Skeletal and Muscular Systems

Flashcards about the skeletal and muscular systems, covering bones, muscles, joints, and related functions and disorders.

Skeletal System

Composed of bones, tendons, ligaments, and joints. Functions include support, movement, protection, blood cell production, and mineral storage.

Functions of the Skeleton

Support body weight, facilitate movement, protect internal organs, produce red blood cells, store minerals and fats.

Axial Skeleton

Includes the skull, vertebral column, ribs, and sternum; supports posture and protects the CNS and thoracic organs.

Appendicular Skeleton

Bones of the upper and lower limbs, pectoral and pelvic girdles; allows limb articulation with the axial skeleton.

Long Bones

Support weight and allow movement (e.g., femur, humerus).

Short Bones

Provide stability and limited movement (e.g., carpals, tarsals).

Flat Bones

Protect internal organs (e.g., skull, pelvis).

Irregular Bones

Unique shape for specific function (e.g., vertebrae).

Sesamoid Bones

Protect tendons from stress (e.g., patella).

Diaphysis

Shaft of a long bone, hollow compact bone surrounding the medullary cavity.

Epiphyses

Enlarged ends of long bones, containing spongy bone.

Periosteum

Outer fibrous membrane of bone (not at joints).

Compact Bone

Dense, solid bone containing osteons (Haversian systems).

Spongy Bone

Bone with irregular trabeculae, containing red marrow.

Red Bone Marrow

Forms red and white blood cells and platelets.

Yellow Bone Marrow

Stores fat and contains stem cells for cartilage, fat, and bone.

Osteoblasts

Bone-forming cells that secrete collagen and lay down matrix.

Osteocytes

Mature bone cells that maintain bone and regulate calcium/phosphate.

Osteoclasts

Bone-resorbing cells that break down matrix and release calcium.

Chondroblasts

Cells that produce cartilage matrix and become trapped as chondrocytes.

Chondrocytes

Mature cartilage cells in lacunae.

Ligaments

Connect bone to bone; strong and slightly elastic.

Tendons

Connect muscle to bone; strong, flexible, and inelastic.

Fibrous Joints

Immovable joints (e.g., skull).

Cartilaginous Joints

Slightly movable joints (e.g., vertebrae).

Synovial Joints

Freely movable joints with a joint cavity (e.g., knee).

Flexion

Movement that decreases the angle of a joint.

Extension

Movement that increases the angle of a joint.

Abduction

Movement away from the midline.

Adduction

Movement toward the midline.

Osteoporosis

Loss of bone mass, leading to brittle bones.

Osteoarthritis

Degenerative joint disease where cartilage wears away.

Skeletal Muscle

Voluntary muscle attached to bones, enabling movement.

Smooth Muscle

Involuntary muscle found in internal organs.

Cardiac Muscle

Involuntary muscle found only in the heart.

Contractility

The ability of a muscle to contract.

Extensibility

The ability of a muscle to stretch.

Excitability

The ability of a muscle to be stimulated.

Elasticity

The ability of a muscle to return to its original length.

Origin

Tendon attachment to the stationary bone.

Insertion

Tendon attachment to the moving bone.

Agonist

The main muscle causing movement (prime mover).

Antagonist

The muscle that opposes or reverses movement.

Synergist

Muscle that assists the prime mover.

Fixator

Muscle that stabilizes the origin of the prime mover.

Sarcolemma

Plasma membrane of a muscle cell.

Sarcoplasm

Cytoplasm of a muscle cell.

Myofibrils

Thread-like structures within muscle fibers, containing myofilaments.

Myofilaments

Actin and myosin, contractile units of muscle.

Sarcomere

The functional unit of a muscle fiber, Z line to Z line.

Sliding Filament Theory

Actin and myosin slide past each other, causing sarcomere shortening.

Rigor Mortis

Post-mortem muscle stiffness due to ATP depletion and calcium buildup.