Exam 3: Chapter 12

This set of flashcards covers essential concepts from the muscle physiology lecture, including muscle types, structure, contraction mechanisms, and the roles of various proteins and ions in muscle function.

What are the three types of muscle tissue?

Skeletal muscle, Cardiac muscle, Smooth muscle.

What are the main functions of skeletal muscle?

Movement of body, posture, generation of body heat, movement of substances, support soft tissues and organs.

What are the components of a skeletal muscle cell?

Sarcolemma, Sarcoplasm, Myofibrils.

What protein forms thick and thin filaments in myofibrils?

Thick filaments are made of myosin and thin filaments are made of actin.

What is a motor unit?

A motor unit is defined as a single motor neuron and all the muscle fibers it innervates.

What is the sliding filament mechanism?

Contraction occurs as thin filaments slide closer together between thick filaments.

What initiates muscle contraction at the molecular level?

Calcium ions (Ca++) bind to troponin, removing the blocking action of tropomyosin.

What function does ATP serve in muscle contraction?

ATP energizes the myosin cross-bridge and allows for detachment from actin.

What roles do troponin and tropomyosin play in muscle contraction?

Troponin binds Ca2+ and removes the blockage of tropomyosin from myosin binding sites on actin.

What is a twitch in muscle physiology?

A twitch is the response of a single muscle fiber to a single action potential.

What are isotonic and isometric contractions?

Isotonic contractions involve a change in muscle length; isometric contractions involve no change in muscle length despite tension.

What factors influence muscle tension?

Frequency of stimulation, motor unit recruitment, muscle properties.

What are the main types of skeletal muscle fibers?

Slow-oxidative (type I), Fast-oxidative Glycolytic (type IIa), Fast-glycolytic (type IIx).

What is muscle fatigue?

Muscle fatigue is the decline in muscle tension as a result of previous contractile activity.

What adaptations occur in skeletal muscle due to endurance training?

Increased ability to use fatty acids as fuel, increased capillary density, increased number of mitochondria.

What adaptations occur in skeletal muscle due to resistance training?

Hypertrophy of fast glycolytic fibers.

What is the role of muscle spindles?

Muscle spindles sense muscle length and resist passive stretch.

What is the function of Golgi tendon organs?

They sense muscle tension and inhibit contraction of the agonist muscle while exciting antagonistic muscles.

How does cardiac muscle differ from skeletal muscle?

Cardiac muscle is striated, involuntary, connected by gap junctions, and can contract as a functional unit due to intercalated discs.

What initiates excitation-contraction coupling in smooth muscle?

A rise in intracellular calcium concentrations begins excitation-contraction coupling.