Ana notes 2

Anatomy & Physiology Muscular System

  • La Progresiva Presbyterian School

Overview of the Muscular System

  • Specialized tissue that enables body movement.

  • Muscle types include:

    • Skeletal

    • Smooth

    • Cardiac

Muscle Types and Functions

Skeletal Muscle

  • Responsible for voluntary movements.

  • Properties include:

    • Striated: Visible stripes across the fiber.

    • Multi-nucleated: Contains several nuclei.

    • Locations: Attached to bones via tendons.

    • Function: Movement, posture, and respiration.

Smooth Muscle

  • Involuntary muscles found in hollow organs.

  • Properties:

    • No striations.

    • Single nucleus.

    • Slow to fatigue.

Cardiac Muscle

  • Found exclusively in the heart.

  • Characteristics:

    • Striated and branched.

    • Autorhythmic (it generates its own rhythm).

    • Controlled involuntarily.

Muscular System Functions

  • Body Movement: Locomotion and manipulating the environment.

  • Posture Maintenance: Stabilizes joints and body position.

  • Respiration: Involves diaphragm and intercostal muscles.

  • Communication: Facilitated by facial expressions and speech.

  • Contractions of Organs: Involved in processes like peristalsis and vasoconstriction.

  • Thermogenesis: Heat production during muscle contraction.

  • Protection: Shields bones and organs.

Muscle Properties

  • Excitability: Ability to respond to stimuli.

  • Contractility: Ability to shorten and generate force.

  • Extensibility: Ability to stretch without damage.

  • Elasticity: Ability to return to resting length.

Skeletal Muscle Structure

  • Muscle fibers are bundled in fascicles, surrounded by connective tissue.

  • Fascia: Encloses muscle groups and provides support.

  • Sarcolemma: Membrane surrounding muscle fibers.

  • Myofilaments: Actin (thin) and Myosin (thick) proteins work together for contraction.

  • Sarcomeres: Contractile units of a muscle fiber.

Muscle Contraction Process

  1. Electrical Impulse: Travels down a motor neuron.

  2. Acetylcholine Release: Binds to receptors on muscle fibers, spreading electrical impulses.

  3. Shortening: Sarcomeres contract, resulting in muscle contraction.

Types of Muscle Actions

  • Flexors: Decrease joint angle.

  • Extensors: Increase joint angle.

  • Abductors: Move limb away from midline.

  • Adductors: Move limb towards midline.

  • Rotators: Rotate a bone around its axis.

  • Sphincters: Constrict openings.

Smooth Muscle Characteristics

  • Thin and spindle-shaped fibers.

  • Involuntary Control: Regulated by nervous and hormonal signals.

  • Functions include regulating blood flow and digestive movements.

Cardiac Muscle Characteristics

  • Unique for its autorhythmic nature, allowing it to contract without nervous stimulation.

  • Controls contractions via specialized tissues known as nodes.

Aging and Muscular System

  • Aging leads to:

    • Reduction in muscle size and strength.

    • Decreased elasticity and coordination.

  • Regular exercise can mitigate these effects.

Neurotoxins and the Muscular System

Tetanus

  • Caused by Clostridium tetani; impairs nerve function and leads to muscle stiffness.

  • Symptoms: Lockjaw, muscle spasms, difficulty swallowing.

  • Prevention: Vaccination (DTaP), proper wound care.

Botulism

  • Caused by toxins from Clostridium botulinum; affects muscle control leading to paralysis.

  • Types: Foodborne, Wound, Infant.

  • Symptoms: Muscle weakness, difficulty speaking/swallowing.

  • Prevention: Proper food storage, wound care.

Interrelationships of the Muscular System with Other Systems

  • Integumentary System: Maintains temperature and allows for movement.

  • Skeletal System: Provides leverage and support for muscle contractions.

  • Nervous System: Controls muscle contractions and movements.

  • Cardiovascular System: Supports blood circulation during muscular activity.

  • Endocrine System: Regulates muscle metabolism and growth.

Key Muscle Anatomy

Muscles of the Head and Neck

  • Facial Muscles: Control facial expressions, chewing, and head movement.

  • Innervation: Primarily by cranial nerves.

Muscles of the Trunk and Pelvis

  • Abdominal Muscles: Support trunk and protect organs.

  • Pelvic Floor Muscles: Support pelvic organs and control urinary functions.

Appendicular Muscles

  • Control movements of limbs; categorized into muscles moving the shoulder, arm, hip, and legs.

Conclusion

  • Understanding muscle anatomy, types, and functions is crucial for comprehending overall body movement and health. Regular exercise and proper care can enhance muscle function and mitigate effects of aging.