Brainscape's Knowledge GenomeTM

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


See full index

Physiology > SM 1 > Flashcards

SM 1 Flashcards

1
Q

Sarcomeres Shorten During Contraction
• Zone of Overlap —
• I-Band —
• H-Zone —

A

Increases
Decreases
Decreases

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

The thin filament

A 
is composed of 
actin (with G-actin molecules, the 
active site which binds myosin), 
tropomyosin, and troponin 
(which binds actin, tropomyosin, 
and calcium).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The myosin (thick) filament

A 
has 
multiple cross-bridges where the 
“heads” can bind to the G-actin 
molecule.  
Myosin also functions as an 
ATPase enzyme.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Dystrophin Protein connects thin filaments to

A

glycoproteins in sarcolemma

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

Dystrophin-Glycoprotein Complex provides

A

scaffolding

for sarcomeres

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

Muscular Dystrophies (5)

A

a. Duchenne
b. Beckers
c. Myotonic
d. Oculopharyngeal
e. Limb Girdle

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

The alpha motor neuron
releases – which binds to
a

A

ACh
nicotinic ACh receptor (NM)
on the muscle fiber

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

Botulinum toxin A inhibits the

release of

A 
ACH at the 
neuromuscular junction. 
Botox can be used in 
dentistry (Bruxism, 
Sialorrhea, Masseteric 
Hypertrophy, etc.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

For contraction to occur, the intracellular calcium

in the muscle fiber must —

A

increase

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

in resting muscle,
tropomyosin prevents a
strong bond between the

A

myosin head and G-actin

molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q 
When troponin binds to 
cytosolic Ca++, 
tropomyosin is pulled 
away from the myosin 
binding site, and allows 
for the
A

power stroke

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

Sarcoplasmic Reticulum (SR):

A

modified ER that sequesters Ca2+

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

Transverse (T)-Tubules:

A

invaginations of sarcolemma

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

Terminal Cisternae:

A

Portion of SR that contact T-tubules

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

Calcium is released from the Sarcoplasmic Reticulum (2)

A

a.The AP travels down the membrane, down T-tubules, & activates
voltage-sensitive dihydropyridine (DHP) receptors on the T-
tubules. These in turn open calcium channels (ryanodine
receptors) on the SR. Calcium goes from SR to the sarcoplasm.
b.The intracellular structure of myocytes ensures spread of action
potential (and calcium) throughout the cell

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

ATP is Necessary for Contraction (3)

A
  1. ATP binding to the myosin head breaks the cross-bridge
    (connection between actin and myosin).
  2. Energy released from ATP hydrolysis by the myosin head
    provides energy for cocking the myosin head (myosin is
    now in the high energy form).
  3. Release of inorganic phosphate from the myosin head
    provides energy for the POWER STROKE (myosin head
    pulling actin towards the center of the sarcomere). This
    shortens the sarcomere.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Muscle cells only have enough ATP for ~– twitches.

A

8

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

Both (2) produce ATP for muscle

fibers.

A

Aerobic and Anaerobic Metabolism

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

However, the contribution of each in a specific muscle fiber depends on (2)

A

(1) the metabolic enzymes are present in the cell (ex. glycolytic
fibers versus oxidative fibers)
(2) the intensity of the exercise.

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

Sources of ATP (3)

A

aerobic/anaerobic metabolism

phosphocreatine

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

Measurement of Creatine
Kinase (CK) levels in the
blood is done to determine if

A 
damage to muscle tissue 
(skeletal and cardiac) has 
occurred (ex. heart attack or 
muscular dystrophy). 
Different isoforms of CK are 
found in skeletal versus 
cardiac muscle.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Fatigued muscles: (3)

A

1.have decreased tension generation,
2.take longer to contract
3.relax more slowly and may not completely
relax.

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

SKIPPED

Theories for fatigue: (6)

A
  1. Change in membrane potential
  2. Decreased ACH
  3. Blockage of blood flow
  4. Central Fatigue
  5. Increased metabolic byproducts
  6. Depleted glycogen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Both (2) must be present for cross-bridge

cycling.

A

Calcium and ATP

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

SKIPPED

Cross-Bridge Cycling (Sliding Filament Theory) (5)

A

A. Rigor State: myosin and actin are tightly bound
B. ATP binds myosin, decreases its affinity for
actin, and the two separate
C. Myosin head moves in the direction of the Z line,
ATP is hydrolyzed
D. Myosin binds the next actin (one closer to Z line)
and power stroke occurs (pulls actin toward the
M Line)
E. ADP is released and the actin and myosin
resume the brief rigor state

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

Relaxation of Skeletal Muscle (2)

A
  • The alpha motor neuron must stop firing

* Cytosolic (intracellular) calcium concentrations must decrease

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

Cytosolic (intracellular) calcium concentrations must decrease (3)

A

A. Calcium ATPases on SR remove calcium from
cytosol
B. Tropomyosin moves, and covers actin’s myosin-
binding site
C. Actin slowly slides back to its original resting place
and the sarcomere returns to its original length.

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

For relaxation to occur, — must be removed,
but — must be present to release myosin from
actin. Otherwise, rigor state is maintained.
Rigor Mortis?

A

Calcium

ATP

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

Diversity of Skeletal Muscle Fibers

3 Types

A

Slow-Twitch: Type I
Fast-Twitch:
Oxidative-Glycolytic: Type IIA
Glycolytic: Type IIB

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

Changes in Size (3)

A
  1. Hypertrophy
  2. Atrophy
  3. Sarcopenia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

The thickness of the jaw muscles decreases

significantly with

A

age, which is caused primarily by a
decrease in the cross-sectional area of their
fibers. These
changes might be explained by the
progressive reduction in the number and the
total duration of activity bursts per day with
age.

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

Certain Characteristics of Skeletal Muscle Fibers

Can Change in Response to Use (2)

A

changes in size

changes in fiber types

33
Q

Human jaw muscles are different from
other skeletal muscle. Human jaw
closing muscles are composed of a
relatively homogenous mixture of

A

type I
and II fibers, the type II fibers being
much smaller than the type I

34
Q 
The fibre-type composition of the 
jaw muscles also changes with age. 
In the jaw-closing muscles of 
elderly subjects, the proportion of 
pure type -- fibres decreases, while 
the proportion of pure type -- fibres 
and that of hybrid fibres increase
A

I

II

35
Q

Motor Units:

A

a motor unit is the alpha motor neuron

and the muscle fibers it innervates

36
Q

Motor units are recruited in order of size (2)

A

a. Small motor units are
recruited first
b. Smallest motor units
control fewer fibers

37
Q 
An increase in the number 
of motor units activated 
increases the total tension 
produced by contraction of 
a muscle—
A

SPATIAL

SUMMATION

38
Q

— Recruitment

A

Asynchronous

39
Q

Small motor units (X) are composed of

A

slow-twitch
oxidative fibers. They have the lowest threshold for
firing and are recruited first.

40
Q

Larger motor units (Z) are composed of

A

fast-twitch
glycolytic fibers. They have the highest threshold
and are recruited last

41
Q

Motor units in jaw muscles are
restricted to specific areas of the
jaw muscles, which permits

A

differential control of separate

muscle portions.

42
Q

Types of Contraction: the amount of (2) determines the type of
contraction

A

load and the

force the muscle generates

43
Q

ISOMETRIC CONTRACTION.

A

Force produced is

less than the load; no movement.

44
Q

ISOTONIC CONTRACTION.

A

Force produced is

great enough to move a load

45
Q 
The force of 
contraction 
increases until 
the isometric 
contraction 
becomes an
A

isotonic
contraction—
NOT always
possible!

46
Q 
The contraction with 
the -- gram load is 
isometric because the 
muscle is not strong 
enough to move the 
load and shorten. The 
maximum isometric 
contraction only 
produces -- grams of 
tension.
A

20

17

47
Q

ncrease total force by (2)

A

(1) increasing the frequency of fiber activation
and/or
(2) increasing the number of muscle fibers contracting (motor
unit recruitment).

48
Q

An increase in the frequency of α motor neuron

stimulation will increase the amount of

A

tension produced.
The tension produced in response
to each action potential will sum if the muscle
has not yet completely relaxed.

49
Q

For a single muscle twitch (one muscle fiber), the

tension developed is altered by

A

sarcomere length

50
Q

Optimal length is where there is the best degree of overlap

between the

A

thick and thin filaments.

51
Q 
At the optimal length 
the greatest number of 
actin/myosin cross-
bridges can form, 
which results to
A

maximal tension

production.

52
Q 
Tension is reduced if 
the muscle (2)
A

is not
stretched enough or if it
stretched too much.

53
Q

The velocity of contraction (distance moved/time)

depends on the

A

load a fiber is contracting against.

54
Q

The greater the load, the
– the speed of
contraction.

A

SLOWER

55
Q

Load isn’t the only factor that dictates the speed of contraction. — dictates it, too. For example,

A

Fiber Type

Type I fibers have an isoform of myosin with
slower ATPase activity while type II fibers have fast myosin ATPase.

56
Q

Skeletal Muscle Reflexes (2)

A

A. Stretch Reflex (Muscle Receptors)
B. Golgi Tendon Reflex (Tendon
Receptors)

57
Q

Extrafusal Fibers

A

Skeletal muscle fibers/cells that produce the

contraction.

58
Q

Alpha Motor Neuron:

A

Efferent neuron that
releases ACh and causes contraction of
the extrafusal fiber (skeletal muscle).

59
Q

Muscle Spindle

A

Small structure within the extrafusal fibers that
contains Intrafusal Fibers that have sensory
nerve endings wrapped around them that are
sensitive to CHANGES IN MUSCLE LENGTH.

60
Q

Gamma Motor Neuron:

A

Efferent neuron
that causes contraction of intrafusal
fibers so they mimic what the EF fibers
are doing.

61
Q 
Jaw --- have 
a lot of muscle 
spindles. 
Jaw --- have 
few to none.
A

closers

openers

62
Q

Components of the Muscle Spindle:

sensitive to

A

muscle length

63
Q

SKIPPED

The Stimulus for the Muscle Spindle Reflex is Stretch

A
  1. When the muscle stretches, the sensory fibers of the muscle
    spindle are squeezed.
  2. Afferent information enters the spinal cord and
    a. Activates the alpha motor neuron.
    i. This stimulates muscle (extrafusal fiber) contraction.
    ii. There is also simultaneous inhibition of the alpha motor
    neuron of antagonistic muscles.
    b. Also activates the gamma motor neuron.
    i. This stimulates intrafusal fiber contraction.
    ii. If the intrafusal fibers did not contract, the sensory fibers
    would not be able to sense a further change in muscle
    length since they would be slack.
64
Q

The Effect of Muscle Spindle Activation is

A

Contraction.
The reflex has dynamic (immediate) and static (maintains
tone—constant contraction) reflex components

65
Q

Anytime the alpha motor neuron is activated, the – motor

neuron is also activated.

A

gamma

66
Q 
Anytime the alpha motor neuron is activated, the gamma motor 
neuron is also activated.
This allows the 
muscle spindle to 
maintain
A

sensitivity
to changes in
muscle length.

67
Q

if the intrafusal fibers did not contract, the sensory fibers would not
be able to sense a further change in

A

muscle length since they

would be slack.

68
Q

Golgi Tendon Organs:

A 
Mechanosensitive receptors 
found at the junction of 
tendons and muscle.  
Sensitive to a change in 
FORCE.
69
Q

The Golgi Tendon
Organ Reflex is a
— reflex.

A

protective

70
Q

SKIPPED
The Stimulus for the Golgi Tendon Organ
(GTO) Reflex is Tendon Stretch (2)

A 
1. Tendons stretch in response to 
contraction (particularly isometric
—maximal—contractions)
2. Extreme stretch of the tendon will 
squeeze the GTO and afferent 
neurons will send information into 
the spinal cord
a. Stimulates an inhibitory 
interneuron.  
b. This neuron decreases the 
activity of the alpha motor 
neuron
c. Skeletal muscle contraction is 
decreased (relaxation)
71
Q

SKIPPED

control of mastication (4)

A

• A mix of voluntary, reflex and central (subconscious)
processes.
• Requires coordination of muscles controlling lips, tongue
and cheeks.
• Voluntary control is usually bilateral, although people tend
to favor one side of the mouth over the other.
• Central component; mastication is a cyclical movement
with develops early in life. It is controlled by the Central
Pattern Generator (CPG) of the brainstem, which when
stimulated, elicits rhythmic, coordinated activation and
inactivation of jaw-closers and jaw-openers.

72
Q

The — cannot by itself adjust muscle force to
deal with changing conditions that occur when different foods are
chewed. Reflexes are important modifiers of force.

A

Central Pattern Generator

73
Q

Input from higher cortical regions can regulate

the CPG frequency via the

A

Corticobulbar

Pathway

74
Q

Jaw opening reflex (2)

A

– Pain inhibits the alpha motor neuron of jaw closing muscles such as
when you bite down on your tongue, a metal spoon, with your
incisors
– Jaw opens

75
Q

Jaw jerk reflex (3)

A 
– Strong tap to the chin stretches the 
jaw closers
– The jaw closers respond by 
contraction so the jaw closes
– Stretch reflex
76
Q

SKIPPED
How do you determine the force needed to
take a bite of something hard?

A

• CPG starts chewing by activating jaw closing muscles
• When the jaw closing muscles connect with the food (ex.
carrot), they initially meet with resistance:
– The force of contraction is initially insufficient to
overcome the load (carrot) – isometric contraction
– Intrafusal fibers in muscle spindle are still contracting and
stretching the muscle spindle so this signals further
contraction of jaw closing muscles
• Constant feedback from the muscle spindle in the jaw
closing muscles is sufficient to overcome the load of the
carrot — isotonic contraction

77
Q

With subsequent chewing strokes, the response is greater and
matches the load of the food with appropriate force more —.

A

quickly

78
Q

SKIPPED

Protection by Muscle Spindles

A

• To crack a nut, a tremendous amount of force is required.
Once the nut cracks, there is potential to damage the intra-
oral structures.
• Muscle spindles decrease the contraction in these
situations.
– When the nut cracks, the force is now greater than the
load (nut).
– At this point, there is more slack in the muscle spindle
which leads to less activation of the muscle (due to
decreased alpha/gamma co-activation).

79
Q

Powerful isometric contractions stimulate both jaw closing and
opening muscles. The jaw openers keep the jaw from

A

snapping shut.

Physiology (53 decks)

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