Skeletal Muscles and Exercise Quiz

Skeletal Muscles and Exercise

• Skeletal muscles are responsible for movement and are comprised of muscle fibers.
• Muscle fibers contain myofibrils, which are made up of sarcomeres.
• Sarcomeres are the basic contractile units of muscle fibers and contain thin (actin) and thick (myosin) filaments.

Chemical Composition of Skeletal Muscles

• Water constitutes the majority of muscle weight.
• Proteins, including myosin and actin, make up a significant portion of muscle mass.
• Other important chemicals include carbohydrates, fats, and minerals.

Sliding Filament Theory of Muscular Contraction

• Actin and myosin filaments slide past each other during muscle contraction, shortening the sarcomere.
• Myosin heads bind to actin, forming cross-bridges, and pull the actin filaments towards the center of the sarcomere.
• This process is fueled by ATP, which is broken down to provide energy for the myosin heads to detach and reattach.

Types of Muscle Fibers

• Type I (slow twitch) fibers are slow-contracting, fatigue-resistant fibers that use aerobic metabolism for energy.
• Type IIa (fast twitch) fibers are fast-contracting, fatigue-resistant fibers that use a mix of aerobic and anaerobic metabolism.
• Type IIb (fast twitch) fibers are fast-contracting, easily fatigued fibers that primarily rely on anaerobic metabolism.

Muscle Tone among Athletic Groups

• Endurance athletes typically have a higher percentage of Type I fibers.
• Power athletes typically have a higher percentage of Type IIa fibers.
• Strength athletes typically have a higher percentage of Type IIb fibers.

Chemistry of Muscular Contraction

• Muscle contraction requires calcium ions, which bind to troponin and expose the binding sites on actin for myosin to attach.
• ATP is broken down to provide energy for the myosin heads to detach and reattach to actin, continuing the sliding filament process.

Heat Production in the Muscle

• Muscle contraction generates heat as a byproduct of metabolic processes.
• This heat contributes to maintaining body temperature.

Effect of Exercises and Training on the Muscular System

• Regular exercise increases muscle mass, strength, and endurance.
• Strength training leads to hypertrophy (increase in the size of muscle cells) and increased number of myofibrils within muscle fibers.
• Resistance training enhances muscle strength and power.
• Endurance training increases mitochondrial density and improves the efficiency of aerobic metabolism.

Muscular Fatigue

• Muscle fatigue occurs when muscles are unable to maintain their desired level of force production.
• Contributors to fatigue include depletion of energy stores, accumulation of metabolic byproducts, and disruption of nerve impulses.

Influence of Age and Sex on Muscle Function

• Muscle mass and strength decline with age, a phenomenon known as sarcopenia.
• Women generally have a lower percentage of muscle mass than men, but this can be offset by regular exercise and training.

Cardiovascular System and Exercise

• The cardiovascular system comprises the heart, blood vessels, and blood.
• It plays a vital role in transporting oxygen and nutrients to the working muscles and removing waste products.

Heart Valves and Direction of Blood flow

• Heart valves ensure unidirectional blood flow, preventing backflow.
• Atrioventricular (AV) valves (mitral and tricuspid) control blood flow between the atria and ventricles.
• Semilunar valves (aortic and pulmonary) regulate blood flow from the ventricles to the aorta and pulmonary artery.

Conduction System of the Heart

• The heart's electrical system coordinates heart contractions.
• Sinoatrial (SA) node is the pacemaker, initiating electrical impulses.
• Impulses travel through the atria, AV node, bundle of His, and Purkinje fibers, leading to ventricular contraction.

Blood Supply to the Heart

• The heart receives oxygenated blood through the coronary arteries.
• Coronary arteries branch from the aorta and supply the heart muscle with oxygen and nutrients.

Functional Capacity at Rest and During Physical Activity

• The cardiovascular system adapts to meet the demands of exercise.
• During exercise, heart rate, stroke volume, cardiac output, and blood pressure increase to deliver more oxygen and remove waste products.

Cardiac Cycle, Stroke Volume

• The cardiac cycle consists of atrial contraction, ventricular contraction, and relaxation phases.
• Stroke volume is the amount of blood ejected by the heart with each beat.

Cardiac Output, Heart Rate & Blood Pressure

• Cardiac output is the amount of blood pumped by the heart per minute.
• Heart rate is the number of heartbeats per minute.
• Blood pressure is the force exerted by blood against the walls of blood vessels.

Factors Affecting Heart Rate

• Heart rate is influenced by factors such as exercise intensity, stress, emotional state, and medication.

Cardiac Hypertrophy

• Cardiac hypertrophy is an increase in the size of the heart muscle.
• It can occur as a result of regular exercise or certain medical conditions.

Test your knowledge on skeletal muscles, their chemical composition, and the sliding filament theory of muscular contraction. This quiz covers muscle fiber types and their characteristics, providing a comprehensive overview of muscular anatomy and physiology.