MIDTERM #2

What are the common properties of muscle tissues?

Excitability, Contractility, Extensibility, and Elasticity.

What are the primary functions of skeletal muscle?

1. producing movement

2. maintaining posture

3. supporting soft tissues

4. guarding body entrances/exits

5. maintaining body temperature

6. storing nutrients.

What layers of connective tissue surround skeletal muscles?

Epimysium, Perimysium, and Endomysium.

What is the role of the sarcolemma in skeletal muscle fibers?

It is the plasma membrane that surrounds the muscle fiber.

What are T-Tubules and their function in skeletal muscle fibers?

They transmit action potentials from the sarcolemma into the cell interior, triggering contraction.

What are the two types of myofilaments in myofibrils?

Thin filaments (actin) and thick filaments (myosin).

What is a sarcomere?

The smallest functional unit of a muscle fiber where contraction occurs.

What is the role of calcium ions in muscle contraction?

Calcium binds to troponin, causing conformational change that allows cross-bridge formation.

What is the neuromuscular junction (NMJ)?

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

What neurotransmitter is released at the neuromuscular junction?

Acetylcholine (ACh).

What happens during excitation-contraction coupling?

An action potential travels down the T Tubules, Ca2+ is released, and myofilaments interact to initiate contraction.

What is the sliding filament theory?

Muscle contraction occurs when actin filaments slide over myosin filaments, shortening the sarcomere.

What initiates the contraction cycle in muscle fibers?

The arrival of calcium ions at the zone of overlap.

What is rigor mortis?

A state of fixed muscular contraction after death due to a lack of ATP.

What determines the amount of tension a muscle fiber can produce?

The number of power strokes, frequency of stimulation, and the fiber's resting length.

What is wave summation?

It is the increase in muscle tension due to repeated stimulation before relaxation phase ends.

What is treppe in muscle contraction?

A gradual increase in muscle tension with successive stimuli delivered shortly after relaxation.

What are isotonic contractions?

Muscle contractions that change length while producing movement.

What are isometric contractions?

Tension produced without a change in muscle length.

What is muscle hypertrophy?

Increase in muscle size due to heavy training.

What factors can contribute to muscle atrophy?

Lack of activity, aging, and loss of muscle fibers.

What are the three types of skeletal muscle fibers?

Fast fibers, slow fibers, and intermediate fibers.

What is the primary energy source for fast-twitch muscle fibers?

Glycolysis.

What role does myoglobin play in muscle fibers?

It binds oxygen, enhancing oxygen delivery for muscle metabolism.

How does aging affect muscle fibers?

Muscle fibers decrease in size and number, impacting strength and recovery.

What is the primary function of cardiovascular performance in relation to muscle?

To deliver oxygen and nutrients to muscles and remove waste products.

What is the role of the Golgi tendon organ?

It prevents excessive tension in muscles to protect tendons.

What are muscle spindles?

Receptors that monitor muscle stretch and the rate of contraction.

How does strength training affect muscle fibers?

It can lead to hypertrophy and increased neural efficiency in motor unit recruitment.

What is meant by muscle tone?

The normal tension and firmness of muscle at rest, aiding posture and stabilization.

What is hypertrophy associated with in muscle tissue?

Increased diameter of muscle fibers, number of myofibrils, and mitochondrial density.

What is the length-tension relationship in muscle fibers?

The tension produced relates to the length of the sarcomeres at rest.

What is the role of ATP in muscle contractions?

It provides the energy needed for muscle contractions and cross-bridge cycling.

What changes occur to a muscle during intense exercise?

Increased production of lactate and temporary fatigue.

What defines muscle fatigue?

The inability of a muscle to maintain its desired level of performance.

What is the primary source of energy during prolonged aerobic exercise?

Fats and glucose metabolism.

What is anaerobic respiration?

Energy production without oxygen, primarily through glycolysis.

What do endurance training improvements involve?

Increased mitochondrial content and better oxygen utilization.

What happens to lactate after intense exercise?

It is either oxidized for energy or converted back to glucose in the liver.

What physiological changes occur with hypertrophy?

Increased myofibril and mitochondrial numbers, leading to stronger muscle fibers.

What is muscular endurance?

The ability to sustain an activity over a period of time.

How do muscle fibers differ in energy usage during exercise?

Fast fibers primarily use glycolysis; slow fibers use aerobic respiration.

What is a motor unit?

A motor neuron and all the muscle fibers it innervates.

What is tetanus in muscle contraction?

A sustained muscle contraction from rapid stimulation without relaxation.

What do skeletal muscle fibers require to contract?

ATP, calcium ions, and action potentials.

How is the muscle contraction cycle regulated?

By the availability of ATP, calcium levels, and neural stimulation.

What is the primary feature of cardiac muscle?

Striated appearance and involuntary control.

What is sarcoplasmic reticulum's role?

It stores and regulates calcium ions needed for muscle contractions.

What are the key components of muscle performance?

Force and endurance affected by muscle fiber type and overall conditioning.

What are the primary effects of resistance training?

Improved strength and muscle size through hypertrophy and neural adaptations.

What happens during muscle recovery post-exercise?

Restoration of ATP and phosphocreatine levels, removal of lactate.

What is the Cori cycle?

The recycling of lactate to glucose in the liver.

What is the purpose of the resting metabolic rate (RMR)?

To quantify calories burned at rest to support basic physiological functions.

What adaptations occur in fast-twitch fibers after training?

Enhanced glycogen storage and increased glycolytic enzyme activity.

What is the significance of skeletal muscle's striated appearance?

It indicates organized contractile units (sarcomeres) for efficient contraction.

What is the effect of dehydration on muscle function?

Decreased performance and increased risk of cramps and fatigue.

How does improving muscle metabolism benefit exercise performance?

It increases endurance and efficiency of energy use during physical activity.

What are isometric contractions used for?

Maintaining posture and stabilizing joints without movement.

What role do elastic forces have in muscle function?

They aid in returning muscles to their resting length after contraction.

What is glycogen's role in muscle metabolism?

It serves as a readily available energy source during high-intensity exercise.

What are the signs of muscle fatigue during exercise?

Tiredness, decreased performance, and an increased perception of effort.

What is the impact of high intensity training on muscle fibers?

It promotes strength and anaerobic capacity, particularly in fast-twitch fibers.

What role does motor unit recruitment play in muscle contraction?

It influences the strength and smoothness of muscle contractions.

What adaptations occur in blood supply to muscles with endurance training?

Increased capillary density and improved blood flow to active tissues.

What do muscle fibers primarily depend on for prolonged activity?

Aerobic metabolism of fats and carbohydrates.

What is the role of heat production in muscle metabolism?

It helps maintain body temperature and is a byproduct of muscular activity.

What is the role of skeletal muscle in overall body function?

It facilitates movement, maintains posture, and generates heat.

What contributes to muscle soreness after intense exercise?

Micro-tears in muscle fibers and the accumulation of metabolic byproducts.

What are the major components affecting muscle contraction strength?

Number of muscle fibers activated and the frequency of stimulation.

What is the role of calcium ions in the muscle contraction cycle?

Calcium binds to regulatory proteins, allowing actin-myosin interactions.

What is the primary energy source at the start of exercise?

Stored ATP and phosphocreatine.

How are actions of the nervous system related to muscular control?

It initiates and coordinates muscle contractions for movement.

What mechanism allows muscles to relax after contraction?

Removal of calcium ions and breakdown of ACh at the neuromuscular junction.

What are the effects of aging on muscle tissue?

Reduction in muscle mass, strength, and regenerative capacity.

What is the effect of consistent resistance training on muscle fibers?

Increased muscle fiber size and alterations in muscle composition.

What physiological adaptations accompany improved aerobic capacity?

Increased mitochondrial density and enhanced oxygen utilization.