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Psych 270 > Ch. 2 - Synapses > Flashcards

Ch. 2 - Synapses Flashcards

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1
Q

Synapse

A

-A specialized gap as a point of communication between two neurons

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2
Q

Reflexes

A

-Automatic muscular responses to stimuli

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3
Q

Reflex arc

A

-The circuit from sensory neuron to muscle response

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4
Q

Temporal summation

A
  • Repeated stimuli within a brief time have a cumulative effect
  • “Summation over time”
  • Several impulses from one neuron over time
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5
Q

Presynaptic neuron

A

-The neuron that DELIVERS transmission

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6
Q

Postsynaptic neuron

A

-The neuron that RECEIVES the transmission

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7
Q

Excitatory postsynaptic potential (EPSP)

A
  • A graded depolarization is known as an EPSP
  • It results from the flow of sodium ions (Na) into the neuron
  • If an EPSP does not cause the cell to reach its threshold, the depolarization decays quickly
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8
Q

Spatial summation

A
  • Summation over spaces
  • Synaptic inputs from separate locations combine their effects on a neuron
  • Impulses from several neurons at the same time
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9
Q

Inhibitory postsynaptic potential (IPSP)

A
  • Hyperpolarization of a membrane (AKA making it MORE negative)
  • An IPSP occurs when synaptic input selectively opens the gates for potassium ions to leave the cell (carrying a positive charge with them) or for chloride ions to enter the cell (carrying a negative charge)
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10
Q

Spontaneous firing rate

A

-Most neurons have a spontaneous firing rate, a periodic production of action potentials even without synaptic input

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11
Q

Catecholamines

A
  • Epinephrin, norepinephrin, and dopamine

- They contain a catechol group and an amine group

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12
Q

Vesicles

A
  • Tiny nearly spherical packets

- The presynaptic terminal stores high concentrations of neurotransmitter molecules in vesicles

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13
Q

Monoamine oxidase (MAO)

A

-Neurons that release serotonin, dopamine, or norepinephrine contain an enzyme, MAO, that breaks down these transmitters into inactive chemicals, thereby preventing the transmitters to accumulate to harmful levels.

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14
Q

Release and diffusion of transmitters…

A
  • At the end of an axon, an action potential itself does not release the neurotransmitter
  • Rather, depolarization (making more positive) opens voltage-dependent calcium gates in the presynaptic terminal
  • Within 1-2ms after calcium enters the terminal, it causes EXOCYTOSIS - bursts of release of neruotransmitter from the presynaptic neuron
  • After its release from the presynaptic cell, the neurotransmitter diffuses across the synaptic cleft to the postsynaptic membrane, where it attaches to a receptor
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15
Q

Ionotropic effects

A
  • Receptor opens a channel, exerting an ionotropic effect, corresponding to the brief on/off effects that Sherrington and Eccles studied
  • When the neurotransmitter binds to an ionotropic receptor, it twists the receptor just enough to open its central channel, which has a shape that lets a particular type of ion pass through
  • For vision and hearing, the brain needs rapid up-to-date information, the kind that ionotropic synapses bring
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16
Q

Transmitter-gated or ligand-gated

A

-The channels controlled by a neurotransmitter, that is, when the neurotransmitter attaches, it opens a channel

17
Q

Metabotropic effects

A
  • At other receptors, neurotransmitters exert metabotropic effects by initiating a sequence of metabolic reactions that start slowly but last longer than ionotropic effects
  • Metabotropic synapses are better suited for more enduring effects such as taste, smell, pain, arousal, attention, pleasure, and emotion (ie. functions that arise more slowly but last longer)
18
Q

Ionotropic vs metabotropic

A

-An ionotropic synapse has effects localized to one point on the membrane, whereas a metabotropic synapse, by way of its second messenger, influences activity in much or all of the cell and over a longer time

19
Q

How do LSD, nicotine, and opiate drugs influence behaviour?

A
  • LSD binds to one type of serotonin receptor
  • Nicotine binds to one type of acetylcholine receptor
  • Opiates bind to endorphin receptors
20
Q

Reuptake

A
  • The presynaptic neuron takes up much or most of the released nerotransmitter molecules intact and reuses them
  • This process is called reuptake, and occurs through special membrane proteins called TRANSPORTERS
  • Any transmitter molecules that the transporters do not take will instead break down by an enzyme called COMT (catechol-o-methyltransferase). The breakdown products wash away and eventually show up in the blood and urine
21
Q

Autoreceptors

A

-Receptors that respond to the released transmitter by inhibiting further synthesis and release. That is, they provide negative feedback

22
Q

Gap junction

A
  • At an electrical synapse. the membrane of one neuron comes into direct contact with the membrane of another. This contact is called a GAP JUNCTION
  • Fairly large pores of the membrane of one neuron line up precisely with similar pores in the membrane of the other cell
  • These pores are large enough for sodium and other ions to pass readily, and unlike other membrane channels, these pores remain open constantly
23
Q

Hormones vs neurotransmitters

A
  • A hormone is a chemical secreted by cells in one part of the body and conveyed by the blood to influence other cells
  • A neurotransmitter is like a telephone signal: it conveys a message from the sender to the intended receiver.
  • Hormones function more like a radio station: they convey a message to any receiver tuned to the right station
  • Hormones are useful for coordinating long-lasting changes in particular parts of the body
24
Q

Two types of hormones…

A
  • Protein hormones and peptide hormones, composed of chains of amino acids
  • Proteins are longer chains and peptides are shorter
  • Protein and peptide hormones attach to membrane receptors, where they activate a second messenger
25
Q

Anterior pituitary

A
  • Synthesizes 6 hormones, but the hypothalamus controls their release
  • The hypothalamus secretes RELEASING HORMONES, which flow through the blood to the anterior pituitary. There they stimulate or inhibit the release of other hormones

Psych 270 (8 decks)

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