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Celine Cercado p.2 Nervous system - Coggle Diagram
Celine Cercado p.2 Nervous system
Major functions of the NS
Thinking, movement, internal process of physiology
Sensory Functions: provide sensory receptors
detect internal / external changes
Info travels from receptors to sensory neurons
transport info to CNS
Integrative functions:
coordination of sensory info in CNS
processing info is basis for decision making
Motor functions:
nerve impulses conducted along motor neurons to effectors
Effectors: muscle/ glands respond to decision made in CNS
Divisions & subdivisions of NS
Subdivisions
Central Nervous System
Brain
Spinal cord
Peripheral Nervous System
Sensory fibers connect for PNS to sensory receptors to CNS
Somatic fibers connect to skin & skeletal muscles
Autonomic fiber connects to viscera
Tissues
Neuroglia
cells that support neurons
fills space, structurally support, protect and insulate neurons
Doesn't not generate or conduct nerve impulses
CNS
Microglia
small cells
function as phagocytes for bacterial cells , cellular debris, and produce scar tissue for injury
Oligodendrocytes
forms myelin sheath around axon in brain and spinal cord
Classification of neurons
Interneurons neurons
multipolar neurons laying with CNS
forms links between other neurons
cell bodies of some interneurons aggregate in nuclei
Bipolar neurons
2 processes extending from the cell body
dendrite and 1 axon
found in special senses (eyes, nose, & ears)
unipolar neurons
1 process extending from cell body ; outside cell body
splits into 2 parts function
1 axon
Sensory neurons
impulses from peripheral receptors to CNS
usually unipolar
some are bipolar
afferent
Multipolar neurons
Many dendrites & 1 axon arising from body
Most neurons in cell bodies are multipolar
Motor neuron
multipolar neurons
conduct impulses from CNS to peripheral neurons
Connective tissue coverings
Epineurium
outer covering of nerves
Perineurium
covering around fascicles of nerve fibers
bundles
Endoneurium
covering around individual nerve fibers
axons
Parts & function of brain
largest and most complex portion of the NS
4 main parts
cerebrum
largest portion
higher mental function and sensory & motor functions
diencephalon
process sensory input
controls homeostatic process
cerebellum
coordinates muscles activity
brainstem
coordinates & regulates visceral activities
connects different parts of NS
4 Lobes
Frontal
higher intellectual
parietal
understanding speech
Occipital
visual patterns & combine visual images with other sensory information
Tempral
hearing
Parts & functions of spinal cord
At the base of the brain
31 segments each connected to the spinal nerve
Cervical enlargement
thickened area at the top of spinal cord
provides nerves to upper limbs
lumbar enlargement
thickened region near the bottom
rise to nerves for the lower limbs.
Cauda equina (horse's tail)
where spinal cord tapers to a point inferiorly
spinal nerves in lumbar and sacral areas
white matter
bundles of myelinated nerve fibers
Gray matter
butterfly shaped core
houses interneurons and neuron cell bodies
Posterior and anterior horns
upper and lower wings of gray matter
lateral horn between
dorsal root ganglia
cell bodies of sensory neurons that enter spinal cord
outside the spinal cord
central canal
middle of gray matter contains cerebrospinal fluid
Functions
tranmits impulses to & from brain
house spinal reflexes
Ascending tracks
carry sensory information to the brain
descending tracts
carry motor information from brain to muscles/ glands
spinal reflexes
controlled by reflex arc
passes through the spinal cord
Action Potential & Nerve impulses
Action Potential either happens or doesn't
occurs when charge reaches -55mv
neurons are the all the same strength
when reached cells respond by going back to their rest place(repolarization)
Impulse conduction
Continuous conduction
occurs in unmyelinated axon
conduct impulses over the entire length of their membrane
Saltatory conduction
occurs in myelinated axons
myelin sheath insulates axons from ion movement across the cell membrane
Impulses “jump” from one Node of Ranvier to the next, since sodium and potassium channels occur only at the nodes
Cranial Nervous
12 pairs of underside of brain
most are mixed ( sensory, & motor nerve fibers)
some are only sensory
others are primarily motor
1st pair arises from cerebrum, & 2nd pair from thalamus
most arise from brainstem
designated by number and name; numbers in order from superior to inferior
Spinal Nerves
31 pairs
1st pair are mixed nerves
Numbered in sequence
Cervical nerves
8 pairs
thoracic nerves
12 pairs
Lumbar Nerves
5 pairs
sacral nerves
5 pairs
coccygeal nerves
Two roots
Dorsal root
a sensory
contains dorsal root ganglion
houses the cell bodies sensory neurons entering spinal cord
ventral root
motor
Neurotransmitter
communication accomplished by a chemical
stores and released from synaptic cleft
released in response to a nerve impulses.
diffuse across the cleft & bind to receptors on the membrane of the postsynaptic neuron
more than 100 neurotransmitter
include acetylcholine, amino acids, neuropeptides
actions depend on type of receptors in specific synapse
some neurons produce one type of transmitter... others produce 2 or more
Compare & contrast autonomic NS
Sympathetic division
fight or flight senses
short preganglionic fibers arise from neurons in gray matter, in thoracic and lumbar regions
Axons exit spinal cord from the ventral roots
axons leave spinal nerves, proceeds into sympathetic ganglia
synapse with postganglionic neurons, long axons return to spinal nerves & proceed to visceral effector
Parasympathetic division
rest and digest
Long preganglionic fibers arise from brainstem and sacral region
Pf extends outward in cranial or sacral nerves
synapse in terminal ganglia in or close to visceral effectors organs
reflex arc
Receptors
Central nervous system
Effectors- muscle/ glands
sensory or afferent neuron
motor / efferent neuron