Muscular system

Muscular System

Responsible for movement, stabilizing joints, maintaining posture, and generating heat.

Irritability

The ability to receive and respond to stimuli.

Contractility

The ability to shorten with adequate stimuli.

Acetylcholine (ACh)

The neurotransmitter that stimulates skeletal muscle and initiates contraction.

Action Potential

An electrical current created by the rush of sodium ions (Na+) into the muscle, causing contraction.

Sliding Filament Theory

Describes how muscle fibers contract when actin slides past myosin.

ATP (Adenosine Triphosphate)

The energy source required for muscle contraction.

Aerobic Respiration

ATP production using oxygen, yielding 36 ATP per glucose.

Anaerobic Respiration

ATP production without oxygen, yielding 2 ATP per glucose and producing lactic acid.

Lactic Acid

A byproduct of anaerobic respiration that builds up in muscles.

Slow Twitch Muscle Fibers

Muscle fibers that are more endurance-oriented, producing energy aerobically.

Fast Twitch Muscle Fibers

Muscle fibers designed for strength and quick energy bursts through anaerobic means.

Skeletal Muscle

Voluntary muscle attached to bones, responsible for body movement.

Cardiac Muscle

Involuntary muscle located in the heart, regulated by pacemaker cells.

Smooth Muscle

Involuntary muscle found in hollow organs, controlled by the autonomic nervous system.

Motor Unit

A motor neuron and the muscle fibers it controls; crucial for muscle contraction.

Endurance Exercise

Improves cardiovascular health and muscle efficiency by increasing mitochondrial density.

Isometric Contractions

Muscle contractions that generate tension without changing length.

Isotonic Contractions

Muscle contractions that change length, such as lifting weights.

Atrophy

A decrease in muscle size due to lack of use or illness.

Hypertrophy

An increase in muscle size from strength training.

Perimysium

Connective tissue surrounding a muscle fascicle.

Epimysium

Connective tissue surrounding the entire muscle.

Endomysium

Connective tissue surrounding individual muscle fibers.

Fascicle

A bundle of muscle fibers.

Myofibril

Substructures within muscle fibers, made of sarcomeres.

Sarcomere

The functional unit of muscle contraction, defined by the area between two Z-discs.

Actin

Thin protein filament that helps form cross-bridges during muscle contraction.

Myosin

Thick protein filament that pulls on actin to contract the muscle.

Muscle Fiber

Elongated muscle cells with many nuclei, responsible for contraction.

Creatine Phosphate (CP) Breakdown

Rapid ATP supply for short bursts of activity lasting about 10-15 seconds.

Muscle Hierarchy

Organization of muscle structure from fascicle to sarcomere.

Major Muscles of the Body

Includes eye muscles, biceps, triceps, gastrocnemius, and pectoralis major.

Nerve Impulse

Electrical signals sent through neurons to stimulate muscle contraction.

Fatigued

The state of being unable to continue contracting due to energy depletion.

Body Benefits of Aerobic Exercise

Includes improved metabolism, digestion, cardiovascular health, and lung efficiency.

Skeletal Muscle Characteristics

Voluntary, striated, multinucleated fibers that control movement.

Cardiac Muscle Characteristics

Involuntary, striated, single nucleus, branched fibers in the heart.

Smooth Muscle Characteristics

Involuntary, non-striated, single nucleus fibers in hollow organs.

Protein Filaments

Actin (thin) and Myosin (thick) are responsible for muscle contractions.

Antagonistic Muscle Pairs

Muscle groups arranged to work in opposing actions for body movements.

Lactic Acid Formation

Occurs during anaerobic respiration and can lead to muscle fatigue.

Sarcoplasmic Reticulum

A specialized endoplasmic reticulum in muscle cells that stores calcium.

Lung Efficiency

Improves through regular aerobic exercise leading to better gas exchange.

Myofibrils

Long, thread-like structures within muscle fibers important for contraction.

Fascicle

A bundle of muscle fibers surrounded by perimysium.

Muscle Contraction Cycle

Involves attachment, pivoting, detachment, and re-cocking of myosin heads.

Energy Requirements for Muscles

Muscles need ATP, which can be supplied via creatine phosphate, anaerobic respiration, and aerobic respiration.

Side Effects of Anabolic Steroids

Harmful effects associated with synthetic substances that mimic testosterone.

Jumping Exercise

A physical activity that engages multiple muscle groups.

Flexibility Training

Involves stretching to improve muscle elasticity and joint function.

Repetitions (Reps)

The number of times an exercise is performed in one set.

Sets

Groups of consecutive repetitions in strength training.

Tendon

Connective tissue that attaches muscle to bone.

Muscle Tone

The continuous and passive partial contraction of the muscles.

Contraction Strength

The force produced by muscles during contraction.

Heat Generation in Muscles

Muscles generate heat during contractions, contributing to body temperature regulation.

Eccentric Contractions

Muscle lengthens under tension, often while lowering weights.

Concentric Contractions

Muscle shortens while generating tension, like lifting weights.

Physical Fitness Components

Includes muscular strength, endurance, flexibility, and body composition.

Respiratory Rate During Exercise

Means the frequency of breaths taken during physical activity.

Body Composition

The ratio of fat to lean mass in the body, influencing fitness.

Balance Exercises

Activities that improve stability and control, crucial for physical fitness.

Muscle Recovery

The healing process of muscles post-exercise, essential for growth.

Strength Training

A form of exercise focused on increasing muscle mass and strength.

Cool Down Exercise

Transitioning activity post-exercise to gradually lower heart rate.

Proper Hydration for Muscles

Maintaining adequate fluid levels to support muscle function.

Nutrition and Muscle Maintenance

Diet's role in providing necessary nutrients for muscle health.

Load-bearing Exercises

Exercises that help build and maintain bone density.

Chronic Exercise Benefits

Long-term advantages of regular physical activity for the body.

Resistance Training

Strength training that involves resistance to muscle contraction.

Biomechanics of Exercise

The study of movement and the forces acting upon muscles and joints.

Functional Training

Exercise that mimics everyday tasks and activities.

Maximum Heart Rate

The highest heart rate an individual can achieve safely during exercise.

Skeletal Health and Exercise

The impact of physical activity on bone strength and density.

Physical Activity Guidelines

Recommendations for frequency and intensity of exercise for health.

Cardiovascular Conditioning

Improvement of heart and lung capacity through aerobic exercises.

Strength-to-Weight Ratio

A measure of strength relative to body weight, important for fitness.