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Nervous System by Marian Mercado - Coggle Diagram
Nervous System by Marian Mercado
Major functions of nervous system
sensory function: detects changes [stimuli] within the body & outside the body
integrative function: analyses sensory information; stores aspects and makes decisions on appropriate behaviors
motor function: respond to stimuli by initiating muscular contractions or glandular secretions
major divisions of nervous system
central nervous system
brain
receiving incoming sensory info
integration of info
thoughts & emotions generated
memories formed & stored
spinal cord
issue instructions
most nerve imputes that influence effector organs
peripheral nervous system
Two divisions of PNS
sensory afferent neurons: carry instructions away from CNS to target or effector
motor/ efferent neurons:carry info from body toward CNS
Somatic Nervous System
Controls voluntary movement
Automatic nervous system
controls voluntary movement
Sympathetic Division (fight or flight)
parasympathetic Division (rest or digest )
tissues [structure & functions of neurons & neuroglia
types of neuroglia (CNS)
OLIOGENDROCYTES- insulate nerve fibers by producing the myelin sheath
MICROGLIA- small, have fewer processes & are phagocytes
EPENDYMAL CELLS- from the CSF
ASTROCYTES- star shaped cells with many processes
types of neuroglia (PNS)
SCHWANN CELL- supply myelin sheethes to axons in PNS
SATELLITE CELL- flattened cells found around cell bodies of neurons in ganglia
Neuron:
cell body
axon
neuroglia:
astrocyte
oligodendrocytes
microglia
classifications of neurons and coverings
DENDRITE - portion of neuron that receives impulses & sends to cell body
CELL BODY - contains nucleus & other organells, the metabolic center
AXON- single fiber, give off branches called collateral axon which conducts signals away from cell body
MYELIN- fatty substance that surrounds axon, allows signals to be sent faster
NODE(S) OF RANVEIR- spaces between myelin/ Schwann cells
3 types of neurons
sensory[ afferent] neurons transmit impulses to CNS
motor [ efferent] neurons; transmit impulses away from CNS
internuerons [ central or connecting] transmit impulses from sensory neurons to motor neurons
basic neuron types
bipolar [ interneuron]
unipolar [sensory neuron]
multipolar [motorneuron]
pyrimidal cell
nerve coverings
ENDONEURIUM; surrounds individual fibers within a nerve
FASCICLE; a group of nerve fibers
PERINEURIUM; surrounds a group of nerve fibers
EPINEURIUM; surrounds the entire nerve
action potential
nerve impulse is transmitted during action potential; only axons are capable of action potentials
strong enough stimulation or nerve impulse causes Na+ gates to open
Na+ rush into cell causing depolarization
membrane potential goes towards 0V or unpolarized creating positive charching
cranial and spinal nerves
CRANIAL
pupillary response
signal travels through Brian stem
tested to determine general health of motor portion of nervous system
12 pairs of cranial nerves
I OLFACTORY- sensory nerve for sense of smell
II OPTIC- arises from the retina of the eye & for vision
III OCULOMOTOR- most motor function; muscles of eye, eyelid, & pupillary
IV TROCHLEAR- superior muscle of eye
V TRIGEMINAL- [ 3 branches]
motor
chewing; sensory
facial skin
VI ABDUCENS - lateral rectus eye muscle
VII FACIAL- facial expressions; sensory taste
IX GLOSSOPHARYNGEAL- secretes saliva; taste; blood pressure regulation; swallowing
X VAGUS- muscle contraction; secretes digestive fluids; heart; lungs; parasympathetic innervation
XI ACCESSORY- swallowing; movements of head; proprioception
XII HYPOGLOSSAL- tongue movement during speech; swallowing; proprioception
SPINAL NERVES
cervical spinal nerves
cervical enlargement
thoracic spinal nerves
dura & arachnoid mater
lumbar enlargement
lumbar spinal nerves
conus medullaris
cauda equina
sacral spinal nerves
filum terminate
NEUROTRANSMITTER: biochemicals carrying out signals to synaptic cleft
at least 30 - 50 different neurotransmitters identified
ex: acetycholine
synaptic end bulbs may contain 2 - 3 different neurotransmitters
needs to be removed or will influence nerve idefinitely
some degraded by enzymes
some reuptake into cells
anatomy of spinal cord
WHITE MATTER: made up of bundles of myelinated fibers
posterior funiculus
lateral funiculus
anterior funiculus
central canal
dorsal root ganglion
anterior commissure
anterior median fissure
posterior median sulcus
anterior root
posterior root
surrounds butterfly shaped core of gray matter
GRAY MATTER: [unmyelinated] forms an butterfly shape in center
posterior horn/ dorsal horns
[ sensory] located in the back
lateral horn
located on side
cell bodies of motor neurons to cardiac & smooth muscle glands
also part of ANS
anterior / ventral horn [ motor]
cell bodies of motor neurons to skeletal muscle
gray commissure
where fibers cross from side to side
central canal
center of gray commissure
continuous w/ 4th ventricle
anterior median sulcus
autonomic nervous system
Automatic, unconscious, involuntary control
respond to internal environment
brings info from receptors in internal organs to CNS & motor neurons to smooth muscle , cardiac muscle and glands
Sympathetic Nervous System
"fight or flight"
emergency or non- normal situations
Parasympathetic nervous system
"freed and breed"
normal organs receive input from both divisions
reflex arc
REFELX
preprogrammed rapid predictable Involuntary response to stimili
functions to prevent damage to the body
REFLEX ARC
nerve pathway of a reflex response
5 Parts of reflex arc:
Sensory receptor: afferent nerve ending detects stimuli
sensory afferent neuron: signals to CNS [reflex center]
Synapse- interneuron integration center; connection between sensory neuron & motor [ efferent] neuron
motor/ efferent neuron- driver's response to target organ
effector- target organ responds to signal
MEMBRANE POTENTIAL
cells generate a small voltage across membrane
cell membrane usually polarized
nerve impulse is an electrical message down the axon
RESTING MEMBRANE POTENTIAL
nerve at rest or intact