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Questions and Answers
What is the primary role of heat released by working muscles?
What is the primary role of heat released by working muscles?
What is the term used for the connection of a muscle to an immovable bone?
What is the term used for the connection of a muscle to an immovable bone?
Which type of lever has the fulcrum located between the effort and the load?
Which type of lever has the fulcrum located between the effort and the load?
In a second class lever, which statement is true regarding the load?
In a second class lever, which statement is true regarding the load?
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Which statement accurately describes third class levers?
Which statement accurately describes third class levers?
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What surrounds each muscle fiber?
What surrounds each muscle fiber?
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Which process initiates the contraction of a muscle fiber?
Which process initiates the contraction of a muscle fiber?
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What is the function of calcium in muscle contraction?
What is the function of calcium in muscle contraction?
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What structure is formed by bundles of muscle fibers?
What structure is formed by bundles of muscle fibers?
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What is the sequence of events related to the release of calcium in muscle contraction?
What is the sequence of events related to the release of calcium in muscle contraction?
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What is the primary benefit of slowly lengthening muscle fibers?
What is the primary benefit of slowly lengthening muscle fibers?
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What is the recommended amount of moderate activity per week according to CDC guidelines?
What is the recommended amount of moderate activity per week according to CDC guidelines?
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What happens to muscle tissue as individuals age without weight training?
What happens to muscle tissue as individuals age without weight training?
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What can cause muscle cramps during exercise?
What can cause muscle cramps during exercise?
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What is atrophy in relation to muscles?
What is atrophy in relation to muscles?
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Approximately how many muscles are in the human body?
Approximately how many muscles are in the human body?
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What is one of the primary functions of muscles?
What is one of the primary functions of muscles?
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Which statement about muscle contractions is FALSE?
Which statement about muscle contractions is FALSE?
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What type of muscle primarily helps in facial expression?
What type of muscle primarily helps in facial expression?
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What is the function of sphincter muscles?
What is the function of sphincter muscles?
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How do muscles contribute to body posture?
How do muscles contribute to body posture?
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Which of the following is NOT a function of muscles?
Which of the following is NOT a function of muscles?
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Which type of muscle is responsible for moving bones?
Which type of muscle is responsible for moving bones?
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What is the contractile unit of a myofibril called?
What is the contractile unit of a myofibril called?
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Which protein is primarily found in thick filaments?
Which protein is primarily found in thick filaments?
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What forms the H zone in a sarcomere?
What forms the H zone in a sarcomere?
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What is the function of the sarcoplasmic reticulum in muscle cells?
What is the function of the sarcoplasmic reticulum in muscle cells?
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Which of the following best describes myofibrils?
Which of the following best describes myofibrils?
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What structure forms the triad in muscle cells?
What structure forms the triad in muscle cells?
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Where are the nuclei found in muscle cells?
Where are the nuclei found in muscle cells?
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What is the primary role of myosin heads during muscle contraction?
What is the primary role of myosin heads during muscle contraction?
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What is found between the sarcoplasm and the sarcolemma in muscle cells?
What is found between the sarcoplasm and the sarcolemma in muscle cells?
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What distinguishes the I band in a sarcomere?
What distinguishes the I band in a sarcomere?
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What is the role of calcium in muscle contraction?
What is the role of calcium in muscle contraction?
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What is a Motor Unit?
What is a Motor Unit?
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Which statement best describes muscle fiber contraction?
Which statement best describes muscle fiber contraction?
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What causes muscle fatigue primarily?
What causes muscle fatigue primarily?
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What is the difference between fused and unfused tetanus?
What is the difference between fused and unfused tetanus?
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Which of the following describes Anaerobic glycolysis?
Which of the following describes Anaerobic glycolysis?
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What happens to muscle fibers during aerobic exercise?
What happens to muscle fibers during aerobic exercise?
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Which type of contraction does not allow any relaxation before the next contraction?
Which type of contraction does not allow any relaxation before the next contraction?
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What is a benefit of increased aerobic exercise on muscle morphology?
What is a benefit of increased aerobic exercise on muscle morphology?
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What is the effect of lactic acid accumulation in muscles?
What is the effect of lactic acid accumulation in muscles?
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Study Notes
Muscular System Anatomy & Physiology
- The muscular system is responsible for all types of body movement.
- There are approximately 650 muscles in the human body.
- Different muscles have different functions when it comes to movement.
- Muscle cells are elongated and are known as muscle fibers.
- Muscle contractions are due to proteins called myofilaments.
Functions of Muscles
- Muscles produce movement or generate tension.
- Muscles help with skeletal movement, communication, body position, posture, protect soft tissues, and guard entrances and exits. They also maintain body temperature.
- Muscles are attached to bones at least at two points.
- Origin is the attachment to an immovable bone.
- Insertion is the attachment to a movable bone.
Lever Systems
- Lever systems involve a rigid bar (lever) that moves on a fixed point (fulcrum) when a force is applied (effort).
- Bones and muscles act as lever systems in the body. The resistance (load) is the weight and tissues the muscles need to move.
Types of Levers
- First-Class Levers: The fulcrum is in between the effort and the load (e.g., seesaw).
- Second-Class Levers: The load is between the effort and the fulcrum (e.g., wheelbarrow).
- Third-Class Levers: The effort is between the load and the fulcrum. Most skeletal muscles are of this type.
Muscle Actions and Types of Muscles
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Agonist: The primary muscle that moves a bone.
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Antagonist: The muscle that opposes the agonist.
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Synergists: Assist the prime mover muscles.
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Fixators: Help to hold bones in place.
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Tendons are thick and rope-like structures that connect muscle to bones.
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Aponeuroses are flat sheet-like structures that also connect muscle to bones
Five Golden Rules of Skeletal Muscle Activity
- All muscles cross at least one joint.
- The bulk of muscles lies proximal to the joint crossed.
- All muscles have at least two attachments (origin and insertion).
- Muscles only pull (never push).
- During contraction, the muscle insertion moves towards the origin.
Muscle Contraction
- The process of muscle contraction is called the sliding filament model.
- Nerve impulses trigger myosin to pull actin filaments closer together.
Sliding Filament Model Parts
- Part 1: Shows the release of calcium removes guard proteins around actin to reveal binding sites.
- Part 2: Shows how myosin heads break down ATP and use energy to bind and pull on the actin.
Neuromuscular Junction
- The neuromuscular junction is where a motor neuron meets a muscle cell.
- The end of the motor neuron meets the muscle cell at a motor end plate.
- Nerve impulses are sent through a neuron to the muscle to begin contraction.
- Acetylcholine (ACh) is released from the neuron and binds to receptors on the motor end plate.
Muscle Fiber Contraction
- Muscle fiber contraction is "all or none," meaning either all fibers contract or none do.
- Different combinations of fiber contractions cause different responses.
Energy for Muscle Contraction
- Initially, muscles use stored ATP for energy.
- After initial energy, other pathways are used to produce ATP.
- Aerobic respiration involves a series of metabolic pathways occurring in the mitochondria, where glucose is broken down.
- In anaerobic glycolysis glucose is broken down.
- Muscle fatigue occurs when a muscle is unable to contract.
Muscle Fatigue and Oxygen Debt
- The common reason for muscle fatigue is oxygen debt--oxygen is required to get rid of accumulated lactic acid.
- Increasing acidity (from lactic acid) and lack of ATP causes the muscle to contract less.
Effects of Exercise on Muscles
- Aerobic exercise increases blood supply to the muscles. It also increases mitochondria and oxygen storage in the muscle fibers and increases muscle fatigue resistance.
- Anaerobic exercise increases the amount of contractile filaments and connective tissue.
- Stretching increases flexibility and helps avoid injuries.
Aging Muscles
- During aging, muscle tissue decreases, and connective tissue increases.
- Muscles become stringier.
- Body weight declines due to loss of muscle mass.
- Strength usually decreases by 50% by age 80 if no weight training is done.
Muscle Complications
- Muscle cramps are painful, uncontrollable muscle contractions, often caused by dehydration and ion imbalance.
- Pulled muscles (torn muscles) occur from stretching muscles too far, resulting in tearing of fibers.
Muscle Diseases & Disorders
- Atrophy is muscle wasting away due to disintegrating protein in the muscles, which is commonly from lack of use.
- Tetanus is a bacterial infection that causes maximal muscle contraction due to overstimulation of nerves.
Muscle Types
- Skeletal muscle: striated, voluntary, attached to bones, multinucleated, surrounded and bundled by connective tissue.
- Cardiac muscle: striated, involuntary, only in the heart, single nucleus, contracts at a steady rate.
- Smooth muscle: non-striated, involuntary, in hollow organs (intestines, stomach, bladder), spindle-shaped cells, single nucleus, pushes food and other substances through body.
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Description
Test your knowledge on muscle anatomy and physiology with this quiz. From muscle fiber structures to lever types and calcium's role in contraction, explore key concepts that are essential for understanding how muscles work. Perfect for students studying biology or physical education.
