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Animal Physiology > 6.8 - 6.13 > Flashcards

6.8 - 6.13 Flashcards

1
Q

The membrane potential of a postsynaptic neuron is ___ at an excitatory synapse, and it is ___ at an inhibitory synapse.

A

depolarized; hyperpolarized or stabilized

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2
Q

Synapses that consist of gap junctions which allow the local currents from action potentials in one neuron to flow directly across the junction to another neuron are called ___ synapses.

A

electrical

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3
Q

Chemical synapses ___.

A
  • have a synaptic cleft between pre- and postsynaptic cells
  • may contain more than one transmitter at a time
  • use neurotransmitters released by the presynaptic cell to transmit signals to the postsynaptic cell
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4
Q

Identify the correct sequence of information in a chemical synapse.

A

Presynaptic terminal, synaptic cleft, postsynaptic membrane

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5
Q

Postsynaptic cell neurotransmitter receptors can be divided into two types: ___, which contain an ion channel in the structure, or ___, which are linked with second-messenger systems and indirectly alter ion channels

A

ionotropic; metabotropic

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6
Q

At an ___, the membrane potential of a postsynaptic neuron is brought closer to threshold (depolarized).

A

excitatory synapse

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7
Q

Electrical synapses ___.

A
  • transmit signals faster than chemical synapses

- conduct an action potential directly between cells via connecting gap junctions

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8
Q

A synapse that transmits information via the release of neurotransmitters into the synaptic cleft between cells is termed a(n) ___ synapse.

A

chemical

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9
Q

Place the events of a chemical synapse in chronological order, starting with the first at the top.

A
  1. an action potential reches the presynaptic terminal
  2. voltage-gated Ca2+ channels open
  3. Ca+ diffuses into the presynaptic terminal
  4. NTs are released into the synaptic cleft
  5. NTs bind to receptors on the postsynaptic membrane
  6. NTs are removed from the synaptic cleft
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10
Q

Neurotransmitter receptors that act indirectly on separate ion channels through a G protein and/or a second messenger are referred to as ___.

A

metabotropic receptors

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11
Q

The membrane potential of a postsynaptic neuron is either driven farther from threshold (hyperpolarized) or stabilized at its resting potential at a(n) ___ synapse.

A

inhibitory

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12
Q

Recognize a figure of an electrical synapse

A

x

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13
Q

Removal of neurotransmitters from synapses occurs by which of the following mechanisms?

A
  • Active transport into nearby cells, such as glial cells
  • Active transport back into the presynaptic terminal
  • Enzymatic transformation into inactive substances
  • Diffusion away from the synapse
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14
Q

T/F: Whether a synapse is excitatory or inhibitory is determined by what neurotransmitter is released from the presynaptic cell.

A

F (determined by the type of postsynaptic ion channel)

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15
Q

An IPSP is ___.

A

a graded potential in a postsynaptic cell that decreases the likelihood that the cell will reach the threshold for an action potential

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16
Q

T/F: Many EPSPs occurring in a short period of time are generally required to initiate an action potential in a postsynaptic neuron.

A

T

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17
Q

Excess neurotransmitters are removed from the synaptic cleft in several ways. For example, they can be actively transported back into the presynaptic axon terminal for reuse, via a process called ___. Alternatively, they can be removed into nearby ___ cells where they are degraded. They could also ___ away from the receptor site.

A

reuptake
glia
diffuse

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18
Q

A synapse could be excitatory or inhibitory depending on ___.

A

the type of postsynaptic ion channel influenced by the signal transduction mechanism

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19
Q

At some chemical synapses, the potential change in the postsynaptic neuron is either a hyperpolarization or a stabilization of the membrane potential. This type of response is known as ___ ___ ___ (IPSP).

A

inhibitory postsynaptic potential

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20
Q

When neurotransmitters such as GABA or ACh are released from neuron A and bind to receptors embedded in the membrane of the axon terminal of neuron B, causing a decrease in the amount of an excitatory neurotransmitter released by neuron B, it is called ___.

A

presynaptic inhibition

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21
Q

Receptors found in postsynaptic densities of synapses that both bind to neurotransmitters and act as ion channels are known as ___.

A

ionotropic receptors

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22
Q

A depolarization of the membrane toward threshold occurs when ___ synaptic input predominates, and either hyperpolarization or stabilization occurs when ___ input predominates.

A

excitatory; inhibitory

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23
Q

What term describes the situation in which a receptor at first responds to a neurotransmitter, but over time becomes non-responsive despite the continued presence of the neurotransmitter signal?

A

Receptor desensitization

24
Q

Neurotransmitters do not stay bound to receptors indefinitely; instead, they ___.

A
  • are broken down into component parts by enzymes
  • diffuse away from the synapse
  • are transported back into the presynaptic cell via reuptake
25
Q

T/F: Whether a synapse is excitatory or inhibitory is determined by what neurotransmitter is released from the presynaptic cell.

A

F

26
Q

A drug that is classified as an agonist ___.

A

binds to a receptor and produces a response similar to what occurs when the normal ligand binds

27
Q

If neurotransmitter release from neuron A increases the amount of Ca2+ that enters neuron B during an action potential, ___ of the synapse between neuron B and C will occur.

A

presynaptic facilitation (makes it more likely that NT will be released)

28
Q

A substance released by cells that alters the effectiveness of a synapse indirectly by acting at non-synaptic locations, for example by altering the presynaptic cell’s release of neurotransmitter or the postsynaptic cell’s response to the neurotransmitter, is called a(n) ___.

A

neuromodulator

29
Q

When a receptor responds normally when first exposed to a neurotransmitter but then eventually fails to respond despite the continued presence of the neurotransmitter, this is known as ___ ___.

A

receptor desitization

30
Q

Acetylcholine (ACh) is ___.

A
  • a neurotransmitter
  • released by neurons within the brain
  • released onto skeletal muscle cells by motor neurons
31
Q

Norepinephrine is ___.

A

a catecholamine neurotransmitter involved in sympathetic regulation of smooth and cardiac muscle

32
Q

An antagonist is a ligand that ___.

A

inhibits the activity of receptor proteins

33
Q

The most common excitatory amino acid neurotransmitter in the central nervous system is ___.

A

glutamate/glutamic acid

34
Q

In general, neurotransmitters cause EPSPs and IPSPs. However, more complex metabolic effects in a postsynaptic cell are mediated by molecules called ___, usually via second messengers.

A

neuromodulators

35
Q

The main neurotransmitter released onto skeletal muscle cells by motor neurons is called ___.

A

Acetylcholine (ACh, acetylcholine)

36
Q

Which three are TRUE about dopamine?

A
  • It is a monoamine.
  • It is a catecholamine.
  • It is a neurotransmitter.
37
Q

Ligands that bind to and activate receptor proteins are called ___.

A

antagonist

38
Q

The primary neurotransmitter at an estimated 50% of excitatory synapses in the CNS is ___.

A

glutamate

39
Q

Which best describes a neuromodulator?

A

A compound that indirectly alters the effectiveness of a synapse by altering release of, or responsiveness to, a neurotransmitter.

40
Q

Drugs that bind to and reduce the activity of receptor proteins are called ___.

A

antagonist

41
Q

Which of the following are classified as endogenous opioids?

A
  • Enkephalins
  • Beta-endorphin
  • Dynorphins
42
Q

Which of the following are receptors for the neurotransmitter glutamate?

A
  • Alpha-amino-3 hydroxy-5 methyl-4 isoxazolepropionic acid (AMPA)
  • N-methyl-D-aspartate (NMDA)
43
Q

What gaseous neurotransmitter is produced from L-arginine by nitric oxide synthetase?

A

NO

44
Q

Which of the following are purines that are co-released from neurons and act as neuromodulators?

A
  • ATP

- adenosine

45
Q

Which of the following may be attributed to the effects of endogenous opioids?

A
  • eating and drinking

- pain relief

46
Q

Which of the following statements about nitric oxide (NO) are true?

A
  • Mediates penile erection
  • Causes an increase in the concentration of cyclic GMP in target cells
  • Acts as a neurotransmitter
47
Q

The major neurotransmitter in the peripheral nervous system at the neuromuscular junction is ___.

A

acetylcholine

48
Q

ATP and adenosine are ___ that act mainly as ___.

A

purines; neuromodulators

49
Q

Which of the following are classified as neuropeptide neurotransmitters/neuromodulators?

A
  • Dynorphin
  • Beta-endorphin
  • Enkephalin
50
Q

Which of the options are correctly identified as lipid neurotransmitters?

A
  • Endocannabinoids
  • Thromboxanes
  • Leukotrienes
  • Prostaglandins
51
Q

At neuroeffector junctions, the receptors on the effector cell ___.

A

may be either ionotropic or metabotropic

52
Q

Identify the true statements relating to endocannabinoids.

A
  • Include 2-arachidonoylglycerol
  • Generated in response to Ca2+ entry into some postsynaptic cells
  • Receptors found in widespread locations throughout the CNS and PNS
53
Q

Which is true about signaling by nitric oxide (NO)?

A

It diffuses into target cells and activates guanylyl cyclase.

54
Q

What are the three cell types with which efferent neurons most commonly form synapses?

A
  • muscle
  • neurons
  • gland
55
Q

The ___ receptors are the targets of tetrahydrocannabinol (THC).

A

cannabinoid

56
Q

T/F: The most common neurotransmitters for neuroeffector communication are acetylcholine and dopamine.

A

F (most common NTs for neuroeffector communication are dopamine and norepinephrine)

Animal Physiology (9 decks)

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