3.1 The Concept Of The Synapse Flashcards

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0
Q

Sherrington (1906) studied ____ - automatic muscular responses to stimuli.

A

reflexes

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1
Q

The specialised area separating one neuron from another is called a ____. Ramón y Cajal.

A

synapse

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2
Q

In a leg flexion reflex, a sensory neuron excites a second neuron, which in turn excites a motor neuron, which excites a muscle. The circuit from the sensory neuron to muscle is called a ____ ___.

A

reflex arc

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3
Q

Sherrington found that the speed of conduction through the reflex arc varied but was never more than about __ m/s. In contrast, previous research had measured action potential velocities along sensory motor neurons in about __ m/s.

A

15 : 40

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4
Q

Shenton concluded that some process was slowing ____ through the reflex, and he inferred that the delay must occur where one neuron communicates with another.

A

conduction

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5
Q

Sherrington found that repeated stimuli within a brief time have a cumulative effect. He referred to this phenomenon as ____ ____ (summation overtime).

A

temporal summation

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6
Q

Sherrington surmised that a single pinch did not reach the ____ of ____ for the neuron.

A

threshold of excitation

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7
Q

The neuron that delivers transmission is the ____ neuron.

A

presynaptic

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8
Q

The neuron that receives the transmission is the ____ neurons.

A

postsynaptic

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9
Q

Sherrington proposed that this _____ excitation in the postsynaptic neuron decays over time, but it can combine with a second excitation that follows it quickly.

A

subthreshold

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10
Q

Eccles (1964) discovered with micro-electrodes, after briefly stimulating an axon, a slight ____ of the membrane of the postsynaptic cell. This depolarisation is a grated potential.

A

depolarisation

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11
Q

Unlike action potentials, which are always depolarisations, ____ ____ may be either depolarisations (excitatory) or hyperpolarisations (inhibitory).

A

graded potentials

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12
Q

A graded depolarisation is known as an ____ ____ ____ (EPSP). It results from a flow of sodium ions into the neuron.

A

excitatory postsynaptic potential

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13
Q

If an EPSP does not cause the cell to reach its threshold, the depolarisation ____ quickly.

A

decays

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14
Q

Sherington also found that synapses have the property of ____ ____ – that is, summation over space. Synaptic inputs from separate locations combine their effects on a neuron.

A

spatial summation

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15
Q

Sherrington concluded that pinching two points activated separate sensory neurons, who’s axons converged onto a neuron in the spinal-cord. Excitation from either sensory axon excited that spinal neuron, but not enough to reach the threshold. A ____ of excitations exceeded the threshold and produced an action potential.

A

combination

16
Q

At inhibitory synapses, input from an axon ____ the postsynaptic cell. That is, it increases the negative charge within the cell, moving it further from the threshold and decreasing the probability of an action potential.

A

hyperpolarises

17
Q

This temporary hyperpolarisation of the membrane – called an ____ ____ ____ or IPSP – resembles an EPSP.

A

inhibitory postsynaptic potential

18
Q

In IPSP occurs when synaptic input selectively opens the gates for ____ ions to leave the cell (carrying a positive charge with them) or for ____ ions to enter the cell (carrying a negative charge).

A

potassium : chloride

19
Q

Most nuerons have a ____ ____ ____, a periodic production of action potentials even without synaptic input.

A

spontaneous firing rate

20
Q

The EPSPs on a neuron ____ with the IPSPs; the balance between the two increases or decreases the neurons frequency of action potentials.

A

compete