Lecture Outline #13: CNS Flashcards
functions of ns
awareness
coordination & control
memory & learning
establishing patterns of response
CNS
brain & spinal cord
PNS nerves
cranial (motor & sensory) & spinal (motor & sensory) (controls skeletal muscle contractions and voluntary/involuntary reflexes) nerves.
PNS subsections
sensory - visceral (organ information) and somatic (info from body)
motor - ANS and somatic (skeletal muscle (voluntary))
ANS componants
involuntary visceral - smooth & cardiac muscle
ANS subsections
sympathetic (thoracolumbar) & parasympathetic (craniosacral)
ANS sympathetic function
speeds heart & slows GI tract
“fight or flight” response, adrenaline
ANS parasympathetic function
slows heart & speeds GI tract
“rest & digest” involuntary control
controls smooth muscle contractions (gut & vasculature)
soma
cell body
contains nucleus & mitochondria
most lack centrioles (can’t divide)
soma - hilum
proximal stump where nerves regenerate
dendrites
receive input from environment or other cells
axon
conducts nerve impulse
hollow extension of soma - cytoplasm
insulated by myelin sheath
synaptic terminals
output to muscle/gland/nerve
3 targets for synaptic terminals
- synapses with other neurons
- neuro-muscular synapses (control)
- neuro-glandular synapses (no control)
structural type of neuron - anaxonic (CNS)
dendrites/axons look alike, no axons
brain & ganglia (processing centers)
structural type of neuron - bipolar
soma is situated btw dendrite & axon
special sensory cells - sight, smell, hearing
structural type of neuron - unipolar
soma is situated on one side of dendrite & axon
sensory nerve endings of the PNS
structural type of neuron - multipolar
several dendrites & single axon
common in CNS, motor nerves, skeletal muscle
afferent axons
sensory nerves
brings sensory information to CNS from tissues/organs
afferent axons - exteroreceptors
somatic (body) - environment info (touch, temp, pain - general sensations)
afferent axons - proprioceptors
somatic (body) - position of muscles & joints (stretching)
afferent axons - interoceptors
visceral - internal environment
efferent axons
motor nerves
carry motor commands from CNS to muscles/glands
efferent axons - somatic motor
PNS - skeletal muscle
efferent axons - visceral motor
ANS - gut
interneurons - CNS
connect between sensory & motor neurons
coordinate sensory input & motor output
difference btw white & grey matter
differ in myeline/insulation amount. white matter - myelination axons, grey matter - unmyelinated axons/cell bodies
white matter locations
CNS - tracts, columns, commissures
PNS - nerves
grey matter locations
CNS - nuclei (single function)
PNS - ganglia (positional renaming - little brain/processing centers outside CNS)
synapses (chemo-electric signal)
not an electrical charge but ion differential (electrolytes within H2O are ions for electrical potential)
1. chemical gradient passes down along axon
2. neurotransmitter released into synaptic gap
3. Gets cleaned immediately or muscle keeps firing.
nueroglia
structures that support neurons
PNS neuroglia - satellite cells
found in large numbers in ganglia
surround neuron cell bodies
exchange in nutrients/wastes
support & fluid balance
PNS neuroglia - Schwann cells (neurolemmocytes)
neurilemma - sheath of myeline that surrounds an axon
aid in repair/regeneration of damaged nerves
similar to oligodendrocytes BUT
1. only associated with a single axon
2. run for a short distance along each axon
CNS neuroglia - astrocytes
wrap around capillaries (blood - brain barrier)
involved in growth & repair of neural tissue
3-D structural framework for neurons
maintain interstitial fluid balance in neural tissue - support & fluid balance
CNS neuroglia - oligodendrocytes
sheath of myelin wraps axons of several cells
insulate each axon from other axons
binds multiple neurons together for support
have cyto-extensions
CNS neuroglia - microglia
small cells w/ small branches
removal (phagocytosis) of debris & pathogens
CNS neuroglia - epindemal
assoc. with CSF
lining of neural tubes
filtering
PNS CT - endoneurium
Schwann cells around axon
PNS CT - perineurium
bundles several axons into a fascicle
PNS CT - epineurium
bundles several fascicles into a nerve
neuron damage
reattach a nerve - NO
potential regrowth of axon within neuroglia & CT
axon distal to neuron dies
severed nerve can grow back together but could misalign
Demyelination pathologies characteristics
occur in CNS & PNS, varying degree of numbness/paralysis, caused by poisoning, disease, and genetics
demyelination pathology - posions
Heavy metal - mercury and lead
Pesticides - roundup
demyelination pathology - disease
diphtheria
demyelination pathology - immune system dysfunction
Guillain - Barre Syndrome - autoimmune disease, attacks myeline (PNS), weakness, tingling, paralysis
Multiple sclerosis - attacks myelin (CNS), find in the mind
Alzheimer’s - environmental aspects, demyelinate axons
rabies virus
body-fluid transfer, travels from bite along PNS to CNS
Lyssavirus symptoms - travels retrograde from PNS to CNS, showing symptoms - 100% mortality
