Muscle System and Muscle Tissue

A comprehensive set of flashcards covering the muscle system, including types of muscle tissue, their functions, structures, and physiological principles.

What is the primary function of muscles in the human body?

Movement, stability, control of body openings, heat production, and glycemic control.

How much of the body's weight is comprised of muscles?

Approximately 50%.

What are the three types of muscle tissue?

Skeletal, cardiac, and smooth muscle.

What is muscle excitability?

The ability of muscle tissue to respond to chemical signals, stretch, and electrical changes.

Define contractility in muscle tissue.

The ability of muscle to shorten when stimulated.

What does extensibility refer to in muscle characteristics?

The capability of muscles to be stretched between contractions.

What is the role of elasticity in muscle tissue?

The ability of muscles to return to their original length after being stretched.

Describe skeletal muscle.

Long, striated, and primarily voluntary muscles that attach to the skeleton.

What does a motor unit consist of?

A motor neuron and the muscle fibers it innervates.

Differentiate between twitch and muscle gradation.

A twitch is a single contraction; muscle gradation involves varying the strength of contraction.

What are the types of muscle contraction?

Isometric and isotonic contractions.

What is myology?

The study of muscles.

What is the role of muscle tissue in heat production?

Skeletal muscles contribute to body heat production, generating 20%-30% of heat at rest and up to 85% during exercise.

How do skeletal muscles control body openings?

Muscles regulate food intake and the movement of materials through the body.

Describe how skeletal muscle facilitates communication.

Through actions like speech, writing, and nonverbal expressions.

What is the role of perimysium in skeletal muscle?

It bundles muscle fibers into fascicles and contains larger nerves and vessels.

What is the largest muscle in the human body?

The gluteus maximus.

What distinguishes smooth muscle from other muscle types?

Smooth muscle has no striations and is involuntary.

What characterizes cardiac muscle?

Striated, involuntary, and has intercalated discs.

What is the function of the sinoatrial (SA) node?

It acts as the pacemaker of the heart.

What type of muscle is primarily involved in voluntary movement?

Skeletal muscle.

What surrounds each muscle fiber?

Endomysium.

Identify the connective tissue that surrounds an entire muscle.

Epimysium.

What is a fascicle in the context of muscle anatomy?

A bundle of muscle fibers.

What are the two main types of muscle attachment?

Direct and indirect attachment to bones.

What is the definition of a fixator muscle?

A muscle that prevents a bone from moving.

How do intrinsic and extrinsic muscles differ?

Intrinsic muscles are entirely contained within a region; extrinsic muscles arise from another region but act on a designated region.

In muscle function, what is the prime mover?

The main muscle responsible for a specific movement.

What does the term 'synergist' refer to in muscle action?

A muscle that assists the prime mover.

What is the role of antagonistic muscles?

Muscles that oppose the action of the prime mover.

Give an example of a prime mover in the human body.

Brachialis during elbow flexion.

What is the function of the sarcolemma?

The plasma membrane of a muscle fiber that is excitable.

What does the term 'myofibril' refer to?

Long protein cords that occupy most of a muscle fiber.

How are thick and thin myofilaments organized within a muscle fiber?

They are organized into sarcomeres, which are the functional units of muscle contraction.

What is the significance of Z-disks in myofilament structure?

They serve as anchorage points for thin and elastic filaments.

What is the function of titin filaments?

They prevent overstretching and provide recoil to muscle tissues.

What do muscle fibers contain to store oxygen?

Myoglobin.

Describe how the actin filaments are structured.

They consist of two strings of polypeptide subunits twisted together.

What blocks the binding sites of actin filaments?

Tropomyosin.

What is troponin in relation to actin filaments?

A calcium-binding protein that regulates actin's interaction with myosin.

What are some effects of aging on muscle tissue?

Loss of muscle mass, strength, and increased adipose tissue.

What is a circular muscle, and where can they be found?

Muscles that form rings around body openings, such as sphincter muscles.

How do Pennate muscles differ from other muscle types?

They have fascicles that attach obliquely to a tendon.

What is the role of blood supply in muscle function?

It delivers oxygen and nutrients necessary for muscle contraction and energy production.

What does contraction of muscle fibers depend on?

Stimulation by nerves.

Explain the significance of the sarcoplasmic reticulum.

It regulates calcium levels and serves as a reservoir during muscle contraction.

What role do capillaries play in muscle tissue?

They branch extensively to supply each muscle fiber with blood.

What is glycogen's role in muscle fibers?

It serves as an energy source for muscle contractions.

What are muscle spindles?

Sensory receptors that monitor muscle stretch and assist in proprioception.

Describe the sliding filament theory.

It states that muscle contraction occurs when actin filaments slide past myosin filaments, shortening the sarcomere.

What happens at the neuromuscular junction?

The motor neuron transmits a signal to stimulate muscle contraction.

What is the role of calcium ions during muscle contraction?

Calcium ions bind to troponin, exposing binding sites on actin for myosin.

What are the basic functional units of skeletal muscle?

Sarcomeres.

Define hypertrophy in muscle fibers.

An increase in the size and power of muscle fibers due to exercise.

What causes muscle fatigue during prolonged activity?

Depletion of glycogen stores, accumulation of lactic acid, and decreased calcium availability.

What is the role of the achilles tendon?

It connects the calf muscles to the heel bone, facilitating walking and running.

How do muscles adapt to resist fatigue in endurance training?

Increased capillary density and mitochondrial proliferation.

Identify a key feature that distinguishes cardiac muscle from skeletal muscle.

The presence of intercalated discs.

What are the characteristics of fusiform muscles?

Thick in the middle with fascicles converging at tapered ends.

How is the strength of a muscle contraction graded?

By varying the number of active motor units.

What is the primary purpose of muscular contractions during breathing?

To change volume in the thoracic cavity to facilitate air movement.

Define myopathy.

A disease that affects muscle tissue, leading to weakness and pain.

What do desmosomes in cardiac muscle do?

They help hold cells together during contraction.

What is the role of the scapula's rhomboid muscle when the biceps contracts?

To stabilize the scapula.

How does the nervous system affect heart rate in cardiac muscle?

Through autonomic nervous system signals influencing pacemaker activity.

What adaptation occurs in skeletal muscle fibers in response to resistance training?

Increased cross-sectional area, leading to greater force production.

What is peristalsis?

The wave-like muscle contractions that move food through the digestive tract.

How can skeletal muscles respond to hormones?

They can increase metabolic activity and alter contraction strength.

Identify a type of muscle that is involuntary and striated.

Cardiac muscle.

How does skeletal muscle play a role in glycemic control?

By absorbing and storing glucose, helping to maintain stable blood glucose levels.

Describe what happens during the Cross Bridge Cycle.

The myosin heads bind to actin, creating cross bridges that draw actin filaments closer together.

What is one characteristic feature of smooth muscle?

It is non-striated and involuntary.

How does the arrangement of myofilaments contribute to muscle contraction?

The specific overlap and interaction facilitate sliding during contraction.

What is the impact of extensive endurance training on muscle fibers?

Enhanced oxidative capacity and increased ability to metabolize fat.

How do myofibrils contribute to the contraction mechanism in muscle?

They contain the myofilaments that slide past each other, shortening the muscle.

What can occur if muscle fibers are overstretched?

They may become damaged, leading to strains or injuries.

What is an aponeurosis?

A broad, flat tendon that connects muscles to each other or to bones.

Discuss the concept of muscle plasticity.

Muscle tissue's ability to adapt its structure and function in response to training or disuse.

What is the basic architectural design of pennate muscles?

They have fibers that run at an angle to the muscle's main line of action, increasing force production.

What aids in the recovery of muscle fibers after exercise?

Adequate rest, nutrition, and hydration.

How does the variability in muscle fiber types affect athletic performance?

Different fibers optimize for endurance or strength, impacting performance in varying sports.

What adaptations occur in the muscular system with aging?

Loss of muscle mass, strength, and increased susceptibility to injury.

What type of joint movement involves decreasing the angle at a joint?

Flexion.

What occurs in muscles during isometric contraction?

Muscle tension increases without changing length.

Define gliding motion at a joint.

When two flat surfaces glide past one another.

How do antagonistic muscle pairs function together?

One muscle contracts while its counterpart relaxes to produce movement.

What are the main components making up a skeletal muscle fiber?

Sarcoplasm, myofibrils, and multiple nuclei.

How might muscle tissue contribute to overall body metabolism?

By utilizing glucose and fatty acids for energy and contributing to thermogenesis.

What happens at heavy exercise in terms of blood supply to muscles?

Blood supply can increase up to 75% of cardiac output to meet energy demands.

What role does the endomysium play in muscle fibers?

It surrounds each muscle fiber, providing space for innervation and nourishment.

How are fascicles oriented differently among muscle types?

Orientation affects the strength and direction of muscle contraction.

What is the structural significance of the A-band in myofibrils?

It contains both thick (myosin) and thin (actin) filaments and appears dark under a microscope.

What is the function of gap junctions in cardiac muscle?

They allow for rapid electrical signaling between cardiac cells.

Describe the process of muscle cell stimulation by the nervous system.

Nerve impulses release neurotransmitters that trigger muscle contraction.

Define the term 'muscle tone.'

The continuous and passive partial contraction of muscles.

What causes muscle cramps?

Increased activity cannot obtain sufficient oxygen, leading to a lack of energy at the muscle.

What is the importance of stretch receptors in muscles?

They detect changes in muscle length and send feedback to maintain balance and posture.

How does training affect muscle fiber distribution?

It can shift the ratio of fiber types, enhancing performance for specific activities.

What is the role of sarcomeres in muscle function?

They are the basic contractile units that shorten during muscle contraction.

Explain why muscle fibers have multiple nuclei.

To manage the high metabolic demand and protein synthesis required for contraction.