Muscular Tissue Chapter 10 Flashcards

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Questions and Answers

What covers myosin binding sites?

Myosin

Actin

Tropomyosin (correct)

Troponin

What is the refractory period?

When a muscle fiber receives enough stimulation to contract, it temporarily loses its excitability and cannot respond for a time.

What is wave summation?

When a second stimulus occurs after the refractory period of the first stimulus is over but before the skeletal muscle fiber has relaxed, resulting in a stronger contraction.

What type of contraction occurs in your neck muscles while you are walking?

Isometric contractions. Signup and view all the answers

What is hypotonia?

Decreased or lost muscle tone; such muscles are said to be flaccid. Signup and view all the answers

What is flaccid paralysis?

Characterized by loss of muscle tone, loss or reduction of tendon reflexes, and atrophy and degeneration of muscles. Signup and view all the answers

What is hypertonia?

Increased muscle tone expressed as spasticity or rigidity. Signup and view all the answers

What is spasticity?

Characterized by increased muscle tone associated with an increase in tendon reflexes and pathological reflexes. Signup and view all the answers

What is spastic paralysis?

Partial paralysis in which the muscles exhibit spasticity. Signup and view all the answers

What does rigidity refer to in muscle tone?

Increased muscle tone in which reflexes are not affected. Signup and view all the answers

What disease is caused by Clostridium tetani?

Tetanus. Signup and view all the answers

What is isotonic contraction?

A contraction where the tension remains almost constant while the muscle changes in length. Signup and view all the answers

What is isometric contraction?

A contraction where the tension generated is not enough to exceed the resistance of the object, and the muscle does not change its length. Signup and view all the answers

What type of smooth muscle is more like cardiac muscle?

Visceral smooth muscle. Signup and view all the answers

What part of a somite differentiates into skeletal muscle?

The myotome. Signup and view all the answers

What does the myotome form?

Skeletal muscles of the head, neck, and limbs. Signup and view all the answers

What does the dermatome form?

Connective tissues including the dermis of the skin. Signup and view all the answers

What does the sclerotome give rise to?

The vertebrae. Signup and view all the answers

What type of muscle develops from mesodermal cells that migrate to and envelop the developing heart?

Cardiac muscle. Signup and view all the answers

What type of muscle develops from mesodermal cells that migrate to and envelop the developing gastrointestinal tract and viscera?

Smooth muscle. Signup and view all the answers

What is the outer layer encircling the entire muscle called?

Epimysium Signup and view all the answers

What connective tissue coat surrounds groups of muscle fibers, separating them into fascicles?

Perimysium Signup and view all the answers

What penetrates the interior of each fascicle and separates individual muscle fibers?

Endomysium Signup and view all the answers

What term describes the built-in rhythm of the heart?

Autorhythmicity Signup and view all the answers

What are the ringlike bands of smooth muscle called that prevent outflow of the contents of a hollow organ?

Sphincters Signup and view all the answers

What process describes heat production due to muscle contractions?

Thermogenesis Signup and view all the answers

What are the electrical signals produced by muscle and nerve cells called?

Action potential (impulses) Signup and view all the answers

What type of connective tissue lines the body wall and surrounds muscles?

Fascia Signup and view all the answers

What attaches muscle to the periosteum of a bone?

Tendon Signup and view all the answers

What is the broad, flat sheet of connective tissue that extends from the muscle called?

Aponeurosis Signup and view all the answers

What chronic disorder affects the fibrous connective tissues of muscles?

Fibromyalgia Signup and view all the answers

What is the plasma membrane of a muscle cell called?

Sarcolemma Signup and view all the answers

What term describes the functional unit of a myofibril?

Sarcomere Signup and view all the answers

What are the proteins that hold thick filaments together in the center of a sarcomere called?

M-line Signup and view all the answers

What happens to the I band and H zone during muscle contraction?

The I band and H zone disappear. Signup and view all the answers

What is oxygen debt?

The added oxygen taken in after exercise to restore metabolic conditions. Signup and view all the answers

What is the role of ATP in muscle contraction?

Activates myosin, detaches myosin from actin, and powers Ca2+ transport. Signup and view all the answers

What happens if ATP suddenly were not available after the sarcomere had started to shorten?

The muscles would remain in a state of rigidity. Signup and view all the answers

What is the effect of the size of a motor unit on its strength of contraction?

Larger motor units are capable of more forceful contractions. Signup and view all the answers

The contraction of skeletal muscle occurs due to thick and thin filaments sliding past one another.

True Signup and view all the answers

What do synaptic end bulbs at the tips of axon terminals contain?

Synaptic vesicles filled with acetylcholine. Signup and view all the answers

What separates a somatic motor neuron and a skeletal muscle fiber?

Synaptic cleft Signup and view all the answers

Study Notes

Connective Tissue of Muscles

Epimysium: Dense irregular connective tissue that surrounds the entire muscle.
Perimysium: Encases groups of 10 to 100 muscle fibers, forming bundles known as fascicles.
Endomysium: Surrounds individual muscle fibers within fascicles, composed of mostly reticular fibers.

Muscle Properties

Autorhythmicity: The heart's intrinsic rhythm.
Sphincters: Smooth muscle bands controlling the outflow from hollow organs.
Thermogenesis: Heat production as a result of muscle contraction.

Muscle Fiber Structure

Sarcolemma: Plasma membrane of a muscle cell housing multiple nuclei.
Sarcoplasm: Cytoplasm of muscle fibers containing glycogen and myoglobin for ATP synthesis.
Myofibrils: Contractile organelles densely packed within muscle fibers.

Filaments and Contraction Mechanism

Thin Filaments: Primarily composed of actin and anchored at Z-discs.
Thick Filaments: Composed of myosin; thick filaments are essential for muscle contraction through cross-bridge formation.
Sarcomeres: Basic functional units of myofibrils, defined by Z-discs, A-bands, I-bands, H-zones, and M-lines.

Muscle Contraction

Sliding Filament Mechanism: Shortening occurs as thin filaments slide over thick filaments without changing their lengths.
Calcium Role: Increased Ca2+ levels initiate contraction, while decreased levels cause relaxation.
ATP Functions: Hydrolyzes to activate myosin, detach myosin from actin, and power calcium pumps in the SR.

Muscle Contraction Phases

Latent Period: Initial stage when muscle potential is generated and calcium ions are released.
Contraction Period: Calcium binds to troponin, exposing myosin-binding sites for cross-bridge formation.
Relaxation Period: Calcium is transported back into the SR, detaching myosin heads and reducing tension.

Neuromuscular Junction

Nerve-Muscle Interaction: Synapse where motor neurons communicate with muscle fibers through neurotransmitters.
Acetylcholine's Role: Triggers muscle action potentials leading to contraction.

Muscle Responses

Wave Summation: Increased tension from stimuli occurring before relaxation is complete.
Motor Units: Composed of a motor neuron and the muscle fibers it stimulates; larger units produce more force.

Muscle Tone and Disorders

Hypotonia: Reduced muscle tone resulting in flaccidity.
Hypertonia: Increased muscle tone, seen in conditions like spasticity and rigidity.
Tetanus: A serious bacterial infection causing severe muscle spasm and stiffness.

Specialized Muscle Proteins

Titin: Provides elasticity and stabilizes thick filaments.
Myoglobin: Oxygen-binding protein facilitating ATP production during muscle contraction.
Dystrophin: Links sarcomeres to the muscle fiber membrane, essential for muscle structure and function.

Key Facts

Muscle fibers are multinucleated and can regenerate through myoblast fusion.
Mitochondria are crucial for ATP production in muscle fibers.
Calcium release from the SR is key for initiating muscle contraction following nerve impulses.

Muscle Contractions

Isotonic Contraction: Muscle tense and shortens, allowing body movements and object manipulation while maintaining constant force.
Isometric Contraction: Muscle generates tension but does not change length due to resistance, thus not moving the object.

Types of Smooth Muscle

Visceral Smooth Muscle: More similar to cardiac muscle than skeletal muscle, characterized by gap junctions enabling action potentials to spread between cells.

Muscle Development

Hyperplasia: Refers to the increase in the number of muscle fibers.
Myotome: A structure within a somite that differentiates into skeletal muscle, forming muscles in the head, neck, and limbs.
Dermatome: A region of a somite that develops into connective tissues, including the dermis of the skin.
Sclerotome: The part of a somite responsible for giving rise to vertebrae.

Developmental Origins of Muscle Types

Cardiac Muscle: Forms from mesodermal cells that migrate to surround the developing heart in the form of endocardial heart tubes.
Smooth Muscle: Develops from mesodermal cells migrating to envelop the developing gastrointestinal tract and other viscera.

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Explore key terms related to muscular tissue with these flashcards. Each card defines essential components such as epimysium, perimysium, and endomysium, helping you solidify your understanding of muscular anatomy. Perfect for students studying muscle structure and function.