Brainscape's Knowledge GenomeTM

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


See full index

Physiology > Unit 2: Muscle Physiology > Flashcards

Unit 2: Muscle Physiology Flashcards

1
Q

What are the 3 types of muscle tissue?

A

1) Skeletal

2) Visceral/Smooth

3) Cardiac

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

The biggest quantity of muscle type (about 40% body mass) is:

A

skeletal muscle

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

Skeletal muscle is found:

A

Attached to skeleton

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

Skeletal muscle plays an important role in:

A

moving/positioning bones within the skeleton

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

Under the microscope, skeletal muscle is:

A

striated [striped pattern]
voluntary [has the potential to be controlled]

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

Which muscle type is voluntary?

A

Only skeletal

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

The 2nd most wide-spread muscle type is:

A

visceral muscle

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

Most of the _________ muscle type is associated with hollow internal structures/organs like intestines/airways

A

visceral

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

Under the microscope, visceral muscle:

A

NONstriated/ smooth muscle
involuntary

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

Cardiac muscle is only found-

A

within the structure of the heart

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

Under the microscope, cardiac muscle:

A

is striated [less so than skeletal muscle]
involuntary

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

What are the 3 basic muscle functions?

A

1) produce movement

2) maintaining posture [prevent movement]

3) heat generation

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

What are the 4 key characteristics of muscle?

A

1) Excitability

2) Contractibility

3) Extensibility

4) Elasticity

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

Muscle excitability is

A

the ability for the cells to change their electrical charge

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

_________ is responsible for electrical signaling within cells

A

Excitability

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

Contractility is the ability to

A

shorten the muscle

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

Extensibility is

A

After contraction, the muscle relaxes and lengthens again

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

Elasticity means

A

when a muscle is stretched, it will spring back to its original shape [force that opposes stretching]

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

the outer layer of the muscle cell is the

A

plasma membrane [sarcolemma]

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

The muscle’s plasma membrane is called

A

sarcolemma

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

The sarcolemma gets its unique name because

A

it forms invaginations [modifications of membrane called Transverse Tubules]

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

The Transverse Tubules pass right up against some key organelles:

A

smooth endoplasmic reticulum
AKA sarcoplasmic reticulum

&

Myofibril

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

The sarcoplasmic reticulum has been highly specialized for the purpose of

A

storing calcium

~internally holds large quantities of calcium

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

The 1-2-3 pattern associated with every T tubule is called

A

a triad

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

The Transverse tubule (really the whole triad) wraps around

A

a myofibril

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

The myofibril is made up of

A

Filament proteins [myofilaments]

~thick & thin overlapping filaments

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

The muscle cells are filled with ____________ that are responsible for production of ATP by way of aerobic mechanisms to fuel muscle contraction activity

A

mitochondria

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

The I band zone is ______ in color

A

Light

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

The A band zone is ______ in color

A

dark

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

The dark line in the center of the I band is the

A

Z line

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

The A band has a lighter center region called

A

H zone

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

The dark line in the center of the H zone is the

A

M line

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

The Z line represents the point where

A

All of the thin myofilaments are bound to each other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

The M line represents the point where

A

all of the thick myofilaments are bound to each other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

The repeating element from Z line to Z line is

A

Sarcomere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

The segment where thin and thick myofilaments overlap is called

A

the zone of overlap

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Contraction occurs in the

A

zone of overlap

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

The zone of overlap is responsible for

A

contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

The area with just thin filaments is the

A

I band

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

The area with thick filaments is the

A

A band

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

There are 3 proteins making up the structure of a thin myofilament:

A

~Actin [looks like a string of pearls/little balls]

~Troponin [responsible for linking tropomyosin complex to actin proteins & can interact w/ calcium]

~Tropomyosin [fibrous; linked to troponin; lays on actin binding sites]; behaves like a competitive inhibitor.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Actin is shaped in a way so it can interact with :

A

myosin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

When __________, the myosin heads latch on to actin and undergo power strokes that pull in the direction towards the middle of the sarcomere [left to right; right to left]

A

contracting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Cross-bridge formation occurs when myosin heads attach to binding sites on _______ which is part of the _______ filaments.

A

actin
thin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

The T-tubule is a part of:

A

the cell membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

identify B

A

I band

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

In a muscle cell at rest the sarcoplasmic reticulum contains an abundance of calcium, while the ________ does not contain any calcium.

A

sarcoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Which of muscle types is described “involuntary”?

A

multiunit smooth muscle
single unit smooth muscle
cardiac muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

The image above depicts a skeletal muscle cell. The structure labeled C (in yellow) is a tubular structure. What flows through that tube?

A

nothing “flows” through the tube, but it is filled with cytosol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Myosin molecules have binding sites for binding with:

A

ATP
Actin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

the excitation event in the transverse tubule triggers the sarcoplasmic reticulum to

A

release its calcium and flood the sarcoplasm

[triggering ion channels in the SR to open]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

The calcium attaches to binding sites on

A

the troponin component of the troponin-tropomyosin complex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

When the ________ & _______bind to each other, this is the trigger releasing energy of the spring

A

myosin and actin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

____ is necessary to get the muscle to relax

A

ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

The next contraction occurs by adding:

A

calcium

[not ATP]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Excitation of a skeletal muscle cell depends on:

A

a triggering event coming from outside, specifically from a neuron

[Somatic Alpha motor neuron]- will connect to a muscle cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

what is a synapse composed of?

A

Axon
Axon terminal
Synaptic vesicles
Synaptic cleft
Motor end plate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

Nerve impulses/action potentials travel down the axon towards the:

A

terminal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

Inside the axon terminal, it is filled with membrane bubbles called

A

synaptic vesicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

Synaptic vesicles are filled with

A

neurotransmitters [chemical signals]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

The extracellular gap between the axon terminal and another cell is called

A

synaptic cleft [aka synapse]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

The entire synapse [of skeletal muscle] is also called

A

neuromuscular junction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

___________ is a common neurotransmitter inside synaptic vesicles that determines whether a target cell becomes excited or not

A

Acetylcholine (ACH)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

The membrane of the post-synaptic muscle cell is called

A

motor end plate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

The _____ _______ _____ has receptors that can respond to neurotransmitter release by the neuron

A

motor end plate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

The combination of one neuron and all of the muscle cells it is connected to, so has control over, is called

A

a motor unit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

Motor units ______ overlap

A

do not

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

Each muscle cell is responding to one single __________, but each ________ can be controlling multiple muscle cells

A
  1. neuron
  2. neuron
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

If all 3 motor units stimulate their muscle cells at the same time, contracting in unison, this phenomenon is called ___________ which produces progressively increasing forces of contraction

A

recruitment/ spatial summation

70
Q

Spatial summation is when

A

the contractile forces of 3 motor units are added together

71
Q

The neuron (alpha motor neuron) excitation/ action potential arrives at the axon terminal and results in

A

exocytosis and release of neurotransmitter into synaptic cleft

72
Q

The neurotransmitter released into the synaptic cleft will bind to a receptor producing a __________________which will then travel along the membrane

A

transduction event (such as an electrical change)

73
Q

There are membrane channels within the T Tubule wall called:

A

L-type/ DHP membrane channels

74
Q

L-type/ DHP membrane channels go through a shape change and open in response to

A

excitation

75
Q

The ____________ is sometimes called the excitation-contraction coupler

A

calcium

[it couples the 2 events of excitation and contraction]

76
Q

The addition of calcium moves the troponin-tropomyosin complex so that myosin can now latch on to actin. This triggers:

A

the power stroke to occur

77
Q

_________ is necessary to get the myosin head released from actin and also to drive the energy of pulling the myosin head back into its high energy state

A

ATP

78
Q

After the excitation is over, all of the _________ is back in the sarcoplasmic reticulum

A

calcium

79
Q

A muscle twitch has _______________ contractile behavior

A

all or none

[rule can be broken]

80
Q

A muscle twitch has 3 parts:

A
  1. Latent period
  2. contractile interval
  3. relaxation interval
81
Q

It takes ___________________________ to shorten the sarcomere enough so we see movement of the Z-lines shortening the muscle and producing force.

A

hundreds of power strokes

82
Q

Muscle cells/ motor units don’t contract continuously, they only:

A

twitch

83
Q

muscles rarely ever fully ______

A

relax

84
Q

muscle tone ________ during sleep

A

decreases

85
Q

When muscle is relaxed, the myosin head will be in its ______________________________ state.

A

cocked and ready (high potential energy)

86
Q

Contraction of motor units in a(n) ________ manner allows a muscle to maintain a smooth level of force for a duration of time without fatiguing.

A

asynchronous / alternating

87
Q

Following a contraction, what is required to return the muscle to the relaxed state?

A

ATP binding to myosin

88
Q

Starting with a muscle at rest, what must happen to initiate a contraction (aka power stroke)?

A

Binding of calcium (Ca2+) to troponin on the thin myofilament

89
Q

The image above depicts a muscle twitch. The time interval labeled A (in yellow) represents the:

A

latent period

90
Q

The image above depicts a muscle twitch. The time interval labeled C (in blue) represents the:

A

relaxation interval

91
Q

A single neuron can connect to and control multiple muscle cells. This is called a:

A

motor unit

92
Q

What are the 2 types of muscle fibers?

A

Type 1- slow-twitch: aerobic

Type 2- fast-twitch: anaerobic

93
Q

The _____________ muscle cell fibers have the greatest density of capillaries surrounding them, so have a continuous exchange of oxygen, Co2, etc.

A

type 1 (slow-twitch) aerobic

94
Q

the_________fibers are darker in color due to myoglobin; fatigue-resistant
~also smaller in diameter

A

slow-twitch

95
Q

Fast-twitch fibers are lighter in color, and larger in diameter because they accumulate:

A

glycogen

this can be converted into glucose and burned during glycolysis to generate ATP anaerobically

96
Q

The distribution of muscle fiber types is determined how?

A

genetically disposed

(not based on training much).

97
Q

why do muscles fatigue? [primary factor]

A

the more you rely on anaerobic metabolism> more lactic acid is made> lactic acid acidifies the cell and changes protein shape> reduces muscle function> decreases ability of thin and thick filaments to interact> weaker muscle response

~fatigue may also be due to dependency on NS; NMJ running low on NTs>not enough NTs to stimulate muscles
~later on, may also be due to lack of ATP

98
Q

The ______________________ is found in the tendon and responds to anything that causes the tendon to stretch [force must be applied]

A

golgi tendon organ

99
Q

muscle spindles are housed in

A

inside the muscle

100
Q

muscle spindles are partially made of muscle cells and they respond to :

A

changes in the length of the muscle

[is it getting longer or shorter]

101
Q

the muscle group or muscle cells/fibers making up the muscle itself are called :

A

extrafusal cells/fibers

99.9% of muscle mass

102
Q

Enclosed in a wrapping of perimysium, the muscle fibers within the spindles are called:

A

intrafusal cells/fibers

103
Q

sensory receptors are always made from:

A

dendritic ends of neurons

104
Q

sensory endings are affiliated with intrafusal muscle cells within the spindle and they detect:

A

changes in length

105
Q

What are the 2 lower motor neuron types?

A
  1. alpha motor neurons [extrafusal fibers]
  2. gamma motor neurons [intrafusal fibers]
106
Q

The alpha motor neurons are the only neurons that connect to the

A

extrafusal cells

107
Q

__________ is the only muscle type without striations

A

smooth/visceral

108
Q

___________ are a consequence of the arrangement of thin and thick myofilaments

A

striations

109
Q

What are the 2 types of smooth muscle?

A
  1. single-unit [cells work as a collective group; “gap junctions”
  2. multi-unit [each cell functions independently]
110
Q

Single-unit smooth muscle is characterized by:

A

having lots of gap junctions

[causing cells to be intimately linked to each other, excitation of one cell leads to excitation of all cells> all cells contract]

111
Q

Smooth muscles are uniquely activated by

A

influx of calcium

[causes phosphorylation of myosin]

112
Q

smooth muscles have an active range, meaning

A

they can contract over a long range of stretch

113
Q

Smooth muscle has myogenic contraction, meaning

A

it can in itself (without nervous system intervention) respond to something that stretches it by contracting

114
Q

Single-unit smooth muscle may exhibit autorhythmic regulation, meaning

A

automatic generation of rhythym

115
Q

cardiac muscle is found :

A

exclusively in the heart

[not even in blood vessels]

116
Q

Cardiac muscles have less defined striations than skeletal muscles due to

A

Lower concentration of thin and thick myofilaments within cardiac muscle cells

117
Q

____________ in cardiac muscle cells intimately and strongly link cells together

A

Desmosomes [many of them]

118
Q

Interspersed with desmosomes, in cardiac muscle cells, there are lots of smaller protein junctions connecting the cells called

A

gap junctions

119
Q

________________ muscle cells contain abundant myoglobin

A

type 1 (slow-twitch) aerobic

120
Q

All muscles are induced to contract by excitation which is coupled to contraction. What serves as the coupler between excitation and contraction?

A

calcium (Ca2+)

121
Q

Muscles contain sensory receptors. The sensory receptor that would provide the necessary information to prevent excessively strong muscle contractions:

A

Golgi tendon organs

122
Q

___________________ muscle fibers fatigue quickly

A

Fast twitch (type II) anaerobic

123
Q

Which of the following muscle types may exhibit autorhythmicity?

slow twitch muscle
smooth muscle
fast twitch muscle
cardiac muscle
skeletal muscle

A

smooth
cardiac

124
Q

Activation of contraction in smooth muscle is unique.

Describe the regulation of contraction in smooth muscle

A

myosin binds to actin when triggered by ATP binding

125
Q

The sensory receptors found in muscle that are sensitive to changes in muscle length:

A

muscle spindles

126
Q

In smooth (aka visceral) muscle, calcium ions bind to ___________ in order to initiate contraction.

A

myosin light chain kinase (MLCK)

127
Q

Starting with a muscle at rest, which of the following must happen to initiate a contraction (aka power stroke)?

A

Binding of calcium (Ca2+) to troponin on the thin myofilament

128
Q

Myosin exhibits three different properties necessary to its role in contraction, what are they?

A

Tadpole like heads -uses energy to create movement

stiff rodlike sections intertwining to form a tail

elastic neck region joining the head to tail

129
Q

What is the functional significance of the troponin-tropomyosin complex?

A

it will lay on top of the actin proteins and covering the binding site on actin that myosin can latch on to.

[actin binding site is covered, producing the resting state].

130
Q

Describe the evidence supporting the sliding filament theory (as opposed to filament shortening)

A

electron micrographic imagery -

Electron microscopy studies have revealed the detailed structure of muscle cells, showing that myofibrils, the contractile units of muscle, contain repeating sarcomeres. Sarcomeres consist of thin (actin) and thick (myosin) filaments arranged in a highly organized pattern.

131
Q

Steps of muscle contraction cycle

A

1) ATP binds to myosin; myosin releases actin

2) myosin hydrolyzes ATP; ATP rotates myosin head to cocked position; myosin binds weakly to actin

3) power stroke begins when calcium binds to troponin; tropomyosin moves off the binding site

4) myosin releases ADP at the end of power stroke; cycle can begin again

132
Q

Explain in detail ALL of the events leading up to contraction beginning at the time the nerve impulse (action potential) arrives at the neuron terminal of the neuromuscular junction

[steps of calcium signals initiating skeletal muscle contraction]

A

1) Calcium levels increase in cytsol

2) Calcium binds to troponin

3) troponin-calcium complex pulls tropomyosin away from actin’s myosin binding site

4) myosin binds strongly to actin and completes power stroke

5) actin filament moves

133
Q

What is a muscle twitch?

A

a single contraction-relaxation cycle in a skeletal muscle fiber

134
Q

Define and describe what is occurring during the latent, contraction and relaxation intervals of a muscle twitch

A

latent- time between stimulus and beginning of twitch

contraction- period of time where the actin-myosin molecules are binding and cycling and the sarcomere is shortening, producing force

relaxation- after the peak of contraction; fewer myosin heads are active

135
Q

What does “all-or-none” mean?

A

in response to a single excitation from a neuron, we should get the same muscle response each time- a twitch of the same strength each time.

if no excitation, no twitch.

136
Q

Define “temporal summation”. Describe temporal summation as it applies to a single muscle cell.

A

A single cell twitches, and continues to twitch in rapid succession, each twitch separated by a little bit of time

A muscle cell contracts repeatedly and rapidly, so that the next contraction occurs before the previous one has totally relaxed.

Twitches will piggyback, level of force increases
AKA piggyback phenomenon

137
Q

Describe and explain how the initial length of the muscle cell (or sarcomere) influences the contractile strength of the muscle cell.

A

There is a curve showing the starting length of the sarcomere impacts contraction strength

if sarcomere is too short at the start, or too long at the start, we’re not generating as much force as we could

but if the sarcomere is at its anatomic length, it is lined up so that it can generate the maximum force possible

138
Q

Define “oxygen debt”.

A

anytime a muscle’s endurance is pushed, oxygen debt is incurred

if muscles start borrowing from reserves to meet their metabolic needs (to be able to continue contracting), at the end of the activity, muscle has debt to pay back> need to maintain an elevated level of oxygen even after the activity ends to pay back the incurred oxygen debt

139
Q

In multi-unit smooth muscle, all cells receive :

A

independent autonomic stimulation

140
Q

The muscle characteristic of contractility is secondary to:

A

Excitability

141
Q

________ is a motor protein with the ability to create movement

A

Myosin

142
Q

the _______________ is the recipient of the excitation event/action potential that travels down the axon

A

axon terminal

143
Q

The action potential triggers the axon terminal to :

A

undergo exocytosis and some of the synaptic vesicles will migrate to the membrane and release contents by exocytosis

144
Q

The electrical/excitation events are limited to the-

A

membrane

145
Q

When the skeletal muscle is in the resting stage, it is in a ________ energy state

A

high

[myosin head already in high energy state]

146
Q

what triggers the power stroke?

A

myosin head latches onto actin

147
Q

Muscle cells only _______, they do not contract continuously. But a whole muscle will contract continuously.

A

twitch

148
Q

How does a whole muscle contract continuously?

A

by alternating timing between motor units

motor unit 1 twitches, relaxes
motor unit 2 twitches, relax
motor unit 3 twitches, relax
^^^alternating repeating pattern > steady state of contraction

149
Q

Physiological tetanus is a state of:

A

continuous contraction induced by stimulating a muscle cell with very rapidly repeating stimuli; the cell will never have an opportunity to relax> stuck at high energy contraction

150
Q

Physiological tetanus can be produced-

A

only in lab setting

151
Q

what is muscle fatigue?

A

the muscle fails to continuously generate the same amount of power outlet over time

the muscle gets weaker and weaker with repetitive use

152
Q

Explain how a muscle can contract continuously without any of the cells within the muscle contracting continuously.

A

asynchronous motor unit recruitment. This ensures that while some muscle fibers are contracting, others are relaxing, creating a coordinated and continuous muscle contraction.

153
Q

Describe the pattern of motor unit recruitment as muscle contraction strength increases. How does this influence the fine control of a muscle as contraction strength increases?

A

the pattern of motor unit recruitment plays a crucial role in maintaining fine control of a muscle as contraction strength increases; It allows for a graded and precise response to varying strength demands while ensuring that the muscle remains adaptable, efficient, and resistant to fatigue during a wide range of activities.

154
Q

During skeletal muscle contraction, Z lines:

A

move closer together

155
Q

During skeletal muscle contraction, the I band:

A

gets smaller

156
Q

During skeletal muscle contraction, overlap between ______________ increases

A

thick and thin filaments

157
Q

Following death, rigor mortis occurs due to:

[2 reasons]

A

insufficient ATP is available to bind to myosin, without ATP myosin cannot detach from actin

increased accumulation of calcium in the sarcoplasm as SR calcium pumps shut down due to insufficient ATP, increased calcium results in exposure of actin-binding sites and actin-myosin binding

158
Q

Transverse tubules (aka T-tubules) are membranous tubes that are continuous with (made of the same membrane as):

A

the sarcolemma

159
Q

Most of the calcium ions in skeletal muscle are sequestered (stored) in the:

A

sarcoplasmic reticulum

160
Q

Both cardiac muscle and single unit smooth muscle are characterized by an abundance of these intercellular structures:

A

gap junctions

161
Q

Beginning from the resting state, skeletal muscle contraction begins when:

A

calcium ions (Ca2+) bind to troponin

162
Q

The functional group composed of a single alpha motor neuron and all of the muscle cells the motor neuron controls (innervates) is called a:

A

motor unit

163
Q

Following contraction, skeletal muscle relaxation cannot occur until:

A

ATP binds to myosin heads

164
Q

What functions as the link (aka coupler) between the process of muscle cell excitation and muscle cell contraction?

A

calcium ions (Ca2+)

165
Q

The process of sequestering (aka storing) calcium in muscle cells is due to active pumping of calcium ions that is occurring:

A

at all times

166
Q

The sensory receptor that is sensitive to changes in muscle length (but not muscle tension) is the:

A

muscle spindle

167
Q

The contraction of a single muscle fiber, called a twitch, is typically described as an all-or-nothing event. However, the strength of a single cells twitch can actually increase or decrease as a result of variations in:

A

the initial length of the cell
the frequency of the stimulus applied

168
Q

What gets shorter when a muscle contracts:

A

I bands
H zone
Sarcomere

169
Q

What is the name of the specific segment indicated by #2?

A

H zone

170
Q

]Which transition (A->B, B->C….) represents the powerstroke?

A

B->C

171
Q

What must be added at point 1 to transition from C to D?

A

ATP

Physiology (20 decks)

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