Muscles Flashcards
1
Q
Muscle tissue is divided into:
A
skeletal
cardiac
smooth
2
Q
Skeletal muscle is attached to:
A
the skeletal system and allows us to move
3
Q
Structure of skeletal muscle
A
muscle fibers
connective fibers
nerves
blood vessels
4
Q
Functions of skeletal muscle
A
produce skeletal movement
maintain body position
support soft tissues
guard body openings
maintain body temperatures
5
Q
Muscles that are opposite of each other
A
antagonistic
6
Q
muscles that cause the same action
A
synergists
7
Q
Muscle fascicle
A
bundles of muscle fibers that are the basic building blocks of skeletal muscles
8
Q
muscle fibers
A
fundamental unit of muscle tissue that contract to enable muscle movement. They are responsible for all voluntary movement and help control the physical forces within the body
9
Q
Myofibrils
A
long contractile fibers, groups of which run parallel to each other
10
Q
Thick myofiliments
A
protein complexes made up of hundreds of myosin molecules that are the primary component of muscle contraction
11
Q
Thin myofiliments
A
protein strands that are made up of actin
12
Q
Epimysium
A
exterior collagen layer connected to deep fascia and separates muscles from surrounding tissues
13
Q
Perimysium
A
surrounds muscle fiber bundles (fascicles) and contain blood vessels and nerve supple to fascicles
14
Q
Endomysium
A
surrounds individual muscle fibers and contain capillary and nerve fibers that contact muscle cells
also contains satellite cells that repair damage
15
Q
Endomysium, perimysium, and epimysium come together at:
A
the ends of muscles to form connective tissue attachment to bone matrix
16
Q
Tendon shape
A
like a bundle
17
Q
Aponeurosis shape
A
flat like a sheet
18
Q
Skeletal muscle cells are:
A
long
develop through fusion of mesodermal cells
contain hundreds of nuclei
19
Q
Sarcolemma
A
the cell membrane of a muscle cell
surrounds the sarcoplasm
20
Q
A change in transmembrane potential:
A
begins contractions
21
Q
Transverse tubules (T tubules)
A
transmit action potential through cells and allow entire muscle fibers to contract simulateously
22
Q
Sarcomeres
A
structural units of myofibrils that form strips or striated pattern
23
Q
M line
A
the center of a band at midline of the sarcomere
24
Q
I bands
A
light, thin filaments composed of actin
25
Z lines
the center of the I bands
26
H zone
area around the M line that has thick filaments but no thin filaments
27
Titin
strands of protein from tips of thick filaments to the Z line
28
Transverse tubules encircle the:
sarcomere near the zones of overlap
29
Ca2+ released by:
sarcoplasmic reticulum causes thick and thin filaments to interact
30
Sarcoplasmic reticulum
membranous structure surrounding each myofibril that help transmit action potential to myofibrils
hold onto calcium
31
Muscle contraction caused by:
free Ca2+ into the sarcoplasm and triggers contraction
32
What are the 4 filament proteins
F actin
Nebulin
Tropmyosin
troponin
33
F actin
2 twisted rows of globular G actin & the active sites on G actin strands that bind to myosin
34
Nebulin
holds F actin strands together
35
Tropomyosin
is double strand that prevents actin-myosin interaction
36
Troponin
a globular protein that binds tropomyosin ti G actin and is controlled by Ca2+
37
Myosin molecule is made up of:
a tail and head
38
Myosin tail
binds to other myosin molecules
39
Myosin head
made of 2 globular protein subunits and reaches the nearest thin filament
40
Sliding filament theory
a muscle fiber contracts when myosin filaments pull actin filaments closer together and thus shorten sarcomeres within a fiber
aka contraction
41
Level 1 (skeletal muscle)
skeletal muscle surrounded by epimysium and contains muscle fascicles
42
Level 2 (muscle fascicle)
muscle fascicle surrounded by perimysium and contains muscle fibers
43
Level 3 (muscle fiber)
muscle fiber surrounded by endomysium and contains myofibrils
44
Level 4 (myofibril)
myofibril surrounded by sarcoplasmic reticulum and consists of sarcomeres (z line to z line)
45
Level 5 (sarcomere)
sarcomere contains thick and think filaments
46
Neural stimulation of sarcolemma:
happens at neuromuscular junction and causes excitation-concentration coupling
47
excitation-concentration coupling
a series of events that links a muscle cell's action potential to its contraction
48
Cisternae of SR release:
Ca2+ that triggers interaction of thick and thin filaments consuming ATP and producing tension
49
Action potential
a rapid change in the voltage across a cell membrane, which is a nerve signal that allows cells to communicate with each other
50
The synaptic terminal:
releases the neurotransmitter acetylcholine (ACh) into the synaptic cleft
51
Synaptic cleft
the gap between synaptic terminal and motor end plate
52
Acetylcholine or ACh travels:
across the synaptic cleft, binds to membrane receptors on sarcolemma and causes sodium-ion rush into sarcoplasm that is quickly broken down by acetylcholinesterase (AChE)
53
Action potential generated:
by increase in sodium ions in sarcolemma, travels along the T tubules and leads to excitation-contraction coupling
54
Excitation-contraction coupling requires:
myosin heads to be in a "cocked" position - or loaded by ATP energy
55
1st step of the contraction cycle
exposure of active sites of F actin of the thin filament
56
2nd step of the contraction cycle
formation of the cross-bridges due to interaction of actin filaments with myosin heads forming cross-bridges that pivot and produce motion
57
3rd step of the contraction cycle
the pivoting of myosin heads
58
4th step of the contraction cycle
detachment of the cross-bridges
59
5th step of the contraction cycle
reactivation of myosin
60
Contraction duration depends on:
duration of neural stimulus and number of free calcium ions in sarcoplasm availability of ATP
61
Relaxation happens when:
Ca2+ concentration falls
Ca2+ detaches from troponin
Active sites are recovered by tropomyosin
Sarcomeres remain contracted
62
Rigor mortis
a fixed muscular contraction after death that is caused when ion pumps cease to function and calci builds up in the sarcoplasm
63
Isotonic contraction
a muscle contraction that involves a change in muscle length while maintaining the same tension
64
Isometric contraction
a muscle contraction that occurs when a muscle generates force without changing its length
65
The heavier the resistance of a muscle:
the longer it takes for shortening to begin and the less the muscle will shorten
66
Muscle relaxation
after contraction a muscle returns to resting length by elastic forces, opposing muscle contractions, or gravity
67
Elastic forces (muscle relaxation)
the pull of elastic elements such as tendons or ligaments that expands the sarcomeres to resting length
68
Opposing muscle contractions (muscle relaxation)
reverse the direction of the original motion that work as opposing skeletal muscle pairs
ex biceps and triceps
69
Gravity (muscle relaxation)
can take place of opposing muscle contraction to return a muscle to its resting length
70
Sustained muscle contraction uses:
a lot of ATP energy
71
Adenosine triphosphate (ATP)
the active energy molecule
72
Creatine phosphate (CT)
the storage molecule for excess ATP energy in a resting muscle
73
What two ways do cells produce ATP?
aerobic metabolism and anaerobic glycolysis
74
Aerobic metabolism
primary energy source of resting muscle that breaks down fatty acids
Aerobic respiration occurs with oxygen and releases more energy but more slowly.
75
Aerobic metabolism produces how many ATP molecules per glucose molecule?
34 ATP
76
Anaerobic glycolysis
is the primary energy source for peak muscular activity that breaks down glucose from glycogen stored in skeletal muscle
77
Anaerobic glycolysis produces how many ATP molecules per glucose molecule?
2 ATP
78
Muscle fatigue
when muscles can no longer perform a required activity
79
What are the results of muscle fatigue?
depletion of metabolic reserves
damage to sarcolemma and SR
low pH due to lactic acid
muscle exhaustion and pain
80
Recovery period
the time required after exertion of muscles to return to normal
81
Cori cycle
the removal and recycling of lactic acid
82
The liver converts lactic acid to:
pyruvic acid
83
Fast fibers
contract quickly
have large diameter
large glycogen reserves
few mitochondria
strong contractions
fatigue quickly
ex: body builders
84
Slow fibers
slow to contract
slow to fatigue
have high oxygen supply
contain myoglobin
ex: long-distance runners
85
myoglobin
red pigment that binds to oxygen
86
intermediate fibers
mid-sized
low myoglobin
have more capillaries than fast fibers
slower to fatigue
87
Muscle hypertrophy
muscle growth from heavy training
88
Muscle atrophy
lack of muscle activity that reduces muscle size, tone, and power
89
Anaerobic endurance
use fast fibers, fatigue quickly with strenuous activity
ex: 50-meter dash or weight lifting
90
Aerobic endurance
prolonged activity that require more oxygen and nutrients
91
7 characteristics of cardiocytes
small
single nucleus
have short, wide t tubules
no triads
SR with no terminal cisternae
are aerobic
have intercalated disks
92
Intercalated discs
specialized contact points between cardiocytes
93
Intercalated discs link:
heart cells mechanically, chemically and electrically, the heart functions like a single, fused mass of cells
94
Cardiac tissue is controlled by what type of cells?
pacemaker cells through electricity
95
Smooth muscle is found in:
blood vessels
reproductive and glandular systems
digestive and urinary symptoms
integumentary system
96
8 characteristics of smooth muscle cells
long, slender, and spindle shaped
single, central nucleus
no T tubules, myofibrils or sarcomeres
have no tendons
have scattered myosin fibers
myosin fibers have more heads per thick filament
have thin filaments attached to dense bodies
97
Parallel muscle fibers
fibers parallel to the long axis of muscle
ex: biceps brachii
98
Parallel muscle contract __ %
30%
99
Convergent muscle fibers
broad area that converges on attachment site where muscle fibers pull in different directions
ex: pectroralis muscles
100
Pennate muscle fibers
muscle fibers that are arranged at an angle to the muscle's line of action, similar to the way the bristles of a feather are arranged
ex: rectus femoris
101
Circular muscle fibers
open and close to guard entrances of the body
ex: sphincters
102
Fulcrum
fixed point
103
Applied force
the force exerted by a muscle when it contracts
104
Resistance
an external force or load that causes muscles to contract
105
First class levers
Resistance - fulcrum - applied force
ex: raising head OR seesaw
106
Second class levers
fulcrum - resistance - applied force
ex: wheelbarrow or calf raises
107
Third class levers
fulcrum - applied force - resistance
the most common lever in the body
ex: bicep curl
108
Muscle origin
the point where a muscle attaches to a bone that remains stationary during contraction
109
Muscle insertion
the point where a muscle attaches to a bone, tendon, or connective tissue that moves when the muscle contracts
110
Origin is usually ___ to insertion?
proximal
111
Agonist muscle
the primary muscle that contracts to move or rotate a bone at a joint. It's also known as the prime mover
112
Antagonist muscle
a muscle that performs the opposite action of another muscle
113
Synergist muscle
smaller muscle that assists a larger agonist and helps start motion or stabilize origin of agonist
114
Rectus
straight
115
Transversus
across body
116
oblique
angle
117
Longus
long
118
longissimus
longest
119
teres
long and round
120
brevis
short
121
magnus
large
122
major
larger
123
maximus
largest
124
minor
small
125
minimus
smallest
