Chapter 11: Muscular System Flashcards
1
Q
3 types of muscular tissue
A
- skeletal
- cardiac
- smooth
2
Q
Characteristics of Muscles (5)
A
- responsiveness
- conductivity
- contractility
- extensibility
- elasticity
(elaine received constant contractions extensively)
3
Q
responsiveness to what? (3)
A
excitable
-to chemical signals, stretch, & electrical charges
4
Q
conductivity
A
electrical change triggers a wave of excitation
5
Q
contractility
A
shortens when stimulated
6
Q
extensibility
A
capable of being stretched
7
Q
elasticity
A
returns to original length after being stretched
8
Q
skeletal muscle
A
striated VOLUNTARY muscle attached to one or more bones
9
Q
Muscle cell =______
A
muscle fiber
10
Q
striations
A
alternating light and dark transverse bands
11
Q
What do tendons attach specifically?
A
muscle to bone matrix
12
Q
endomysium
A
connective tissue around muscle cells
13
Q
perimysium
A
connective tissue around muscle fascicles
14
Q
epimysium
A
connective tissue surrounding entire muscle
15
Q
what is the purpose of collagen? (3)
A
returns muscle to resting length
protects muscles from excessive stretching
contributes to power output & muscle efficiency
16
Q
sarcolemma
A
plasma membrane of a muscle fiber
17
Q
sarcoplasma
A
cytoplasm of a muscle fiber
18
Q
myofibrils
A
long protein bundles that occupy the main portion of the sarcoplasma
19
Q
what are the components of myofibrils?what do they store?
A
glycogen (provide energy for heightened exercise) & myoglobin (stores oxygen)
20
Q
where are mitochondria packed in muscle fibers?
A
in spaces between myofibrils
21
Q
myoblast
A
stem cells that fuse to form each muscle fiber
22
Q
sarcoplasmic reticulum (SR)
A
smooth ER that forms a network around each myofibril
23
Q
what is the sarcoplasmic reticulum a reservoir for?
A
calcium
24
Q
what activates the muscle contraction process?
A
calcium
25
terminal cisternae
dilated end sacs of SR which cross the muscle fiber from one side to the other
26
T tubules
tubular infoldings of the sarcolemma that penetrate through the cell & emerge on the other side
27
triad
a T tubule & two terminal cisterns
28
thick filaments
made of several hundred myosin (golf club)
29
thin filaments
fibrous actin of 2 intertwined stands
30
What portion of the actin subunit can bind the head of the myosin molecule?
gobular (G) actin
31
tropomyosin
blocks the active sites of G actin & prevents myosin from binding when muscles are relaxed
32
troponin
small calcium binding protein on each tropomyosin molecule
33
contractile proteins?
myosin & actin
34
regulatory proteins?
tropomyosin & troponin
35
what happens when calcium is released into the sacroplasm?
Ca binds to troponin which then changes shape and moves tropomyosin from the active site of actin
36
sarcomere
Z disc to Z disc
| functional contractile of muscle fiber
37
Which myofilament is free floating?
myosin, it is not anchored like actin
38
A band
dark; overlapping of thick and thin filaments
39
H band
middle of A band (thick filaments ONLY)= bare zone
40
M line
middle of H band
41
I band
light; crosses over 2 sacromeres
42
Z disc
provides anchorage for thin filaments and elastic filaments
43
what myofilaments do muscle fibers contain? (3)
thin, thick, and elastic
44
which band shortens during contraction
H band
45
Why do muscle cells shorten?
because their individual sarcomeres shorten (Z disc pulled closer together)
46
a skeletal muscle never contracts unless stimulated by ______? what happens if this is severed?
a nerve; muscle is paralyzed
47
somatic motor neurons
nerve cells whose cell bodies are in the brainstem & spinal cord that serve skeletal muscles
48
what portion of somatic motor fibers lead to the skeletal muscle?
their axons
49
1 nerve fibers= ______ muscle fiber
several
50
what does an effective contraction require?
the contraction of several motor units (one nerve fiber + muscle fibers) at once
51
average motor unit?
200 muscle fibers for each motor unit
52
small motor units are used for what?
fine degree of control
| ex. eye & hand muscles
53
large motor units are used for what?
more strength than control
54
synapse
point where a nerve fiber meets its target cell
55
neuromuscular junction
when target cell is a muscle fiber
56
synaptic knob
swollen end of nerve fiber
57
synaptic cleft
tiny gap between synaptic knob & muscle sarcolemma
58
What is the purpose of Schwann cells?
to isolate & insulate all of the NMJ from surrounding tissue fluid
59
synaptic vesicles undergo ______ releasing ACh into ______
exocytosis; synaptic cleft
60
Lack of ACh receptors leads to?
paralysis in disease
61
What separates the Schwann cells & the entire muscle cell from surrounding tissue?
basal lamina
62
What does the basal lamina contain?
acetylcholinesterase (AChE) to break down ACh after contraction causing relaxation
63
What helps hold the synaptic knob in place?
Schwann cells & basal lamina
64
voltage=______ def?
electrical potential; a dif in electrical charge from one point to another
65
What is the resting membrane potential?How is it maintained?
about -90mV; Na-K pumps
66
What is happening in an unstimulated resting cell? (3)
- more anions on the inside of the plasma membrane
- plasma membrane is polarized
- excess Na (ECF) and excess K (ICF)
67
What else is inside the ICF?
proteins, nucleic acids, and phosphates (all which cant penetrate the membrane)
68
What is happening in a stimulated muscle fiber?
- ion gates open in the plasma membrane
- Na moves inside (down concentration gradient)
- cations override negative charge of ICF (depolarization)
- Na gates close/ K open
69
What turns the membrane back into its negative state?
loss of positive K ions (repolarization)
70
action potential
quick up & down
| polarized(resting)-> depolarization-> repolarization
71
what type of paralysis is tetanus?
spastic paralysis caused by C. tetani
72
flaccid paralysis
state in which the muscles are limp & cannot contract
73
botulism
type of food poisoning caused by neuromuscular toxin secreted by C. botulinum (prevent contraction)
74
What does the RMP shift to when Na is moved into the cell?
-90mV to +75mV
75
length tension relationship
amount of tension generated by a muscle & the force of contraction depends on how stretched/contracted it was before stimulated
76
What does the optimum resting length produce?
greatest force when muscle contracts
77
muscle tone
monitored by the nervous system that adjusts the length of the resting muscle & maintains a state of partial contraction
78
What does overly contraction cause?
crick in your neck
79
What does overly stretched cause?
actin filament have no myosin heads to attach to
80
rigor mortis
hardening of muscles & stiffening of body beginning 3 to 4 hours after death
81
muscle relaxation requires _____, which is no longer produced after death
ATP
82
myogram
chart of the timing & strength of a muscle contraction
83
_____, subthreshold electrical stimulus cause ___ contraction
weak; no
84
threshold
min voltage necessary to generate an action potential in the muscle fiber & produce contraction
85
twitch
quick cycle of contraction when stimulus is at threshold or higher
86
Twitches vary depending on?
- stimulus frequency
- concentration of Ca in sarcoplasma
- how stretched the muscle was
- temp of muscle
87
If the pH of the sarcoplasma is lower than normal, what happens?
fatigue
88
When stimulus intensity remains _____ twitch strength_____?
constant; vary with the stimulus frequency
89
10-20 stimuli per second produces what type of twitch? (staircase) describe
treppe; the muscle still recovers fully between twitches, but each twitch develops more tension than the one before
90
20-40 stimuli per second produces what? describe
incomplete tetanus (piggy back); each new stimulus arrived before the previous twitch is over
91
40-50 stimuli per second produces what? describe
complete tetanus; muscle has no time to relax between stimuli
92
isometric contraction
producing internal tension; but external resistance causes it to stay at the same length or become longer (NO MOVEMENT)
93
concentric contraction
muscle shortens as it maintains tension
94
eccentric contraction
muscle lengthens as it maintains tension
95
ATP supply depends on availability of: (2)
oxygen
| organic energy sources (glucose & fatty acids)
96
2 pathways of ATP synthesis? which yields the most ATP?
aerobic respiration (use oxygen) yields more ATP (36 per molecule) anaerobic fermentation (without the presence of oxygen)
97
For short intense exercises how is oxygen supplied?
via myoglobin for limited aerobic respiration
98
What enzymes are used by muscles for transfer of phosphate? (2)
```
myokinase (makes cyclic AMP)
creatine kinase (uses creatine phosphate)
```
99
What system is used for nearly all energy used for short bursts of intense activity?
phosphagen system
100
After the phosphagen system-> a muscle enters ___ ____ which uses ___ to produce _____. How many ATPs are gained?
Anaerobic fermentation; glucose ; lactic acid
| 2 ATPs per molecule
101
long term energy uses which synthesis pathway?
aerobic respiration
102
What happens during fatigue? (4)
- ATP synthesis decline as glycogen consumed
- ATP shortage; slows down Na-K pumps
- lactic acid lowers pH of sarcoplasm
- motor nerve fibers use up ACh
103
endurance? how is it determined?
ability to maintain high intensity exercise for more than 4-5 minutes; by one's max oxygen uptake
104
How can you "beat" fatigue? (2)
- taking oral creatine (increases level of creatine phosphate in tissue: increase speed of ATP regeneration)
- carbohydrate overload (extra glycogen packed in)
105
slow oxidative muscle fibers (3)
- slow twitch, red, type I fibers
- abundant in mitochondria, myoglobin
- adapted for aerobic respiration & fatigue resistance
106
fast glycolytic muscle fiber
- fast twitch, white, type II fiber
| - quick response, but not fatigue resistance
107
properties of cardiac muscle? (5)
- contraction w/ regular rhythm
- must contract in unison
- contractions must last long to expel blood
- must work in sleep
- tightly resistant to fatigue
108
Cardiac muscles are _____ and contain _____
striated; myocytes
109
in cardiac muscle, myocytes are joined at notched linkages called what?
intercalated disc
110
Cardiac muscles contain _____, so they can contract without need for nervous stimulation
built in pacemaker
111
How are damaged cardiac muscle cells repaired?
via fibrosis (not capable of mitosis-very little)
112
which synthesis is used almost exclusively by cardiac muscle?
aerobic respiration
113
Smooth muscle does not contain?
t-tubule or sarcomere structure
114
characteristics of smooth muscle (3)
- capable of mitosis & hyperplasia
- injured muscle can regenerate well
- some lack nerve supply
115
Describe myocyte structure in smooth muscle?
- fusiform shape
- no visible striations
- Z discs are replaced by dense bodies
116
Which type of smooth muscle is more widespread? does it require a nerve supply?what does it use
single unit smooth muscle; NO; gap junctions
117
Smooth muscle can contract in response to ____. Such as (3)
- chemicals
| - hormones, CO2, stretch, oxygen deficiency
118
Does stimulation mean contraction in smooth muscle?
NO; relax arteries or contract bronchiles
119
What do the smooth single units contain?
autonomic nerve fibers varicosities
120
What are varicosities?
beadlike swellings that contain synaptic vesicles & few mitochondria
121
How is contraction different in smooth vs skeletal muscle?
- calcium binds calmodulin on thick filaments
- calcium enters from the cell EC
- very slow due to arrangement (Ca must be actively removed)
- smooth contract forcefully when greatly stretched
122
the ______ ______ is resistant to fatigue
latch bridge mechanism
123
stress relaxation response
helps hollow organs gradually fill (bladder)
