Ch 4 Neural Conduction and Synaptic Transmission

Question 1

resting membrane potention

Answer 1

polarized (not 0)
-70mV

Question 2

at rest, which ions are more prominent inside and outside of cell membrane

Answer 2

Na+ and Cl- outside, K+ inside and negative proteins

Question 3

what causes pressure for Na+ to come into cell

Answer 3

electrostatic pressure

random motion 9wants to move down gradient)

Question 4

at rest, which channels are closed and open

Answer 4

Na+ closed
K+ open (dont move too much due to wanting inside cell to be negative

Question 5

how does resting membrane stayed fixed

Answer 5

sodium potassium pump
3Na out for each 2K in

Question 6

what are postsynaptic potentials

Answer 6

Disturbances of the resting membrane potential from input from other cells across the synapse

Question 7

post synaptic potentials from neurotransmitters are either

Answer 7

excitatory post-synaptic potentials (depolarize)

inhibitory post-synaptic potentials (hyperpolarize)

Question 8

all PSPs are graded potentials which means

Answer 8

Amplitudes are proportional to the intensity of the signals that elicit them
Instantaneous

Question 9

the two important characteristics of PSP transmission

Answer 9

rapid (instant regardless of duration)

decremental (decrease in amplitude as they go through the neuron)

Question 10

describe how PSPs impact if there is an Action Potential

Answer 10

firing depends on the balance of EPSPs and IPSPs

if the sum of potentials that reaches the axon initial segment is enough to depolarize to threshold of excitation (65mV) an AP is generated

Question 11

summation of PSPs can be described over space and time, explain both

Answer 11

Spatial summation
Sum to form greater PSPs when multiple are present, E and I cancel each other out

Temporal summation
Rapid succession of PSPs builds their strength

Question 12

purpose of the refractory period

Answer 12

APs travel in one direction along the axon

Rate of neuronal firing is related to the intensity of the stimulation

Question 13

refractory period (and its types)

Answer 13

Brief period after an AP where it is impossible to send another AP
The absolute refractory period

Followed by the relative refractor period (possible to fire again but only with higher-than-normal stimulation)

End of the period is when stimulation required returns to baseline

Question 14

how does axon conduction and PSPs differ

Answer 14

axon conduction is nondecrememental, intensity of each fire is the same along the axon as the influxes of sodium along the axon recharge it

Question 15

an AP that travels along the axon back to the cell body is called ___ conduction, and an AP that goes down the axon to the terminal buttons is called ___ conduction

Answer 15

antidromic

orthodromic

Question 16

what direction does dendrodentritic synapses go in

Answer 16

either direction!

Question 16

Conduction in Neurons without Axons

Answer 16

Interneurons use graded potentials, and normally do not have APs

Question 16

what is special about axoaxonic synapses

Answer 16

Mediate presynaptic facilitation and inhibition - selectively impact the effects of that button on the postsynaptic neuron

Advantage is that they can selectively influence one particular synapse rather than the entire presynaptic neuron

Question 17

most synapses in the brain form what kind of synapse

Answer 17

tripartite

two neurons and an astroglial cell

Question 18

directed vs non directed synapse

Answer 18

Directed synapse
Site of neurotransmitter release and the site of neurotransmitter reception are in close proximity

Nondirected synapse
Site of release is at some distance from the site of reception
§ Ex. NTs released from varicosities (bulges/swellings) in the axon branches and are thus widely spread to targets
□ String of beads synapses

Question 19

describe how exocytosis releases NT

Answer 19

NT congregate near Ca2+ channels in the presynaptic neuron

Channels are stimulated by AP and open, Ca2+ floods in

this triggers a chain reaction where NT vesicles fuse with presynaptic neuron and empty into the synapse

Question 20

neurotransmitters vs neuropeptides

Answer 20

NTs
released in pulses each time AP triggers influx of calcium

NPs
released gradually in response to general increase of intracellular calcium

Question 21

any molecule that binds to another is called a

Answer 21

ligand

Question 22

what are receptor subtypes and why are they advantageous

Answer 22

The different types of receptors to which a particular NT can bind are called the receptor subtypes for that NT
§ Typically located in different brain areas, and respond in different ways
□ Advantage: one NT can have multiple effects

Question 23

what are ionotropic receptors and metabotropic receptors associated with

Answer 23

Ionotropic receptors are associated with ligan-activated ion channels Metabotropic receptors are associated with signal proteins and G proteins

Question 24

Differentiate between ionotropic and metabotropic receptors:

Answer 24

Ionotropic receptors are faster, as they open/close ion channels directly, leading to immediate postsynaptic potentials (PSPs) like EPSPs and IPSPs. Metabotropic receptors are slower and more complex, often triggering secondary messengers that can cause longer-lasting changes in the neuron.

Question 25

NT binds to metabotropic receptor, what are the two things that can happen

Answer 25

Subunit of G breaks away and either binds to ion channel (PSP) Triggers synthesis of a second messanger (longer)

Question 26

two ways to stop NTs from being in synapse

Answer 26

reuptake degradation

Question 27

gap junctions are important for what kind of synapse

Answer 27

electrical

Question 28

what glial cell is particularily important for synaptic communication in the brain

Answer 28

astrocytes

Question 29

3 types of membrane transporters

Answer 29

pumps co-transporters exchangers

Question 30

neurotoxins from environment

Answer 30

palytoxin: from corals, affects sodium potassium pump and is lethal tetrodotoxin: pufferfish, stops depolarization and muscles stop working

Question 31

basis of electroencephalography

Answer 31

neurons create a field of neurons in which we can record their activity gives high temporal resolution

Question 32

the 3 classes of small-molecule NTs

Answer 32

amino acids monoamines acetylcholine

Question 32

what are some animo acids and what do amino acids do

Answer 32

they are fast acting, working in directed synpases of CNS glutamate: excitatory GABA: inhibitory aspartate glycine

Question 33

monoamines

Answer 33

more diffuse effects and larger than amino acids dopamine, epinephrine, norepiniephrine, serotonin

Question 34

the 2 groups that monoamines are in

Answer 34

Catecholamines: synthesized from the amino acid tyrosine (converted into L-dopa which converts into them) □ Dopamine □ Norepinephrine ® Neurons that release this have an extra enzyme which converts dopamine into them ◊ Neurons are noradrenergic □ Epinephrine ® Neurons that release this are called adrenergic Indolamines □ Serotonin ® Synthesized from the amino acid tryptophan

Question 35

acetylcholine

Answer 35

NT at neuromuscular junctions, at many synapses in the autonomic nervous system and at synapses in several parts of the central nervous system Neurons that release this are cholinergic

Question 36

unconventional NTs

Answer 36

soluble-gas (nitric oxide and carbon monoxide) diffuse through and stimulate a second messenger retrograde transmission (post->presynaptic neuron) endocannabinoids synthesized by fatty compounds released by dendrites affect presynaptic neurons/their transmission

Question 37

Neuropeptides:

Answer 37

Larger molecules that include: Pituitary peptides, hypothalamic peptides, brain-gut peptides, and opioid peptides. Neuropeptides can act on a variety of brain functions and behavioral processes.

Question 38

agonist

Answer 38

facilitate effects

Question 39

steps of NT action

Answer 39

1. synthesize them 2. put them in vesicles 3. those that leak are degraded 4. AP causes vesicles to fuse to presynaptic membrane and release NTs 5. Inhibitory feedback: bind to autoreceptors to prevent more NTs from being releases 6. NTs bind to postsynaptic membrane 7. Nts deactivated or reuptake

Question 40

antagonists

Answer 40

block/reduce/inhibit

Question 40

are endogenous opioids NTs or NPs

Answer 40

NPs, there are metabotropic

Question 41

what makes an NT an NT

Answer 41

presence in presynaptic neuron AP dependent release or Ca2+ dependent release action at postsynaptic neurons

Question 42

diff between NT and neuromodulator

Answer 42

NT released from axon terminal that excites or inhibits postsynaptic neuron neuromodulator released from neuron and affects a population of neurons released into ECF alter strength of neural activity across a population of neurons rather than excite/inhibit one specific neuron

Question 43

if a drug is an allosteric modulator, what does it do

Answer 43

Can bind to specialized sites on the receptor to affect its ability to attract agonists/NTs

Question 44

acetylcholine and cholinesterase have shown what benefit to memory

Answer 44

spatial learning