The nervous system: brain and spinal cord

spinal nerves

31 pairs, each nerve attached to spinal cord by two roots, dorsal root, ventral root. Nerves near end of cord travel together in the cord until each exits from its respective intervertebral foramen, mixed nerves

Central nervous system

Brain and spinal cord

CNS

Brain, spinal cord

Cranial nerves

Carry impulses to and from the brain

Spinal nerves

Carry messages to and from the spinal cord

Somatic nervous system

Controlled voluntarily and all it's effectors are skeletal muscles

Role of the nervous system

Coordinates all body systems, detects and responds to stimuli, brain and spinal cord acts as switching centers, nerves carry messages to and from centers

PNS

Cranial nerves, spinal nerves

Autonomic nervous system

Involuntary, effectors are smooth muscle, cardiac muscle, and glands. Subdivided into sympathetic and parasympathetic

Peripheral nervous system

Made up of all the nerves outside the CNS, includes the cranial nerves and all the spinal nerves

Any group of nerve cel bodies located outside the CNS is known as what

a ganglion

dendrite

a neuron fiber that conducts impulses to the cell body

dermatome

a region of the skin supplied by a single spinal nerve

epinephrine

adrenaline

PNS

arise in craniosacral areas, cholinergic system, reverses fight or flight; rest and digest; acetycholine

endoneurium

around nerve fiber

neurons

basic functional unit of nervous system, highly specialized, unique structure, do not reproduce, do not divide

spinal cord

begins at the foramen magnum and ends at L2

cauda equina

bundle of nerves where spinal cord ends

cell fibers

carry impulses

spinal cord ends at the

cauda equina

"docking site" on a postsynaptic cell membrane

cellular receptor

central canal

center chamber contains CSF

interneurons (central or association neurons)

connect messages from sensory to motor neurons; conduct info within CNS

gray commisure

connects right/left horns

SNS effect on blood vessels

constricts blood vessels in viscera and skin; dilates vessels in skeletal muscle and heart; increases blood pressure

SNS effect on kidney

constricts blood vessels that cause decreased urine output

PNS effects on lungs and bronchial tubes

constricts bronchioles

SNS effect on urinary bladder/urethra

constricts sphincters (prevents voiding); stimulates relaxation of muscular wall

neuron cell body

contains nucleus and cytoplasm

SNS effect on digestive system

decreases or inhibits motility; constricts digestive system sphincters

anterior median fissure

deeper groove divides anterior right/left sides

SNS effect on lungs and bronchial tubes

dilates brochioles

posterior median sulcus

divides left/right side

unmyelineated tissue of spinal cord

dorsal horn, ventral horn, gray commissure, central canal

dendrites

extensions that receive messages

perineurium

fascicle

nerve

fiber bundle of axons within PNS

nerve tract

fiber bundle within CNS

Schwann cells

form the myelin

nodes

gaps between myelin sheath

neuroglia

glial cells; protect and nourish nervous tissue, support nervous tissue, aid in cell repair, remove pathogens and impurities

SNS effect on sex organs, penis, uterus

in female inhibits contraction if not pregnant, stimulates contraction if pregnant; in male vasoconstriction of ductus deferens, seminal vesicle, prostrate results in ejaculation.

SNS effect on heart

increases rate and strength of contraction; dilates coronary vessels

SNS effect on eye (ciliary muscle)

inhibits decrease bulging of lens to prepare for distant vision

SNS effect on glands (salivary, lacrimal)

inhibits secretion (vasaconstriction) resulting in dry mouth and dry eyes

myelin sheath

insulate, protect, speed the impulse

synapse

junction point for transmitting nerve impulse

spinal cord

links PNS and brain, helps coordinate impulses within CNS, contained in and protected by vertebrae

P)NS effects on glands (sweat)

no effect

PNS effect on adrenal cortex

no effect

PNS effect on adrenal medulla

no effect

PNS effects on kidney

no effect

PNS effects on arrector pili of hair follicles

none

PNS effects on blood vessels

none

norepinephrine

noradrenaline

spinal reflex

passes through spinal cord alone; coordinated in spinal cord, stretch reflex is example, responds by contracting

cervical plexus

phrenic nerve

myelineated axons (white matter)

posterior median sulcus, anterior median fissure, ascending and descending tracts

dendrite

postsynaptic cell

axon

presynaptic cell

brachial plexus

radial nerve

simple reflex

rapid, uncomplicated, automatic

sensory neurons (afferent neurons)

receive from all over body sends to CNS; conduct impulses to spinal cord and brain

reflex arc

receptor, such as a dendrite or receptor cell in a sensory organ, detects stimulus. sensory neuron transmits impulses to CNS. CNS coordinates impulses and organizes response. Motor neuron carries impulses away from CNS. Effector carries out response.

ANS

regulates the action of glands, smooth muscles of hollow organs and vessels, and heart muscle; sympathetic/ parasympathetic

PNS effects on urinary bladder/urethra

relaxes sphincters; stimulates contraction of muscular wall

lumbosacral plexus

sciatic nerrve

PNS effect on eye (iris)

stimulates constrictor muscles; constricts pupils

SNS effect on eye (iris)

stimulates dilater muscles; dilates pupils

SNS effect on adipose tissue

stimulates free fatty acid release from fat cells

SNS effect on liver

stimulates glycogen breakdown; promotes glycogenolysis; decreases bile secretion

PNS effects on liver

stimulates glycogen production; promotes glycogenesis; increases bile secretion

PNS effects on digestive system

stimulates or increases smooth muscle motility and amount of secretion; relaxes spinchters

PNS effects on glands (salivary, lacrimal)

stimulates secretion (vasodilation); increases production of saliva and tears

SNS effect on adrenal medulla

stimulates secretion of epinephrine and norepinephrine

SNS effect on adrenal cortex

stimulates secretion of glucocorticoid

PNS effects on eye (ciliary muscle)

stimulates to increase bulging of lens to prepare for close vision

SNS effect on glands (sweat)

stimulates to produce perspiration

SNS effect on arrector pili of hair follicles

stimulates; produces "goosebumps"

the point of junction for transmitting a nerve impulse is called

synapse

cytoplasm

thick fluid inside cell but outside nucleus

neurilemma

thin sheath that covers the myelin

SNS

thoracolumbar area, adrenergic system, activated in the four E's: excitement, emergency, embarassment, exercise, response to stress; fight or flight response; adrenaline

axons

transfers info away from cell body to another neuron; can be as long as 3 ft, some are protected by myelin sheath

motor neurons (efferent neurons)

transmits from CNS to all over body; conduct impulses to muscles, glands

PNS effects on sex organs, penis, uterus

vasodilation and erection in both sexes; secretion in female

epineurium

whole nerve

Somatic nervous system

"Fight or flight" response, effectors are skeletal muscles; release of epinephrine, norepinephrine, adrenaline to speed everything up heart rate, deeper breaths

Visceral nervous system

ANS; it's effectors are smooth muscle, cardiac muscle, and glands, which are found in the soft body organs, the viscera

Effector

Any tissue or organ that carries out a nervous system command; all of which are muscles or glands

Autonomic nervous system

Nervous systems involuntary division

Parasympathetic effects on adipose

None