Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Chapter 9 Muscles and Muscle Tissue > Muscles and Muscles Tissue Part B > Flashcards

Muscles and Muscles Tissue Part B Flashcards

(99 cards)

Start Studying
1
Q

Whole Muscle Contraction

A

Same principles apply to contraction of both single fibers and whole muscles

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

muscle tension

A

Contraction produces muscle tension, the force exerted on load or object to be moved

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

Contraction may

A

may/ may not shorten muscle

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

Isometric contraction

A

no shortening; muscle tension increases but does not exceed load numbers

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

Isotonic contraction

A

muscle shortens because muscle tension exceeds load

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

Force and duration of contraction

A

contraction vary in response to stimuli of different frequencies and intensities.

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

Each muscle is served

A

by at least one motor nerve

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

Motor nerve contains

A

axons of up to hundreds of motor neurons

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

Axons branch

A

into terminals, each of which forms NMJ with single muscle fiber

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

Motor unit define

A

is the nerve-muscle functional unit

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

Motor unit

A

unit consists of the motor neuron and all muscle fibers (four to several hundred) it supplies
Smaller the fiber number, the greater the fine control

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

The smaller fiber number is

A

the greater the fine control

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

Muscle fibers from a motor unit

A

are spread throughout the whole muscle, so stimulation of a single motor unit causes only weak contraction of entire muscle

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

Muscle twitch

A

simplest contraction resulting from a muscle fiber’s response to a single action potential from motor neuron

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

In muscles twitch the muscles fiber

A

Muscle fiber contracts quickly, then relaxes

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

Myogram

A

is when twitch can be observed and recorded

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

Tracing

A

line recording contraction activity

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

Three phases of muscle twitch

A

Latent period
Period of contraction
Period of relaxation

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

Latent period

A

events of excitation-contraction coupling.

No muscle tension seen

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

Period of contraction

A

cross bridge formation

Tension increases

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

Period of relaxation

A

Ca2+ reentry into SR

Tension declines to zero

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

Muscle contracts

A

faster than it relaxes

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

Differences in strength and duration of twitches causes

A

are due to variations in metabolic properties and enzymes between muscles.

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

Example twitches

A

eye muscles contraction are rapid and brief, whereas larger, fleshy muscles (calf muscles) contract more slowly and hold it longer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Normal muscle contraction
is relatively smooth, and strength varies with needs
26
A muscle twitch is seen
only in lab setting or with neuromuscular problems, but not in normal muscle
27
Graded muscle responses
vary strength of contraction for different demands | Required for proper control of skeletal movement
28
Responses are graded by:
Changing frequency of stimulation | Changing strength of stimulation
29
Muscle response
to changes in stimulus frequency
30
Single stimulus
results in single contractile response (i.e., muscle twitch)
31
Wave Temporal summation
results if two stimuli are received by a muscle in rapid succession.
32
Muscle fibers do not have time
completely relax between stimuli, so twitches increase in force with each stimulus
33
Additional Ca2+ that
is released with second stimulus stimulates more shortening
34
If stimuli frequency increases
muscle tension reaches near maximum
35
Produces smooth
continuous contractions that add up (summation)
36
Further increase in stimulus frequency
frequency causes muscle to progress to sustained, quivering contraction referred to as unfused (incomplete) tetanus
37
fused (complete) tetanus
because contractions “fuse” into one smooth sustained contraction plateau
38
Prolonged muscle contractions
lead to muscle fatigue
39
Recruitment (or multiple motor unit summation):
stimulus is sent to more muscle fibers, leading to more precise control
40
Types of stimulus involved in recruitment:
Subthreshold stimulus Threshold stimulus Maximal stimulus
41
Subthreshold stimulus
stimulus not strong enough, so no contractions seen
42
Threshold stimulus
stimulus is strong enough to cause first observable contraction
43
Maximal stimulus
strongest stimulus that increases maximum contractile force
44
All motor unit
have been recruited
45
Recruitment works
on size principle
46
Motor units with smallest
muscle fibers are recruited first
47
Motor units with larger
larger fibers are recruited as stimulus intensity increases
48
Largest motor units
activated only for most powerful contractions
49
Motor units in muscle
usually contract asynchronously
50
Some fibers contract
while others rest, | Helps prevent fatigue
51
Muscle Tone
Constant, slightly contracted state of all muscles. Due to spinal reflexes
52
Groups of motor units
alternately activated in response to input from stretch receptors in muscles
53
Muscle Tone
Keeps muscles firm healthy, and ready to respond
54
Isotonic contractions
muscle changes in length and moves load. Isotonic contractions can be either concentric or eccentric:
55
Concentric contractions and examples
muscle shortens and does work | Example: biceps contract to pick up a book
56
Eccentric contractions and examples
muscle lengthens and generates force. Example: laying a book down causes biceps to lengthen while generating a force
57
Isometric contractions
Load is greater than the maximum tension muscle can generate, so muscle neither shortens nor lengthens
58
Electrochemical and mechanical events
same in isotonic or isometric contractions, but results are different
59
In isotonic contractions
actin filaments shorten and cause movement
60
In isometric contractions
cross bridges generate force, but actin filaments do not shorten.
61
Myosin heads
“spin their wheels” on same actin- binding site
62
ATP supplies the energy needed for the muscle fiber | first to:
Move and detach cross bridges
63
ATP supplies the energy needed for the muscle fiber second to:
Pump calcium back into SR
64
ATP supplies the energy needed for the muscle fiber third to:
Pump Na+ out of and K+ back into cell after excitation-contraction coupling
65
Available stores of ATP
depleted in 4–6 seconds
66
ATP is the only source of energy
for contractile activities; therefore it must be regenerated quickly
67
ATP is regenerated quickly by three mechanisms:
Direct phosphorylation of ADP by creatine phosphate (CP) Anaerobic pathway: glycolysis and lactic acid formation Aerobic pathway
68
Creatine phosphate
is a unique molecule located in muscle fibers that donates a phosphate to ADP to instantly form ATP
69
Creatine kinase
kinase is enzyme that carries out transfer of phosphate
70
Muscle fibers have enough ATP
and CP reserves to power cell for about 15 seconds
71
Muscle fibers have enough ATP
CP reserves to power cell for about 15 seconds
72
Creatine phosphate + ADP →
creatine + ATP
73
ATP can also be generated
by breaking down and using energy stored in glucose
74
Glycolysis
first step in glucose breakdown. Does not require oxygen. Glucose is broken into 2 pyruvic acid molecules. 2 ATPs are generated for each glucose broken down
75
Low oxygen levels prevent pyruvic acid
from entering aerobic respiration phase
76
Normally, pyruvic acid enters
mitochondria to start aerobic respiration phase; however, at high intensity activity, oxygen is not available
77
Bulging muscles compress
blood vessels, impairing oxygen delivery
78
In the absence of oxygen
referred to as anaerobic glycolysis, pyruvic acid is converted to lactic acid.
79
Lactic acid
Diffuses into bloodstream. Used as fuel by liver, kidneys, and heart. Converted back into pyruvic acid or glucose by liver
80
Anaerobic respiration yields only
5% as much ATP as aerobic respiration, but produces ATP 2½ times faster
81
Aerobic Respiration
Produces 95% of ATP during rest and light-to-moderate exercise. Slower than anaerobic pathway
82
Aerobic Respiration consist of
of series of chemical reactions that occur in mitochondria and require oxygen
83
Aerobic Respiration breaks
glucose into CO2, H2O, and large amount ATP (32 can be produced)
84
Fuels used include (Aerobic Respiration)
glucose from glycogen stored in muscle fiber, then bloodborne glucose, and free fatty acids.
85
Fatty acids(Aerobic Respiration)
are main fuel after 30 minutes of exercise
86
Energy systems used during sports
Aerobic endurance | Anaerobic threshold
87
Aerobic endurance
Length of time muscle contracts using aerobic pathways | Light-to-moderate activity, which can continue for hours
88
Anaerobic threshold
Point at which muscle metabolism converts to anaerobic pathway
89
Muscle Fatigue
Fatigue is the physiological inability to contract despite continued stimulation
90
Possible causes of muscles fatigue include:
Ionic imbalances can cause fatigue | Levels of K+, Na+ and Ca2+ can change disrupting membrane potential of muscle cell
91
Increased inorganic phosphage
(Pi) from CP and ATP breakdown may interfere with calcium release from SR or hamper power
92
Decreased ATP and increases magnesium.
As ATP levels drop magnesium levels increase and this can interfere with voltage sensitive T tubule proteins
93
glycogen
decreases in muscles fatigue
94
Lack of ATP
rarely a reason for fatigue, except in severely stressed muscles
95
Excess Postexercise Oxygen Consumption
All replenishing steps require extra oxygen. | Formerly referred to as “oxygen debt”
96
muscles pre-exercise state:
Oxygen reserves are replenished.
97
muscles pre-exercise state:
Lactic acid is reconverted to pyruvic acid
98
muscles pre-exercise state:
Glycogen stores are replaced
99
muscles pre-exercise state:
ATP and creatine phosphate reserves are resynthesized

Chapter 9 Muscles and Muscle Tissue (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions