Skeletal and Muscular Systems: Study Guide for Anatomy & Physiology

Chapter 5: The Skeletal System

Overview of Bone Structure and Function

The skeletal system provides structural support, protection for internal organs, and facilitates movement. Understanding bone anatomy and physiology is essential for comprehending how the body maintains its framework and repairs itself.

• Microscopic Structure of Bone: Bone tissue consists of compact and spongy bone. Osteons (Haversian systems) are the structural units of compact bone, containing concentric lamellae around a central canal.

• Epiphyseal Plate vs. Epiphyseal Line: The epiphyseal plate is a region of hyaline cartilage in growing bones where lengthwise growth occurs. After growth ceases, it becomes the epiphyseal line, a remnant of the plate.

• Bone Remodeling: Bone is a dynamic tissue, constantly being broken down by osteoclasts and rebuilt by osteoblasts in response to stress and calcium levels.

Types of Bone Cells

• Osteoblasts: Cells responsible for bone formation.

• Osteocytes: Mature bone cells that maintain bone tissue.

• Osteoclasts: Cells that break down bone matrix, aiding in bone resorption.

Bone Disorders and Abnormalities

• Osteoporosis: A condition characterized by decreased bone mass and increased fracture risk, often due to aging or hormonal changes.

• Abnormal Spinal Curvatures: Includes scoliosis (lateral curvature), kyphosis (excessive thoracic curvature), and lordosis (excessive lumbar curvature).

Types of Fractures

• Common Types: Simple (closed), compound (open), comminuted, greenstick, spiral, and impacted fractures.

• Example: A greenstick fracture is common in children, where the bone bends and cracks, rather than breaking completely.

Axial vs. Appendicular Skeleton

• Axial Skeleton: Consists of the skull, vertebral column, and thoracic cage. Provides central support and protects vital organs.

• Appendicular Skeleton: Includes the limbs and girdles (shoulder and pelvic), facilitating movement.

Key Figures to Study

• Figure 5.3 (p. 138): Likely illustrates bone structure or types of bone cells.

• Figure 5.8 (p. 147): Likely compares axial and appendicular skeletons or shows bone remodeling.

• Additional info: Review these figures in your textbook for visual reinforcement.

Chapter 6: The Muscular System

Types and Structure of Muscle Tissue

Muscle tissue is specialized for contraction, enabling movement and force generation. There are three main types of muscle tissue, each with unique structure and function.

• 3 Types of Muscle Tissue:

  • Skeletal Muscle: Voluntary, striated, attached to bones for movement.

  • Cardiac Muscle: Involuntary, striated, found only in the heart.

  • Smooth Muscle: Involuntary, non-striated, found in walls of hollow organs.

Muscle Attachments and Movement

• Origin vs. Insertion: The origin is the fixed attachment, while the insertion moves with contraction.

• Tendon vs. Ligament: Tendons connect muscle to bone; ligaments connect bone to bone.

• Types of Body Movements: Includes flexion, extension, abduction, adduction, rotation, and circumduction.

Neuromuscular Junction and Muscle Physiology

• Neuromuscular Junction: The synapse where a motor neuron communicates with a muscle fiber, triggering contraction via neurotransmitter (acetylcholine) release.

• Sarcomere Functioning: The sarcomere is the basic contractile unit of muscle, composed of actin and myosin filaments. Muscle contraction is explained by the sliding filament theory.

• Atrophy vs. Hypertrophy: Atrophy is the decrease in muscle size due to disuse; hypertrophy is the increase in muscle size from use or training.

Muscle Roles in Movement

• Prime Movers vs. Antagonists: Prime movers (agonists) are muscles primarily responsible for movement; antagonists oppose the action of prime movers.

• Example: In elbow flexion, the biceps brachii is the prime mover, while the triceps brachii is the antagonist.

Key Figures to Study

• Figure 6.3 (p. 186): Likely depicts muscle tissue types or neuromuscular junction structure.

• Additional info: Review these figures for visual understanding of muscle anatomy and physiology.