Chapter 10 Muscular Tissue (ch. review)

What is the primary function of muscle tissue?

Converting chemical energy into mechanical energy to perform work.

What are the three types of muscular tissue?

Skeletal, cardiac, and smooth muscle.

Which muscle type is striated and voluntary?

Skeletal muscle.

Which muscle type is nonstriated and involuntary?

Smooth muscle.

What are the four special properties of muscular tissue?

Electrical excitability, contractility, extensibility, and elasticity.

What is the function of subcutaneous tissue in relation to muscles?

It separates skin from muscles, provides a pathway for blood vessels and nerves, and protects against trauma.

What is the difference between a tendon and an aponeurosis?

A tendon is ropelike, while an aponeurosis is wide and flat.

What type of neurons stimulate skeletal muscle to contract?

Somatic motor neurons.

What are satellite cells in the context of muscle tissue?

Myoblasts that persist after birth.

What is the sarcolemma?

The plasma membrane of a muscle fiber.

What are T tubules?

Invaginations of the sarcolemma.

What are the contractile elements of skeletal muscle called?

Myofibrils.

What two filaments are arranged in compartments called sarcomeres?

Thick filaments and thin filaments.

What are the two primary contractile proteins in myofibrils?

Myosin (thick filament) and actin (thin filament).

What are the two regulatory proteins found in the thin filament?

Tropomyosin and troponin.

What is the function of titin in a sarcomere?

It links the Z disc to the M line and stabilizes the thick filament.

What is the role of dystrophin?

It links thin filaments to the sarcolemma.

What happens to the Z discs during muscle contraction?

They move closer together, shortening the sarcomere.

What molecule must be hydrolyzed to energize the myosin head?

ATP.

What is a cross-bridge in muscle contraction?

The attachment of a myosin head to actin.

What ion triggers the sliding of filaments?

Calcium ions (Ca2+).

What causes tropomyosin to move away from myosin-binding sites on actin?

Calcium ions binding to troponin.

What is the length-tension relationship?

The principle that a muscle fiber develops its greatest tension when there is an optimal zone of overlap between thick and thin filaments.

What is a neuromuscular junction?

The synapse between a somatic motor neuron and a skeletal muscle fiber.

What neurotransmitter is released at the neuromuscular junction to initiate a muscle action potential?

Acetylcholine (ACh)

What enzyme breaks down acetylcholine in the synaptic cleft?

Acetylcholinesterase

What are the three primary sources of ATP for muscle fibers?

Creatine phosphate, anaerobic glycolysis, and aerobic respiration

How long can creatine phosphate and ATP provide energy for maximal muscle contraction?

About 15 seconds

What is the primary difference between anaerobic glycolysis and aerobic respiration in muscle metabolism?

Aerobic respiration requires oxygen and occurs in the mitochondria, while anaerobic glycolysis does not use oxygen

What is muscle fatigue?

The inability of a muscle to contract forcefully after prolonged activity

What is a motor unit?

A motor neuron and all the muscle fibers it stimulates

What is the process of increasing the number of active motor units called?

Recruitment

What are the three phases of a twitch contraction recorded on a myogram?

Latent period, contraction period, and relaxation period

What is wave summation?

Increased contraction strength occurring when a second stimulus arrives before the muscle has completely relaxed

What is the difference between unfused and fused tetanus?

Unfused tetanus involves partial relaxation between stimuli, while fused tetanus is a sustained contraction without partial relaxation

What is muscle tone?

Continuous involuntary activation of a small number of motor units, essential for maintaining posture

What distinguishes concentric from eccentric isotonic contractions?

In concentric contractions the muscle shortens, while in eccentric contractions the muscle lengthens

What are the three types of skeletal muscle fibers?

Slow oxidative (SO), fast oxidative-glycolytic (FOG), and fast glycolytic (FG) fibers

In what order are motor units typically recruited?

First SO fibers, then FOG fibers, and finally FG fibers

What structural feature connects cardiac muscle fibers to one another?

Intercalated discs, which contain desmosomes and gap junctions

Why does cardiac muscle remain contracted longer than skeletal muscle?

Due to prolonged delivery of Ca2+ into the sarcoplasm

What are dense bodies in smooth muscle?

Structures that function similarly to Z discs in striated muscle

What is the difference between visceral and multi-unit smooth muscle?

Visceral smooth muscle fibers contract in unison as a network, while multi-unit smooth muscle fibers operate independently

Which type of muscle tissue has the best capacity for regeneration?

Smooth muscle

From which embryonic tissue do most muscles develop?

Mesoderm

What are somites?

Cube-shaped structures formed by the segmentation of the mesoderm

What happens to skeletal muscle mass during the aging process?

It undergoes a slow, progressive loss and is replaced by fibrous connective tissue and fat

What is recovery oxygen uptake?

The elevated use of oxygen by the body after exercise