Muscle Physiology
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Questions and Answers

Which muscle is responsible for closing the eyelids and aiding in tear drainage?

  • Masseter
  • Orbicularis Oculi (correct)
  • Trapezius
  • Sternocleidomastoid

    • Which muscle spans the width of the back and connects the humerus to the thoracic and lumbar spine and hip?

  • Trapezius
  • Latissimus Dorsi (correct)
  • Pectoralis Major
  • Deltoid

    • Which muscle is responsible for flexing and supinating the forearm?

  • Triceps Brachii
  • Deltoid
  • Pectoralis Major
  • Biceps Brachii (correct)

    • What is the function of the internal intercostal muscles?

    <p>Inhalation</p> Signup and view all the answers

    Which muscle is responsible for compressing the abdomen and bending the vertebral column laterally?

    <p>External Oblique</p> Signup and view all the answers

    What is the origin of the Gluteus Maximus muscle?

    <p>Iliac crest, sacrum, and coccyx</p> Signup and view all the answers

    Which muscle is responsible for extending the leg?

    <p>Quadriceps Femoris</p> Signup and view all the answers

    What is the function of the Diaphragm muscle?

    <p>Expansion of the thoracic cavity</p> Signup and view all the answers

    Which muscle is responsible for rotating the arm?

    <p>Pectoralis Major</p> Signup and view all the answers

    Which muscle is responsible for adducting the arm?

    <p>Pectoralis Major</p> Signup and view all the answers

    What is the ability of muscles to stretch without rupture called?

    <p>Extensibility</p> Signup and view all the answers

    What is the connective tissue wrapping that surrounds the entire muscle called?

    <p>Epimysium</p> Signup and view all the answers

    What is the point at which a motor nerve meets the muscle called?

    <p>Neuromuscular junction</p> Signup and view all the answers

    What is the neurotransmitter released by the axon to stimulate the muscle fiber?

    <p>Acetylcholine</p> Signup and view all the answers

    What type of muscle contraction is responsible for posture?

    <p>Muscle tone</p> Signup and view all the answers

    What is the effect of exercise on the heart?

    <p>Strengthening of heart</p> Signup and view all the answers

    What is the muscle that produces the opposite movement of the prime mover called?

    <p>Antagonist</p> Signup and view all the answers

    What is the point of attachment on the bone that moves during an action called?

    <p>Insertion</p> Signup and view all the answers

    What is the result of dramatically increased muscle tone?

    <p>Contractures</p> Signup and view all the answers

    What is the type of muscle contraction where the tone of the muscle increases but the length of the muscle stays the same?

    <p>Isometric contraction</p> Signup and view all the answers

    What is the main function of the hamstring group?

    <p>to flex the leg and extend the thigh</p> Signup and view all the answers

    Which muscle is responsible for plantar flexion of the foot and flexing the leg?

    <p>Gastrocnemius</p> Signup and view all the answers

    What is the term for the sudden, always painful, involuntary muscle contraction in smooth muscle?

    <p>Spasm</p> Signup and view all the answers

    What is the result of oxygen debt during periods of strenuous exercise?

    <p>Breakdown of glucose without oxygen producing lactic acid</p> Signup and view all the answers

    What is the term for a muscular ring that tightly regulates an opening?

    <p>Sphincter</p> Signup and view all the answers

    What is the principle of muscle contraction that states that a muscle is either going to receive enough stimulation to contract or it is not?

    <p>All or none</p> Signup and view all the answers

    What is the unit of contraction of a skeletal muscle?

    <p>Sarcomere</p> Signup and view all the answers

    What is the effect of aging on muscles?

    <p>Decreased size and strength</p> Signup and view all the answers

    What is the term for muscle injury caused by overuse or overstretching?

    <p>Strain</p> Signup and view all the answers

    Which muscle holds the patella in place?

    <p>Quadricep femoris</p> Signup and view all the answers

    What is the primary mechanism of smooth muscle contraction in response to stretching?

    <p>Depolarization of the muscle fiber membrane</p> Signup and view all the answers

    Which of the following is a characteristic of cardiac muscle contraction?

    <p>Spontaneous contraction and relaxation without nervous stimulation</p> Signup and view all the answers

    What is the functional unit of skeletal muscle contraction?

    <p>Sarcomere</p> Signup and view all the answers

    What is the purpose of muscle tone in skeletal muscles?

    <p>To maintain posture and prevent muscle atrophy</p> Signup and view all the answers

    Which type of muscle is found in the walls of hollow organs?

    <p>Smooth muscle</p> Signup and view all the answers

    What is the role of intercalated discs in cardiac muscle?

    <p>To facilitate fast impulse transmission</p> Signup and view all the answers

    Which protein is responsible for generating muscle tension during contraction?

    <p>Myosin</p> Signup and view all the answers

    What is the primary function of skeletal muscle in maintaining posture?

    <p>To maintain steady partial contraction</p> Signup and view all the answers

    What is the result of the sliding of actin past myosin during muscle contraction?

    <p>Shortening of the sarcomere</p> Signup and view all the answers

    What is the primary mechanism of heat generation in skeletal muscle?

    <p>Muscle contraction and relaxation</p> Signup and view all the answers

    Which muscle is responsible for raising and lowering the mandible?

    <p>Masseter</p> Signup and view all the answers

    Which muscle has an origin at the xiphoid process and costal cartilage of the last 6 ribs and lumbar vertebrae?

    <p>Diaphragm</p> Signup and view all the answers

    Which muscle is responsible for adducting and rotating the arm?

    <p>Pectoralis Major</p> Signup and view all the answers

    What is the primary mechanism by which cardiac muscle contraction occurs?

    <p>Through simultaneous contraction of cells due to fast impulse transmission by intercalated discs</p> Signup and view all the answers

    Which muscle is responsible for compressing the abdomen and bending the vertebral column laterally?

    <p>External Oblique</p> Signup and view all the answers

    What is the primary function of the sarcomere in skeletal muscle contraction?

    <p>To act as the functional unit of muscle contraction</p> Signup and view all the answers

    Which muscle is responsible for extending the forearm and extending the arm?

    <p>Triceps Brachii</p> Signup and view all the answers

    What is the primary mechanism by which skeletal muscle contraction produces movement?

    <p>Through the sliding of actin past myosin</p> Signup and view all the answers

    What is the characteristic of smooth muscle contraction that allows it to maintain long-lasting contractions?

    <p>Slow and long-lasting contraction</p> Signup and view all the answers

    Which muscle is responsible for abducting and rotating the thigh medially?

    <p>Gluteus Medius</p> Signup and view all the answers

    What is the role of intercalated discs in cardiac muscle contraction?

    <p>To facilitate fast impulse transmission between cells</p> Signup and view all the answers

    Which muscle has an insertion at the deltoid tuberosity of the humerus?

    <p>Deltoid</p> Signup and view all the answers

    What is the primary function of skeletal muscle in maintaining posture?

    <p>To maintain a steady partial contraction</p> Signup and view all the answers

    What is the characteristic of skeletal muscle contraction that allows it to produce rapid and powerful contractions?

    <p>Fast impulse transmission</p> Signup and view all the answers

    What is the main function of the endomysium, perimysium, and epimysium in skeletal muscles?

    <p>To provide a framework for muscle fibers and facilitate muscle contraction</p> Signup and view all the answers

    What is the primary role of acetylcholine in muscle contraction?

    <p>To stimulate the contraction of muscle fibers by binding to receptors</p> Signup and view all the answers

    What is the primary mechanism of muscle contraction that leads to an increase in muscle strength?

    <p>An increase in the amount of protein filaments in muscle fibers</p> Signup and view all the answers

    What is the primary function of the fixed point of attachment (origin) of a skeletal muscle?

    <p>To provide a anchor point for muscle contraction</p> Signup and view all the answers

    What is the primary effect of vasodilation on blood pressure during exercise?

    <p>A decrease in blood pressure due to decreased resistance</p> Signup and view all the answers

    What is the primary function of the synergist muscle during muscle contraction?

    <p>To stabilize the joint during muscle contraction</p> Signup and view all the answers

    What is the primary mechanism of muscle relaxation after contraction?

    <p>The redistribution of sodium and potassium ions across the cell membrane</p> Signup and view all the answers

    What is the primary function of the gastrocnemius muscle?

    <p>Plantar flexion of the foot and flexing the leg</p> Signup and view all the answers

    What is the result of muscle injury caused by overuse or overstretching?

    <p>Strain</p> Signup and view all the answers

    What is the term for the sudden, always painful, involuntary muscle contraction in skeletal muscle?

    <p>Cramp</p> Signup and view all the answers

    What is the effect of oxygen debt during periods of strenuous exercise?

    <p>Muscle breakdown of glucose without oxygen, producing lactic acid</p> Signup and view all the answers

    What is the term for the muscular ring that tightly regulates an opening?

    <p>Sphincter</p> Signup and view all the answers

    What is the principle of muscle contraction that states that a muscle is either going to receive enough stimulation to contract or it is not?

    <p>All or none</p> Signup and view all the answers

    What is the unit of contraction of a skeletal muscle?

    <p>Sarcomere</p> Signup and view all the answers

    What is the effect of aging on skeletal muscles?

    <p>Decreased size and strength</p> Signup and view all the answers

    What is the function of the hamstring group?

    <p>Flex the leg and extend the thigh</p> Signup and view all the answers

    What is the primary function of the Gastrocnemius muscle?

    <p>Plantar flexion of the foot and flexion of the leg</p> Signup and view all the answers

    What is the term for the decrease in size and strength of muscles with age?

    <p>Atrophy</p> Signup and view all the answers

    What is the term for the sudden, painful, involuntary muscle contraction in skeletal muscle?

    <p>Cramp</p> Signup and view all the answers

    What is the primary function of the Tibialis Anterior muscle?

    <p>Dorsiflexion and inversion of the foot</p> Signup and view all the answers

    What is the result of oxygen debt during periods of strenuous exercise?

    <p>Muscle fatigue</p> Signup and view all the answers

    What is the term for the muscle injury caused by overuse or overstretching?

    <p>Strain</p> Signup and view all the answers

    What is the effect of aging on skeletal muscle elasticity?

    <p>It decreases</p> Signup and view all the answers

    What is the primary function of the Hamstring group?

    <p>Flexion of the leg and extension of the thigh</p> Signup and view all the answers

    What is the term for the muscular ring that tightly regulates an opening?

    <p>Sphincter</p> Signup and view all the answers

    What is the principle of muscle contraction that states that a muscle is either going to receive enough stimulation to contract or it is not?

    <p>All or none</p> Signup and view all the answers

    Study Notes

    Muscle Structure and Function

    • Smooth muscle fibers contract like a wave (peristalsis) in response to nerve impulse, hormonal stimulation, or stretching.
    • Smooth muscles contract slowly and can remain contracted for long periods of time, and relax slowly.
    • Smooth muscles make up the walls of hollow organs such as the stomach, esophagus, small intestines, blood vessels, and respiratory passageways.

    Cardiac Muscle

    • Cardiac muscle is also known as myocardium or heart muscle.
    • It is made up of cells joined by intercalated discs, which are capable of fast impulse transmission.
    • Cardiac muscle contracts and relaxes automatically without conscious control, pumping blood at a rate of 60-100 times per minute.

    Skeletal Muscle

    • Skeletal muscle consists of muscle cells (fibers) that are grouped together in bundles called fascicles.
    • Muscle cells are called myocytes, and muscle fibers are composed of myofibrils, which are made up of sarcomeres linked in series.
    • The sarcomere is the functional unit of the muscle where contraction occurs.
    • Actin and myosin are the force-generating proteins of the sarcomere that work together to produce movement.

    Properties of Muscles

    • Contractility: the ability to contract or get shorter.
    • Excitability: responsiveness to stimuli.
    • Conductivity: the ability to conduct electrical charge.
    • Extensibility: the ability to stretch without rupture.
    • Elasticity: the ability to return to their original shape after contraction or extension.

    Muscle Contraction

    • Muscle contraction involves the sliding of actin past myosin, generating muscle tension.
    • Myosin pulls on actin to shorten the sarcomere, producing movement.

    Types of Muscle Contraction

    • Muscle tone: a state of partial contraction responsible for posture.
    • Isotonic contractions: the tone of the muscle remains the same, but the muscle gets shorter in length.
    • Isometric contractions: the tone of the muscle increases, but the length of the muscle stays the same.

    Effects of Exercise on Muscles

    • Increased capillaries in muscles, increased protein filaments, and increased glycogen storage.
    • Muscle hypertrophy: increased muscle size and strength.
    • Vasodilation: increased blood flow and decreased resistance, leading to a drop in blood pressure.
    • Strengthening of the heart and improvement in respiration.

    Action of Muscles

    • Prime mover or agonist: provides most force for a given muscle action.
    • Antagonist: has opposite action of agonist, producing the opposite movement.
    • Synergist: muscles that aid agonists or prime movers, helping to stabilize joints.
    • Fixator: specialized synergist that helps to fix the position of the bone being moved.

    Muscles of the Body

    • Muscles of the head produce facial expressions, speech, and chewing.
    • Muscles of the neck, such as the sternocleidomastoid and trapezius, are important for flexing and turning the head.
    • Muscles of the upper extremities, such as the latissimus dorsi, pectoralis major, and deltoid, are involved in movements of the arm and shoulder.
    • Muscles of the forearm and hand, such as the biceps brachii and triceps brachii, are involved in flexion and extension of the forearm.
    • Muscles of the trunk, such as the intercostal muscles and diaphragm, are involved in respiration.
    • Muscles of the abdomen and pelvis, such as the rectus abdominis and external oblique, are involved in compressing the abdomen and bending the vertebral column.
    • Muscles of the lower extremities, such as the gluteus maximus and quadriceps femoris, are involved in movements of the thigh and leg.

    Muscular Disorders

    • Atrophy: wasting or decrease in size brought about by lack of use.
    • Spasm: sudden, painful, involuntary muscle contraction.
    • Strains: muscle injury caused by overuse or overstretching.
    • Sprains: more severe than strains, involving twisting of a joint with partial rupture to the muscle and tendon.

    Effects of Aging on Muscles

    • Decrease in size and strength of all muscles.
    • Decrease in skeletal muscle size, strength, and endurance.
    • Decrease in skeletal muscle elasticity and flexibility.
    • Decrease in exercise tolerance and ability to recover from muscle injury.
    • Oxygen debt: the inability to deliver enough oxygen to the muscles during strenuous exercise, leading to muscle fatigue.
    • Sphincter: a muscular ring that tightly regulates an opening, such as the urethral sphincter, anal sphincter, or pyloric sphincter.
    • All or none: the principle that a muscle is either fully stimulated to contract or not at all.

    Muscle Structure and Function

    • Smooth muscle fibers contract like a wave (peristalsis) in response to nerve impulse, hormonal stimulation, or stretching.
    • Smooth muscles contract slowly and can remain contracted for long periods of time, and relax slowly.
    • Smooth muscles make up the walls of hollow organs such as the stomach, esophagus, small intestines, blood vessels, and respiratory passageways.

    Cardiac Muscle

    • Cardiac muscle is also known as myocardium or heart muscle.
    • It is made up of cells joined by intercalated discs, which are capable of fast impulse transmission.
    • Cardiac muscle contracts and relaxes automatically without conscious control, pumping blood at a rate of 60-100 times per minute.

    Skeletal Muscle

    • Skeletal muscle consists of muscle cells (fibers) that are grouped together in bundles called fascicles.
    • Muscle cells are called myocytes, and muscle fibers are composed of myofibrils, which are made up of sarcomeres linked in series.
    • The sarcomere is the functional unit of the muscle where contraction occurs.
    • Actin and myosin are the force-generating proteins of the sarcomere that work together to produce movement.

    Properties of Muscles

    • Contractility: the ability to contract or get shorter.
    • Excitability: responsiveness to stimuli.
    • Conductivity: the ability to conduct electrical charge.
    • Extensibility: the ability to stretch without rupture.
    • Elasticity: the ability to return to their original shape after contraction or extension.

    Muscle Contraction

    • Muscle contraction involves the sliding of actin past myosin, generating muscle tension.
    • Myosin pulls on actin to shorten the sarcomere, producing movement.

    Types of Muscle Contraction

    • Muscle tone: a state of partial contraction responsible for posture.
    • Isotonic contractions: the tone of the muscle remains the same, but the muscle gets shorter in length.
    • Isometric contractions: the tone of the muscle increases, but the length of the muscle stays the same.

    Effects of Exercise on Muscles

    • Increased capillaries in muscles, increased protein filaments, and increased glycogen storage.
    • Muscle hypertrophy: increased muscle size and strength.
    • Vasodilation: increased blood flow and decreased resistance, leading to a drop in blood pressure.
    • Strengthening of the heart and improvement in respiration.

    Action of Muscles

    • Prime mover or agonist: provides most force for a given muscle action.
    • Antagonist: has opposite action of agonist, producing the opposite movement.
    • Synergist: muscles that aid agonists or prime movers, helping to stabilize joints.
    • Fixator: specialized synergist that helps to fix the position of the bone being moved.

    Muscles of the Body

    • Muscles of the head produce facial expressions, speech, and chewing.
    • Muscles of the neck, such as the sternocleidomastoid and trapezius, are important for flexing and turning the head.
    • Muscles of the upper extremities, such as the latissimus dorsi, pectoralis major, and deltoid, are involved in movements of the arm and shoulder.
    • Muscles of the forearm and hand, such as the biceps brachii and triceps brachii, are involved in flexion and extension of the forearm.
    • Muscles of the trunk, such as the intercostal muscles and diaphragm, are involved in respiration.
    • Muscles of the abdomen and pelvis, such as the rectus abdominis and external oblique, are involved in compressing the abdomen and bending the vertebral column.
    • Muscles of the lower extremities, such as the gluteus maximus and quadriceps femoris, are involved in movements of the thigh and leg.

    Muscular Disorders

    • Atrophy: wasting or decrease in size brought about by lack of use.
    • Spasm: sudden, painful, involuntary muscle contraction.
    • Strains: muscle injury caused by overuse or overstretching.
    • Sprains: more severe than strains, involving twisting of a joint with partial rupture to the muscle and tendon.

    Effects of Aging on Muscles

    • Decrease in size and strength of all muscles.
    • Decrease in skeletal muscle size, strength, and endurance.
    • Decrease in skeletal muscle elasticity and flexibility.
    • Decrease in exercise tolerance and ability to recover from muscle injury.
    • Oxygen debt: the inability to deliver enough oxygen to the muscles during strenuous exercise, leading to muscle fatigue.
    • Sphincter: a muscular ring that tightly regulates an opening, such as the urethral sphincter, anal sphincter, or pyloric sphincter.
    • All or none: the principle that a muscle is either fully stimulated to contract or not at all.

    Muscle Types and Characteristics

    • Smooth muscle fibers contract in a wave-like manner (peristalsis) and respond to nerve impulses, hormonal stimulation, and stretching.

    • They contract slowly and can remain contracted for long periods, relaxing slowly.

    • Smooth muscles make up the walls of hollow organs, such as the stomach, esophagus, and blood vessels.

    • Cardiac muscle (myocardium) is composed of cells joined by intercalated discs, allowing for fast impulse transmission and simultaneous contraction.

    • It contracts and relaxes automatically without conscious control, typically 60-100 times per minute.

    • Skeletal muscle consists of muscle cells (fibers) bundled into fascicles, surrounded by perimysium and epimysium.

    • Muscle cells are called myocytes, and muscle fibers are composed of myofibrils, which are made up of sarcomeres linked in series.

    Muscle Contraction and Relaxation

    • Muscle contraction involves the sliding of actin past myosin, generating muscle tension.
    • Myosin pulls on actin to shorten the sarcomere, resulting in muscle contraction.
    • The nervous system stimulates skeletal muscle contraction, which is usually fast and relaxes quickly.

    Muscle Properties

    • Contractility: the ability to contract or get shorter.
    • Excitability: responsiveness to stimuli.
    • Conductivity: the ability to conduct electrical charge.
    • Extensibility: the ability to stretch without rupture.
    • Elasticity: the ability to return to original shape after contraction or extension.

    Muscle Structure and Function

    • Motor nerves carry signals to muscles to facilitate movement and function.
    • The neuromuscular junction is the point at which a motor nerve meets a muscle cell.
    • An axon or nerve fiber meets the muscle fiber, releasing acetylcholine (a neurotransmitter) across the synapse, causing muscle contraction.

    Muscle Contraction Types

    • Muscle tone: a state of partial contraction responsible for maintaining posture.
    • Isotonic contractions: muscle tone remains the same, but the muscle shortens in length.
    • Isometric contractions: muscle tone increases, but muscle length remains the same.

    Effects of Exercise on Muscles

    • Increased capillaries, protein filaments, and glycogen storage in muscles.
    • Muscle hypertrophy (size and strength increase).
    • Vasodilation and increased blood flow, leading to decreased blood pressure.
    • Strengthening of the heart and increased blood circulation to the lungs.

    Muscle Actions and Functions

    • Prime mover (agonist): provides the most force for a given muscle action.
    • Antagonist: has the opposite action of the agonist.
    • Synergist: muscles that aid the agonist by stabilizing joints.
    • Fixator: specialized synergist that helps to fix the position of the bone being moved.

    Muscles of the Body

    • Muscles of the head: produce facial expressions, speech, and chewing.
    • Muscles of the neck: flex and turn the head.
    • Muscles of the upper extremities: adduct, rotate, and flex the arm.
    • Muscles of the trunk: support respiration, flex and rotate the vertebral column.
    • Muscles of the lower extremities: flex, rotate, and extend the leg.

    Muscle Disorders and Aging

    • Atrophy: wasting or decrease in muscle size due to lack of use.
    • Spasm: sudden, painful, involuntary muscle contraction.
    • Strains: muscle injury caused by overuse or overstretching.
    • Sprains: twisting of a joint with partial rupture of the muscle and tendon.
    • Effects of aging on muscles: decreased size, strength, and endurance, with reduced flexibility and exercise tolerance.

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    Description

    Learn about the characteristics and functions of smooth muscle fibers and cardiac muscle, including their contraction mechanisms and locations in the body.

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