Module 6: The Muscular System Quiz

Questions and Answers

For antagonistic muscle groups to move a limb, flexor contraction occurs coincident with:

Relaxation of the extensor (correct)

No changes in the extensor

Contraction of the tendon

Contraction of the extensor

The function of transverse tubules in skeletal muscles is to:

Conduct ATP molecules out of the mitochondria throughout the sarcoplasm

Store Ca2+ ions inside the muscle fiber

Ensure a supply of glycogen throughout the muscle sarcoplasm

Rapidly conduct action potentials to the interior of the muscle fiber (correct)

Most of the time, the parallel thick and thin filaments of the myofibrils are connected by ________.

crossbridges

The function of the titin protein is to:

Stabilize the position of the myosin filaments Signup and view all the answers

The brief period of time between the beginning of the action potential in the muscle and the beginning of contraction is referred to as the:

Latent period Signup and view all the answers

________ is the backup energy molecule that can be rapidly converted to ATP in active skeletal muscle.

Phosphocreatine Signup and view all the answers

During heavy exercise, the ATP requirements of active muscle are likely to be met by metabolism of:

Carbohydrates Signup and view all the answers

Which of the following is a characteristic of slow-twitch oxidative skeletal muscle fibers?

Long contraction duration and high capillary density Signup and view all the answers

Motor units that control skeletal muscles involved with fine motor movements have ________ muscle fibers.

fewer Signup and view all the answers

Which fibers generate more force?

Fast-twitch fibers Signup and view all the answers

A contraction that generates enough force to move a load is known as , whereas one that generates force that equals the load is known as .

Isotonic, isometric Signup and view all the answers

Compared to skeletal muscle, contraction of smooth muscle cells is:

A slower response to a stimulus and sustained without fatigue Signup and view all the answers

Which protein is activated by the Ca2+-calmodulin complex to phosphorylate the myosin light chain protein?

Myosin light chain kinase Signup and view all the answers

After death, when metabolism stops, in which step of the contractile cycle must skeletal muscles remain?

The rigor state Signup and view all the answers

The effector in a reflex is the:

Muscle or gland Signup and view all the answers

Identify the FALSE statement.

All reflexes require input from the brain Signup and view all the answers

Which class of movement can be considered a combination of the other two?

Rhythmic Signup and view all the answers

Match the structures with the accurate description:

T-tubules = Inward extensions of the muscle cell membrane Sarcomere = Basic contractile unit in a skeletal muscle from Z disc to Z disc Muscle fiber = A single muscle cell Sarcolemma = The muscle cell membrane Fascicle = A bundle of adjacent muscle cells Signup and view all the answers

The T-tubular membrane contains _ receptors that are __ and therefore respond to action potentials.

dihydropyridine (DHP), voltage sensing Signup and view all the answers

Calcium, released by the sarcoplasmic reticulum, binds to _________ to move the _, which allows actin to form a __________ with myosin.

troponin C, tropomyosin, high-force crossbridge Signup and view all the answers

The heavy chain of myosin contains 2 important regions: the first acts as _ to convert energy into movement whereas the second binds to _.

ATPase, actin Signup and view all the answers

Asynchronous activation of motor units is important because it functions to _______________.

prevent fatigue Signup and view all the answers

Autonomic reflexes are also called ______________ reflexes.

visceral Signup and view all the answers

Rhythmic reflexive motor activities, such as breathing or walking, are controlled by networks of neurons in the central nervous system called _____________________________.

central pattern generators Signup and view all the answers

____________ reflexes involve skeletal muscles.

somatic Signup and view all the answers

In a _____________ reflex, a sensory neuron synapses directly on a motor neuron.

monosynaptic Signup and view all the answers

Muscle spindles are _______ receptors and cause reflex _, whereas Golgi tendon organs respond primarily to _ and cause a _______ reflex.

stretch, contraction, tension, relaxation Signup and view all the answers

Study Notes

Antagonistic Muscle Action

Flexor contraction happens simultaneously with relaxation of the extensor to move limbs.

Transverse Tubules Function

Transverse tubules rapidly conduct action potentials to the interior of skeletal muscle fibers.

Myofibril Structure

Parallel thick and thin filaments in myofibrils are connected by crossbridges that link myosin and actin.

Titin Protein Role

Titin stabilizes the position of myosin filaments within the sarcomere structure.

Latent Period

The latent period is the time between the onset of action potential and the start of muscle contraction.

Energy Sources in Muscle

Phosphocreatine serves as a backup energy source that can be rapidly converted to ATP in active skeletal muscle.

Muscle Metabolism During Exercise

During intense exercise, active muscles primarily obtain ATP from the metabolism of carbohydrates.

Characteristics of Muscle Fibers

Slow-twitch oxidative skeletal muscle fibers exhibit long contraction durations and high capillary density.

Motor Unit Composition

Motor units controlling fine motor movements have fewer muscle fibers compared to those responsible for gross movements.

Force Generation in Muscle Fibers

Fast-twitch fibers are capable of generating more force than slow-twitch fibers.

Types of Contraction

Isotonic contractions generate enough force to move a load, while isometric contractions generate force equal to the load without movement.

Smooth Muscle Contraction

Smooth muscle cells respond more slowly to stimuli and maintain contraction without fatigue compared to skeletal muscle.

Activation of Myosin Light Chain

The myosin light chain kinase is activated by the calcium-calmodulin complex and phosphorylates the myosin light chain protein.

Rigor State Post-Mortem

After death, muscles remain in the rigor state if metabolism halts, preventing muscle relaxation.

Reflex Action Components

The effector in a reflex arc is typically a muscle or gland that executes the reflex action.

False Statement Identification

Not all reflexes require input from the brain; some can operate independently.

Rhythmic Movements

Rhythmic movements are a combination of reflexive and voluntary actions.

Muscle Structure Identification

Muscle structures include T-tubules (inward extensions), sarcomeres (basic contractile unit), muscle fibers (single muscle cells), sarcolemma (muscle membrane), and fascicles (bundles of muscle cells).

Membrane Receptor Functions

T-tubular membranes contain voltage-sensing dihydropyridine (DHP) receptors connected mechanically to ryanodine receptors in the sarcoplasmic reticulum.

Calcium and Muscle Interaction

Calcium binds to troponin C, causing movement of tropomyosin and facilitating the formation of high-force crossbridges with actin.

Myosin Heavy Chain Regions

The myosin heavy chain has an ATPase region for energy conversion and a binding site for actin.

Motor Unit Activation

Asynchronous motor unit activation helps to prevent muscular fatigue during prolonged activity.

Types of Reflexes

Autonomic reflexes are also known as visceral reflexes, while somatic reflexes involve skeletal muscles.

Central Pattern Generators

Rhythmic reflexive actions, such as walking and breathing, are managed by networks of neurons known as central pattern generators.

Monosynaptic Reflex Definition

Monosynaptic reflexes involve a direct synapse between a sensory neuron and a motor neuron.

Muscle Receptors and Reflexes

Muscle spindles act as stretch receptors prompting reflex contraction, while Golgi tendon organs detect tension and promote reflex relaxation.

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Description

Test your knowledge on the muscular system with this quiz based on Module 6. The quiz covers key concepts such as muscle groups, flexor and extensor contractions, and the role of transverse tubules in skeletal muscles. Perfect for students studying human anatomy or physiology.