Types of Muscle Tissue Flashcards
1
Q
What are the three types of muscle tissue?
A
Skeletal
Cardiac
Smooth
2
Q
Which of the three types of muscles tissue are muscle fibers?
A
Skeletal and Smooth muscles are elongated which are muscles fibers.
3
Q
Skeletal muscle (Voluntary muscles)
A
is packages into skeletal muscles and are organs that are attached to bones and skin and cover the bones
single, very long, multinucleate
4
Q
Skeletal muscle fibers
A
the longest of all muscles and have striations (strips)
5
Q
skeletal muscle(Voluntary muscles)
A
can be consciously controlled
6
Q
Skeletal muscles
A
contract fast, tired easily and powerful or strong
7
Q
What is the keyword for skeletal muscle?
A
skeletal, striated, and voluntary
8
Q
Cardiac muscle tissue
A
Striated
found only in the heart. makeup bulks of the heart walls.
uni or binucleate
9
Q
Cardiac muscle tissue(Involuntary)
A
cannot be controlled consciously.
10
Q
Cardiac muscle tissue(contractions)
A
contract at steady rate due to heart’s own pacemaker(SA node).
NV can increases the rate.
11
Q
What are the keywords for cardiac muscle?
A
cardiac, striated, and involuntary
12
Q
Smooth muscle tissues
A
found in walls of hollow organs
Examples: stomach, urinary bladder, and airways.
Not striated.
single spindle-shaped and uninucleate.
13
Q
Smooth muscle tissues (Involuntary)
A
cannot be controlled consciously.
14
Q
What are the keywords for smooth muscle?
A
visceral, nonstriated and involuntary
15
Q
Characteristics of Muscle Tissue
A
Excitability
Contractility
Extensibility
Elasticity
16
Q
Excitability
A
(responsiveness): ability to receive and respond to stimuli
17
Q
Contractility
A
ability to shorten forcibly when stimulated
18
Q
Extensibility
A
ability to be stretched
19
Q
Elasticity
A
ability to recoil to resting length
20
Q
Four Important Function
A
Produce movement
Maintain posture and body position
Stabilize joints
Generate heat as they contract
21
Q
Produce movement (examples)
A
Responsible for all locomotion and manipulation
Example: walking, digesting, pumping blood
22
Q
Skeletal Muscle Anatomy
A
Skeletal muscle is an organ made up of different tissues with three features
23
Q
What is the three features of skeletal muscle tissue?
A
Nerve and blood supply, connective tissue sheaths, and attachments
24
Q
Nerve of skeletal muscle
A
Each muscle receives a nerve, artery, and vein.
Consciously controlled skeletal muscle has nerves supplying every fiber to control activity
25
Blood Supply of skeletal muscle
Contracting muscle fibers require huge amounts of oxygen and nutrients.
Also, need waste products removed quickly(Metabolic wastes)
26
Connective Tissue Sheaths
Muscles fibers and skeletal muscles are covered in connective tissue.
27
The function of the Connective tissues in the skeletal muscle?
Support cells and reinforce whole muscle which prevents the bulging muscles from nursing during exceptionally strong connections.
28
Sheaths from external to internal
Epimysium
Perimysium
Endomysium
29
Epimysium
dense irregular connective tissue surrounding entire muscle; may blend with fascia
30
Perimysium
fibrous connective tissue surrounding fascicles (groups of muscle fibers).
31
Endomysium
fine areolar connective tissue surrounding each muscle fiber
32
Attachments
Muscles span joints and attach to bones
33
What are the two-place muscles attach to bones
Insertion and origin
34
Insertion
attachment to the movable bone
35
Origin
attachment to the immovable or less movable bone
36
Attachments can be direct or indirect
Direct (fleshy): epimysium fused to the periosteum of bone or perichondrium of cartilage
Indirect: connective tissue wrappings extend beyond muscle as ropelike tendon or sheetlike aponeurosis. (more common)
37
Muscle Fiber Microanatomy
Skeletal muscle fibers are long, cylindrical cells that contain multiple nuclei
38
Sarcoplasm
muscle fiber cytoplasm
| Contains many glycosomes for glycogen storage, as well as myoglobin for O2 storage
39
Modified organelles
Myofibrils
Sarcoplasmic reticulum
T tubules
40
Myofibrils
Densely packed, rodlike elements.
Single muscle fiber can contain 1000s.
Accounts for ~80% of muscle cell volume
41
Myofibril features
Striations
Sarcomeres
Myofilaments
Molecular composition of myofilaments
42
Striations(Myofibril features)
stripes formed from repeating series of dark and light bands along length of each myofibril
43
A bands
dark regions
44
H zone
lighter region in middle of dark A band
45
M line
line of protein (myomesin) that bisects H zone vertically
46
I bands
lighter regions
47
Z disc (line)
coin-shaped sheet of proteins on midline of light I band
48
Sarcomere
Smallest contractile unit (functional unit) of muscle fiber
| Contains A band with half of an I band at each end
49
What does sarcomere consist of?
Consists area between Z discs
50
Individual Sarcomere
Individual sarcomeres align end to end along myofibril, like boxcars of train.
51
Myofilaments
Orderly arrangement of actin and myosin myofilaments within sarcomere.
52
Actin myofilaments
thin filaments.
Extend across I band and partway in A band.
Anchored to Z discs
53
Myosin myofilaments
thick filaments.
Extend length of A band.
Connected at M line.
54
Sarcomere cross
section shows hexagonal arrangement of one thick filament surrounded by six thin filaments
55
Molecular composition of myofilaments
Thick filaments
56
Thick filaments(Myosin myofilaments) are composed of?
composed of protein myosin that contains two heavy and four light polypeptide chains
57
Heavy chains of thick filaments.
intertwine to form myosin tail
58
Light chains of thick filaments?
form myosin globular head
59
What happens during contraction of the thick filaments?
During contraction, heads link thick and thin filaments together, forming cross-bridges.
Myosins are offset from each other, resulting in staggered array of heads at different points along thick filament
60
Thin filaments(Actin myofilaments)
composed of fibrous protein actin
61
Actin is
polypeptide made up of kidney-shaped G actin (globular) subunits
62
G actin
subunits bears active sites for myosin head attachment during contraction.
subunits link together to form long, fibrous F actin (filamentous)
63
F actin
Two strands twist together to form a thin filament
64
Tropomyosin and Troponin
regulatory proteins bound to actin.
65
Other proteins
help form the structure of the myofibril
66
Elastic filament
composed of protein titin
Holds thick filaments in place; helps recoil after stretch; resists excessive stretching
67
Dystrophin
Links thin filaments to proteins of sarcolemma
68
Nebulin, myomesin, and C proteins
proteins bind filaments or sarcomeres together.
Maintain alignment of sarcomere
69
Duchenne muscular dystrophy (DMD)
is most common and serious form of muscular dystrophies, muscle-destroying diseases that generally appear during childhood
70
How does someone get (DMD)
Inherited as a sex-linked recessive disease, so almost exclusively in males (1 in 3600 births).
71
At what age does DMD appears?
between 2 and 7 years old when boy becomes clumsy and falls frequently .
72
Disease progresses(DMD)
from extremities upward, finally affecting head, chest muscles, and cardiac muscle.
73
Treatment of DMD
With supportive care, people with DMD can live into 30s and beyond.
chest muscles, and cardiac muscle
74
Causes of DMV
defective gene for dystrophin, a protein that links thin filaments to extracellular matrix and helps stabilize sarcolemma
Sarcolemma of DMD patients tear easily, allowing entry of excess calcium which damages contractile fibers
75
defined Sarcoplasmic Reticulum
network of smooth endoplasmic reticulum tubules surrounding each myofibril.
Most run longitudinally
76
Sarcoplasmic Reticulum
Terminal cisterns form perpendicular cross channels at the A–I band junction
77
Sarcoplasmic Reticulum function
regulation of intracellular Ca2+ levels
| Stores and releases Ca2+
78
T tubules
formed by protrusion of sarcolemma deep into cell interior
79
T tubules increase
muscle fiber’s surface area greatly
80
T tubules(Lumen)
continuous with extracellular space
81
What does T tubules allow?
electrical nerve transmissions to reach deep into interior of each muscle fiber
82
Tubules penetrate cell’s
interior at each A–I band junction between terminal cisterns
83
Triad
area formed from terminal cistern of one sarcomere, T tubule, and terminal cistern of neighboring sarcomere
84
Triad(Relationship)
T tubule contains integral membrane proteins that protrude into intermembrane space (space between tubule and muscle fiber sarcolemma)
Tubule proteins act as voltage sensors that change shape in response to an electrical current
85
Triad(Relationship) SR
cistern membranes also have integral membrane proteins that protrude into intermembrane space.
SR integral proteins control opening of calcium channels in SR cisterns
86
Triad(Relationship) electrical
When an electrical impulse passes by, T tubule proteins change shape, causing SR proteins to change shape, causing release of calcium into cytoplasm
87
Sliding Filament Model of Contraction
the activation of cross bridges to generate force
88
Shortening of Sliding Filament Mode
occurs when tension generated by cross bridges on thin filaments exceeds forces opposing shortening
89
when does contraction ends?
ends when cross bridges become inactive(relax).
90
Relaxed state of Sliding Filament Mode
thin and thick filaments overlap only slightly at ends of A band
91
Sliding filament model of contraction
states that during contraction, thin filaments slide past thick filaments, causing actin and myosin to overlap more.
Neither thick nor thin filaments change length, just overlap more
92
When nervous system stimulates muscle fiber
, myosin heads are allowed to bind to actin, forming cross bridges, which cause sliding (contraction) process to begin
93
Cross bridge attachments
attachments form and break several times, each time pulling thin filaments a little closer toward center of sarcome in a ratcheting action.
Causes shortening of muscle fiber
94
Z discs (Sliding filament model of contraction )
are pulled toward M line
95
I bands (Sliding filament model of contraction)
shorten
96
Z discs (Sliding filament model of contraction)
become closer
97
H zones (Sliding filament model of contraction)
disappear
98
A bands (Sliding filament model of contraction)
move closer to each other.
99
Muscle Fiber Contraction
Decision to move is activated by brain, signal is transmitted down spinal cord to motor neurons which then activate muscle fibers
100
Neurons and muscle cells
excitable cells capable of action potentials.
Excitable cells are capable of changing resting membrane potential voltages.
101
AP crosses
from neuron to muscle cell via the neurotransmitter acetylcholine (ACh)
102
Ion Channels
Play the major role in changing of membrane potentials
103
What are the two classes of ion channels?
Chemically gated ion channels and Voltage-gated ion channels
104
Chemically gated ion channels and example
opened by chemical messengers such as neurotransmitters
| Example: ACh receptors on muscle cells
105
Voltage-gated ion channels
open or close in response to voltage changes in membrane potential.
106
Anatomy of Motor Neurons
Skeletal muscles are stimulated by somatic motor neurons
107
Axons
(long, threadlike extensions of motor neurons) travel from central nervous system to skeletal muscle.
Each axon divides into many branches as it enters muscle
108
neuromuscular junction or motor end plate
Axon branches end on muscle fiber, forming.
Each muscle fiber has one neuromuscular junction with one motor neuron.
109
Axon terminal (end of axon)
Muscle fiber are separated by gel-filled space called synaptic cleft
110
synaptic vesicles
Stored within axon terminals are membrane-bound.
111
acetylcholine (ACh)
Synaptic vesicles contain neurotransmitter
112
Junctional folds
Infoldings of sarcolemma
| contain millions of ACh receptors
113
NMJ
NMJ consists of axon terminals, synaptic cleft, and junctional folds
114
Four steps must occur for skeletal muscle to contract:
Events at neuromuscular junction
Muscle fiber excitation
Excitation-contraction coupling
Cross bridge cycling
115
First events at the Neuromuscular Junction
AP arrives at axon terminal
116
Seconds events at the Neuromuscular Junction
Voltage-gated calcium channels open, calcium enters motor neuron
117
Third events at the Neuromuscular Junction
Calcium entry causes release of ACh neurotransmitter into synpatic cleft
118
Fourth events at the Neuromuscular Junction
ACh diffuses across to ACh receptors (Na+ chemical gates) on sarcolemma
119
Fifths events at the Neuromuscular Junction
ACh binding to receptors, opens gates, allowing Na+ to enter resulting in end plate potential
120
Six events at the Neuromuscular Junction
Acetylcholinesterase degrades ACh.
121
Many toxins, drugs, and diseases
interfere with events at the neuromuscular junction.
122
Myasthenia gravis
disease characterized by drooping upper eyelids, difficulty swallowing and talking, and generalized muscle weakness
123
Myasthenia gravis involves shortage
Ach receptors because person’s ACh receptors are attacked by own antibodies
124
Suggests this
an autoimmune disease
125
Resting sarcolemma
is polarized, meaning a voltage exists across membrane.
| Inside of cell is negative compared to outside.
126
Action potential
is caused by changes in electrical charges
127
Occurs in three steps
Generation of end plate potential
Depolarization
Repolarization
128
End plate potential
ACh released from motor neuron binds to ACh receptors on sarcolemma
129
End plate potential Causes
Causes chemically gated ion channels (ligands) on sarcolemma to open
Na+ diffuses into muscle fiber
130
End plate potential diffuses.
Some K+ diffuses outward, but not much
| Because Na+ diffuses in, interior of sarcolemma becomes less negative (more positive)
131
Depolarization
Generation and propagation of an action potential (AP).
132
Excitation-contraction (E-C) coupling
events that transmit AP along sarcolemma (excitation) are coupled to sliding of myofilaments (contraction).
133
AP
is propagated along sarcolemma and down into T tubules, where voltage-sensitive proteins in tubules stimulate Ca2+ release from SR
134
AP
Ca2+ release leads to contraction
135
AP is brief
AP is brief and ends before contraction is seen
