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General Physiology (Prelims) > Neuromuscular Synapse & Muscle Physiology > Flashcards

Neuromuscular Synapse & Muscle Physiology Flashcards

1
Q

The points of contact between neurons where information is passed from one neuron to the next.

A

SYNAPSE

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2
Q

An action potential in the presynaptic cell causes __________ of the presynaptic terminal

A

depolarization

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3
Q

As a result of the depolarization, Ca 2+ enters the presynaptic terminal, causing release of
_______________ into the synaptic cleft

A

neurotransmitter

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4
Q

Neurotransmitter diffuses across the synaptic cleft and combines with receptors on the postsynaptic cell membrane, causing a change in its permeability to ions and, consequently, a change in its ________________

A

membrane potential

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5
Q

____________ neurotransmitters hyperpolarize the postsynaptic membrane: ____________ neurotransmitters depolarize the postsynaptic membrane.

A

INHIBITORY; EXCITATORY

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6
Q

It is the synapse between axons of motoneurons and
skeletal muscle.

A

NEUROMUSCULAR JUNCTION

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7
Q

(In Neuromuscular transmission) The neurotransmitter released from the presynaptic terminal is ____, and the postsynaptic membrane contains a ____________ receptor.

A

ACh, nicotinic

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8
Q

(In Neuromuscular transmission) ________________ catalyzes the formation of ACh from acetyl coenzyme A (CoA) and choline in the presynaptic terminal.

A

Choline acetyltransferase

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9
Q

(In Neuromuscular transmission) In the synthesis of ACh in the presynaptic terminal, ACh is stored in ______________ with ATP and proteoglycan for later release.

A

synaptic vesicles

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10
Q

(In Neuromuscular transmission) When action potentials are conducted down the motoneuron, depolarization of the presynaptic terminal opens ______ channels.

A

Ca 2+

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11
Q

(In Neuromuscular transmission) Ca 2+ uptake causes release of ACh into the___________

A

synaptic cleft.

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12
Q

(In Neuromuscular transmission) Diffusion of ACh to the _____________ (muscle end plate) allows binding of ACh to nicotinic receptors.

A

postsynaptic membrane

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13
Q

What is EPP (that is not an action potential, but simply a depolarization of the specialized muscle end plate)?

A

End plate potential

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14
Q

(In Neuromuscular transmission) The EPP is transient because ACh is ____________ to acetyl CoA and choline by ____________ (AChE) on the muscle end plate.

A

degrade, acetylcholinesterase

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15
Q

It is the most potent of neurotoxins that blocks presynaptic release of the neurotransmitter (acetylcholine) at the neuromuscular junction.

A

Botulinum toxin

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16
Q

It is a neurotoxin that competes with Ach for receptors on motor end plate, decreasing the size of the EPP

A

Curare

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17
Q

Acetylcholine (ACh) is made from ______ and _________

A

choline, acetyl COA

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18
Q

Type of synaptic transmission that is found at the neuromuscular junction

A

One-to-one synapse

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19
Q

As an example, many cells synapse on the postsynaptic cell to depolarize it to threshold, producing an action potential. What ty[e of synaptic transmission is this?

A

Many-to-one synapses

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20
Q

The postsynaptic cell integrates excitatory and inhibitory inputs. When the sum of the input brings the membrane potential of the postsynaptic cell to
threshold, it fires an ______________.

A

action potential

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21
Q

It is a postsynaptic potential that depolarize the postsynaptic cell, bringing it closer to threshold and closer to firing an action potential.

A

Excitatory postsynaptic potentials (EPSPs)

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22
Q

It is a postsynaptic potential that hyperpolarize the postsynaptic cell, moving it away from threshold and farther from firing an action potential; caused by opening Cl- channels.

A

Inhibitory postsynaptic potentials (IPSPs)

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23
Q

It is a chemical messenger, transmitting messages between neurons, or from neurons to muscles.

A

Neurotransmitters

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24
Q

A neurotransmitter that PROMOTES the generation of an electrical signal called an action potential in the
receiving neuron

A

Excitatory neurotransmitter

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25
Q

A neurotransmitter that PREVENTS the generation of action potential

A

Inhibitory neurotransmitter

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26
Q

What are the adrenergic receptors?

A

alpha-1, alpha-2, beta-1, and beta-2 receptors

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27
Q

Give some examples of EXCITATORY neurotransmitters

A

Glutamate
Aspartate
Nitric Oxide

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28
Q

Give some examples of INHIBITORY neurotransmitters

A

Glycine
GABA
Serotonin

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29
Q

Give some examples of neurotransmitters that act BOTH as excitatory and inhibitory

A

Acetylcholine
Norepinephrine
Dopamine

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30
Q

It is an inhibitory neurotransmitter that is present in high concentrations in the BRAIN STEM, being converted to melatonin in the pineal gland.

A

SEROTONIN

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31
Q

A neurotransmitter present in the neurons of the HYPOTHALAMUS (involved in allergic reactions)

A

HISTAMINE

32
Q

A neurotransmitter prominent in MIDBRAIN neurons (correlated with Parkinson’s disease and schizophrenia)

A

DOPAMINE

33
Q

The loss of dopaminergic neurons cause this disease

A

Parkinson’s disease

34
Q

Increased levels of dopamine receptors is correlated to this disease

A

Schizophrenia

35
Q

The primary transmitter released from postganglionic sympathetic neurons, which binds with α or β receptors on the postsynaptic membrane

A

NOREPINEPHRINE

36
Q

It is synthesized from norepinephrine that binds with α or β receptors on the postsynaptic membrane

A

EPINEPHRINE

37
Q

The most prevalent excitatory neurotransmitter in the brain, which binds to ionotropic receptors (ligand-gated ion channels) including the NMDA (N-methyl-D-aspartate) receptor.

A

GLUTAMATE

38
Q

It is an inhibitory neurotransmitter that is synthesized from glutamate

A

GABA (Gamma-aminobutyric acid)

39
Q

An inhibitory neurotransmitter found primarily in the SPINAL CORD and BRAIN STEM, which increases Cl− conductance.

A

GLYCINE

40
Q

A primarily INHIBITORY neurotransmitter (and excitatory as well) in the GI tract, blood vessels, and the central nervous system; a PERMEANT GAS that diffuses from the presynaptic terminal to its target cell

A

NITRIC OXIDE

41
Q

These are the three types of muscle tissue in the body.

A

Skeletal muscle
Smooth muscle
Cardiac muscle

42
Q

It is striated, multi-nucleated, and usually attached to skeleton (voluntary).

A

SKELETAL MUSCLE

43
Q

It is non-striated, spindle-shaped, uninucleated, and usually covering wall of internal organs (like GI tract, kidney, etc.) (Involuntary).

A

SMOOTH MUSCLE

44
Q

It is striated, branched, uninucleated, and only covering walls of heart (Involuntary).

A

CARDIAC MUSCLE

45
Q

The contractile proteins (that enable muscle contraction) are arranged in repeating subunits known as _____________. They give the skeletal muscle cells their striated appearance when viewed with a light microscope.

A

sarcomeres

46
Q

A skeletal muscle is a group of muscle _________, which then consist of muscle _______ (that also consist of _________).

A

fascicles, fibers, myofibrils

47
Q

Each muscle fiber is multinucleate and behaves as a single unit. It contains bundles of myofibrils, surrounded by _________ and invaginated by
____________.

A

sarcoplasmic reticulum (SR), transverse tubules (T tubules)

48
Q

______ filaments: present in the A band in the center of the sarcomere. They contain myosin.

A

Thick

49
Q

The myosin heads bind ______ and _____ and are involved in cross-bridge formation.

A

ATP, actin

50
Q

It is a filament anchored at the Z lines and present in the I bands, containing actin, tropomyosin, and troponin.

A

Thin

51
Q

It is a regulatory protein that permits cross-bridge formation when it binds Ca 2+.

A

Troponin

52
Q

It is a troponin molecule that attaches the troponin complex to tropomyosin.

A

Troponin T

53
Q

It is a troponin molecule that inhibits the interaction of actin and myosin.

A

Troponin I

54
Q

It is a troponin molecule that binds with Ca 2+, permitting the interaction of actin and myosin.

A

Troponin C

55
Q

It is an extensive tubular network, open to the extracellular space, that carries the depolarization from the sarcolemmal membrane to the cell interior.

A

Transverse tubules (T tubules)

56
Q

The depolarization carried by T tubules cause a conformational change in the ____________ receptor, a voltage-sensitive protein.

A

dihydropyridine

57
Q

It is an internal tubular structure that is the site of Ca 2+ storage and release for excitation–contraction coupling. It has terminal cisternae that make intimate contact with the T tubules in a triad arrangement.

A

Sarcoplasmic reticulum (SR)

58
Q

The sarcolemmal membrane contains Ca2+ -ATPase (_________), which transports Ca 2+ from intracellular fluid into the SR interior, keeping intracellular [Ca 2+ low.].

A

Ca 2+ pump

59
Q

It is is an essential process in muscle physiology, responsible for linking electrical signals from the somatic nervous system (action potentials) to mechanical muscle contractions

A

Excitation-contraction coupling (ECC)

60
Q

[Steps in excitation–contraction coupling in skeletal muscle]

___________ in the muscle cell membrane initiate depolarization of the T tubules.

A

Action potential

61
Q

[Steps in excitation–contraction coupling in skeletal muscle]

Depolarization of the T tubules causes a ____________ in its dihydropyridine receptor, which opens Ca 2+ release channels (ryanodine receptors) in the nearby SR, causing release of Ca 2+ from the SR into the _____________.

A

conformational change, intracellular fluid

62
Q

[Steps in excitation–contraction coupling in skeletal muscle]

Ca 2+ binds to __________ on the thin filaments, causing a conformational change in troponin
that moves _________ out of the way.

A

troponin C, tropomyosin

63
Q

The cross-bridge cycle repeats as long as ______ is bound to __________. Each cross-bridge cycle “walks” myosin further along the actin filament.

A

Ca2+, troponin C

64
Q

As long as intracellular Ca 2+ concentration is low, cross-bridge cycling _________ (can, cannot) occur.

A

cannot

65
Q

When intracellular Ca 2+ concentration decreases, Ca 2+ is released from troponin C, and tropomyosin again ________ the myosin-binding site on actin.

A

blocks

66
Q

What mechanism does it explain when muscles do not relax and are stimulated repeatedly, releasing more Ca2+ from the SR, producing a cumulative increase in intracellular [Ca 2+], and extending the time for cross-bridge cycling?

A

Mechanism of tetanus

67
Q

This is a type of muscle tissue that has thick and thin filaments that are not arranged in sarcomeres; therefore, it appears homogeneous rather than striated.

A

Smooth muscle

68
Q

The most common type of smooth muscle that is present in the uterus, gastrointestinal tract, ureter, and bladder. It has a high degree of electrical coupling between cells and, therefore, permits coordinated
contraction of the organ (e.g., bladder)

A

Unitary (single-unit) smooth muscle

69
Q

The type of smooth muscle that behaves as separate motor units and has little or no electrical coupling between cells. It is densely innervated; contraction is controlled by neural innervation (autonomic nervous
system) and is present in the iris, ciliary muscle of the lens, and vas deferens.

A

Multiunit smooth muscle

70
Q

It is a type of smooth muscle that has properties of both multiunit and single-unit smooth muscle.

A

Vascular smooth muscle

71
Q

[Steps in excitation–contraction coupling in smooth muscle]

There is no troponin; instead, ______ regulates myosin on the thick filaments.

A

Ca 2+

72
Q

[Steps in excitation–contraction coupling in smooth muscle]

Ca 2+ binds to calmodulin. The Ca 2+–calmodulin complex binds to and activates _________________. When activated, myosin light chain kinase ____________ myosin and allows it to bind to actin, thus initiating cross-bridge cycling.

A

myosin light chain kinase, phosphorylates

73
Q

Which characteristic or component is shared by skeletal muscle and smooth muscle?

(A) Thick and thin filaments arranged in sarcomeres
(B) Troponin
(C) Elevation of intracellular [Ca 2+ ] for excitation–contraction coupling
(D) Spontaneous depolarization of the membrane potential

A

C

74
Q

Which of the following causes rigor in skeletal muscle?

(A) Lack of action potentials in motoneurons
(B) An increase in intracellular Ca 2+ level
(C) A decrease in intracellular Ca 2+ level
(D) An increase in adenosine triphosphate (ATP) level
(E) A decrease in ATP level

A

E

75
Q

Where can you find multi-unit type of smooth muscles?

A. Duodenum
B. Sperm Duct
C. Aorta
D. Kidney

A

B

76
Q

Choose the purely excitatory neurotransmitter:

A. Glycine
B. GABA
C. Glutamate
D. Acetylcholine

A

C

General Physiology (Prelims) (4 decks)

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