Chapter 9 Flashcards
(113 cards)
1
Q
Muscle tissue is specialized for _____.
A
muscle contraction
2
Q
Three types of muscle tissue
A
Skeletal muscle tissue
Cardiac muscle tissue
Smooth muscle tissue
3
Q
Is skeletal muscle voluntary or involuntary?
A
voluntary
4
Q
Is cardiac muscle voluntary or involuntary?
A
involuntary
5
Q
Is smooth muscle voluntary or involuntary?
A
involuntary
6
Q
Six functions of skeletal muscle tissue
A
Produce skeletal movements Maintain posture and body position Support soft tissues Guard entrances and exits Maintain body temperature Provide nutrient reserves
7
Q
Dense layer of collagen fibers surrounding entire muscle
Separates muscle from surrounding tissues and organs
A
Epimysium
SKeletal muscle
8
Q
Fibrous layer that divides muscle into bundles of fibers called muscle fascicles
Contains collagen and elastin fibers, blood vessels, and nerves
A
Perimysium
Skeletal muscle
9
Q
Delicate connective tissue surrounding individual muscle fibers
Contains capillaries, myosatellite cells, and axons of neurons that control muscle fibers
A
Endomysium
Skeletal muscle
10
Q
Bundle of fibers that attach muscle to bone
A
tendon
11
Q
Sheet of fibers that attaches muscle to broader area
A
aponeurosis
12
Q
What do skeletal muscle cells develop from?
A
myoblasts
13
Q
Instead of fusing, a few myoblasts remain as _____ cells in endomysium and aid in muscle repair
A
myosatellite
14
Q
Many nuclei = many genes = faster _____ production
A
protein
15
Q
How many nuclei does a skeletal muscle cell contain?
A
hundreds
16
Q
Skeletal muscle cell
A
muscle fiber
17
Q
Skeletal muscle cell membrane
A
sarcolemma
18
Q
Skeletal muscle cytoplasm
A
sarcoplasm
19
Q
Skeletal muscle endoplasmic reticulum
A
sarcoplasmic reticulum
20
Q
Each is banded and gives the skeletal muscle cells their banded appearance
A
myofibrils
21
Q
Thin filaments composed mostly of _____
A
actin
22
Q
Thick filaments composed primarily of _____
A
myosin
23
Q
Repeating functional units of skeletal muscle fiber
A
sarcomeres
24
Q
Thin and thick filaments interspersed
A
Zone of overlap
25
Boundary between adjacent sarcomeres
Z lines
26
Connects central portion of each thick filament
M lines
27
Darker, dense sarcomere region containing thick filaments and thin filaments
The length of the thick filament
A band
28
Lighter band containing only thin filaments (no thick)
| Extends from A band of one sarcomere to the next A band
I band
29
Lighter region around M line
| Contains only thick filaments (no thin)
H line
30
Separates sarcoplasm from interstitial fluid
sarcolemma
31
Changes in skeletal muscle membrane permeability cause drastic change in _____
electrical charge distribution
32
Encircle sarcomere and tightly bind to sarcoplasmic reticulum
Transverse tubules (T tubules)
33
Pair of terminal cisternae and one T-tubule form _____
triad
34
Tubular network around each myofibril
| Forms enlarged sections (terminal cisternae) on either side of T-tubule
Sarcoplasmic reticulum (SR)
35
Sarcoplasmic reticulum function
SR contains calcium
Pumps on membrane moves calcium from cytosol to inside SR
Beginning of muscle contraction
36
Two regulatory proteins of thin filaments
Tropomyosis (muscle relaxed)
| Troponin (muscle contracting)
37
Contain myosin molecules
thick filaments
38
Composed primarily of actin
thin filaments
39
When muscles contract, thin filaments slide past thick filaments
Sliding filament theory
40
In the sliding filament theory, do H bands and I bands get smaller or lager?
smaller
41
In the sliding filament theory, do zones of overlap get smaller or lager?
larger
42
In the sliding filament theory, does the width of the A band get smaller or lager?
remains constant
43
In the sliding filament theory, do Z lines move closer together or further apart?
closer together
44
All cells in the body are _____
polarized
45
Unequal distribution represents potential difference, referred to as _____
membrane potential
46
Is the inside of the cell more positive or negative than the outside of the cell?
negative
47
Extracellular fluid contains excess ___ and ___ and the intracellular fluid contains excess ___
NA+
Cl-
K+
48
Allow constant slow flow of sodium and potassium down their concentration gradients (Na in and K out)
leak channels
49
Sends 3 sodium ions out of the cell and brings 2 potassium ions into the cell
Sodium–potassium ion pumps
50
Changes in _____ can activate (or inactivate) voltage-gated channels that affect ion movement and distribution of electrical charges
membrane potential
51
Five steps in action potential
Increase in sodium membrane permeability / MP to threshold
Voltage gated Na channels open / depolarization
Na channels close and K channels open / repolarization
K channels close / resting potential
Membrane potential stabilizes
52
Time to restore levels (and during which membrane cannot respond to another stimulus)
refractory period
53
Depolarization/repolarization sequence produces _____
action potential
54
Function of action potential
allows rapid communication
55
Intercellular connection between motor neuron and skeletal muscle fiber
Neuromuscular junction (NMJ)
56
space between neuron and muscle fiber
synaptic cleft
57
Contains vesicles filled with neurotransmitter ACh
Synaptic terminal of motor neuron
58
```
Has junctional folds (creases)
Contains acetylcholinesterase (AChE), an enzyme that breaks down ACh
```
Motor end plate of muscle fiber
59
Three steps of activities at the neuromuscular junction
```
Electrical impulse (action potential) arrives at the synaptic terminal
ACh diffuses across synaptic cleft and binds to receptors in motor end plate
Rush of Na into sarcoplasm generates action potential on sarcolemma
```
60
What triggers muscle contractions?
excitation-contraction coupling
61
Three steps of excitation-contraction coupling
```
Action potential (AP) generated at motor end plate moves across sarcolemma
Action potential moves down T tubules between terminal cisternae of SR
Calcium released from SR to sarcomeres
```
62
Entire contraction cycle repeated as long as _____ and _____
Ca2+ concentrations remain high and ATP is available
63
Single stimulus-contraction-relaxation sequence in a muscle fiber
muscle twitch
64
Involuntary “muscle twitch” under skin
Fasciculation
65
Amount of tension developed in muscle fibers shown on a _____
myogram
66
No tension developed (contraction cycle not begun)
Action potential sweeps across sarcolemma
Calcium released from sarcoplasmic reticulum
latent period
67
From beginning of tension development to peak tension
Calcium binds to troponin
Cross-bridge cycling occurring
contraction phase
68
Calcium levels fall
Active sites covered by tropomyosin
Cross-bridges detach
Tension returns to resting levels
relaxation phase
69
What is the amount of tension produced by a skeletal muscle determined by?
Amount of tension produced by each muscle fiber
| Total number of muscle fibers stimulated
70
Stimulation of skeletal muscle fiber immediately after relaxation phase produces increasing maximum tension
Treppe (German for staircase)
71
Stimulation of skeletal muscle fiber before relaxation phase completion produces increasing maximum tension
wave summation
72
Rapid cycle of contraction and relaxation producing almost peak tension
Incomplete tetanus
73
Higher stimulation frequency eliminates relaxation phase and results in peak tension and continuous contraction
Complete tetanus
74
single motor neuron and all the muscle fibers it controls
motor unit
75
Size of motor unit varies with _____
muscle control
76
Motor units activated on a rotating basis to maintain a sustained contraction
Asynchronous motor unit summation
77
Smaller motor units activated first
Followed by larger, more powerful motor units with faster and more powerful fibers
Results in smooth, steady increase in muscle tension
recruitment
78
Resting tension in a skeletal muscle
muscle tone
79
Tension rises and skeletal muscle length changes
isotonic contraction
80
Two types of isotonic contractions
Concentric contraction
| Eccentric contraction
81
Muscle tension rises until it exceeds load
Muscle shortens
Tension remains constant
Concentric contraction
82
Load is more than peak tension produced
| Muscle lengthens
Eccentric contraction
83
When contraction ends, load stretches muscle until
Muscle tears
Tendon breaks
Elastic recoil of muscle opposes load
84
Muscle length does not change
| Tension never exceeds load
Isometric contraction
85
Four sources of ATP in mucles
Free ATP
Creatine phosphate
Glycolysis
Aerobic metabolism
86
Most energy in the muscles is stored as what?
Glycogen
87
Occurs is sarcoplasm
| Produces 2 ATP and 2 pyruvate molecules for each glucose
Glycolysis
88
Is glycolysis aerobic or anaerobic?
anaerobic: does not require oxygen
89
Provides 95 percent of ATP demands of resting muscle cell
| Occurs in mitochondria
aerobic metabolism
90
ATP demands increase when ____ increases
activity level
91
What is ATP produced by?
mitochondria
92
Glucose is converted to pyruvate. What does excess pyruvate convert to?
lactic acid
93
When a muscle can no longer perform at the required activity level
fatigue
94
What is a major factor in muscle fatigue?
decline in pH
95
What happens under conditions of insufficient oxygen?
pH lowers
Fast ATP production
Elevated body temperature
96
Intercellular conditions return to normal
recovery period
97
Lactate produced by muscle fibers during strenuous activity
Lactate cycling (Cori cycle)
98
Liver converts lactate to pyruvate then glucose
recovery period
99
Lactate carried to liver by bloodstream
| Liver absorbs and recycles lactate to glucose
Lactate cycling (Cori cycle)
100
Amount of oxygen needed to return to pre-exertion conditions
oxygen debt
101
What are the three types of skeletal muscle fibers?
Fast fibers
Slow fibers
Intermediate fibers
102
Large in diameter
Have densely packed myofibrils, large glycogen reserves, few mitochondria
Produce powerful contractions
Fatigue rapidly because most ATP produced anaerobically
fast fibers
103
Half diameter of fast fibers
Can maintain longer sustained contractions
Primarily use aerobic metabolism for ATP production
Increased oxygen reserves due to:
Extensive capillary network
Myoglobin pigment (stores O2 like hemoglobin)
Appear dark red from myoglobin and blood supply
slow fibers
104
Contain little myoglobin
Relatively pale
More capillaries and more fatigue resistant than fast fibers
Intermediate fibers
105
Hypertrophy
increase in muscle size
106
Atrophy
Decrease in muscle size, tone, and power
107
Inherited disease that produce muscular weakness and deterioration
Muscular dystrophy
108
Causes progressive muscular weakness
Most individuals die from respiratory paralysis
Affects only males
Duchenne/Becker muscular dystrophy (DBMD)
109
Virus attacks motor neurons of brain and spinal cord causing paralysis
Polio
110
Toxin from bacteria that suppresses motor neuron activity, results in sustained, powerful contractions of affected muscles
tetanus
111
Toxin from bacteria that blocks ACh release at neuromuscular junctions
Result is paralysis of skeletal muscle
Botulism
112
Loss of ACh receptors at neuromuscular junctions
| Results in progressive muscular weakness
Myasthenia gravis
113
Generalized muscle contraction shortly after death
rigor mortis
