Muscles and Muscle Tissue

These flashcards cover key concepts and definitions from the lecture on muscle and muscle tissue, providing a comprehensive review for the exam.

What are the three types of muscle tissue?

Skeletal, Cardiac, and Smooth.

What is the primary function of smooth muscle?

Controls the movement of hollow visceral organs.

What is contractility in relation to muscle tissue?

The ability to shorten forcibly when stimulated.

What are the four main characteristics shared by all muscles?

Excitability, Contractility, Extensibility, Elasticity.

What is the role of the sarcoplasmic reticulum in muscle contraction?

Stores and releases calcium ions (Ca2+) for muscle contractions.

What are myofibrils?

Densely packed, rodlike elements in muscle fibers containing contractile units.

What are the two types of myofilaments in muscle tissue?

Actin and Myosin.

What is the sliding filament model of contraction?

Thin filaments slide past thick filaments, increasing overlap, leading to muscle contraction.

What is tetany?

Sustained muscle contraction due to increased stimulus frequency.

What causes muscle fatigue?

Ionic imbalances, decreased glycogen, and decreased ATP among others.

What is the neuromuscular junction?

The connection between a motor neuron and a muscle fiber.

What triggers the release of acetylcholine (ACh) at the neuromuscular junction?

Calcium ions entering the axon terminal.

What happens during depolarization of a muscle fiber?

A local change in membrane potential occurs, leading to action potential propagation.

What is rigor mortis?

A state of muscle stiffness post-death due to calcium influx and lack of ATP.

What distinguishes isotonic from isometric contractions?

Isotonic contractions shorten the muscle, while isometric contractions do not shorten the muscle.

What are slow oxidative fibers best suited for?

Low-intensity, endurance activities like maintaining posture.

What initiates muscle contraction in skeletal muscle?

Binding of calcium ions to troponin, causing tropomyosin to shift and expose myosin-binding sites.

What is the function of dystrophin?

Links thin filaments to proteins of the sarcolemma.

What is muscle tone?

The constant, slightly contracted state of all muscles due to involuntary nervous stimulation.

What increases the force of skeletal muscle contraction?

Recruitment of more motor units and increased frequency of stimulation.

What is the relationship between muscle fiber type and fatigue resistance?

Fast glycolytic fibers fatigue quickly, while slow oxidative fibers resist fatigue.