Synapse Flashcards
What are the benefits for electrical signaling?
Covers long distance with minimal loss of signal
Rapid
Quickly Repeated
Information can be conveyed in patterns
What are the limitations for electrical signaling?
Binary
Difficult to modify
Energy Intensive
Microenvironment dependent
What is resting membrane potential?
The potential energy in the electrical gradient formed across the plasma membrane.
What causes the Resting Membrane Potential?
The K+ (Potassium) Leak Channels
Is the inside of the membrane positive or negative?
Negative
Is the outside of the membrane positive or negative?
Positive
Is the concentration of K+ high or low inside the cell?
High
Is the concentration of K+ high or low outside the cell?
Low
At resting membrane potential, the membrane is permeable to what Ion?
Potassium (K+)
What is Ohm’s Law
V=IR
What is Electrochemical Equilibrium?
When the concentration and electrical gradients for an ion are in balance
What is an active transporter?
Actively moves selected ions against concentration gradient.
What is an ion channel?
Allows ions to diffuse down concentration gradient. (Passive)
What are some examples of Ion channels?
K+,
Na+,
Ca2+,
Cl-
What is an example of an active transporter?
Na+/K+ ATPase
What allows the neuron electrical activity?
Membrane Potential
Are the Potassium (K+) leak channels fast or slow flowing?
Slow
What helps maintain the electrochemical gradient at the Resting Membrane Potential?
Na+/K+ ATPase pump
What is the Nernst Equation used for?
To find the Equilibrium potential of an individual ion.
What is Goldmans Equation?
To find the Equilibrium potential of the entire plasma membrane.
What creates the Neuron Passive Electrical state?
Cytoplasm is electrically resistant
Passive current decays rapidly over space and time
What causes the Action Potential?
The sequential opening of Na+ and K+ channels in a voltage and time dependent manner.
What is an Action Potential?
A rapid change in membrane potential.
How does the Action Potential move?
It is propagated down axons.
Is a Voltage Gated Ion channel Passive or Active?
Passive
Is a Ligand Gated Ion channel Passive or Active?
Passive
When a Voltage Gated ion channel is open which direction do the ions flow?
Down their concentration gradient
Do Voltage-Gated Ion channels have a refractory period?
Yes
What makes a Ligand-Gated ion channel work?
The ligand binds to ion channel
What are some examples of ligands?
Neurotransmitters
Ions
Proteins
Lipids
How much Na+ is moved from the Na+/K+ ATPase working?
3 Na+ out
What channels are open during the resting phase?
The K+ leakage channel
What causes the Activation Phase?
A stimulus that opens stimulus induced Na+ Channels.
Which direction does Na+ flow during the activation phase?
Inside the cell
What does the influx of Na+ do to the membrane potential.
Raises it in the Positive direction.
What channels are open during the Activation Phase?
K+ leakage channels
Stimulus induced Na+ Channels
After you hit threshold which phase happens?
Rising Phase
What channels are open during the Rising Phase?
K+ Leakage channel
Stimulus induced Na+ Channel
Voltage Gated Na+ channels
What happens when the Voltage Gated Na+ channels are opened?
Rapid cell Depolarization
What happens in the Falling Phase?
Voltage Gated Na+ Channels are closed
Voltage gated K+ Channels are opened
Can the Voltage Gated Na+ Channels open during the falling phase?
No they are in a refractory period.
What is a refractory period?
When the Voltage Gated Na+ Channels can NOT open
What helps reestablish the Resting Potential after Hyper-polarization?
The K+ Leak channels
Where are axons potentials initiated?
Axon Hillock
Where is the Axon Hillock?
Where the axon meets the cell body
What direction does the Action Potential travel?
Anterograde (Unidirectional)
What are two ways to increase action potential conductance?
Increase Axon Caliber
Insulate Axons
The CNS insulated axons are called?
Oligodendrocytes
The PNS insulated axons are called?
Schwann Cells
What are neurotransmitters?
Small molecules
Neuropeptides
What is an example of a Neuropeptide?
Opioid
What are some examples of small molecule neurotransmitters?
GABA
Glutamate
Acetylcholine
What causes the depolarization of the Presynaptic membrane?
The Action potential
What does the depolarization of the presynaptic membrane do?
Opens Voltage Gated Ca2+ channels
What causes the release of the neurotransmitter?
The increased intracellular Ca2+
What are the three distinct pools that Synaptic Vesicles reside in?
Readily Releasable Pool
Recycling pool
Reserve pool
What complex allows vesicle release?
SNARE complex
What is the first step of Neurotransmitter release?
Vesicle Docks
What is the second step of Neurotransmitter release?
SNARE complex form to pull membranes together
What is the third step of neurotransmitter release?
The entering Ca2+ binds to synaptotagmin
What is the fourth step of the neurotransmitter release?
The Ca2+ bound synaptotagmin catalyzes membrane fusion by binding to SNARE and the plasma membrane
How is the terminal bouton membrane kept in balance from becoming to large?
The ultrafast synaptic vesicle cycle
What is the Metabotropic Neurotransmitter ?
G-Protein coupled
Slower activation time
Prolonged signal duration
What does EPSP do?
Depolarization of the Post synaptic membrane
What does IPSP do?
Hyperpolarization of the postsynaptic membrane
What does Postsynaptic potential do?
It has a summation of the total charge in the membrane from EPSP and IPSP
When are neuronal networks established?
Early in life
What is information processing dictated by?
Network connectivity
What is included in the CNS?
Brain
Spinal Cord
What is included in the PNS?
Cranial nerves
Spinal nerves
What pathway does sensory use?
Afferent
What pathway does motor use?
Efferent
What does the brain do to the neuronal networks?
Maps them to discrete regions of the cortex
Where do you find the emotional and abstract states?
Deep Brain areas
What is a spinal reflex?
Sensory and motor loops that function independent of descending brain control
Is the Nervous system a summation of reflexes?
NO
What is the Hebbian Theory?
Neuronal networks undergo activity dependent plasticity throughout life
What does neuronal inactivity lead to?
Decay
What does neuronal activity lead to?
Network consolidation
When does synapse pruning occur?
During Development
What is Long-term potentiation?
An increase in the strength of neuronal connections
What is Long-term depression?
A Decrease in the number of neuronal connections
What constantly changes the nervous system?
Activity or Inactivity
How many neurons are used in the somatosensory circuit?
Three
What is a 1st order somatosensory neuron?
Goes from the Mechanosensory neuron to the Brainstem (Medulla)
What is a 2nd order somatosensory neuron?
Goes from the Brainstem (Medulla) to the Thalamus
What is a 3rd order somatosensory neuron?
Goes from the Thalamus to the Somatosensory Cortex
When do neuron decussate in the somatosensory circuit?
During 2nd order neurons at the Medulla
On what side of the brain do you perceive something that happened on the left side of your body?
Right
What is a Dermatome?
A cutaneous division of spinal nerve innervation
What fills Dermatomes?
Sensory Fields
What determines the size of a sensory field?
The number of neurons innervating a dermatome.
Mechanosensory neurons are ____?
Psudeounipolar
Nociceptors and thermoreceptors have ____?
Free nerve endings
What are the four types of mechanosensory nerve endings?
Merkel’s cells disks
Meissner Corpuscle
Ruffini Endings
Pacinian Corpuscle
How many neurons innervate a single mechanoreceptor cell type?
A single type
How can you increase the somatosensory cortex?
Using it
What are three types of Pain?
Somatic
Visceral
Neuropathic
What is Somatic pain?
Pain perceived from peripheral cutaneous perception
What is Visceral Pain?
Pain perceived from internal organ systems
What is Neuropathic pain?
Pain caused by damage to the PNS and CNS neurons experienced as burning or shocking pain
What are the different types of nociceptors?
Thermal
Mechanical
Polymodal
Silent
What is the first step in pain signaling?
Cutaneous nociceptors are activated
How many neurons are used in pain signaling?
Three
Where can pain be gated?
Spinal Cord
Where do pain neurons decussate?
Spinal Cord
What drug interacts with central pain receptors to block the transmission of pain stimulus?
Opiates
How do NSAIDS block pain?
Inhibit Cox 1/2 function
Prevent pain peripherally
How do Opiates block pain?
Inhibit nociceptor to second order neuron transmission
Prevent pain centrally
How does the nervous system asses the environment?
By networks and maps
What are the 4 types of CNS glial cells?
Astrocyte
Ependymal cells
Microglial cells
Oligodendrocytes
What are the functions of Astrocytes?
Help form Blood Brain Barrier
Regulates Interstitial fluid
Most abundant glial cell
What is the function of Ependymal cells?
Line ventricles of the brain
Assist in circulation of CSF
What is the function of Microglial cells?
Phagocytosis through the CNS
What is the function of Oligodendrocytes?
Myelinates and insulates CNS axons
What are the PNS glial cells?
Schwann Cells