Muscle Flashcards
(116 cards)
1
Q
Muscle functions
A
- Responsible for locomotion and movement of the different parts of the body
- Maintain an erect or seated position, or posture * Convert chemical energy to mechanical energy * Produce heat in the body
2
Q
is the tendency of muscle cells to shorten significantly.
A
Contractility
3
Q
is a muscle’s capacity to extend
A
Extensibility
4
Q
is the tendency to rebound upon contracting.
A
Elasticity
5
Q
is the ability to react to a stimulation that a hormone or motor neuron may deliver.
A
Excitability
6
Q
Staining of muscle cells is
A
acidophilic or pinkish
7
Q
The unit structure of muscles is ___________ in shape which is an adaptation to its function of ______
A
elongated
contraction
8
Q
Sarcoplasm appears fibrillar due to its contents of
A
myofibrils
9
Q
Cells are bound together by varying amounts of _________ containing blood vessels and nerves
A
areolar connective tissue
10
Q
is responsible for muscle cell contraction
A
Myofilament
11
Q
two types of Myofilament
A
Thick and thin
12
Q
thin filaments are _____ in diameter and ___ long and composed primarily of the protein _____
A
6 to 8 nm in diameter, 1.0 um long
actin
13
Q
thick filaments are _____ in diameter and ___ long and composed primarily of the protein _____
A
15 nm in diameter, 1.5 um long
mysosin II
14
Q
Types of muscle tissue
A
Skeletal muscle
Cardiac muscle
Smooth muscle
15
Q
is composed of bundles of very cylindrical, long, multinucleated cells that show striations cross
A
Skeletal muscle
16
Q
Skeleteal muscle Contraction
A
quick, forceful, and usually under voluntary control
17
Q
has cross-striations and is composed of elongated, branched individual cells that lie parallel to each other
A
Cardiac muscle
18
Q
Cardiac muscle Contraction
A
involuntary, vigorous, and rhythmic
19
Q
consists of collections of fusiform cells that do not show striations
A
Smooth muscle
20
Q
Smooth muscle Contraction
A
process is slow and not subject to voluntary control
21
Q
the cytoplasm of muscle cells and fibers which is acid in staining
A
Sarcoplasm
22
Q
cell membrane complex
A
Sarcolemma
23
Q
granules in the cytoplasm which under the electron microscope is actually mitochondrion
A
Sarcosome
24
Q
fine threadlike structures in the sarcoplasm which is responsible for muscle contraction
A
Myofibrils
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a linear unit
Sarcomere
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refers to endoplasmic reticulum
Sarcoplasmic reticulum
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Skeletal muscle consists of muscle fibers, which are
long, cylindrical multinucleated cells with diameters of 10–100 um
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* Skeletal muscle nuclei characteristics
Long oval
Found in periphery of cell under cell membrane
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Development of Skeletal Muscle
Myoblasts align and fuse together to make longer, multinucleated tubes called myotubes
Myotubes differentiating continue to form functional myofilaments and the nuclei are displaced against the sarcolemma
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are unfused myeloblasts population located on the external surface of muscle fibers inside the developing external lamina
Satellite cells
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these cells proliferate and produce new muscle fibers following muscle injury
Satellite cells
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are responsible for the formation of primary myotubes, chainlike structures stretching between tendons of the developing muscle.
Early myoblasts
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allow secondary myotubes to grow in the innervated region of muscle growth where the myotubes have close contact with nerve terminals.
Late myoblasts
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increase cell volume
Hypertrophy
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increase number of cells
Hyperplasia
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dense connective tissue that enclosed the entire skeletal muscle
Epimysium
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wraps each fascicle of muscle fibers
Perimysium
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delicate layer which surrounds muscle fibers individual (elongated multinuclear cells)
Endomysium
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Basis of Muscle Fiber Types Classification
Contractile speed
Velocity of the myosin ATPase reaction
Metabolic profile
40
defines how easily fiber can contract and relax.
Contractile speed
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determines the rate at which this enzyme will break down ATP molecules during the contraction process.
Velocity of the myosin ATPase reaction
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reveals the ability of the oxidative phosphorylation or glycolysis to generate ATP
Metabolic profile
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Muscle Fiber types
I, IIa, IIb
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Type I or slow, red oxidative fibers Metabolic profile
many mitochondria
abundant myoglobin and cytochrome complexes.
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Red fibers (Type I) derive energy primarily from
aerobic oxidative phosphorylation of fatty acids
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Type I fivers Contractile speed.
are slow-twitch, fatigue-resistant motor units
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These fibers have great resistance to fatigue but generate less tension than other fibers
Type I or slow, red oxidative fibers
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a ____ is a single, brief contraction of the muscle
twitch
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Type I Velocity of the myosin ATPase reaction
SLOWEST
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medium in size and are adapted for rapid contractions and short bursts of activity
Type IIa or fast, intermediate oxidative-glycolytic fibers
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Type IIa or fast, intermediate oxidative-glycolytic fibers Metabolic profile
many mitochondria and
much myoglobin
considerable glycogen.
52
Type IIa or fast, intermediate oxidative-glycolytic fibers Contractile speed.
fast-twitch,
fatigue-resistant motor
high peak muscle tension.
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Type IIa or fast, intermediate oxidative-glycolytic fibers Velocity of the myosin ATPase
intermediate
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Type IIa or fast, intermediate oxidative-glycolytic fibers source of energy
BOTH oxidative metabolism and anaerobic glycolysis
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are typically small muscles adapted for rapid contraction with a relatively large number of neuromuscular junctions allowing precise, fine movements.
Type IIb or fast, white glycolytic fibers
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Type IIb or fast, white glycolytic fibers Metabolic profile
fewer mitochondria
less myoglobin
abundant glycogen
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Type IIb or fast, white glycolytic fibers Contractile speed
fast-twitch
generate high peak muscle tension
fatigue-prone motor units
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Type IIb or fast, white glycolytic fibers Velocity of the myosin
is the fastest of all the fibers
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long, multi-nucleated, cylindrical with a diameter of 10–100 um and packed with longitudinally organized structural subunits, myofibrils.
Muscle fibers
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are evident in favorable histological preparations and are better seen in muscle fiber cross-sections that give it a speckled appearance.
Myofibrils
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Myofibrils have a diameter of ________ and are made of
1–2 um
myofilament tubes.
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are the single filamentous polymers of myosin II (thick filaments) and actin (thin filaments) and its related proteins.
Myofilaments
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darker bands
A bands (anisotropic)
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lighter bands
I bands (isotropic)
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dark transverse line that bisects the I band
Z line
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the sarcomere, extends from Z line to Z line about _________ long in resting muscle
2.5 um
67
associated with tropomyosin, which also forms a long fine polymer, and troponin, a globular complex of three subunits
F-actin
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is a long, thin molecule about 40 nm in length containing two polypeptide chains, which assembles to form a long polymer located in the groove between the two twisted actin strands
Tropomyosin
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TnT TnC TnI
troponin complexes
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Troponin complex that attaches to tropomyosin
TnT
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Troponin complex which binds calcium ions
TnC
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Troponin complex which inhibits the actin-myosin interaction
TnI
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Is a large complex: into two identical heavy chains and two pairs of light chains
Myosin
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are thin, rod-like molecules made up of two heavy chains twisted together as myosin tails
Myosin heavy chains
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Events of muscle contraction
ATTACHMENT
RELEASE
BENDING
FORCE GENERATION (POWER STROKE)
REATTACHMENT
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is a specialized stretch receptor in muscle; it consists of two types of modified muscle fibers
muscle spindle
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muscle spindle two types of modified muscle fibers
spindle cells
neuron terminals
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The muscle spindle transmits information via sensory________ nerve fibers to the central nervous system about the extent to which a muscle is stretched
afferent
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Sensory nerve fibers modulates the activity of the
gamma (y) motor (efferent) nerve fibers
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Cardiac muslces exhibit densely staining cross-bands, termed _________-, that cross the fibers in a linear fashion
intercalated discs
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consist of multiple end-to-end organized cylindrical cells
cardiac muscle fibers
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exhibit densely staining cross-bands, termed intercalated discs, that cross the fibers in a linear fashion
Cardiac Muscle
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has either one or two centrally located pale-staining nuclei
cardiac muscle cell
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Fatty acids- major fuel of the heart and are stored as
triglycerides in numerous lipid droplets
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often found near the nuclei of cardiac cells
Lipofuscin pigment
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In cardiac muscles The tubules are ________ in cardiac muscle than in skeletal muscle and the sarcoplasmic reticulum is _____
more numerous and larger
less well developed
87
Mitochondria occupies _____ of the cytoplasmic volume in cardiac muscles
40%
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A localized injury to cardiac muscle tissue that results in the death of cells is repaired by replacement with
fibrous connective tissue.
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T OR F Cardiac function can be regained at the site of injury
F
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where TnI is used as a marker for diagnosis
Myocardial Infarction
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Cells or fibers of smooth muscle are
long, tapering structures with elongated nuclei centrally located at the cell's widest part
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Smooth muscle Concentrated near the nucleus are
mitochondria, polyribosomes, cisternae of rough ER, and the Golgi apparatus
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bundles of thin and thick myofilaments in smooth muscle cells crisscross ___________ through the membrane _______
obliquely
lattice network
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Thin filaments of smooth muscle cells lack ________________ and instead utilize _________
troponin complexes
calmodulin
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a calcium-binding protein that is also involved in the contraction of nonmuscle cells
calmodulin
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the enzyme that phosphorylates myosin, which is required for myosin's interaction with F-actin
myosin light chain kinase (MLCK)
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major intermediate filament protein in all smooth muscles
Desmin
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additional component in vascular smooth muscle.
Vimentin
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[Smooth muscle] contain-actinin functionally similar to the Z discs of striated and cardiac muscles
Dense bodies
100
What components of smooth muscles insert to Dense bodies
Both intermediate filaments and F-actin filaments
101
Contraction of Smooth Muscle
Events that lead to elevation of intracellular Ca2+ concentration, which is directly responsible for muscle contraction
Electrical depolarizations
Chemical stimuli
Mechanical impulses
102
Electrical depolarizations is described as release of
acetylcholine and norepinephrine neurotransmitters
103
Chemical stimuli by which chemicals
angiotensin II, vasopressin or thromboxane A2
104
Mechanical impulses examples
passive vascular smooth muscle stretching
105
each cell is innervated and can contract independently
multiunit smooth muscle
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only a few cells are innervated but all cells are interconnected by gap junctions
unitary smooth muscle
107
cause the contraction stimulation to spread across adjacent cells as a synchronized wave.
gap junctions
108
The smooth muscles are composed of simpler, mononucleated cells that are
capable of dividing to maintain or increase their number.
109
Smooth muscle cells have also been shown to develop from the division and differentiation of ______________ during the repair process after vascular injury
endothelial cells and pericytes
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Skeletal muscle- tissue can undergo regeneration
LIMITED
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Skeletal muscle source of regenerating cells is the sparse population of _________ that lies within the external lamina of each mature muscle fiber
mesenchymal satellite cells
112
become activated, proliferating and fusing to form new skeletal muscle fibers after injury
Satellite cells
113
Cardiac muscle_______ beyond early childhood
no regenerative capacity
114
defects or damage in heart muscle are generally replaced by _______- forming myocardial scars
fibroblast proliferation and growth of connective tissue,
115
Smooth muscle- capable of a ________ regenerative response.
more active
116
participate in the repair of vascular smooth muscle
contractile pericytes
