Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PHYSIOLOGY > Chapter 9: Cellular Physiology of Skeletal, Cardiac and Smooth Muscle > Flashcards

Chapter 9: Cellular Physiology of Skeletal, Cardiac and Smooth Muscle Flashcards

1
Q

Tor F:
The primary function of muscle is to generate force or movement
in response to a physiological stimulus.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

three fundamentally different types of muscle

adapted to specialized functions.

A

Skeletal muscle

Cardiac muscle

Smooth muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

is responsible
for the voluntary movement of bones that underlie
locomotion and work production.

controls
the breathing cycle of the lungs through contraction of
the diaphragm

A

Skeletal muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

is
specifi c to the heart as the biomechanical pump driving the
delivery of blood to the lungs and tissues.

A

Cardiac muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

provides mechanical control of organ systems such as the
digestive, urinary, and reproductive tracts as well as the
blood vessels of the circulatory system and the airway passages
of the respiratory system.

A

Smooth muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

_____is initiated either by a chemical
neurotransmitter or paracrine factor or by direct electrical
excitation.

A

Contraction of muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

T OR F

The unique
physiological role of each of the three basic muscle types
dictates inherent differences in the rate and duration of contraction,
metabolism, fatigability, and ability to regulate contractile
strength.

A

T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

all three types of muscle: a rise in the________

A

free cytosolic Ca2+

concentration ([Ca2+]i).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

This chapter describes the fundamental physiology of
muscle excitation, the ______to contraction,
the ______of contraction, the _____of
contraction, and the related issues of muscle diversity.

A

coupling of excitation

molecular mechanism

regulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Contraction of skeletal muscle is initiated by

_____that innervate motor units

A

motor neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The smallest contractile unit of skeletal muscle is a multinucleated,
elongated cell called

A

muscle fi ber or myofi ber

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

A bundle of linearly aligned muscle fi bers forms

a_____. In turn, bundles of fascicles form a _____.

A

fascicle

muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

The whole muscle is contained within an external

sheath extending from the tendons called

A

epimysium.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Fascicles within the muscle are enveloped by a sheath

called

A

perimysium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Single muscle fi bers within individual

fascicles are surrounded by a sheath called

A

endomysium.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Beneath the endomysium surrounding each muscle fi ber is

the plasma membrane of the muscle cell called

A

sarcolemma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

An individual skeletal muscle cell contains a densely

arranged parallel array of cylindrical elements called

A

myofi -

brils.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Each myofi bril is essentially an end-to-end chain of
regular repeating units.

repeating unit between
adjacent Z disks or Z lines

A

sarcomeres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

sarcomeres—that consist of
smaller interdigitating fi laments called

contain both thin fi laments and thick fi laments

A

myofi laments,

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

motor nerve axon contacts
each muscle fi ber to form a synapse near the middle of the
fi ber called the

A

neuromuscular junction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

The specialized
region of sarcolemma in closest contact with the presynaptic
nerve terminal is called the

A

motor end plate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

physiological excitation of skeletal muscle
always involves chemical activation by release of _____ from the motor nerve terminal. Binding of ACh
to the nicotinic receptor gives rise to a graded depolarizing _____

A

acetylcholine
(ACh)

end-plate potential.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

All skeletal muscle is under ____control by

motor neurons of the somatic motor system.

A

voluntary or reflex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

The group of muscle fi bers innervated by all of
the collateral branches of a single motor neuron is referred
to as a

A

motor unit.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

defi ned as the
number of muscle fi bers innervated by a single motor
neuron.

A

innervation ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Action potentials propagate from the
___to the interior of ____
along the _____network

A

sarcolemma .

muscle fi bers

muscle fi bers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

can enter the cytoplasm from the extracellular
space through voltage-gated ion channels, or alternatively,
can be released into the cytoplasm from the intracellular,storage reservoir of the sarcoplasmic reticulum.

A

Ca2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

SKELETAL MUSCLE

TRIAD:

A 
Sarcoplasmic
reticulum
cisterna
Sarcoplasmic
reticulum
cisterna
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

___ tubules penetrate
the muscle fi ber and surround the myofi brils at two points
in each sarcomere: at the junctions of the __and ___bands.

A

T

A and I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Depolarization of the T-tubule membrane results
in ___release from the sarcoplasmic reticulum
at the ____

A

Ca2+

Triad

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

EC coupling in skeletal muscle.

1.Mechanical coupling between
the L-type Ca2+ channel and the
Ca2+-release channel causes the
Ca2+-release channel to open.

2.Ca2+ entering the cell via L-type
Ca2+ channels also can activate
the Ca2+-release channels.
However, this pathway is not
essential in skeletal muscle.

3.Membrane depolarization opens
the L-type Ca2+ channel.

4.Ca2+ exits the SR via the
Ca2+-release channel and
activates troponin C, leading
to muscle contraction.

A

3,1,4,2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

The L-type

Ca2+ channel is also often referred to as the____

A

DHP receptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q 
it is inhibited by a class of antihypertensive and
antiarrhythmic drugs known as dihydropyridines.
A

L-type

Ca2+ channel /DHP receptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q 
The Ca2+-release channel in the SR is also known as the
\_\_\_\_\_because it is inhibited by a class of drugs
that include the plant alkaloids ryanodine and caffeine
A

ryanodine receptor

35
Q

T OR F

Striations of skeletal muscle fi bers correspond
to ordered arrays of thick and thin fi laments
within myofi brils

A

T

36
Q

______5 to 8 nm in diameter
and 1 μm in length. Thin fi laments are tethered together
at one end, where they project from a dense disk known as____

A

thin fi laments

Z disk (oriented perpendicular)

37
Q

___are 10 nm in diameter and, in striated

muscle, 1.6 μm in length

A

Thick fi laments

38
Q

_____ they are isotropic
to polarized light as .

The ____ is visible as a dark perpendicular line
at the center of the I band.

The dark bands, which represent
the myosin fi laments, are known as ___because they
are anisotropic to polarized light.

A

I bands

Z disk

A bands

39
Q

During contraction, the
A bands are ___ in length, whereas the I bands
___.

A

unchanged

shorten

40
Q

_____are supramolecular

assemblies of protein subunits

A

Thin and thick fi laments

41
Q

_____its backbone is a

double-stranded α-helical (F-actin)polymer of actin molecules

A

Thin Filaments

42
Q

F-actin is associated with two important
regulatory, actin-binding proteins: _____and
____.

A

tropomyosin
-molecules consist of two identical
α helices that coil around each other and sit near the two
grooves that are formed by the two helical actin strands.

and

troponin
-is a heterotrimer consisting of (1) troponin T
(TnT or TNNT), which binds to a single molecule of tropomyosin;
(2) troponin C (TnC or TNNC), which binds Ca2+;
and (3) troponin I (TnI or TNNI), which binds to actin and
inhibits contraction.

43
Q

___are also an intertwined complex of proteins.
is a bipolar assembly of ___
molecules

A

Thick Filaments

multiple myosin II

44
Q

_____Running alongside the thick fi laments of skeletal muscle
is a large protein. tethered from the M line.

____is another large protein
of muscle that runs from the Z disk along
the actin thin fi laments.

A

Titin

Nebulin

45
Q

An _______ triggers contraction by

removing the inhibition of cross-bridge cycling

A

increase in [Ca2+]i

thus initiates and allows cross-bridge cycling

46
Q

The ___ in [Ca2+]i is the signal to cease

cross-bridge cycling and to relax. ,

A

subsequent decrease

The tightly regulated
decrease in [Ca2+]i is achieved by transport processes that
remove Ca2+ from the sarcoplasm

47
Q

During the cross-bridge cycle, contractile
proteins convert the energy of ATP hydrolysis
into _______

A

mechanical energy

48
Q

In this rigid state, the myosin head is fi xed at a ___degree
angle with respect to the actin and myosin fi laments.

A

45-

ATTACHED STATE

Step 1: ATP binding.
—-ATP binds to myosin head, causing the
dissociation of the actin-myosin complex.

RELEASED STATE

Step 2: ATP hydrolysis.
—-ATP is hydrolyzed, causing
myosin heads to return to
their resting conformation.

COCKED STATE

Step 3: Cross-bridge formation.
—–A cross-bridge forms and
the myosin head binds to a
new position on actin.

CROSS-BRIDGE STATE

Step 4: Release of Pi from the myosin.
—-P is released. Myosin heads change
conformation, resulting in the power
stroke. The filaments slide past each other.

POWER-STROKE STATE

Step 5: ADP release.
—-ADP is released.
—-Dissociation of ADP from myosin completes
the cycle, and the actomyosin complex is left in a
rigid state. The myosin head remains in the same position
and at a 45-degree angle

49
Q

t or f

Because ATP stores are small, the cell
must regenerate the ATP needed for
muscle contraction

A

t

50
Q

Termination of contraction requires re-uptake of

Ca2+ into the ______

A

sarcoplasmic reticulum

51
Q

Mechanisms of Ca2+ removal from the cytoplasm.

1.Ca2+ is bound in the
sarcoplasmic reticulum by
calreticulin and calsequestrin.

2.Ca2+ pump sequesters
Ca2+ within the
sarcoplasmic reticulum.

3.Na–Ca and exchanger and Ca2+ pump in the
plasma membrane both extrude Ca2+ from the cell.

A

3,2,1

52
Q

____produce force or shortening
and, in the extreme, can be studied under either
isometric or isotonic conditions.

This force is referred to as the ___

A

Muscle contractions

tension

53
Q

stimulation causes an increase in tension, but no shortening.
Because these contractions occur at constant length, they are
referred to as ____

A

isometric contractions
(A constant
length)

attachment
points are immobile, thereby fi xing the muscle length.

54
Q

stimulation causes
shortening, provided the tension developed by the muscle is greater than the opposing load. Because these shortenings
occur at constant load, they are referred to as _______

A

isotonic contractions
(A constant
load)

one of the two attachment points is
mobile, and a force—or load—tends to pull this mobile
point away from the fi xed one.

55
Q

Muscle length infl uences tension development
by determining the_____between
actin and myosin fi laments

A

degree of overlap

56
Q

At _____, the velocity of shortening
is lower because more cross-bridges are
simultaneously active.

Under _____, the velocity of shortening
decreases as the applied load opposing contraction of the
muscle fi ber increases.

A

higher loads

isotonic conditions

57
Q

In a ___ fi ber, the force
developed may be ___ by summing
multiple twitches in time

A

single skeletal muscle

increased

58
Q

the muscle twitch far exceeds the duration
of the action potential, it is possible to initiate a second
action potential before a fi rst contraction has fully subsided.

A

summation.

59
Q

If multiple action potentials occur close enough in time,
the multiple twitches can summate and thus greatly increase
the tension developed.
depends
on the frequency of muscle stimulation.

A

frequency summation.

60
Q

cause the muscle tension to
remain at a steady plateau. The state in which the individual
twitches are no longer distinguishable from each other is
referred to as

A

tetanus

successive action potentials is insuffi cient to return enough
Ca2+ to the SR to lower [Ca2+]i below a level that initiates
relaxation

61
Q

In a ____, the force developed
may be ____by summing the contractions
of multiple fi bers

A

whole skeletal muscle

increased

62
Q

motor neuron cell body within the spinal cord is excited,
those muscle fi bers that are part of the motor unit of that
motor neuron are added to the contracting pool of fibers This effect is known as _____

A

multiple-fi ber summation

63
Q

The group of all motor

neurons innervating a single muscle is called

A

motor

neuron pool.

64
Q

Action potentials that propagate between
adjacent cardiac myocytes through ___
initiate contraction of cardiac muscle.

– link cells electrically

A

gap junctions

65
Q

The intercalated disks connecting
the ends of adjoining cardiac myocytes contain__

that link adjacent cells mechanically

A

desmosomes

66
Q

____requires Ca2+ entry through

L-type Ca2+ channels

A

Cardiac contraction

67
Q

t or f
Cross-bridge cycling and termination of cardiac
muscle contraction are not similar to the events in
skeletal muscle

A

f

similar

68
Q

In cardiac muscle, SR Ca2+ pump activity is inhibited

by the regulatory protein ____

A

phospholamban

69
Q

In cardiac muscle, increasing the entry of Ca2+

__the contractile force

A

enhances

70
Q

___ may contract in response to
either neuromuscular synaptic transmission or
electrical coupling

A

Smooth muscles

71
Q

____ of smooth muscles may be

brief or prolonged

A

Action potentials

72
Q

Each smooth muscle cell receives its own synaptic input.

Electrical isolation
of cells allows finer
motor control.

A

MULTIUNIT

73
Q

Only a few of the smooth muscle cells receive direct synaptic input.

Gap junctions
permit coordinated
contraction.

A

UNITARY

74
Q

Action potentials and slow waves in smooth muscle.

1.Slow hyperpolarization.

2.Ca2+-dependent
K+ channels close

3.Voltage-gated Ca2+
channels open

4.Ca2+ influx, rise in internal
Ca2+ concentration

5.Voltage-gated Ca2+ channels close;
internal Ca2+ concentration decreases

6.Action potential spike

7.Open Ca2+-dependent
K+ channels

A

3,6,4,7,1,5,2

75
Q

t or f
Some smooth muscle cells can initiate
not spontaneous electrical activity

A

f

can initiate spontaneous

results from pacemaker currents.

76
Q

In other smooth muscle cells, this spontaneous electrical
activity results in ___,____ in Vm. These
Vm oscillations occur at a frequency of several oscillations
per minute and are referred to as ___

A

regular, repetitive oscillations

slow waves

77
Q

t or f
Some smooth muscles contract without
action potentials

A

t

78
Q

t ot f
In smooth muscle, both extracellular and
intracellular Ca2+ can’t activate contraction

A

f

it activate

79
Q

Smooth muscle cells use three major pathways—

EC coupling in smooth muscle.

A
  1. Ca2+ Entry Through Voltage-Gated Channels

—-Ca2+ enters the cytoplasm
through channels located
in caveoli.

2.Ca2+ Release from the SR

------Ca2+ release from the sarcoplasmic
reticulum can occur either via
Ca2+-induced Ca2+ release or more
importantly, via IP3 activation of
SR Ca2+ channels.

3.Ca2+ Entry Through Voltage-Independent Channels
—-When the SR Ca2+ stores become
depleted, the SR signals—by an unknown
mechanism—a store-operated Ca2+
channel to open, allowing Ca2+ to enter.

80
Q

The cross-bridge cycle in smooth muscle is
controlled by ___ of myosin light
chain by myosin light chain kinase

A

phosphorylation

81
Q

Termination of smooth muscle contraction
requires ___ of myosin
light chain

A

dephosphorylation

82
Q

t or f
Smooth muscle contraction may also occur
independently of increases in [Ca2+]i

A

t

83
Q

In smooth muscle, contractile force is enhanced
by increasing the entry of Ca2+ as well as
by increasing the Ca2+ sensitivity of the
_____

A

contractile apparatus

84
Q

Smooth muscle maintains ___ force at __
energy consumption

This low-energy
consumption/high-tension state is referred to as the ___

A

high

low

latch
state

PHYSIOLOGY (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions