Neurophysiology - Hu

Question 0

Electric Synapse

Answer 0

Uses ionic currents as the main method of communication with other cells. Here the synapses are mechanically connected via a gap junction, so current can be exchanged.

Question 1

Chemical Synapse

Answer 1

Synapse that uses neurotransmitters as a messenger to talk to each other and pass a signal

Question 2

Metabotropic Receptor

Answer 2

Couples with G-proteins

Question 3

Ionotropic receptor

Answer 3

functions as a ligand-gated (activated) ion channel

Question 4

Presynaptic heteroreceptor

Answer 4

located on presynaptic terminals

Question 5

Presynaptic autoreceptor

Answer 5

located on presynaptic terminals, serves as a negative feedback mechanism to regulate firing and neurotransmitter release

Question 6

Postsynaptic receptors

Answer 6

Located on postsynaptic target cells

Question 7

Excitatory postsynaptic current (EPSC)

Answer 7

positively charged ions flow into a postsynaptic cell during membrane depolarization

Question 8

Excitatory postsynaptic potential (EPSP)

Answer 8

membrane potential (Vm) depolarization in postsynaptic cell (in response to excitatory impulses)

Question 9

Inhibitory postsynaptic current (IPSC)

Answer 9

Negatively charged ions flow into a postsynaptic cell during membrane hyperpolarization

Question 10

Inhibitory postsynaptic potential (IPSP)

Answer 10

Vm hyperpolarization in postsynaptic cell (in response to excitatory impulses)

Question 11

Acetylcholine (ACh)

Answer 11

Memory, sensory processing, motor coordination, neuromuscular junction, ANS and PANS function

Question 12

Norepinephrine (NE)

Answer 12

CNS sensory processing, cerebellar function, sleep, mood, learning, memory, anxiety, and SANS

Question 13

Dopamine (DA)

Answer 13

Motor regulation, mood, addiction, reinforcement, olfaction, hormone control concentration, and hypoxic drive

Question 14

Serotonin (5-HT)

Answer 14

Emotional processing, mood, appetite, sleep, pain processing, hallucinations, and reflex regulations

Question 15

Histamine (H)

Answer 15

Sleep, sedation, and temp regulation

Question 16

Gamma amino butyric acid (GABA)

Answer 16

Major inhibitory neurotransmitter in the CNS

Question 17

Glutamate (Glu)

Answer 17

Long-term potentiation, memory, major excitatory fxn in the CNS and PNS

Question 18

Glycine (Gly)

Answer 18

Major inhibitory fxn in the CNS

Question 19

Monamine Pathways in CNS

Answer 19

Norepinephrine (NE) - Locus Coeruleus–> cerebral cortex, limbic sys, cerebellum, and spinal cord
Serotonin (5-HT) - Raphe nuclei (RN)–> whole brain and spinal cord
Dopamine (DA) - Ventral tegmental area and Substantia nigra pars compacta (SNPC)–> basal ganglia, limbic system, and prefrontal cortex
Acetylcholine (ACh)–> Septal nuclei, nucleus basalis—>brain regions

Question 20

G-Proteins/Second messengers

Answer 20

Bind GDP and GTP, coupled with metabotropic receptors (GPCRs), activate or inhibit activity of effectors,

Question 21

Gs

Answer 21

Stimulatory, Active during high levels of cAMP

Question 22

Gi

Answer 22

Inhibitory, Active during low levels of cAMP

Question 23

Gq

Answer 23

Hydrolyzes, Second messenger is IP3 and DAG

Question 24

Go

Answer 24

Second Messenger is Arachidonic Acid

Question 25

Gap junction

Answer 25

A type of synapse that mechanically connects the cytoplasm of two cells allowing for the conductance of electrical signal as the messenger. Can be conducted bi-directionally and are smaller in the postsynaptic cell than in the presynaptic originating cell
Formed by connexon, made up of 6 connexin units - 4 membrane spanning regions, and the opening is smaller than a chemical synapse 3.5 nm v.s 20-40 nm

Question 26

Resting Membrane Potential (RMP)

Answer 26

cell is at equilibrium and the net current (I) = 0

RMP depends on equilibrium potential (Ek) of K+, membrane at rest is primarily permiable to potassium

Question 27

Ohm’s Law

Answer 27

The strength of a direct current (I) is directly proportional to the potential (voltage) different (^E, ^V and inversely proportional to the resistance (R) or reciprocal of the conductance R= 1/C) of the circuit.
V = IR
or
I = V/R

Question 28

Nernst Equation

Answer 28

Relates the concentration gradient to the electric (potential) gradient that balances it. Determine equilibrium potential of a cell.
Es = E1 - E2 = RT/zsF(ln)[S]2/[S]1
S: arbitrary ion
S2 and S1: external and internal concentration of ion
E1-E2: membrane potential difference
R: universal gas constant
T: absolute temperature (kelvin) 273.15 + degrees in C
z: valence of the arbitrary ion (elementary change Na+=1 Ca2+=2 etc)
F: the Faraday constant
ln: natural log

Question 29

Voltage Gated Ion Channels

Answer 29

Na, K, Ca
alpha1 subunit: “pore-forming” protein that has 4 homologous transmembrane domains (TM), each TM is a helix with 6 transmembrane spannings
Selective filter SS1-SS2 connects S5 and S6 to form pore
S4 segment fxns as a voltage gated sensor

Question 30

Ligand gated Ion channels (Ionotropic receptors)

Answer 30

clustered in the postsynaptic membrane and open rapidly after binding with selective agonists.
Activation of ligand-gated ion channels induced Vm change
Ex: Nicotinic ACh receptor, Glutamatergic N-methyl-D-aspartate receptor (NMDAR), y-aminobutyric acid A-receptor (GABAaR)

Question 31

Nicotinic Acetylcholine (ACh) Receptor (nAChR)

Answer 31

17 subunits, belongs to the superfamily pentametric ligand gated receptors (GABAaR, GlyR, 5-HT3R)
Positive ion channel, Na and others, but does not allow passage of anions. Depolarizes Vm and causes muscle contraction or neuron firing.
Agonists: ACh, nicotine, choline, cabachol, etc
Antagonists: alpha-bungarotoxin (venom) and tubocuraine (arrow poison) = irreversible binding of ACh receptors causing paralysis, respiratory failure, and death.
Prolonged or repeated exposure to ACh reduces nAChR conductance, sensitivity recovers only when ACh is removed.
Used in motor neurons for transmission of AP signal to muscles at the neuromuscular junction, also in the release of dopamine in the brain from nicotine stimulus.

Question 32

Glutamatergic NMDA Receptor (NMDAR)

Answer 32

ligand gated, ionotropic receptor; belongs to the glutamate receptor family.
Non-specific cation channel (highly conductive for Ca2+) found only in CNS of vertebrates.
Tetramer of homologous subunits, at least 7 genes
Agonist and co-agonist: Requires simultaneous binding of glutamate (agonist) and glycine (co-agonist). Interacting with AMPA receptor
Antagonist: selectively blocked by AP5 and memantine
Mediates excitatory synaptic activity, acts as a coincidence detector for presynaptic glutamate release and postsynaptic Vm depolarization
Critical in synaptic plasticity; can induce excitotoxicity.
Phosphorylation increases its activity and Ca influx

Question 33

GABAa Receptor

Answer 33

Are ion channels
Belong to the superfamily of pentameric ligand-gated ionotropic receptors. Has 5 subunits, each with 4 helical membrane spannings
15 different subunits in 7 families, combinations may alter function in regulating Cl opening (hyperpolarization of Vm)
Agonist: GABA
Function: a binding substrate for the major inhibitory neurotransmitter GABA in the CNS. Regulates inhibitory neuronal responses by conducting Cl influx via activating GABAaR/Cl channels = Vm hyperpolarization.
Mutation of GABAaR is related to Huntington’s disease, Epilepsy, and alcoholism