What are thick filaments composed of?
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Myosin molecules.
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What are thick filaments composed of?
Myosin molecules.
What holds the strands of tropomyosin in position?
Troponin.
What does the sarcoplasmic reticulum form around each myofibril?
A network.
What produces the banded or striated appearance of a muscle fiber?
The arrangement of thick and thin filaments.
What is the neuromuscular junction?
A specialized intercellular connection between a motor neuron and a skeletal muscle fiber.
What does muscle excitability refer to?
The ability of muscle tissue to respond to stimuli.
Where is the M line located in a sarcomere?
In the center of each sarcomere.
In which direction do the heads of myosin molecules project?
Outward.
What is a possible outcome of the Treppe phenomenon?
Contracture.
What is myography?
Myography is the study or recording of muscle activity.
What do the specific active sites on actin interact with?
Myosin.
What system is required to stimulate skeletal muscles?
The central nervous system.
What type of movements are associated with larger motor units?
Gross movements.
How can anaerobic endurance be increased?
By brief, intense workouts.
Are skeletal muscles under voluntary or involuntary control?
Voluntary control.
What are the two types of smooth muscle?
Single-unit (visceral) smooth muscle and multiunit smooth muscle.
Approximately how many skeletal muscles are included in the muscular system?
About 700 skeletal muscles.
What is each skeletal muscle cell called?
A muscle fiber.
What role do T tubules play in muscle contraction?
T tubules trigger the release of calcium ions.
How are skeletal muscles attached to bones?
They are directly or indirectly attached to bones.
What are the different types of muscle tone?
Normal, flaccid, spastic.
What is the result of high calcium ion concentration in the cytosol?
It leads to complete tetanus, producing maximum tension.
How can aerobic endurance be increased?
By sustained, low levels of activity.
What is a muscle twitch?
A muscle twitch is a single, rapid contraction and relaxation of muscle fibers following a single stimulus.
What is a threshold stimulus?
The minimum level of stimulation required to cause a muscle fiber to contract.
What is the result of increased anaerobic endurance?
Hypertrophy of muscles.
What are the three types of muscle tissue?
Skeletal muscle, cardiac muscle, and smooth muscle.
What is the primary function of muscle cells?
Specialized for contraction.
What is skeletal muscle tissue composed of?
Skeletal muscle tissue, connective tissue, nerves, and blood vessels.
How does muscle tissue contribute to the maintenance of posture?
Muscle contractions help maintain body posture by stabilizing joints and supporting the skeleton.
Which body systems are supported by muscle tissue?
Nervous, endocrine, cardiovascular, respiratory, digestive, urinary, and immune systems.
How is muscle performance measured?
In force and endurance.
Are dying muscle fibers replaced during atrophy?
No, dying muscle fibers are not replaced.
What role does gravity play in muscle elongation?
Gravity assists in the passive process of returning a muscle to its elongated state after contraction.
What is a key feature of multiunit smooth muscle?
It consists of many independent single-cell units.
What is multiple wave summation?
Summation is the addition of one muscle twitch to another. This causes a more powerful contraction, and is the result of a second stimulus arriving before the relaxation phase ends.
How many sarcomeres does each myofibril have?
About 10,000 sarcomeres end to end.
What encircles myofibrils?
T tubules.
What is the function of T tubules in muscle cells?
T tubules allow electrical impulses from the sarcoplasm to reach the cell’s interior.
What is the epimysium?
A connective tissue that covers the entire muscle.
What happens to muscle length and tension during isotonic contraction?
Tone or tension remains the same, but the length changes.
How are tendons formed?
Collagen fibers from all three layers of connective tissue come together at the end of the muscle to form a tendon.
Why do muscle contractions require large amounts of energy?
Because muscle contraction requires large amounts of ATP.
What happens when calcium binds to troponin?
It causes a shift in tropomyosin, exposing binding sites on actin filaments.
What is one of the four primary tissue types?
Muscle tissue.
What are sarcomeres made of?
Hundreds of thick and thin myofilaments.
What is muscle fatigue?
Muscle fatigue is when a muscle will no longer perform at the required level, even if stimulated.
What are the three phases of a twitch contraction?
Latent phase, contraction phase, and relaxation phase.
Which reflex is associated with muscle tone?
Spinal reflex.
What is muscle recovery?
The process of returning muscle to normal pre-exertion conditions.
Is muscle atrophy reversible?
Yes, if it is caused by a temporary reduction in use.
What happens to lactate during muscle recovery?
Lactate is converted back to pyruvate.
What is the primary function of skeletal muscle cells?
To facilitate movement by contracting and generating force.
What causes muscle fiber contraction?
The shortening of myofibrils.
What are the main components of the neuromuscular junction?
An axon terminal and a motor end plate.
What is automaticity in cardiac muscle?
The ability of cardiac muscle tissue to contract without neural stimulation.
What advantage does the arrangement of myofilaments in smooth muscle provide?
More freedom of movement in contraction.
What are the two main pathways for energy sources in muscle contraction?
Aerobic pathway and anaerobic pathway.
What does the amount of tension produced in an individual muscle fiber depend on?
The number of cross-bridges in the muscle fiber.
What runs through connective tissue layers to innervate individual muscle fibers?
Axons (nerve fibers).
What are cross bridges in the context of muscle cell structure?
Cross bridges are connections formed between myosin heads and actin filaments during muscle contraction.
How does a muscle twitch differ from tetanus?
A muscle twitch is a single contraction and relaxation cycle, while tetanus is a continuous, sustained contraction due to high-frequency stimulation.
How many myofibrils can be found in each muscle fiber?
Hundreds to thousands.
What initiates the excitation of the sarcolemma?
The excitation of the sarcolemma is initiated at the neuromuscular junction (NMJ).
What does the perimysium do?
It divides the muscle into fascicles or bundles of muscle fibers and contains blood vessels and nerves supplying the fascicles.
To which protein does calcium bind during muscle contraction?
Calcium binds to troponin.
What happens during muscle relaxation?
The sarcoplasmic reticulum (SR) actively pumps calcium back into its sacs.
What process involves the breakdown of ATP to release energy?
Hydrolysis
What is the result of myosin heads bending?
They pull thin filaments past them.
Where are smooth muscle cells commonly found?
In the walls of most organs, in the form of sheets, bundles, or sheaths.
What is ratcheting?
The repeated process of myosin heads binding, pulling, and releasing.
What structural components does smooth muscle lack?
Smooth muscle lacks myofibrils, sarcomeres, and striations.
Why do fast muscle fibers fatigue rapidly?
Because they have relatively few mitochondria and rely on glycolysis for energy.
What are the characteristics of slow muscle fibers?
Slow muscle fibers are about half the diameter of fast fibers, take three times as long to reach peak tension, are specialized to contract for extended periods, and are fatigue resistant.
Why is an extensive network of blood vessels necessary in skeletal muscle?
To supply high energy use.
Why are myofilaments crucial?
They are crucial to muscle contraction.
What is the thin filament composed of?
A thin twisted strand of actin molecules.
How does muscle fatigue affect endurance athletes?
It affects them after they use up their stores of glycogen and lipids.
Which molecules are found in thin filaments?
Actin molecules.
How do T tubules contribute to muscle contraction?
T tubules allow for the unified contraction of the entire muscle fiber.
What are the passive processes involved in muscle elongation following contraction?
Elastic forces, movements of opposing muscles, and gravity.
What role do elastic forces play in muscle elongation?
Elastic forces contribute to the passive process of returning a muscle to its elongated state after contraction.
What is muscle contractility?
The ability of muscle tissue to contract and generate force.
What is a tendon?
A bundle of fibers that attaches muscle to bone.
What is calmodulin?
The protein involved in smooth muscle contraction.
What causes an entire muscle fiber to contract?
Sarcomere shortening.
With what do the heads of myosin molecules interact during muscle contraction?
Active sites on actin.
What type of metabolism do cardiac muscle cells rely on?
Cardiac muscle cells rely on aerobic metabolism.
Which two substances are essential for producing ATP through aerobic pathways?
Glucose and oxygen
How many ATP molecules are produced per pyruvate entering the citric acid cycle in the aerobic pathway?
Approximately 15 ATP.
How does muscle length affect muscle contraction?
The optimal muscle length allows for maximum force generation.
What are the two types of muscle fibers based on their color?
Red and white fibers
How many sarcomeres does a muscle fiber contain?
About 15,000 sarcomeres.
What is another term for muscle tone?
Tonic contraction.
What are the primary causes of muscle fatigue?
Depletion of energy reserves or a decline in pH from lactic acid production.
What mechanisms are involved in regulating muscle tone?
Negative feedback mechanisms.
What are the main contributions of muscle tissue to homeostasis?
Movement, maintenance of internal temperature, maintenance of posture, and supporting various body systems.
What is muscle atrophy?
It occurs in a muscle that is not regularly stimulated by a motor neuron.
How does the nervous system contribute to muscle movement?
The nervous system 'smooths out' movement.
What are the key processes involved in muscle recovery?
Restoring oxygen levels, removing lactic acid, replacing intracellular energy reserves, losing heat produced during contraction.
Why do breathing rate and depth remain increased after exercise?
To repay oxygen debt and restore resting conditions.
What is the sliding filament theory?
The theory that muscle contraction occurs when actin filaments slide over myosin filaments, shortening the sarcomere.
What are examples of activities involving isotonic contraction?
Lifting a book, walking.
How do skeletal muscles help maintain body temperature?
Muscle contractions generate heat.
What is an example of an activity involving isometric contraction?
Pushing against a wall.
Can cardiac muscle cells undergo tetanus (sustained contraction)?
No, cardiac muscle cells cannot undergo tetanus.
How long do energy reserves from creatine phosphate last during muscle contraction?
About 15 seconds.
Where does the aerobic pathway occur?
In the mitochondria. It involves the break down of organic substrates through a series of chemical reactions.
What constitutes a motor unit?
A motor neuron plus muscle fibers.
What type of movements are associated with smaller motor units?
Fine movements.
What are the four different kinds of protein molecules found in myofilaments?
Myosin, Actin, Tropomyosin, Troponin.
What is tetanus in muscle physiology?
Tetanus is a sustained muscle contraction that occurs when the muscle is stimulated at a high frequency, preventing relaxation between stimuli.
What components are found in skeletal muscles?
Skeletal muscle tissue, connective tissues, blood vessels, and nerves.
In what way does muscle tissue help maintain internal temperature?
Muscle contractions generate heat, which helps maintain body temperature.
When can muscle atrophy be observed?
After a cast comes off a fracture.
What is a triad?
A combination of two terminal cisternae and one T tubule.
Is there an active mechanism for returning a muscle to a pre-contracted, elongated state?
No
What does the axon terminal of the neuron contain?
Vesicles filled with acetylcholine (ACh), a neurotransmitter.
What happens to acetylcholine (ACh) after it is released from the axon terminal?
It diffuses across the synaptic cleft and binds to the receptor on the motor end plate.
What enzyme is found in the synaptic cleft and the motor end plate, and what is its function?
Acetylcholinesterase (AChE), which breaks down acetylcholine (ACh).
What ions are related to the Treppe phenomenon?
Calcium ions.
How do smooth muscle cells compare in size to cardiac muscle cells?
They are similar in size.
What is myositis?
Inflammation of muscle tissue.
Can muscle cells generate compression?
No, muscle cells can only contract and produce tension.
How does the speed of the aerobic pathway compare to the anaerobic pathway?
The aerobic pathway is slower than the anaerobic pathway.
What makes cardiac muscle self-exciting?
It can generate its own electrical impulses without external stimuli.
How are adjacent smooth muscle cells connected?
Adjacent cells are bound together.
What characteristic is associated with single-unit (visceral) smooth muscle?
Autorhythmicity and peristalsis.
What is incomplete tetanus?
It is a state where the muscle produces almost peak tension during rapid cycles of contraction and relaxation.
What is the sarcolemma?
The sarcolemma is a muscle cell’s plasma membrane.
Where are thin filaments located in a sarcomere?
At either end of a sarcomere.
What role do skeletal muscles play in maintaining posture?
They maintain posture and body position.
What are the two factors that determine muscle performance?
Types of fibers in muscle (fast-twitch and slow-twitch) and physical conditioning or training.
What are pacemaker cells?
Specialized cardiac muscles, which determines the timing of contraction in cardiac muscles.
What is the primary function of isometric contraction?
Stabilizing.
What is the primary energy source for muscle contraction?
ATP
What are muscle strains and sprains?
Muscle strains are injuries to muscle fibers or tendons, while sprains are injuries to ligaments.
What is another name for cardiac muscle?
Striated involuntary muscle.
What is a muscle contusion?
A muscle contusion is a bruise caused by a direct blow or impact to the muscle.
How do cardiac muscle cells differ from skeletal muscle cells in terms of structure?
Cardiac muscle cells are striated and branched, and they have diads rather than triads.
What is the stretch reflex and how does it relate to muscle contraction?
The stretch reflex is a muscle contraction in response to stretching within the muscle, helping to maintain muscle tone and posture.
What is the primary energy source for fast muscle fibers?
Glycolysis.
How does the diameter of slow muscle fibers compare to fast muscle fibers?
Slow muscle fibers are about half the diameter of fast muscle fibers.
What is a sarcomere?
The segment of a myofibril between two Z disks.
How can physical conditioning and training affect muscle performance?
It can increase power and endurance.
What is the primary difference between aerobic and anaerobic pathways?
Aerobic pathways require oxygen, while anaerobic pathways do not.
What is a muscle fiber made of?
1000 or more parallel myofibrils.
Which protein molecules make up the thin filaments in muscle cells?
Actin, Tropomyosin, Troponin.
What does muscle graphing refer to?
Muscle graphing refers to the visual representation of muscle activity.
What is a twitch contraction?
A single, rapid contraction of a muscle followed by relaxation.
What occurs during complete tetanus?
The rate of stimulation is increased until the relaxation phase is eliminated, producing maximum tension.
What does the sarcolemma surround?
The sarcolemma surrounds the sarcoplasm or cytoplasm.
What does force mean in terms of muscle performance?
The maximum amount of tension produced by a muscle or muscle group.
How do opposing muscles contribute to muscle elongation?
Movements of opposing muscles help in the passive process of returning a muscle to its elongated state after contraction.
What happens to muscle length and tension during isometric contraction?
Length remains the same, but tension increases. The tension does not exceed the load, therefore it does not produce movement.
What form of energy storage is used in muscle fibers?
Creatine phosphate (CP).
What is the function of mitochondria in skeletal muscle cells?
To produce ATP, the energy source for muscle contractions.
What is the role of the neuromuscular junction in skeletal muscle cells?
To transmit nerve impulses to muscle fibers, triggering contraction.
What happens when a muscle fiber contracts?
It pulls on the collagen fibers of tendons, creating tension.
What is required to uncover the active sites on actin for myosin interaction?
Movement of troponin and tropomyosin.
What is the shape and nuclear characteristic of smooth muscle cells?
Spindle-shaped and have a single nucleus.
What are muscle cells also known as?
Myocytes or fibers.
What does glycolysis break down glucose into?
Pyruvate.
What happens to pyruvate in the anaerobic pathway when oxygen levels are low?
It is converted to lactate.
What is a triad in muscle cells?
A structure formed by a T tubule and two SR sacs.
What protein molecule is almost entirely found in thick filaments?
Myosin.
What characterizes muscle tone?
A low level of continuous muscle contraction while awake.
What covers the active sites on actin when the muscle is at rest?
Strands of tropomyosin.
What is the smallest functional unit of a skeletal muscle fiber?
Sarcomere.
What are the four functional characteristics of muscle?
Excitability, Contractility, Extensibility, Elasticity.
What is the function of the endomysium?
It covers each muscle fiber and ties fibers together, containing capillaries and nerve fibers.
What structural feature is absent in smooth muscle cells?
T tubules.
What occurs during muscle contraction at the molecular level?
Each cross-bridge breaks down ATP into ADP and a phosphate group.
How is ADP recharged back to ATP during muscle contraction?
Energy stored in creatine phosphate (CP) is used to recharge ADP back to ATP.
Why is the entry of additional calcium important for cardiac muscle cells?
It is important because it allows for the proper contraction of cardiac muscle cells.
What compound helps in the rapid resynthesis of ATP in muscles?
Creatine phosphate
What is fibromyositis?
Inflammation of muscle, tendon, and connective tissue.
In what form is glucose stored in muscles?
As glycogen
What is the function of intercalated discs in cardiac muscle?
They connect cells to other cells and contain gap junctions that allow rapid communication between all cells which results in simultaneous contraction.
What are satellite cells in muscle tissue?
Cells that assist in muscle repair and regeneration.
What does EPOC stand for?
Excess Postexercise Oxygen Consumption.
How much slower are slow muscle fibers compared to fast muscle fibers in reaching peak tension?
Slow muscle fibers take three times as long to reach peak tension compared to fast muscle fibers.
How are actin and myosin organized in smooth muscle?
Actin and myosin are not rigidly organized.
What is the contraction phase of a twitch contraction?
The period of cross-bridge interaction. This is when muscle fibers shorten and generate force, and maximum tension is reached within about 15 milliseconds.
What are myofibrils?
Cylinder-shaped structures running the length of a muscle fiber.
What happens to muscle fibers during atrophy?
Muscle fibers become smaller and weaker.
What are the openings in the sarcolemma connected to?
The openings in the sarcolemma lead into a network of tubules called transverse tubules, or T tubules.
How does the body increase the rate of heat loss during muscle recovery?
By increasing sweat gland secretions and blood flow to the skin.
What protein filaments are involved in skeletal muscle contraction?
Actin and myosin.
How do skeletal muscles guard entrances and exits of the body?
They encircle openings of the digestive and urinary tracts.
What is muscle elasticity?
The ability of muscle tissue to return to its original length after being stretched or contracted.
What is an aponeurosis?
A broad sheet of fibers that connects muscles to each other.
What is the primary function of isotonic contraction?
Mobilizing.
What happens to the active sites on actin during muscle contraction?
Active sites on actin are exposed and myosin heads bind to them.
What does the I band contain?
The lighter region containing the thin filaments and includes the Z line.
How does the metabolic condition of individual fibers affect muscle contraction?
It influences the muscle's ability to generate force.
What is a syncytium in the context of cardiac muscle?
A network of cells that function as a unit.
What is muscular dystrophy?
Muscular dystrophy is a group of genetic disorders characterized by progressive muscle weakness and degeneration.
How are thick filaments arranged in smooth muscle?
Thick filaments are scattered throughout the sarcoplasm.
How are the anchoring sites of thin filaments arranged in smooth muscle?
The anchoring sites are not in a straight line.
Over what range of lengths can smooth muscle contract?
Smooth muscle can contract over a greater range of lengths.
Why do sprinters experience muscle fatigue more quickly?
Because they rapidly build up lactic acid.
What is the sarcoplasmic reticulum?
A specialized smooth endoplasmic reticulum.
How does muscle tissue contribute to movement?
Muscle contractions enable movement of the body and its parts.
Where do thick filaments lie in a sarcomere?
In the center of the sarcomere.
Which molecules are found in thick filaments?
Myosin molecules.
How do skeletal muscles support soft tissues?
The abdominal wall and pelvic cavity floor are composed of skeletal muscle.
What does muscle extensibility mean?
The ability of muscle tissue to be stretched without being damaged.
What are the two main parts of each myosin molecule?
A tail and a globular head.
In which direction do the tails of myosin molecules point?
Inward.
What is the A band in a sarcomere?
The darker region running the length of the thick filaments, including the zone of overlap containing both thick and thin filaments.
What can occur as a result of the Treppe phenomenon?
Muscle fatigue.
What is compression?
A push applied to an object.
How do intensity and frequency of stimulation affect muscle contraction?
They influence the strength and duration of the muscle contraction.
What is the main process involved in the anaerobic pathway?
Glycolysis.
What is a hernia?
Weakness in the wall of the abdominal muscles.
What is the relaxation phase of a twitch contraction?
Muscle tension decreases and the muscle returns to its resting state. Calcium levels drop and active sites are covered. This phase lasts for about 25 milliseconds.
What are myofibrils composed of?
Bundles of thick and thin myofilaments.
What does endurance measure in terms of muscle performance?
The amount of time a particular activity can be performed.
What is the role of the sarcoplasmic reticulum in skeletal muscle cells?
To store and release calcium ions during muscle contraction.
What is the motor end plate?
The portion of the muscle sarcolemma.
What marks the boundary at each end of the sarcomere?
Z lines.
What is the Treppe phenomenon?
A gradual, steplike increase in contraction strength.
What do neurons stimulate in the sarcolemma?
The production of an action potential (electrical impulse).
What happens to the relaxation phases during the Treppe phenomenon?
They are shortened.
When will movement occur in relation to tension and resistance?
Movement will occur only if the tension is greater than the object's resistance.
What role does the recruitment of motor units play in muscle contraction?
It determines the number of muscle fibers activated to produce force.
Are all sarcomeres in a muscle fiber involved in contraction?
Yes, all sarcomeres in a muscle fiber are involved in contraction.
What cellular components are abundant in muscle cells?
Multiple nuclei and many mitochondria.
How does load affect muscle contraction?
The load determines the amount of force the muscle needs to generate to move or support it.
What role do T tubules play in muscle cells?
They help in impulse transmission.
How does smooth muscle function?
Smooth muscle functions involuntarily.
What is the Treppe phenomenon also known as?
The staircase phenomenon.
How do the contraction durations of cardiac muscle cells compare to skeletal muscle cells?
Cardiac muscle cells have contractions that are about 10 times longer than those of skeletal muscle cells.
How does the action potential affect the permeability of cardiac muscle cell plasma membranes?
The action potential increases the permeability of the cardiac muscle cell plasma membrane to calcium.
What does tension tend to do?
Pull an object towards the source of tension.
What is the H band and when is it visible?
The H band contains only thick filaments and is visible when the fiber is relaxed. It includes the M line and light regions on either side.
How are glucose and oxygen supplied to muscles?
By blood
What is the length-tension relationship in muscle contraction?
It describes how the force a muscle generates varies with its length.
What are the characteristics of fast muscle fibers?
Fast muscle fibers reach peak tension very quickly, are large in diameter, have large glycogen reserves, relatively few mitochondria, fatigue rapidly, and produce very powerful contractions.
Where are thin filaments anchored in smooth muscle?
Thin filaments are anchored to the sarcolemma.
How are contractions triggered in smooth muscle?
Contractions are triggered differently, with most of the calcium for the trigger entering from extracellular fluid.
What happens to excess ATP in resting muscle fibers?
It transfers energy to creatine forming, which makes creatine phosphate (CP).
What model explains the process of muscle contraction?
The sliding filament model.
What is the M line made of?
Proteins that connect central portions of the thick filaments.
What is the graded strength principle?
The ability to match the force of movement to the demands of the task.
What must happen after creatine phosphate energy reserves are exhausted?
ATP must be generated by different means, such as anaerobic glycolysis and aerobic metabolism.
What are the end products of the aerobic pathway?
ATP, water, and carbon dioxide.
What are some examples of muscle infections?
Examples of muscle infections include tetanus and poliomyelitis.
How is oxygen stored in muscle cells?
By attraction to myoglobin
Why are slow muscle fibers fatigue resistant?
Because they have a greater oxygen supply, have high levels of oxygen storage by myoglobin, and they use oxygen efficiently due to large numbers of mitochondria.
What are the two types of myofilaments?
Thick and thin filaments.
What factors contribute to the graded strength principle?
Metabolic condition of individual fibers, recruitment of motor units, intensity and frequency of stimulation, muscle length, length-tension relationship, load, and stretch reflex.
Where is cardiac muscle found?
Only in the heart.
What is a key characteristic of cardiac muscle cells?
They are relatively small with usually only one central nucleus.
What is myasthenia gravis?
Myasthenia gravis is an autoimmune disorder that causes weakness in the skeletal muscles.
How many ATP molecules are yielded per glucose molecule in the anaerobic pathway?
2 ATP.
What is the unique characteristic of smooth muscle contraction?
Contraction causes twisting like a corkscrew.
Why is oxygen required in muscle cells?
For the aerobic pathway
Can tension be varied by changing the number of contracting sarcomeres in a muscle fiber?
No, tension cannot be varied by changing the number of contracting sarcomeres.
What are the sarcolemma and sarcoplasm?
The sarcolemma is the muscle cell membrane, and the sarcoplasm is the cytoplasm of a muscle cell.
How do individual muscle fibers operate in terms of contraction?
Individual muscle fibers are either fully contracted ('on') or relaxed ('off').
What is the function of the sarcoplasmic reticulum (SR) in muscle cells?
Calcium ion storage.
How is contractile force transmitted in smooth muscle?
Contractile force is transmitted throughout the tissue.
How do the impulses in cardiac muscle compare to those in skeletal muscle?
Cardiac muscle has more prolonged impulses.
What are myofibrils made of?
Myofilaments.
What contributes to the powerful contractions produced by fast muscle fibers?
The densely packed myofibrils.
What role does myoglobin play in slow muscle fibers?
Myoglobin stores high levels of oxygen, contributing to the fatigue resistance of slow muscle fibers.
What stimuli can smooth muscle respond to?
Smooth muscle can respond to hormones, pacemaker cells, and motor neurons.
What is one of the general functions of skeletal muscles?
Move the skeleton - they do this by pulling on tendons which then moves bones.
What is the terminal cisterna?
The expanded portion of the sarcoplasmic reticulum on either side of T tubules.
What is titin?
A strand of protein that connects the Z lines to the thick filament to maintain alignment
What is acethylcholine?
The neurotransmitter involved in muscle contraction at the neuromuscular junction.
What do myosin heads do after pulling the thin filaments?
The heads release, then binds to the next active site.
What is anaerobic endurance and aerobic endurance?
Anaerobic endurance is the length of time muscle contractions can be supported by glycolysis and existing ATP reserves.
Aerobic endurance is the length of time muscle contractions are supported by mitochondrial activity.
What is the latent phase of a twitch contraction?
The latent phase begins at stimulation and lasts about 2 milliseconds.. This includes the action potential and release of Ca2+, and no tension is produced.
