Ch. 3-6 Flashcards
what is the final step in synaptic transmission
clear the synapse and re-set
Little pores in the axon that vaccum back up the neurotransmitter. Helps get everything ready for the next signal
re-uptake transporter
disassemble neurotransmitter to clear synapse space
enzymes
synapse from axon to soma
axosomatic
synapse from axon to dendrite
axodendritic
synapse from one axon to another axon
axoaxonic
2 kinds of potentials that can happen on the postsynaptic (receiving) membrane
EPSP and IPSP
excitatory postsynaptic potential. Depolarizing. Na+ or Ca++ into cell. “Facilitation” of nerve communication
EPSP
inhibitory postsynaptic potential. Hyperpolarizing. Cl- into cell. “Inhibition” of nerve communication
IPSP
2 types of presynaptic potentials
presynaptic facilitation and presynaptic inhibition
causes an enhancement of Ca++ influx and facilitates neurotransmitter release
presynaptic facillitation
causes a reduction of Ca++ influx and inhibits neurotransmitter
presynaptic inhibition
modality that operates on the presynaptic inhibition principle
TENS unit
what causes an IPSP
hyperpolarization, Cl- coming into cell, a ligand channel that lets Cl- in
Where is a neurotransmitter released
into synaptic cleft
What does a neurotransmitter act upon
synaptic receptors
Types of neurotransmitters
fast acting, slow acting
what type of effect does a fast acting neurotransmitter have on the postsynaptic membrane
direct, quick, short-lived response
what type of effect does a slow acting neurotransmitter have on the postsynaptic membrane
indirect (from inside cell), slow, longer-lived response (tends to stay open longer)
what makes a neurotransmitter fast or slow acting
the type of receptor it binds to
a substance, other than a neurotransmitter, released by a neuron and transmitting information to other neurons, altering their activities. CAN AFFECT MANY NEURONS
neuromodulator
where does a neuromodulator act
at a distance from the synaptic cleft
what type of onset does a neuromodulator have
slow, longer response
BIG 3 IMPORTANT LIGANDS
Acetylcholine, Glutamate, and GABA
Neurotransmitter of the neuromuscular junction. Excitatory ligand that is fast acting at the PNS
Acetylcholine
Most prevalent fast acting excitatory neurotransmitter in the CNS (can also be slow acting)
Glutamate
Most prevalent fast acting inhibitory neurotransmitter in the CNS (can also be slow acting)
GABA
3 kinds of synaptic receptors
directly open ion channels (fast), indirectly open ion channels (slow), and activate intracellular events (slow )
how does a synaptic receptor indirectly open an ion channel
neurotransmitter binds to receptor and energizes G protein, a piece of the G protein breaks off and opens the gate from the inside and holds it open as long as it as energy
how the second messenger system works (synaptic receptor that activates intracellular events)
ligand (first messenger) binds to G-protein receptor, G-protein is activated. G-protein turns on the machine and produces a product (second messenger) that affects the cell function from the inside
receptor protein is pulled down inside the cell and the membrane is closed over it to inactivate it
internalization
receptor protein stays in the membrane but gets denatured so it no longer can do what it used to do
inactivation
receptor protein is brought to the surface of the membrane
externalization
ligands which are not released by the presynaptic terminal but still bind post synaptic receptors and cause action on the postsynaptic membrane
agonist
example of an agonist
nicotine
on or ligand that diminishes the effect of a neurotransmitter at a synapse
antagonist
2 ways an antagonist reduces the effect of a neurotransmitter
- preventing it from getting out 2. blocking it’s receptors
example of an antagonist
Botox
how does Botox work
acts at the presynaptic terminal by inactivating the calcium channels on the presynaptic terminal so calcium can’t get in and neurotransmitter doesn’t get shoved out. Muscle won’t contract
pathology associated with acetylcholine receptors where they have trouble contracting and sustaining a muscle contraction
Myasthenia Gravis
What is 1 tx of MG
prescription drug that contains an anti cholinesterase that “turns off” the esterase (things that eat Ach) in order to prolong the time the Ach is in the synaptic cleft. Increase the chances that Ach will bind to a receptor. Promotes stronger, longer muscle contractions
drug that turns off the re-uptake transporter, keeping serotonin in the synapse and increasing the chances it will bind and cause an effect on the post synaptic membrane
Selective Serotonin Reuptake Inhibitor (SSRI)
a decrease in response to a repeated, benign stimulus
habituation
short term habituation of the nervous system
not releasing as much neurotransmitter so you get less of a response
long term habituation of the nervous system
internalize receptors on the post synaptic membrane
2 ways you can turn down the response of a repeated, benign stimulus
short term and long term habituation
Example of how you can use habituation by creating a systematic program of touch
tactile defensiveness
Example of how you can use habituation by creating a program of head movements
vestibular disorders
Long-term change in the synapse that makes signaling stronger
LTP long-term potentiation
The extension of habituation. Structural change at the synapse that turns down the signaling. It’s an adaptation or conversion of silent synapses.
LTD long-term depression
The foundation of declarative learning and procedural learning
long-term potentiation
turning down the strength of synaptic connections
long term depression
importance of astrocytes
Can store and release both calcium and glutamate, which are essential for remodeling the synapse
how does cellular recovery occur after axonal injury in the periphery (2 ways nervous system tries to repair itself in the peripheral )
collateral sprouting and regenerative sprouting
intact surviving neurons send out a new branch to innervate target tissue that have lost their innervation
collateral sprouting
Where the intact end (proximal end) of a neuron regrows where it used to be
regenerative sprouting
if regenerative sprouting doesn’t work, what happens
collateral sprouting
tissue that is currently just asleep surrounding dead tissue. Can wake up and return function.
penumbra
how does cellular recovery occur after axonal injury in the CNS
return of synaptic effectiveness, denervation hypersensitivity, synaptic hypereffectiveness, and unmasking of silent synapses
process that allows the penumbra to wake back up. Compressed neuron falls asleep, removing the compression causes it to wake back up
return of synaptic effectivenss
when a neuron’s input goes away, it tries to remodel itself with more channels in the membrane to get a signal back.
denervation hypersensitivity
a neuron that loses some of it’s axon branches sends extra neurotransmitter to the branches that survive.
synaptic hypereffectiveness
Neurons that have either died or are under stress tend to leak
glutamate
Excitotoxicity Process
Dead or damaged cell releases a flood of glutamate
Flood of glutamate lets in flood of calcium that can kill a cell by lowering ph, eating up cellular proteins, creating oxygen free radicals, or causing the cell to swell
Why is it important to restore blood flow after CVA
So that cells that are just damaged don’t become excitotoxic
the degeneration of axon and myelin distal to the point of cell death. Typically takes about 2 weeks to complete
Wallerian degeneration
stages of development
pre-embryonic stage, embryonic stage, and fetal stage
when is the pre-embryonic stage
conception to 2nd week
when is the embryonic stage
2nd week to 8th week
what does the ectoderm develop into
sensory organs, epidermis, and nervous system
what does the mesoderm develop into
dermis, muscles, skeleton, and circulatory system
what does the endoderm develop into
gut, liver, pancreas, and respiratory system
when is the fetal stage
8th week to birth
When is neural tube formation
days 18-26
last section of neural tube to close at the rostral end
superior neuropore
last section of neural tube to close up at the caudal end
inferior neuropore
what does the neural tube develop into
spinal cord, brainstem, and brain
what type of cells does the neural crest contain
pseudounipoloar
inner layer of the neural tube that contains ALL cell bodies (gray matter)
mantle layer
outer layer of the neural tube that contains axons (white matter)
marginal layer
bundle of cells that differentiate and grow into skin, muscles, and skeleton
somite
3 pieces of a somite
sclerotome, dermatome, and myotome
dermatome becomes
skin (but not the epidermis)
sclerotome becomes
skeleton
myotome becomes
skeletal muscle
part of neural tube that contains cells that are going to connect to the myotome of the somite
motor plate
how do we end up with 31 pairs of spinal nerves
neural cells cluster next to the 31 pairs of somites
in the developed adult, all muscles innervated by a single spinal nerve
myotome
every muscle in your body is innervated by
at least 2 spinal levels
in the developed adult, dermis innervated by a single spinal nerve
dermatome
where does the spinal cord approximately end
L1
what does the bottom of our spinal column contain
axons
everything rostral to the midbrain. Thalamus, basal ganglia, cerebral cortex
Forebrain
“Gray” matter is in the ____ ring of neural tube, but ____ layer of cerebral and cerebellar cortex
inner, outer
When do neurons differentiate
after reaching final location
what does a growth cone do during cellular remodeling
helps guide the axon to the cell that needs a connection
Motor neuron that is white, glycolytic, high tension.
In development, it’s the neuron that drives what the muscle fiber does
fast motor neuron
motor neuron that is smaller, less heavily myelinated, and aerobic (use oxygen for metabolism)
slow motor neuron
when does myelination begin and end
begins the 4th fetal month. ends at 3 years of age
4 modalities of somatosensation
discriminative touch, coarse touch, proprioception, and pain and temperature
modality of somatosensation where you know where something is touching you and can describe the characteristics of that touch
discriminative touch
modality of somatosensation where you know you’re being touched but can’t locate it well or describe characteristics of it
coarse touch
modality of somatosensation where you know where you’re body is in space and how your body is moving in space
proprioception
the raw modality of touch. Being able to describe or locate touch
sensation
making meaning out of raw sensation
perception
what are the 3 different destination for sensation
cerebral cortex, cerebellum, and limbic and autonomic areas
area where every sensation involving CONSCIOUS awareness goes. Goes to parietal lobe. Ex. joint position testing
cerebral cortex
area of UNCONSCIOUS sensation. Automatic correction of posture and movement (+ other).
cerebellum
destination of sensation that helps modulate emotional and autonomic responses to sensation
limbic and autonomic responses
specialized receptor that let ions in in response to mechanical stimulation like touch, stretch, pressure, vibration, etc. Mechanical touch will open modality-gated channels
mechanoreceptor
specialized receptors that open in response to chemicals
chemoreceptor
specialized receptors that open in response to temperature.
thermoreceptor
2 types of mechanoreceptors
tonic and phasic receptors
type of mechanoreceptor that responds when a touch is initially applied. Continue to respond if touch is maintained
tonic receptors (slow adapting)
type of mechanoreceptor that signals when the touch changes but not when it’s maintained
phasic receptors (fast adapting)
type of mechanoreceptor that signals when the touch changes but not when it’s maintained
phasic receptors (fast adapting)
piece of skin that is innervated by one sensory axon
receptive field
parts of body that explore the environment (hands, face, feet) we have ___ receptive fields
smaller
Smaller receptive fields = ____ degree of discrimination and ___ axons
higher, more
closer to the surface of the skin, receptive fields are ____
smaller
At the surface of the skin, we can transduce what 4 things
touch, vibration, pressure, and hair movement
Deep in the skin, we can transduce what 3 things
touch, vibration, and stretch
group of axons that allow us to feel light touch on the skin
A-beta
Specialized sensory receptors in muscle
Tells you how much muscle is being stretched (length) and how fast the stretch is changing
muscle spindles
muscle spindles are ____ in shape
fusiform
1a tells you ___
length and rate of change of length
II tells you
length only
where do spindles send signals
brain and directly to A-alphas (motor neurons in spinal cord)
Contract intrafusal muscle
Keep spindle sensitive to stretch throughout movement
A-gamma
Contract extrafusal muscle
Shorten overall muscle
A-alpha
Sense “tension” in a tendon whether it’s active contraction or passive stretch. Send signals on 1b sensory neurons
Golgi Tendon Organs
what do specialized capsule receptors sense in joints
position and movement of joint
what do ligament receptors sense
tension on the joint
what do free nerve endings sense
pain/inflammation of joint
pathways that have a great degree of body mapping
high fidelity pathways
pathways that help mobilize the autonomic and emotional responses to pain
divergent
carry proprioception messages to cerebellum
unconscious relay
Dorsal column/medial lemniscus pathway is a pathway that tells us
conscious touch and proprioception
Order the dorsal column/medial lemniscus pathway
1st order: sensory receptors to caudal medulla
2nd order: caudal medulla (crosses) to thalamus
3rd order: thalamus to cerebral cortex
Spinothalamic pathway is a pathway that tells us
conscious discriminative pain and temperature
Order the spinothalamic pathway
1st order: free nerve endings to dorsal horn
2nd order: dorsal horn crosses to thalamus
3rd order: thalamus to cerebral cortex
what does the spinoreticular pathway (divergent) do
adjusts your arousal in response to pain
what does the spinomesencephalic pathway (divergent) do
helps you orient to pain
what does the spinolimbic pathway (divergent) do
adjusts autonomic/emotional responses to pain
