Test 2 Flashcards
Ch. 6 slide 12 - Ch. 11 Slide 11
What are the events @ the synapse?
AP reaches end of presynaptic terminal
Calcium is released into presynaptic terminal
vesicles move towards release site
terminal releases neurotransmitter
neurotransmitters bind to post-syn membrane receptor
membrane channel changes shape, and ions enter
transporters and enzymes enter synapse to clear and re-set for next AP
What are the three types of synapses?
axoaxonic - axon - axon
axodendritic - axon-dendrite
axosomatic - axon-somite
Which type of synapse(s) can increase/decrease chances of AP? Change number of neurotransmitters sent?
Chances of AP - axodendritic, axosomatic # sent -axoaxonic
Describe an EPSP’s.
Excitatory post-synaptic potential
local
depolarize
Na+/Ca++ into cell
Describe IPSP’s.
Inhibitory post-synaptic potential
local
hyper polarize
Cl- in/ K+ out
Describe the two Presynaptic potentials
pre-syn facilitation
Increases influx of Ca++
pre-syn Inhibition
decreases influx of Ca++
Differences between Neurotransmitters and Neuromodulators.
Neurotransmitter - released into synaptic cleft, acts on receptors, excites or inhibits, quickness’s and short
Neuromodulator - act at distance, can affect many neurons, slow and long
What are the 3 kinds of synaptic receptors?
- ligand-gated
- G-Protein
- G- Protein 2nd messenger
What does an agonist do?
bind and mimic
enhance release
What does an antagonist do?
bind and block
diminishes releasing
ACl
facilitatory/excitatory, depolarize
fast: pns-neuromuscular jx -nicotinic
slow: ans and cns - muscarinic
Glutamate
Facilitatory/Excitatory/depolarize
brain works - too much =toxic
Fast: CNS (AMPA most prevalent excitatory in CNS)
slow: NMDA CNS
GABA
inhibitory - most prevalent in CNS
hyper polarize
fast: GABAa
slow: GABAb
Dopamine
slow acting nt
motor act, cognition, behavior
pleasure - associated with addiction
Norepinephrine
slow acting nt
increases attn. to sensory info in and
sympathetic fight/flight
serotonin
slow acting nt
blood and perception of P
adjusts arousal
Histamine
slow acting nt
inflammation of nt
endogenous opioids
peptide
inhibit perception of P
substance P
peptide
transmitter/modulator
send signal or enhances route
chronic pain - substance p is overactive
What kind of neurotransmitters are in the PNS?
only excitatory
In terms of receptor regulation, what does it mean to “down-regulate?” - re-map
decrease chance of AP
inactivate - protein in synapse but not used
internalize
In terms of receptor regulation, what does it mean to “up-regulate?”
increase chance of AP
activate - unlock gate and allow ions to flow in
externalize - bring receptor from outside cell into membrane
What does LTP do?
Turns up cell signaling passive --> active Ca released by NMDA AMPA active into post-sun membrane split into two dendritic spines less effort required
What does LTD do?
Turns down cell signaling
active to passive
remove ampa
less likely to depolarize when glutamate is released
penumbra
cells that fall asleep because of reduced O2
excitotoxicity glycolysis protease protein enzymes solute
too much glutamate - too much Ca++ lactic acid> decrease in pH degrade cell protein O2 free radicals cell swelling > pop
What happens to connection in an axonal injury?
distal axon and myelin degenerates, Mm atrophy
collateral axonal injury
the denervated is innervated by intact neighbors * ----- * ----- * \--- *----- regenerative sprouting * ----- * ----- * -----/
regenerative sprouting
axon and target cell damage, injured axon sprouts
- —– * —–
- —–/
Is there final regeneration in the CNS
no
recovery of synaptic effectiveness
decrease swelling and wake up sleeping cells
denervation hypersensitivity
new receptors at remaining terminals
synaptic hypereffectiveness
excessive nt released
unmasking of silent synapses
repeated NMDA receptor stimulation
AMPA moved into post-synaptic membrane
synapse activates
What are to times and duration of the stages of development?
Pre-embryonic - conception to the 2nd week
embryonic - 2nd week to 8th week
fetal- 8th week to birth
In which stage does a cluster of cells become suspended from the placenta?
pre-embryonic
In which stage does the ectoderm, mesoderm and endoderm out of the embryonic disc?
embryonic
In which stage does the nervous system develop more fully and myelination begins?
Fetal
Describe the 3 layers of the embryonic disc.
ectoderm - epidermin, sensory organs and NS
mesoderm - dermis, skeleton, Mm, circulation;atory system
endoderm - gut, liver, pancreas, respiratory system
When does the neural tube form and describe the process.
Days 18-26
- longitudinal thickening of ectoderm
- edges of plate fold to become neural groove and folds grow towards each other
- closes first in cervical region, zips close rostrally to caudally - leaving ends called neuropores open.
- adjacent cells to neural tube and remaining ectoderm form the neural crest.
- two rings form inside - concentric
Describe the two concentric circles that form inside the mesoderm.
Inner-mantle-gray matter-motor-cell bodies
outer - marginal - white- axons and glial cells
What does the mesoderm develop into as the neural tube forms?
somites
appear on surface of embryo (occipital to caudal)
become the sclerotome (skull and skeleton){, myotome (dermis), dermatome (lateral)
What will develop and become peripheral sensory neurons, myelin cells, autonomic neurons, and endocrine organs?
Neural crest
hindbrain
pons, medulla, cerebellum, 4th ventricle
midbrain
midbrain, cerebral aqueduct
forebrain
dicephalon, 3rd ventricle, telencephalon:hemispheres, BG, cerebral cortex, lateral ventricles
When does myelination begin and end?
4th fetal month - 3 years
peripheral motor neurons -1 month
central motor neurons - 2 months
mechanoreceptors
detect pressure and stretch
chemoreceptors
detect chemical changes
in blood
nociceptors
detect pain stretch ischemia viscera walls, arterial walls A-delta, C
thermoreceptor
temp change
hypothalamus
What are the two ways that information enters the CNS from the autonomic system?
sc - via dorsal root ganglion
into brainstem - via cranial Nn 7,9 and 10
Where does visceral info converge?
solitary nucleus
differences in somatic and autonomis
somatic is voluntary, autonomic is not
somatic is 1 neuron/auto is 2
somatic is skeletal M/auto is everything else
auto visceral organs can fx independently
where are cell bodies of sympathetic pre gang efferent located?
T1-L2
Where are axons of control located?
Only down to L2
Which systems are both s&p, and what others are not regulated?
heart-both bowel -both vessels - s sweat - s curvature of lens - P
How do tonic receptors work?
slow
always receipting as long as stimulus present
How do phasic receptors work?
responds to change - fast
Name the sensory axons from largest to smallest.
1a>1b>II/Abeta>Adelta>c>III>IV
Discriminative touch
A-beta, peripheral to CNS
Course touch
A-delta, C
free N ending
no specialized receptor
Temperature
A-delta, C
Dermatonal v periphery
spinal n and peripheral N
dermatomal - spinal
periphery-peripheral
If the SC is damaged, does a whole are or just a portion lose sensation?
whole area
In M spindles, what does the nuclear bag detect?
change in length
In M spindles, what does the nuclear chain detect?
length
Where are the primary endings found?
1a
change of length
nuclear bag and chain
Where are the secondary endings found?
II
length
chain
What neuron stretches intrafusal fibers?
gamma motor
what neuron stretches extrafusal fibers?
a-alpha
What axons are the GTO found on?
1b
specialized jt receptor
movement and position
II
Ligament receptor
tension on ligament
1b
Freen N endings
damage
A-delta, C
What uses Large 1a and 1 b sensory axons?
mm, its, tendons
What uses medium sensory axons?
muscle spindles II, specialized cutaneous A beta
What uses small A-delta?
Free N A-delta
What uses unmyelinated small C
Free n endings
What is the order of loss with compression of sensory axons?
con cold fast pain heat slow pain
