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