Muscle Tissue Quiz

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Questions and Answers

What is the primary function of cardiac muscle tissue?

To move bones

To regulate passage of substances

To move blood through the heart (correct)

To stabilize body positions

Skeletal muscle tissue is responsible for regulating the passage of substances through the body.

False

What are the cells of skeletal muscle tissue called?

muscle fibers or myocytes

Muscular tissue is excitable, allowing it to produce electrical signals called muscle action potentials.

electrically Signup and view all the answers

The fascia is composed of three layers: epimysium, perimysium, and endomysium.

endomysium Signup and view all the answers

Which type of muscle tissue can be stretched without tearing?

Smooth muscle tissue Signup and view all the answers

Match the following properties of muscular tissue with their descriptions:

Excitable = Can generate electrical signals Contractile = Can generate tension to produce movement Extensible = Can be stretched without tearing Elastic = Can return to resting length after stretching Signup and view all the answers

What is myology?

The scientific study of muscular tissue. Signup and view all the answers

What is the primary product of glycolysis?

Pyruvate Signup and view all the answers

Aerobic respiration can occur in the absence of oxygen.

False Signup and view all the answers

What is formed when pyruvate is fermented under low-oxygen conditions?

lactic acid Signup and view all the answers

Muscles need oxygen after exercise to replenish _ and convert lactic acid back to __.

myoglobin; glucose Signup and view all the answers

Which type of muscle fiber primarily uses aerobic respiration?

Slow oxidative fibers Signup and view all the answers

Match the following types of muscle fibers with their main characteristics:

Slow oxidative fibers = Fatigue-resistant, endurance activities Fast oxidative-glycolytic fibers = Capable of both aerobic and anaerobic metabolism Fast glycolytic fibers = Quick contractions, easily fatigued Signup and view all the answers

The final electron acceptor in aerobic respiration is oxygen.

True Signup and view all the answers

What is the term used to describe the oxygen requirement for muscle recovery after exercise?

oxygen debt Signup and view all the answers

What type of fibers primarily compose the endomysium?

Reticular fibers Signup and view all the answers

Aponeuroses are a type of fascia that connects muscle to skin.

False Signup and view all the answers

What type of neurons regulate voluntary muscle contractions?

somatic motor neurons Signup and view all the answers

Myocytes receive oxygen through _ and __.

inside; outside Signup and view all the answers

Match the terms with their correct descriptions:

Myofibrils = Thread-like structures of contractile proteins Sarcoplasm = Cytoplasm of muscle cells T-tubules = Invaginations of sarcolemma Calcium = Essential for muscle contraction Signup and view all the answers

Which protein acts as a motor protein in the thick filaments?

Myosin Signup and view all the answers

Hypertrophy refers to a decrease in muscle fiber size.

False Signup and view all the answers

What is the primary function of myoglobin in muscle cells?

To bind oxygen Signup and view all the answers

Skeletal muscle fibers can lay down new protein and cause _________.

hypertrophy Signup and view all the answers

Match the parts of a sarcomere with their descriptions:

M-line = Center of the sarcomere where thick filaments are anchored Z-disks = Ends of the sarcomere that anchor thin filaments H-zone = Area containing only thick filaments I-band = Area containing only thin filaments Signup and view all the answers

What is the role of troponin in muscle contraction?

Binds calcium and moves tropomyosin Signup and view all the answers

Dystrophin connects thin filaments to the sarcolemma.

True Signup and view all the answers

What are the contractile proteins in muscle fibers?

Myosin and Actin Signup and view all the answers

The specialized smooth endoplasmic reticulum in muscle cells is called the __________.

sarcoplasmic reticulum Signup and view all the answers

Which muscle structure is primarily responsible for the striated appearance of skeletal muscle?

Sarcomeres Signup and view all the answers

Muscle fibers can divide to increase muscle mass.

False Signup and view all the answers

Where is dystrophin located within muscle cells?

Within the cytoskeleton at the inner surface of the plasma membrane Signup and view all the answers

Dystrophin connects actin filaments to the dystrophin-glycoprotein complex.

True Signup and view all the answers

What is the term for the process when myosin pulls the thin filaments toward the M-line?

power stroke Signup and view all the answers

Myosin binds and __________ ATP.

hydrolyzes Signup and view all the answers

Match the following terms with their descriptions:

Dystrophin = Links actin to the dystrophin-glycoprotein complex Sarcomere = Basic contractile unit of muscle Tropomyosin = Blocks myosin-binding sites on actin Calcium = Essential for muscle contraction Signup and view all the answers

What occurs to the H zone during muscle contraction?

It disappears Signup and view all the answers

Muscle contraction requires the presence of both ATP and calcium ions.

True Signup and view all the answers

Where is calcium stored in muscle fibers?

sarcoplasmic reticulum Signup and view all the answers

What is the role of voltage-gated potassium channels (VGKCs) in repolarization?

Open slowly and allow K+ to flow out of cells Signup and view all the answers

The sliding filament model states that the filaments do not change in __________.

length Signup and view all the answers

Action potentials directly trigger muscle contractions by causing Ca2+ to be released from the sarcoplasmic reticulum.

True Signup and view all the answers

What initiates an action potential in muscle fibers?

Release of neurotransmitters from somatic motor neurons Signup and view all the answers

What component in the somatic nervous system is involved at the neuromuscular junction?

acetylcholine Signup and view all the answers

During muscle contraction, Ca2+ binds to _____ to move tropomyosin off the myosin-binding sites.

troponin Signup and view all the answers

The inside of a muscle cell is normally positively charged compared to the outside.

False Signup and view all the answers

What happens to the membrane potential during depolarization?

it becomes positive Signup and view all the answers

Match the following phases of muscle contraction with their descriptions:

Latent period = Delay before muscle action Contraction period = Sarcomeres shorten Relaxation period = Ca2+ pumped back into the sarcoplasmic reticulum Refractory period = Period of temporary unresponsiveness to new signals Signup and view all the answers

The restoration of a negative membrane potential after depolarization is called __________.

repolarization Signup and view all the answers

What is the average number of skeletal muscle fibers in a motor unit?

150 Signup and view all the answers

Muscle fatigue is prevented when all motor units within a muscle contract simultaneously.

False Signup and view all the answers

Which of the following statements about the length-tension relationship is true?

Too much overlap prevents effective contraction Signup and view all the answers

What type of muscle contraction occurs when the muscle shortens to decrease the angle around a joint?

concentric isotonic contraction Signup and view all the answers

Creatine phosphate is used by muscles to rapidly regenerate _____ during contraction.

ATP Signup and view all the answers

What happens to voltage-gated calcium channels (VGCCs) after the muscle action potential has passed?

They close in the sarcolemma Signup and view all the answers

Muscle tone refers to the slight stiffness of muscle due to involuntary contractions.

True Signup and view all the answers

What are the two types of isotonic contractions?

concentric and eccentric Signup and view all the answers

The enzyme that dephosphorylates creatine to regenerate ATP is called _____ kinase.

creatine Signup and view all the answers

What is achieved when frequent action potentials are generated in motor units?

Increased muscle tension Signup and view all the answers

Muscle fibers can respond to new action potentials while already contracted.

False Signup and view all the answers

Study Notes

Introduction to Muscular Tissue

There are three types of muscular tissue: skeletal, cardiac, and smooth.
Skeletal muscle tissue contracts to move bones and stabilize body positions.
Cardiac muscle tissue contracts to move blood through the heart.
Smooth muscle tissue contracts to regulate the passage of substances through the body, such as in the gastrointestinal tract and blood vessels.
All muscles generate heat during contraction.
The scientific study of muscular tissue is called myology.
Muscular tissue has four special properties: excitability, contractility, extensibility, and elasticity.
Muscular tissue is electrically excitable because it produces electrical signals called muscle action potentials.
Nerve tissue is also excitable, similar to muscle tissue.
Muscular tissue is contractile because muscle action potentials stimulate contraction.
Contractions generate tension on bones resulting in movement.
Muscular tissue is extensible because tissue can be stretched without tearing.
Muscular tissue is elastic because resting length is restored after stretching.

The Structure of Skeletal Muscle

The cells of skeletal muscle tissue are called muscle fibres, also known as myocytes, elongated cells containing bunched protein filaments called myofibrils.
Muscle fibres, connective tissue, nerve and blood supply compose a muscle (an organ).
Muscles are surrounded by connective tissue layers called fascia, which physically groups muscles with similar functions together and provides passage for nerves and vasculature.
The fascia is composed of three layers: epimysium, perimysium, and endomysium.
Epimysium, the most superficial layer, is dense irregular CT that wraps muscles.
Perimysium, the intermediate layer, is dense irregular CT that wraps fascicles, bundles of muscle fibres (cells).
Endomysium, the deepest layer, is mostly reticular fibres that wrap individual muscle fibres.
The fascia forms tendons, thick rope-like structures that connect muscles to bones.
Aponeuroses are a special type of tendon that forms broad sheets, such as the epicranial aponeurosis connecting the two bellies of the occipitofrontalis muscle.

The Blood and Nerve Supply of Muscle

Muscular tissue requires access to oxygen-rich blood, as it requires a lot of oxygen and is extensively vascularized.
Oxygen is required for aerobic cellular respiration.
Skeletal muscles are also extensively innervated (supplied) by somatic motor neurons, which regulate voluntary muscle contraction.
Axons branch from the spinal cord to muscles.
Typically, one axon branch synapses with one muscle fibre.

Skeletal Muscle Fibre Structure

Muscle fibres develop from immature cells called myoblasts in the womb.
Cells fuse as they mature resulting in large, multinucleate cells.
The plasma membrane of myocytes is called the sarcolemma, carrying electrical signals and folding inwards or invaginating to form T-tubules.
The cytoplasm of myocytes is called the sarcoplasm, densely packed with myofibrils, rich in glycogen (carbohydrate energy store), and containing myoglobin.
Myoglobin is only found in muscle cells, binds oxygen at an Fe-containing centre called heme, allowing myocytes to receive oxygen from inside and outside the cell.
The sarcoplasm is densely packed with myofibrils, long threads of contractile protein filaments (~2 nm diameter), which have a regular pattern of overlapping filaments giving skeletal and cardiac muscle a striated appearance.

The Sarcoplasmic Reticulum

The SR is the specialized smooth endoplasmic reticulum in muscle cells, extensively folded around each myofibril.
Membrane folds of the SR are called cisternae (singular: cistern).
Terminal cisternae specifically release Ca2+ to each T-tubule.
Where two terminal cisternae meet a T-tubule is called a triad.
Muscle fibres do not divide, but they can grow by laying down new protein and enlarging (hypertrophy).

Muscular Hypertrophy

Muscular hypertrophy is an increase in sarcoplasmic volume, where each muscle fibre increases the volume of cellular contents, especially myofibrils.
Other cellular contents increase as well, such as mitochondria and the SR.
Hypertrophy is a response to increased mechanical stress (e.g. weight-bearing exercise), hormones (e.g. anabolic steroids), and disease (e.g. increased demand on a diseased heart).

Sarcomere Structure

Myofibrils are bundles of thread-like structures called myofilaments.
Each myofilament is made of contractile units called sarcomeres joined end-to-end.
Each sarcomere consists of overlapping thick and thin filaments.
The thick filaments extend from the midline (M-line) of the sarcomere and are made of myosin.
The thin filaments extend from the ends (Z-discs) of the sarcomere and are made of actin.
The sarcomere is divided into zones and bands, including the A band, H zone, and I band.
The A band encompasses the regions where the thick and thin filaments overlap and everything in between.
The H zone is the region between the zones of overlap around the M-line, containing only thick filaments.
The I band is the region between zones of overlap around the Z-discs, containing only thin filaments.

Muscle Contraction

Muscles generate force by contraction, a process involving three types of proteins: contractile, regulatory, and structural.
Contractile proteins shorten the sarcomere, including myosin and actin.
Myosin, a motor protein, converts chemical potential energy in ATP to mechanical energy.
Each thick filament consists of approximately 300 myosin proteins with "heads" extending radially from the ends of thick filaments, contacting thin filaments and pulling them toward the M-line.
Each myosin head has an ATP-binding site and an actin-binding site.
Actin, a cytoskeletal protein, forms long threads twisted around one another to form helical thin filaments.
Actin filaments contain myosin-binding sites.
Regulatory proteins associate with the thick and thin filaments to control contraction, including troponin and tropomyosin.
Troponin binds Ca2+ and moves tropomyosin, which blocks myosin-binding sites on thin filaments.
Structural proteins stabilize and/or connect the sarcomere and surrounding structures, including titin and dystrophin.
Titin is a large elastic protein that spans from the M-line to Z-discs, stabilizing the position of thick filaments.
Dystrophin connects thin filaments to integral membrane proteins in the sarcolemma, reinforcing sarcomere structure and transmitting tension of sarcomeres to tendons.

Muscle Contraction by the Sliding Filament Model

The sarcomere shortens as the thin filaments slide over the thick filaments, a mechanism called the sliding filament model.
Importantly, the filaments themselves do not change in length during contraction.
The contraction cycle involves the iterative binding and release of myosin to thin filaments.
Myosin binds and hydrolyzes ATP, energizing myosin and changing its conformation (cocked, like a gun).
Myosin binds thin filaments to form a cross-bridge.
Myosin pulls the thin filaments toward the M-line, a conformational change called the power stroke.
Myosin releases the thin filaments, requiring the binding of a new ATP molecule to myosin for a new cycle to begin.
Myosin-binding sites on thin filaments are obscured by tropomyosin until troponin binds Ca2+.
Ca2+ changes the conformation of troponin, which then moves tropomyosin off the myosin-binding sites on actin.
This allows myosin to form a cross-bridge, highlighting the requirement for both ATP and Ca2+ for muscle contraction.
As myosin pulls on the thin filaments, the Z-discs come together, shortening the sarcomere, causing the H zone to disappear and the I band to narrow.
The shortening of individual sarcomeres pulls on adjacent sarcomeres, transmitting tension until the whole muscle fibre shortens.

The Length-Tension Relationship

The amount of filament overlap influences the amount of tension a muscle can generate.
If the thick and thin filaments completely overlap at rest, myosin cannot generate tension effectively because there is no room for thin filaments to slide.
If the thick and thin filaments barely overlap at rest, myosin also cannot generate much tension because there are too few cross-bridges.
Therefore, there is an optimal sarcomere length with sufficient filament overlap to generate maximal tension.

Muscle Action Potentials

Muscle fibres are electrically excitable, stimulated by signals from somatic motor neurons.
The neuromuscular junction (NMJ) is where neurons and muscles meet, where somatic motor neurons release chemical signals called neurotransmitters (e.g. acetylcholine).
Neurotransmitters bind protein receptors on muscle cells, leading to an action potential in the muscle cell.
The Na+-K+ pump keeps the inside of animal cells negative compared to the outside, moving 3 Na+ out of the cell and 2 K+ into the cell per ATP hydrolyzed.
Every cell maintains a negative resting membrane potential, where the inside of the cell is slightly more negative than the outside of the cell.

The Muscle Action Potential

During an action potential, the membrane potential rapidly becomes positive, a process called depolarization.
The cell needs to return to resting potential through repolarization, the restoration of a negative membrane potential after depolarization.
Changes in membrane potential during action potentials are caused by plasma membrane transporters, specifically voltage-gated ion channels, which are opened by a change in membrane potential and facilitate diffusion (ions flow down their concentration gradients).
Voltage-gated sodium (Na+) channels (VGNCs) allow Na+ ions to enter the cell, opening only with a change in membrane potential.
Acetylcholine binding opens some Na+ channels, causing slight depolarization.
Repolarization is achieved by voltage-gated K+ (potassium) channels (VGKCs), which are slower to open in response to membrane potential changes.
Once open, K+ flows rapidly out of cells, restoring resting membrane potential.
VGNCs close as the membrane repolarizes.

Excitation-Contraction Coupling

Action potentials travel along the sarcolemma to voltage-gated Ca2+ channels (VGCCs) at T-tubules.
Triads formed with terminal cisternae of the SR are physically connected to the sarcolemma, as VGCCs plug Ca2+ release channels in the SR membrane.
Action potentials open VGCCs at triads, releasing and opening the Ca2+ release channels of the SR.
Ca2+ spills into the sarcoplasm and binds troponin, initiating muscle contraction by moving tropomyosin off the myosin-binding sites on thin filaments.
During contraction, the Ca2+ release channels increase intracellular Ca2+ concentration by ~10X.
After the muscle action potential passes, VGCCs in the sarcolemma close, SR Ca2+ release channels close and reassociate with the VGCCs at triads, and Ca2+-ATPases actively pump Ca2+ back into the SR and out of the cell to allow muscle relaxation.
This entire process is called excitation-contraction coupling.
Acetylcholine at the NMJ is taken out and destroyed by an enzyme called acetylcholinesterase.

Control of Muscle Tension

One action potential typically results in one contraction.
Increased frequency of action potentials results in increased tension.
Each somatic motor neuron axon can form multiple NMJs with muscle fibres.
A motor unit is one somatic motor neuron plus all of the skeletal muscle fibres it synapses with (average = 150).
Large muscles have many motor units distributed throughout the muscle, with all muscle fibres in a motor unit contracting and relaxing synchronously.
A twitch contraction is the contraction generated in all skeletal muscle fibres of one motor unit due to one action potential.
Twitch contractions proceed in three phases: latent period, contraction period, and relaxation period.
The latent period (2 msec) is the delay between stimulus and muscle action, where the action potential moves through the sarcolemma and Ca2+ is released from the SR.
The contraction period (10-100 msec) involves the formation of cross-bridges and shortening of sarcomeres, reaching maximum tension.
The relaxation period (10-100 msec) involves Ca2+ being pumped back into the SR, myosin detaching from actin, and tension decreasing.
A refractory period occurs if a muscle fibre is in the middle of responding to an action potential, making it temporarily unresponsive to new signals.

Muscle Tone

All fibres within a motor unit contract simultaneously, but not all motor units in a muscle are active at the same time, preventing muscle fatigue and ensuring smooth, non-jerky movements.
For large muscles, weaker motor units work first, and stronger motor units work second, a process called motor unit recruitment.
Muscle tone is the slight stiffness of a muscle caused by small involuntary contractions of alternating motor units, which stabilize positions without moving bones.
There are different types of muscle contractions: isotonic and isometric.
Isotonic contractions involve constant tension in the muscle as it changes length, including concentric and eccentric isotonic contractions.
Concentric isotonic contractions occur when the muscle shortens to decrease the angle around a joint, such as biceps brachii contracting to pick up a book.
Eccentric isotonic contractions occur when the muscle resists a load as it lengthens, such as biceps brachii lengthening as you slowly put a book down.
Isometric contractions generate tension that is not sufficient to overcome the resistance of the load, resulting in no bone movement, such as holding a book out or holding a plank position.
Isometric contractions function to stabilize many joints during movement.

Muscle Metabolism

Muscles require a lot of ATP for the contraction cycle and other functions, including providing energy for the active-transport Ca++ pumps in the SR.
Muscles generate ATP in three ways: consuming creatine phosphate, anaerobic glycolysis, and aerobic respiration.
Creatine phosphate is a small molecule made in the liver, kidneys, and pancreas.
At rest, unused ATP is dephosphorylated to make creatine phosphate.
At work, muscles can rapidly dephosphorylate creatine phosphate and regenerate ATP.
Both phosphate transfers are catalyzed by creatine kinase.
Anaerobic glycolysis is the breakdown of glucose in the absence of oxygen, producing 2 ATP molecules per glucose molecule and lactic acid as a byproduct.
Aerobic respiration is the breakdown of glucose in the presence of oxygen, producing 38 ATP molecules per glucose molecule and water and carbon dioxide as byproducts.

Anaerobic Glycolysis

Anaerobic glycolysis occurs when there is not a sufficient amount of oxygen available for aerobic respiration.
This process allows for the production of ATP without oxygen but is less efficient.
Lactic acid produced during anaerobic glycolysis can build up in muscle tissue, causing muscle fatigue and soreness.

Aerobic Respiration

Aerobic respiration is the most efficient method of ATP production, but it requires oxygen.
This process occurs in the mitochondria and uses both glucose and fatty acids as fuel.
Aerobic respiration produces significantly more ATP than anaerobic glycolysis.

Fatigue

Muscle fatigue is a decline in muscle force output caused by various factors, including:
- Depletion of ATP and creatine phosphate: these energy reserves are used up during sustained muscle activity.
- Accumulation of lactic acid: lactic acid buildup can impair muscle function.
- Depletion of glycogen: glycogen is the body's main source of stored carbohydrate, and its depletion can limit energy availability.
- Disruption of calcium regulation: changes in calcium levels can affect muscle contraction.
- Psychological factors: mental fatigue can also contribute to muscle fatigue.

Muscle Fiber Types

There are three main types of muscle fibers:
- Slow oxidative (type I): These fibers are slow-twitch and fatigue-resistant. They are rich in mitochondria and myoglobin, giving them a red appearance. They are best suited for endurance activities.
- Fast oxidative-glycolytic (type IIa): These fibers are intermediate in speed and fatigue resistance. They are able to use both aerobic and anaerobic metabolism. They are well-suited for activities requiring both speed and endurance.
- Fast glycolytic (type IIb): These fibers are fast-twitch and easily fatigable. They rely primarily on anaerobic metabolism and have low levels of mitochondria and myoglobin. They are best suited for short bursts of high-intensity activity.

Summary

Muscle tissue is a specialized tissue responsible for movement, regulating the passage of substances, and generating heat.
Muscle contraction occurs through the sliding filament model, involving the interaction of actin and myosin filaments and regulated by calcium.
Different types of muscle contraction include isometric and isotonic.
Muscles generate ATP to fuel contraction through various metabolic pathways, including creatine phosphate, anaerobic glycolysis, and aerobic respiration.
Muscle fatigue occurs when the muscle's ability to produce force declines due to various factors, such as energy depletion and metabolite buildup.
Muscle fibers can be classified based on their metabolic and contractile properties.

Aerobic Respiration

Muscles can release glucose monomers from glycogen stores or uptake glucose from blood
Glucose is broken down into two 3-carbon molecules called pyruvate in 10 chemical reactions
This process of splitting glucose is called glycolysis
If sufficient oxygen is provided, pyruvate will be transported to the mitochondrion
Many reactions convert the carbons in glucose to CO2, which is exhaled
Electrons from the chemical bonds are transferred to the electron transport chain (ETC)
The flow of electrons down the ETC releases free energy that is harnessed to synthesize ATP
Oxygen is the final electron acceptor, allowing the release of energy

Anaerobic Glycolysis

If muscles have restricted access to oxygen, they cannot respire the products of glycolysis
Pyruvate will be fermented into lactic acid
Lactic acid fermentation converts the 3-carbon pyruvate to the 3-carbon lactic acid and regenerates NAD+ in the process, allowing glycolysis to continue to make ATP in low-oxygen conditions.

Oxygen Debt

Muscles need oxygen after exercise to:
- Replenish myoglobin
- Convert lactic acid back to glucose in the liver
- Replenish creatine phosphate

Types of Muscle Fibres

There are three types of skeletal muscle fibres:
- Slow oxidative fibres
  - Dark red (lots of myoglobin and capillaries)
  - “Slow” refers to length of contraction cycle (100–200 msec)
  - Sometimes called “slow twitch”
  - Do not fatigue easily; therefore, function during endurance activities and in postural muscles
  - “Oxidative” refers to aerobic respiration as main metabolic mode
- Fast oxidative-glycolytic fibres
  - Dark red (lots of myoglobin and capillaries)
  - Largest fibres
  - “Fast” refers to length of contraction cycle (50–100 msec)
  - Sometimes called “fast twitch”
  - Fatigue more quickly, thus function in activities of short duration
  - “Oxidative-glycolytic” refers to both aerobic and anaerobic respiration as main metabolic mode
- Fast glycolytic fibres
  - White (few myoglobin and capillaries)
  - “Fast” refers to length of contraction cycle (50–100 msec)
  - Sometimes called “fast twitch”
  - Fatigue very quickly, thus function in activities of very short duration
  - “Glycolytic” refers to anaerobic respiration as main metabolic mode

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Test your knowledge on the different types of muscle tissue, including cardiac, skeletal, and smooth muscle. Explore the primary functions, structural properties, and important terminology related to muscular tissue. This quiz will enhance your understanding of myology and its components.

Muscle Tissue Quiz

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Questions and Answers

What is the primary function of cardiac muscle tissue?

Skeletal muscle tissue is responsible for regulating the passage of substances through the body.

What are the cells of skeletal muscle tissue called?

Muscular tissue is excitable, allowing it to produce electrical signals called muscle action potentials.

The fascia is composed of three layers: epimysium, perimysium, and endomysium.

Which type of muscle tissue can be stretched without tearing?

Match the following properties of muscular tissue with their descriptions:

What is myology?

What is the primary product of glycolysis?

Aerobic respiration can occur in the absence of oxygen.

What is formed when pyruvate is fermented under low-oxygen conditions?

Muscles need oxygen after exercise to replenish _____ and convert lactic acid back to ______.

Which type of muscle fiber primarily uses aerobic respiration?

Match the following types of muscle fibers with their main characteristics:

The final electron acceptor in aerobic respiration is oxygen.

What is the term used to describe the oxygen requirement for muscle recovery after exercise?

What type of fibers primarily compose the endomysium?

Aponeuroses are a type of fascia that connects muscle to skin.

What type of neurons regulate voluntary muscle contractions?

Myocytes receive oxygen through _________ and __________.

Match the terms with their correct descriptions:

Which protein acts as a motor protein in the thick filaments?

Hypertrophy refers to a decrease in muscle fiber size.

What is the primary function of myoglobin in muscle cells?

Skeletal muscle fibers can lay down new protein and cause _________.

Match the parts of a sarcomere with their descriptions:

What is the role of troponin in muscle contraction?

Dystrophin connects thin filaments to the sarcolemma.

What are the contractile proteins in muscle fibers?

The specialized smooth endoplasmic reticulum in muscle cells is called the __________.

Which muscle structure is primarily responsible for the striated appearance of skeletal muscle?

Muscle fibers can divide to increase muscle mass.

Where is dystrophin located within muscle cells?

Dystrophin connects actin filaments to the dystrophin-glycoprotein complex.

What is the term for the process when myosin pulls the thin filaments toward the M-line?

Myosin binds and __________ ATP.

Match the following terms with their descriptions:

What occurs to the H zone during muscle contraction?

Muscle contraction requires the presence of both ATP and calcium ions.

Where is calcium stored in muscle fibers?

What is the role of voltage-gated potassium channels (VGKCs) in repolarization?

The sliding filament model states that the filaments do not change in __________.

Action potentials directly trigger muscle contractions by causing Ca2+ to be released from the sarcoplasmic reticulum.

What initiates an action potential in muscle fibers?

What component in the somatic nervous system is involved at the neuromuscular junction?

During muscle contraction, Ca2+ binds to _____ to move tropomyosin off the myosin-binding sites.

The inside of a muscle cell is normally positively charged compared to the outside.

What happens to the membrane potential during depolarization?

Match the following phases of muscle contraction with their descriptions:

The restoration of a negative membrane potential after depolarization is called __________.

What is the average number of skeletal muscle fibers in a motor unit?

Muscle fatigue is prevented when all motor units within a muscle contract simultaneously.

Which of the following statements about the length-tension relationship is true?

What type of muscle contraction occurs when the muscle shortens to decrease the angle around a joint?

Creatine phosphate is used by muscles to rapidly regenerate _____ during contraction.

What happens to voltage-gated calcium channels (VGCCs) after the muscle action potential has passed?

Muscle tone refers to the slight stiffness of muscle due to involuntary contractions.

What are the two types of isotonic contractions?

The enzyme that dephosphorylates creatine to regenerate ATP is called _____ kinase.

What is achieved when frequent action potentials are generated in motor units?

Muscle fibers can respond to new action potentials while already contracted.

Study Notes

Introduction to Muscular Tissue

The Structure of Skeletal Muscle

The Blood and Nerve Supply of Muscle

Skeletal Muscle Fibre Structure

The Sarcoplasmic Reticulum

Muscular Hypertrophy

Sarcomere Structure

Muscle Contraction

Muscle Contraction by the Sliding Filament Model

The Length-Tension Relationship

Muscle Action Potentials

The Muscle Action Potential

Excitation-Contraction Coupling

Control of Muscle Tension

Muscles need oxygen after exercise to replenish _ and convert lactic acid back to __.

Myocytes receive oxygen through _ and __.