

info gathered by sensory receptors about internal and external changes

activation of effector organs (muscles and glands) produces a response

brain and spinal cord of dorsal body cavity; integration and control center: interprets sensory input and dictates motor output

Visceral sensory fibers: covey impulses from visceral organs to CNS

Somatic sensory fibers: convey impulses from skin, skeletal muscles, and joints to CNS

somatic motor nerve fibers conduct impulses from CNS to skeletal muscle; conscious control of skeletal muscles

Ventral roots: contain motor (efferent) fibers from ventral horn motor neurons that innervate skeletal muscles

Dorsal roots: contain sensory (afferent) fibers from sensory neurons in dorsal root ganglia that conduct impulses from peripheral repeaters

make adjustments to ensure optimal support for body activities

keeps body energy use low as possible, even while carrying out maintenance activities (directs digestion, diuresis, defecation)

blood pressure, heart rate, and respiratory rates are low; gastrointestinal tract activity is high; pupils constricted

exercise, excitement, emergency, embarrassment activates sympathetic system

increased heart rate, dry mouth, cold and sweaty skin, dilated pupils

during vigorous phy activity: shunts blood to skeletal muscles and heart; dilates bronchioles; causes liver to release glucose

long preganglionic fibers extend from CNS almost to target organs

synapse w/ postganglionic neurons in terminal gangia that close or within target organ; short postganglionic fibers synapse w/ effectors

some structures innervated only by sympathetic: sweat glands, arrector pili muscle of hair follicle, smooth muscles of all blood vessels

one division usually predominates, but in a few cases, divisions have cooperative effects

both ANS divisions are partially active, resulting in a basal sympathetic and parasympathetic tone

surround all peripheral nerve fibers and form myelin sheaths in thicker nerve fibers

special characteristics: extreme longevity (last a person's lifetime); amitotic w/ few exceptions; high metabolic rate: requires continuous supply of oxygen and glucose

convey incoming messages toward cell bodies as graded potentials

either short or absent, or almost entire length of cell (nerve fibers)

carries on many convos w/ dif neurons at same time; movements occur towards and away from cell body

generates nerve impulses and transmits them along axolemma to axon terminal

function: protect and electrically insulate axon; increase speed of nerve impulse transmission

nonmyelinated fibers: do not contain sheath (conduct impulses more slowly)

myelinated fibers: segmented sheath surrounds most long or large diameter axons

processes wrap CNS nerve fibers, forming insulating myelin sheaths in thicker nerve fibers

functions: support and brace neurons; role in exchange between capillaries and neurons; guide migration of young neurons; control chem env around neurons; respond to nerve impulses and neurotransmitters; influence neural function; and participate in info processing in brain

form permeable barrier between cerebrospinal fluid in cavities and tissue fluid bathing CNS cells

small, ovoid cells w/ thorny processes that touch and monitor neurons

can transform to phagocytize microorganisms and neural debris

muscle strength or ability to preform discrete individual movement is not impaired; only movement control is lost

other premotor neurons can be reprogrammed to take over skill of damaged neurons

by contrast, individuals w/ a damaged visual association area can see, but they do not comprehend what they are looking at

occurs in 1% of pop; genetic factor play a role, but brain injuries, stroke, infections, or tumors can also be causes

may lose consciousness, fall stiffly, and have uncontrollable jerking

control includes anticonvulsive drugs, vagus nerve stimulator or deep brain stimulator implantations that deliver pulses to vagus nerve or directly to brain to stabilize brain activity

torrent of electrical discharges by groups of neurons; prevent any other messages from getting through

may spread to CNS, which would lead to inflammation of the brain (encephalitis)

usually diagnosed by observing microbes in a sample of CSF obtained via lumbar puncture

obstruction blocks CSF circulation or drainage, result in increased pressure

in newborns, skull bones are unfused so increased pressure causes head to enlarge

in adults, rigidity of the skull keeps pressure within, potentially leading to brain damage (can compress blood vessels and crush soft nervous tissue)

memory loss, short attention span, disorientation, eventual lang loss, irritability, moodiness, confusion, hallucinations

progressive degenerative disease of brain that results in dementia (key proteins appear misfolded and malfunction)

neurofibrillary tangles inside neurons interfere w/ transport mechanisms, eventually killing neuron

degeneration of dopamine; releasing neurons of substantia nigra

basal nuclei deprived of dopamine become overactive, result in tremor at rest

cause unknown; theories: mitochondrial abnormalities or protein degration pathway

treatment includes L-dopa, deep brain stimulation, gene theory

fatal hereditary disorder caused by accumulation of protein huntingtin in brain cells (degeneration of basal nuclei and cerebral cortex)

later marked by mental disorientation (usually fatal within 15 yrs of onset

neuromuscular disability involving poorly controlled or paralyzed voluntary muscles

due to brain damage, possibly from lack of oxygen during birth

spasticity, speech difficulties, motor impairments can be seen

some patients have seizures, are intellectually impaired, and/or deaf

cerebrum and parts of brain stem never develop b/c neural fold fails to fuse

incomplete formation of vertebral arches; typically involves lumbosacral region

laminae and spinous processes are missing on at least one vertebre

US incidence dropped w/ recommendations for supplementation

spina bifida occulata: least serious, involves only one or few missing vertebrae and usu causes no neural probs; sacral dimple or patch of pair may indicate hint at underlying omally

more severe situation if meninges protrude through dorsal spinal (form saclike cyst called meningocele) (portion of spinal cord and nerve roots protrude inside it's called myelomenigocele) (child may have hydrocephalus, paralysis, and bowler and bladder dysf

myelin sheaths in CNS are destroyed when immune system attack myelin (myelin hardened lesions called scleroses) (impulse conduction slows and ceases)

symptoms: visual disturbances, weakness, loss muscular control, speech disturbances, incontinence

may not be able to prevent, but maintaining high blood levels of vitamin D may reduce risk develp

now use as epidural anesthesia during surgery to reduce phantom pain

damage to autonomic nerves that is common complication of diabetes mellitus

other frequent symptoms: dizziness, urinary incontinence, sluggish eye pupil, impaired sweating

heart must work harder, and artery walls are subjected to increased wear and tear

life threatening, uncontrolled activation of autonomic neurons in quadriplegics and people w/ spinal cord injuries above T6