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Neurology > Neurotransmitters I Lecture Powerpoint > Flashcards

Neurotransmitters I Lecture Powerpoint Flashcards

1
Q

90% of neurons in the body are what type? Where do they reside?

A

Interneurons/association neurons, between sensory and motor pathways in the CNS

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2
Q

Cerebellum acts as a ____ between movement ____ vs movement ____ to modify actions

A

Comparer, intended, actualized

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3
Q

Majority of all sensory information is….

A

….ignored (for example the constant noise in surroundings)

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4
Q

Spinal cord level circuits that do not require simple conduit of signals from periphery of body to brain and vise versa (4)

A
  • Walking circuits
  • withdrawal reflexes
  • support against gravity circuits
  • other reflex control of organ function such as defecation and micturition
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5
Q

2 divisions of afferent division of PNS

A

Visceral sensory division and somatic sensory division

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6
Q

2 divisions of efferent division of PNS

A

Viceral motor division to cardiac, smooth muscle, and glands (autonomic, sympathetic and parasympathetic) and somatic motor division to skeletal muscle

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7
Q

Electrical synapses definition and locations they are found (3)

A

Electrical current passing from cell to cell often thru gap junctions that is not common in the CNS or the body except in certain areas, useful to rapidly recruit and conduct more quickly than thru chemical synapses

  • retina
  • olfactory bulb
  • smooth and cardiac muscle
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8
Q

Chemical synapses

A

More common method of synapse in the body thru release of neurotransmitters (chemical messengers)

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9
Q

Neurotransmitters

A

One of over 40 compounds that are used in neuron communication thru release into the synapse that can then excite/inhibit postsynaptic neuron at a receptor, one way and thus allows signals directed toward a specific goal, must be present in nerve terminal, released during action potential, and have reproducible effect

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10
Q

2 structures important to function of synapse

A
  • presynaptic vesicles housing the neurotransmitter

- mitochondria to provide energy to produce neurotransmitter

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11
Q

Axodendritic, axosomatic, and axoaxonic synapses

A
  • Where the axon of one neuron synapses on the dendrite of the other
  • Where the axon of one neuron synapses on the body of the other
  • Where the axon of one neuron synapses on the axon of another
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12
Q

Number of synapses on a postsynaptic cell is variable based on…

A

….decision making capacity of that postsynaptic cell (for example cerebellum receives many more than a spinal motor neuron)

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13
Q

Quantum

A

Several thousand molecules of neurotransmitter stored in synaptic vesicles at the nerve terminals kept relatively constant thru reabsorption or degradation to maintain a relative constant amount

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14
Q

Neuropeptides vs small molecule neurotransmitters

A

Neuropeptides are stored in larger granules that act at lower conc. and have longer lasting effects, with some functioning hormonally as well and being released from other tissue unlike small molecule neurotransmitters

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15
Q

Lock and key fit

A

Idea that only specific neurotransmitters or very closely related substances can bind to a specific receptor

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16
Q

What determines if a neurotransmitter is excitatory or inhibitory?

A

The receptor it binds (heart ones may be inhibitory while skeletal muscle are excitatory for the same neurotransmitter)

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17
Q

Neuromodulators and an example

A

Hormones, neuropeptides, or other messengers that modify synaptic transmission, act pre or postsynaptically to influence likelihood an AP will result in production of an AP in post synaptic terminal (ex - nitric oxide released by postsynaptic neurons diffuses into presynpatic neurons and stimulates release of more neurotransmitter)

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18
Q

Ca2+ mech of neurotransmitter release

A

Depolarization of presynpatic membrane by action potential opens voltage gated Ca2+ channels, influx of Ca2+ induces release of neurotransmitter thru unknown mechanism resulting in exocytosis via fusion of the vesicle to the membrane

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19
Q

Transmitters that open ____ excite postsynaptic neuron (depolarization), transmitters that are open ___ inhibit the postsynaptic neuron (hyperpolarization)

A

sodium channels, chloride channels

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20
Q

Secondary messenger activators

A

Cause prolonged changes in activity of neurons from seconds to months, some processes like memory require long term changes in neuronal activity in function, about 75% transduced via G protein coupled receptors, upon binding a portion of G protein dissociates and perform different functions

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21
Q

4 changes G protein bring about in post synaptic membrane

A
  • Opening specific ion channels in the post synaptic membrane
  • activation of an enzye system in cells membrane
  • activation of one or more intracellular enzymes
  • activate gene of transcription
22
Q

Inactivation of ___ is acheived by phosphodiesterase

A

cAMP

23
Q

Ways neurotransmitters are removed from synaptic cleft and ensure short term effect on post synpatic terminals

A
  • Catabolism of enzymes located near receptor
  • active transport(quickly pump back in nerve terminals)
  • diffusion (into extracellular fluid
24
Q

More ___ a neuron has the greater its info processing capability

A

-Synapses

25
Q

Excitatory postsynaptic potential (EPSP) and 2 examples

A

A positive voltage change causing postsynaptic cell to become more likely to fire (depolarization) resulting from Na+ flowing into cell,
-glutamate and aspartate

26
Q

Inhibitory postsynaptic potential (IPSP) and 2 examples

A

A neg voltage change causing postsynaptic cell to be less likely to fire (hyperpolarization) resulting from Cl- flowing into cell or K+ leaving the cell
-glycine and GABA

27
Q

What 2 neurotransmitters can be either EPSP or IPSPs?

A

Ach and norepi

28
Q

Normal resting membrane potential and general distribution of Na, K, Cl, and protein anions

A

-65mV due to excess Na+ outside, K+ inside, Cl- outside, and proteins and such inside (neg charged)

29
Q

Nernst potential

A

Potential that exactly electrically opposes the movement of an ion across the neuronal membrane down its conc. gradient (electrochemical equilibrium of a particular ion), determined by the balance when conc. gradient and electric gradient directly oppose each other (61mV for Na+ to prevent influx, -87mV for K+ to prevent efflux, and -69mV in Cl- to prevent influx)

30
Q

Threshold value for neuronal AP

A

Potential required for opening of voltage gated sodium channels causing rapid movement of Na+ inward in a neuron

31
Q

Excitatory cholinergic synapse mech of action

A
  • Ach crosses synapse
  • Ach receptors trigger opening of Na+ channels producing local potential
  • Upon reaching -55 mV see AP triggered
32
Q

Inhibitory post synaptic potential mech of action

A

-Inhibitory synapses open K+ or Cl- channels causing hyperpolarization of neuron, cell membrane potential becoems more negative resulting in inhibitory post synaptic potential (-65 to -90mV)

33
Q

Presynaptic inhibition, what neurotransmitter does this?

A
  • Activation of presynaptic synapses decreasing ability of Ca2+ channels to open on the presynaptic terminals resulting in reduced neurotransmitter release
  • Typically facilitated by GABA
34
Q

When action potentials from peripheral baroreceptors begin firing very frequently due to high pressure, this is relayed to the brain to cause what physiologic response?

A

Vasodilation

35
Q

Criteria for a chemical to be considered a neurotransmitter (3)

A
  • chemical must be present in nerve terminal
  • chemical must be released from nerve terminal by action potential
  • chemical when applied experimentally to receptor must produce identical effect
36
Q

Example of a small molecule neurotransmitter and example of a neuropeptide

A
  • GABA

- cholecystokinin or B endorphins

37
Q

2 components of receptors on postsynaptic membranes

A
  • Binding component

- Ionophore component (opens an ion channel or activates 2ndary messenger system

38
Q

75% of second messenger activators are ____. How do these systems work?

A

G protein coupled receptors, work thru dissociation with alpha portion moving about cytoplasm and either oopening an ion channel, activating an enzyme system, or allowing gene transcription

39
Q

Ability to process, store, and recall info is due to…

A

….neural integration

40
Q

Neural integration is based on…

A

….types of postsynaptic potentials produced by neurotransmitters (excitatory or inhibitory)

41
Q

Excitatory adrenergic synapse mech of action

A
  • NE binds receptor on post synaptic cell
  • activates cAMP
  • wide variety of effects such as activating enzymes and opening ligand gates
  • post synaptic potential formed
42
Q

GABA is ____ through producing ___polarization

A

inhibitory, hyper

43
Q

Facilitation of neurons

A

When a neuron potential is closer to threshold than normal but not yet to firing level that can be easily stimulated by summated by subsequent input

44
Q

2 types of summation of postsynaptic potentials

A

Spatial - multiple terminal excitation simultaneously by an EPSP exceeding threshold for inducing action potential
Temporal summation - when post synaptic neuron is stimulated repeatedly by the same presynaptic neuron, with more rapid firing of EPSP in shortened period of time can exceed threshold for inducing action potential

45
Q

Macro example of summation in action

A
  • Accidentally touching a hot pan on stove results in EPSPs in motor neurons causing hand to jerk back quickly
  • Intentionally touching a hot pot of coffee keeps you from withdrawing and dropping it by having IPSP’s dominating effect overriding the EPSPs
46
Q

Synaptic fatigue

A

Occurs when exhaustion of stores of transmitter in synaptic terminals occurs

47
Q

Post tetanic facilitation

A

Enhanced responsiveness following repetitive stimulation due to build up of Ca2+ ions in presynaptic terminals causing more vesicular release of transmitter

48
Q

Synaptic delay

A

Depending on length of delay of neurotransmission, can calculate number of neurons in a circuit

49
Q

Effect of acidosis, alkalosis, and hypoxia on neuronal activity

A
  • depresses
  • increases excitability (seizures)
  • can’t go long without!
50
Q

Neural coding of qualitative vs quantitative info

A
  • Qualitative depends on which neurons are fired

- quantitative depends on # of neurons recruited with stronger stimuli causing more rapid firing rate

51
Q

Threshold, maximal, submaximal, supramaximal stimuli

A

Threshold causes AP, maximal is max # of AP that can be generated per unit time, submaximal is between threshold and maximal, supramaximal sees no more frequency than max in # of AP that can be generated

Neurology (23 decks)

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