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MUSCULAR TISSUE STUDY GUIDE
five properties of muscular tissue: excitability, conductivity, contractility, extensibility, and
elasticity.
- Excitability means muscular tissue gets excited in response to chemical or electrical
signals
- Conductivity means that muscular tissues conduct electricity through the muscular
membrane
- Contractility means that muscular tissue contracts or shortens in response to an action
potential
- Extensibility means that muscle tissue can stretch without damaging, but can be damaged
by overstretch; however, range of motion varies among individuals
Skeletal muscle tissue attaches to bones via tendons, fashia, or appendoris. They are striated and
voluntary and have light and dark areas that become visible beneath a microscope.
- Skeletal muscle tissue are usually part of the origin and insertion for some movement
- They are made up of myofilaments, myofibrils, muscle fibers, and fascicles
o Myofibrils are bunches of myofilaments and bundles of proteins that are thread
like, approximately 1-3 nanometers in diameter, that extend though the length of
the muscle fibers and are arranged in the contractile elements of a muscular cell
o Muscle fibers or cells are individuals’ cells made up of bundles of myofibrils.
They contain organelles, a plasma membrane called the sarcolemma, and
cytoplasm called sarcoplasm
The plasma membrane turns conducted electrical stimuli into action
potentials
Skeletal muscles have multiple, fat muscle that lie beneath the sarcolemma
Invagination or transverse tubules aid muscle action potentials in traveling
through and down the cell
Action potentials go down the transverse tubules or t tubules and
similar to terminal cisterns, they release the calcium contained
within the special ER, causing microfuges
Mitochondria are arranged in rows throughout the cells, close to the fibers
and proteins that cause muscles to contract because muscle contractions
take energy
Sarcoplasm contains large amounts of glycogen and myoglobin
The sarcoplasmic reticulum or special er is made up of membranous tissue
that encircles myofibrils and stores calcium ions, which are vital in
triggering muscle contractions
o Fascicles are bundles of muscle fibers and skeletal muscle tissue are bundles of
fascicles
There are three main types of connective tissue bundles: the endomysium, the perimysium, and
the epimysium.
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- The endomysium surrounds muscle fibers
- The perimysium surrounds fascicles
- The epimysium surrounds muscles and other organs/internal body structures
Cardiac muscle tissue is striated, involuntary, and branching. They also contain cells that create
the natural or auto pacemaker rhythm system of the body; this system involves cells that create
rhythmic impulses that sets the pace for blood pumping and directly controls heart rate
Smooth muscle tissue has no striations and are involuntary. Erector pili muscle contains smooth
muscle tissue that aid in connecting hair follicles to the connective tissue of the basilar
membrane
Muscle tissues work to produce body movements, stabilize and maintain body position, store and
move substances (blood, urine, food, air, fluids, sperm, etc.), regulate organ volumes, produce
heat through thermogenesis, and aid in both nonverbal and verbal communication.
- The reason why individuals get hot while running is because your muscles are working
and producing heat through that movement. This is also why someone may shiver when
it’s cold, our bodies are attempting to produce heat to maintain out body temperature.
- Mature muscles cells develop from hundreds of myoblasts fused together during the fetal
stages of development. These cells are multinucleated and cannot divided, so any growth
that occurs is sue to the enlargement instead of the division of muscle cells. Instead of
muscle cells dividing and forming new cells during muscle damage, satellite cells retain
the ability to regenerate new cells; this helps fix muscle damages to a degree. Muscle
damaged can be exercise induced; intense exercise can cause damage to muscle and
delayed onset muscle soreness
The sarcomere is the smallest functional unit of both striated and cardiac muscle and are usually
described in terms of bands that are organized according to the type of filament present in each
section; it is made up of a complex mesh of thick filaments, thin filaments, and the giant protein
titin, that slides past each other when muscles contract or relax. The sarcomere is made up of the
myofilaments actin (thin filaments) and myosin (thick filaments) that come together in a sliding
filament mechanism that explains how skeletal fibers contract and relax.
- The I band is isotropic and uniform in each direction
- The Z line is between
- The M line is in the middle
- The H zone is bright
- The A band is anisotropic and directionally dependent
The sliding filament mechanism involves the myofilaments actin and myosin moving relative to
one another, which causes contractions. These myofilaments overall within myofibrils, this leads
to thick and thin filaments binding in cross bridges; if the muscle is relaxed, few cross brides
form and the H and I zones are larger, if the muscles are contracting then cross bridges form, and
the pulling and movement caused by contraction cause the H-zone to become non-existent. The
myosin heads attach to the myosin attaching sites exposed by regulatory proteins on actin, the
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myosin goes through a continuous cycle of reaching and pulling, and as they reach and pull they
are pulling the thin filament towards the center of the sarcomere. The Z discs come closer
together and the sarcomere shortens, causing the shortening of the entire muscle, affecting the H-
zone and causes a contraction.
- Myosin is a thick filament that typically lies between the A band and H zone of the
sarcomere. Its made up of a head, tail, and neck; and it’s functions involving coupling
hydrolysis of ATP, charging myosin heads, and allowing binding and movement along
the actin-which creates movements.
- Actin is a thin filament, best described as “beads”, whose function is to aid in cell
movement and the tensing of muscle fibers (muscle contractions)
Contractions are switched on and off by the regulatory protein’s tropomyosin and troponin.
- Tropomyosin isa regulatory protein located on actin and primarily used in relaxed
muscles.
- Troponin is a regulatory component of actin that moves tropmyosin away from the
myosin binding sit on actin due to the shape changed caused from calcium ion binding.
This allows separates myosin heads from their binding sites on actin, freeing them from
the cross-bridge formation.
Key structural proteins titin and dystrophin align thick and thin filaments, provide elasticity
and extensibility, and link myofibrils to the sarcolemma.
- Titin stabilizes the position of myosin and accounts for the elasticity and extensibility of
muscle tissue
- Dystrophin links filaments to sarcolemma, allows transfer and transmission of tension
made through contractile proteins/contractions, and helps strength the sarcolemma
Muscle contractions are caused by the indirect stimulation of somatic motor neurons. The
synaptic cleft is the area between the end od the neuron and the beginning of the muscle, due to
this area somatic neurons are not able to directly stimulate muscle. Instead, somatic motor
neurons relays nerve impulses from the central nervous system to effector organs, muscles,
and/or glands, and when that stimulus reaches a threshold good enough to open violated-gated
ions channels, the action potential is triggered. This action potential triggers the neurotransmitter
acetylcholine that directly stimulates the muscle, activated the acetylcholine receptors, produces
muscle action potential, and terminated acetylcholine activity. This process causes a
depolarization that change the change if the plasma membrane from resting to negative; this
depolarization occurs due to released acetylcholine binding to nicotinic receptors, causing the
nicotinic receptor channels to open and let sodium and a few potassium ions to enter the muscle
fiber. Once the actin potential ahs been received, the synaptic vesicles begin to fuse to the
presynaptic membrane. The synapse is where communication coming down the nerve occurs, the
axon terminal divides into synaptic end bulbs that produce synaptic vesicles. These vesicles
release acetylcholine, which travels down the synaptic cleft and attached to the receptors on the
muscle side of the motor end plate. Post-depolarization of the post synaptic membrane,
acetylcholine is broken down and removed
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- The neuromuscular junction is the connection between the muscle and neurons. The
nerve is on top, and the muscle is on bottom; the nerve releases a neurotransmitter that
goes across the synaptic cleft and reaches the muscles. The somatic motor neurons on the
surface of the muscle are stripped in layers in an onion-bulb like process
- The motor end plate is the part of the muscle fiber that has been innervated by the
somatic motor neurons; it is opposite the nerve, contains receptors, is highly excitable,
and contains acetylcholine receptors.
Excitation-contraction coupling is the relaxation of the skeletal muscle. A stimulus triggers
acetylcholine and causes it to break down the acetylcholine within the synaptic cleft, stopping
the muscle action potential. A calcium channels close, calcium, is released. This causes myosin
binding to be exposed and recovered by a tropomyosin-troponin complex. Released calcium is
pumped into storage within the special ER through active transport, and is kept there by the
calcium binding protein calsequestrin.
Muscle contractions occur through a cycle that beings with an increase in calcium ion
concentration due to action potentials causing the special ER to release there calcium ions into
the muscle cells, this is the stimulus that triggers the myosin head and allows it to being to
hydrolyze ATP and becoming reoriented and energized. The calcium ions move tropomyosin
away from the myosin binding sites, allowing for myosin heads to bind to actin and allowing
cross-bridges to form. The power stroke allows for the newly formed cross-bridges to rotate
towards the center of sarcomere. The cross bridges detach from the actin, and the myosin heads
binds to ATP; as long as ATP is available and the special ER still has high levels of calcium, the
cycle continues.
- The muscle cell membrane contains ion pumps that return calcium to the special ER
- Decreased levels of calcium ions cause myosin-binding sites to become covered and
muscles relax, brining the cycle to a stop
The number of skeletal muscle fibers is set before you are born. Any muscle growth occurs
through hypertrophy, which can be stimulated by testosterone and human growth hormones.
Atrophy is a decrease in muscle size, this van be caused by a lack of physical activity due to
illness or injury, nutrition, genetics, and certain medical conditions.
Rigor mortis a state of muscle rigidity that occurs 3-4 hours after death and can last about 24
hours. After death, calcium ions leak out of the special ER and allows myosin heads to begin to
bind to actin. Because ATP synthesis has stopped, the cross bridges will remain unable to detach
from action until proteyclic enzymes begin to digest decomposing cells.

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MUSCULAR TISSUE STUDY GUIDE five properties of muscular tissue: excitability, conductivity, contractility, extensibility, and elasticity. - Excitability means muscular tissue gets excited in response to chemical or electrical signals Conductivity means that muscular tissues conduct electricity through the muscular membrane Contractility means that muscular tissue contracts or shortens in response to an action potential Extensibility means that muscle tissue can stretch without damaging, but can be damaged by overstretch; however, range of motion varies among individuals Skeletal muscle tissue attaches to bones via tendons, fashia, or appendoris. They are striated and voluntary and have light and dark areas that become visible beneath a microscope. - Skeletal muscle tissue are usually part of the origin and insertion for some movement They are made up of myofilaments, myofibrils, muscle fibers, and fascicles o Myofibrils are bunches of myofilaments and bundles of proteins that are thread like, approximately 1-3 nanometers in diameter, that extend though the length of the muscle fibers and are arranged in the contractile elements of a muscular cell o Muscle fibers or cells are individuals’ cells made up of bundles of myofibrils. They contain organelles, a plasma membrane called the sarcolemma, and cytoplasm called sarcoplasm ▪ The plasma membrane turns conducted electrical stimuli into action potentials ▪ Skeletal muscles have multiple, fat muscle that lie beneath the sarcolemma ▪ Invagination or transverse tubules aid muscle action potentials in traveling through and down the cell • Action potentials go down the transverse tubules or t tubules and similar to terminal cisterns, they release the calcium contained within the special ER, causing microfuges ▪ Mitochondria are arranged in rows throughout the cells, close to the fibers and proteins that cause muscles to contract because muscle contractions take energy ▪ Sarcoplasm contains large amounts of glycogen and myoglobin ▪ The sarcoplasmic reticulum or special er is made up of membranous tissue that encircles myofibrils and stores calcium ions, which are vital in triggering muscle contractions o Fascicles are bundles of muscle fibers and skeletal muscle tissue are bundles of fascicles There are three main types of connective tissue bundles: the endomysium, the perimysium, and the epimysium. - The endomysium surrounds muscle fibers The perimysium surrounds fascicles The epimysium surrounds muscles and other organs/internal body structures Cardiac muscle tissue is striated, involuntary, and branching. They also contain cells that create the natural or auto pacemaker rhythm system of the body; this system involves cells that create rhythmic impulses that sets the pace for blood pumping and directly controls heart rate Smooth muscle tissue has no striations and are involuntary. Erector pili muscle contains smooth muscle tissue that aid in connecting hair follicles to the connective tissue of the basilar membrane Muscle tissues work to produce body movements, stabilize and maintain body position, store and move substances (blood, urine, food, air, fluids, sperm, etc.), regulate organ volumes, produce heat through thermogenesis, and aid in both nonverbal and verbal communication. - - The reason why individuals get hot while running is because your muscles are working and producing heat through that movement. This is also why someone may shiver when it’s cold, our bodies are attempting to produce heat to maintain out body temperature. Mature muscles cells develop from hundreds of myoblasts fused together during the fetal stages of development. These cells are multinucleated and cannot divided, so any growth that occurs is sue to the enlargement instead of the division of muscle cells. Instead of muscle cells dividing and forming new cells during muscle damage, satellite cells retain the ability to regenerate new cells; this helps fix muscle damages to a degree. Muscle damaged can be exercise induced; intense exercise can cause damage to muscle and delayed onset muscle soreness The sarcomere is the smallest functional unit of both striated and cardiac muscle and are usually described in terms of bands that are organized according to the type of filament present in each section; it is made up of a complex mesh of thick filaments, thin filaments, and the giant protein titin, that slides past each other when muscles contract or relax. The sarcomere is made up of the myofilaments actin (thin filaments) and myosin (thick filaments) that come together in a sliding filament mechanism that explains how skeletal fibers contract and relax. - The I band is isotropic and uniform in each direction The Z line is between The M line is in the middle The H zone is bright The A band is anisotropic and directionally dependent The sliding filament mechanism involves the myofilaments actin and myosin moving relative to one another, which causes contractions. These myofilaments overall within myofibrils, this leads to thick and thin filaments binding in cross bridges; if the muscle is relaxed, few cross brides form and the H and I zones are larger, if the muscles are contracting then cross bridges form, and the pulling and movement caused by contraction cause the H-zone to become non-existent. The myosin heads attach to the myosin attaching sites exposed by regulatory proteins on actin, the myosin goes through a continuous cycle of reaching and pulling, and as they reach and pull they are pulling the thin filament towards the center of the sarcomere. The Z discs come closer together and the sarcomere shortens, causing the shortening of the entire muscle, affecting the Hzone and causes a contraction. - - Myosin is a thick filament that typically lies between the A band and H zone of the sarcomere. Its made up of a head, tail, and neck; and it’s functions involving coupling hydrolysis of ATP, charging myosin heads, and allowing binding and movement along the actin-which creates movements. Actin is a thin filament, best described as “beads”, whose function is to aid in cell movement and the tensing of muscle fibers (muscle contractions) Contractions are switched on and off by the regulatory protein’s tropomyosin and troponin. - Tropomyosin isa regulatory protein located on actin and primarily used in relaxed muscles. Troponin is a regulatory component of actin that moves tropmyosin away from the myosin binding sit on actin due to the shape changed caused from calcium ion binding. This allows separates myosin heads from their binding sites on actin, freeing them from the cross-bridge formation. Key structural proteins titin and dystrophin align thick and thin filaments, provide elasticity and extensibility, and link myofibrils to the sarcolemma. - Titin stabilizes the position of myosin and accounts for the elasticity and extensibility of muscle tissue Dystrophin links filaments to sarcolemma, allows transfer and transmission of tension made through contractile proteins/contractions, and helps strength the sarcolemma Muscle contractions are caused by the indirect stimulation of somatic motor neurons. The synaptic cleft is the area between the end od the neuron and the beginning of the muscle, due to this area somatic neurons are not able to directly stimulate muscle. Instead, somatic motor neurons relays nerve impulses from the central nervous system to effector organs, muscles, and/or glands, and when that stimulus reaches a threshold good enough to open violated-gated ions channels, the action potential is triggered. This action potential triggers the neurotransmitter acetylcholine that directly stimulates the muscle, activated the acetylcholine receptors, produces muscle action potential, and terminated acetylcholine activity. This process causes a depolarization that change the change if the plasma membrane from resting to negative; this depolarization occurs due to released acetylcholine binding to nicotinic receptors, causing the nicotinic receptor channels to open and let sodium and a few potassium ions to enter the muscle fiber. Once the actin potential ahs been received, the synaptic vesicles begin to fuse to the presynaptic membrane. The synapse is where communication coming down the nerve occurs, the axon terminal divides into synaptic end bulbs that produce synaptic vesicles. These vesicles release acetylcholine, which travels down the synaptic cleft and attached to the receptors on the muscle side of the motor end plate. Post-depolarization of the post synaptic membrane, acetylcholine is broken down and removed - - The neuromuscular junction is the connection between the muscle and neurons. The nerve is on top, and the muscle is on bottom; the nerve releases a neurotransmitter that goes across the synaptic cleft and reaches the muscles. The somatic motor neurons on the surface of the muscle are stripped in layers in an onion-bulb like process The motor end plate is the part of the muscle fiber that has been innervated by the somatic motor neurons; it is opposite the nerve, contains receptors, is highly excitable, and contains acetylcholine receptors. Excitation-contraction coupling is the relaxation of the skeletal muscle. A stimulus triggers acetylcholine and causes it to break down the acetylcholine within the synaptic cleft, stopping the muscle action potential. A calcium channels close, calcium, is released. This causes myosin binding to be exposed and recovered by a tropomyosin-troponin complex. Released calcium is pumped into storage within the special ER through active transport, and is kept there by the calcium binding protein calsequestrin. Muscle contractions occur through a cycle that beings with an increase in calcium ion concentration due to action potentials causing the special ER to release there calcium ions into the muscle cells, this is the stimulus that triggers the myosin head and allows it to being to hydrolyze ATP and becoming reoriented and energized. The calcium ions move tropomyosin away from the myosin binding sites, allowing for myosin heads to bind to actin and allowing cross-bridges to form. The power stroke allows for the newly formed cross-bridges to rotate towards the center of sarcomere. The cross bridges detach from the actin, and the myosin heads binds to ATP; as long as ATP is available and the special ER still has high levels of calcium, the cycle continues. - The muscle cell membrane contains ion pumps that return calcium to the special ER Decreased levels of calcium ions cause myosin-binding sites to become covered and muscles relax, brining the cycle to a stop The number of skeletal muscle fibers is set before you are born. Any muscle growth occurs through hypertrophy, which can be stimulated by testosterone and human growth hormones. Atrophy is a decrease in muscle size, this van be caused by a lack of physical activity due to illness or injury, nutrition, genetics, and certain medical conditions. Rigor mortis a state of muscle rigidity that occurs 3-4 hours after death and can last about 24 hours. After death, calcium ions leak out of the special ER and allows myosin heads to begin to bind to actin. Because ATP synthesis has stopped, the cross bridges will remain unable to detach from action until proteyclic enzymes begin to digest decomposing cells. Name: Description: ...
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