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First Semester: Physiology 1 > Lecture 6: Nervous System 5 and 6 > Flashcards

Lecture 6: Nervous System 5 and 6 Flashcards

1
Q

A synapse may be either excitatory or inhibitory depending on

A

Permeability changes induced in the post synaptic neuron by the combination of neurotransmitter with receptor sites

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2
Q

Excitatory synapse

A

Opening of Na channels within the postsynaptic membrane-leads to an increase in permeability to these ions
A large number of Na enters the cell, causing a net movement of positive ions into the cell, which results in a small depolarization of the postsynaptic neuron

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3
Q

The postsynaptic change in an excitatory synapse is called

A

An excitatory postsynaptic potential (EPSP)

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4
Q

EPSP brings the membrane potential closer to

A
  • threshold

- firing an action potential

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5
Q

Excitatory neurotransmitters include (4)

A

acetylcholine
norepinephrine
epinephrine
glutamate

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6
Q

Inhibitory synapse

A

Neurotransmitter-receptor combo causes an increase in permeability of postsynaptic membrane to K or Cl, resulting in ion movement into the cell and a small hyperpolarization of the postsynaptic membrane

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7
Q

Postsynaptic change in an inhibitory synapse

A

inhibitory postsynaptic potential

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8
Q

ISPS takes the membrane potential away from

A
  • threshold

- farther from firing an action potential

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9
Q

Two types of inhibitory neurotransmitters

A

acetylcholine

glycine

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10
Q

What is the mechanism responsible for integration of EPSPs, IPSPs, or a combo of the two in a postsynaptic neuron

A

summation

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11
Q

The postsynaptic neuron can be brought to threshold in one of two ways

A

Temporal summation

Spatial summation

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12
Q

Temporal summation

A

The summing of several EPSP’s occurring very close together in time because of successive firing of single presynaptic neuron

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13
Q

Spatial summation

A

Summation of EPSPs originating simultaneously from several different presynaptic inputs

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14
Q

Not all info received by a postsynaptic neuron is

A

passed along

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15
Q

When will information be passed along?

A

Only if an excitatory presynaptic signal is reinforced by other supporting signals

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16
Q

Interacting of postsynaptic potentials provide a way for one set of signals to

A

offset another set (IPSPs negating EPSPs)

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17
Q

Neurotransmitter

A

chemical compound released by one neuron to affect the membrane potential of postsynaptic cell

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18
Q

Neuromodulator

A

A chemical that adjusts the sensitivities of another cell to specific neurotransmitters

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19
Q

Presynaptic inhibition

A

The amount of neurotransmitter released from the presynaptic terminal decreases

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20
Q

Presynaptic facilitation

A

The amount of neurotransmitter released from the presynaptic terminal increases

21
Q

Axoaxonic synapse

A
  • The axon of one neuron synapses with the presynaptic terminal of another
  • When action potential reaches the presynaptic terminal, neuromodulators released in the axoaxonic synapse can alter the amount of neurotransmitter released from the presynaptic terminal
  • Does not initiate an action potential in the presynaptic terminal
22
Q

Example of presynaptic inhibition (tetanus)

A
  • Tetanus toxin prevents the release of the inhibitory neurotransmitter, gamma amino butyric acid (GABA) from inhibitory presynaptic inputs terminating on neurons that supply skeletal muscle
  • Unchecked excitatory inputs to these neurons result in uncontrolled muscle spasms
23
Q

Example of presynaptic inhibition (pain prevention)

A

Enkephalins and endorphins in the CNS produces presynaptic inhibition of neurons transmitting pain sensation. They bind to opiate receptors and terminate pain signals by inhibiting the release of substance P from pre-synaptic neurons

24
Q

Presynaptic facilitation example

A

A pre-synaptic neuron releases glutamate, which binds to glutamate receptors on the postsynaptic membrane and stimulates the postsynaptic neuron to produce nitric oxide, which diffuses out of the postsynaptic neuron, crosses the synaptic cleft, diffuses into the presynaptic neuron and stimulates the release of additional glutamate from the presynaptic neuron

25
Q

Reflexes

A

rapid, automatic responses to stimuli

26
Q

How do reflexes preserve homeostasis

A

by making rapid adjustments in the function of organs or organ systems

27
Q

The response shows little variability because

A

activation of a particular reflex usually produces the same motor response

28
Q

What body functions are controlled through reflexes

A

movement of respiration and digestion

29
Q

The basic functional unit of the nervous system

A

The reflex arc

30
Q

Reflex arc

A

The smallest, simplest portion capable of receiving a stimulus and yielding a response

31
Q

Two types of reflex

A

Neural

Endocrine

32
Q

Neural reflex

A
  • Sensory fibers deliver info to the CNS and motor fibers carry motor commands to the peripheral effectors
  • Can be spinal or cranial
33
Q

Endocrine reflex

A

A stimulus triggers the production of a hormone whose activities lead to a reduction in the magnitude of the stimulus

34
Q

Two types of neural reflex

A

Spinal and cranial

35
Q

Spinal neural reflex

A

Spinal cord serves as the integrating center

36
Q

5 steps of a reflex arc

A
  1. Arrival of a stimulus and activation of a receptor
  2. Activation of a sensory neuron
  3. Information processing in the CNS
  4. Activation of a motor neuron
  5. Response by an effector
37
Q

Negative feedback

A

corrective mechanism that opposes or negates a variation from normal limits

38
Q

Reflexes can be classified according to (4)

A
  1. Development
  2. Processing site
  3. Motor response
  4. Complexity of circuit
39
Q

What is the simplest arc

A

monosynaptic arc

40
Q

Monosynaptic arc

A

A sensory neuron synapses directly on a motor neuron, which itself serves as the processing center

41
Q

Polysynaptic arc

A

One or more interneurons synapse with the sensory and motor neurons
Can produce more complicated responses because the interneurons can control several groups

42
Q

5 Steps of the Stretch reflex mechanism

A
  1. Stretch muscle stimulates muscle spindle
  2. Propagation of action potentials along sensory neurons to the spinal cord
  3. Information processing at the motor neuron
  4. Activation of motor neurons
  5. Contraction of muscle
43
Q

Stretch reflex maintains a _____ _____ ______ length at rest

A

normal skeletal muscle

44
Q

Is the stretch reflex mono or polysynaptic reflex?

A

Monosynaptic

45
Q

The stretch reflex provides

A

autonomic regulation of skeletal muscle length

46
Q

In the stretch reflex, what is the stimulus

A

increasing muscle length, which activates a sensory neuron which triggers the response

47
Q

In the stretch reflex, what is the response?

A

Contraction of the stretched muscle, which counteracts the stimulus

48
Q

In the stretch reflex, action potentials traveling towards and away from the spinal cord are conducted along

A

large myelinated Type A Fibers

First Semester: Physiology 1 (34 decks)

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