BIOL116 Anatomy and Physiology I - Week 4: The Skeletal System (Part 1)

Vocabulary practice flashcards covering Week 4 (Part 1) of BIOL116 Anatomy and Physiology I, including skeletal functions, cartilage types, bone classification, gross anatomical landmarks, histology, and microscopic bone architecture.

Skeletal System

The organ system composed of bones and cartilage that supports the body, facilitates movement, protects internal organs, produces blood cells, and stores and releases minerals and fat.

Bone

A hard, dense connective tissue produced by osteoblasts that forms the majority of the adult human skeleton.

Cartilage

A semi-rigid, avascular connective tissue produced by chondrocytes that provides flexibility and smooth articulating surfaces in joints.

Chondrocytes

Mature cartilage cells that reside within lacunae and maintain the cartilage extracellular matrix.

Fetal Skeleton

The early developmental skeletal framework composed primarily of cartilage and fibrous membranes, providing flexibility necessary for the labor and delivery process before being replaced by bone.

Hyaline Cartilage

The most abundant type of skeletal cartilage, featuring spherical chondrocytes and an imperceptible collagen fiber matrix that provides support with flexibility and resilience.

Articular Cartilage

A type of hyaline cartilage covering the opposing ends of bones at movable joints to act as a resilient cushion and lessen mechanical stress.

Costal Cartilage

Hyaline cartilage segments that connect the anterior ends of the ribs directly or indirectly to the sternum.

Respiratory Cartilages

Hyaline cartilages that form the structural framework of the larynx and reinforce passageways across the neck and thorax, including the trachea.

Nasal Cartilage

Hyaline cartilage that supports the external structures of the nose.

Elastic Cartilage

A type of cartilage containing abundant stretchy elastic fibers in its matrix, allowing it to maintain structural shape while withstanding repeated bending.

Pinna

The external ear structure formed and supported by elastic cartilage.

Epiglottis

A flexible flap in the larynx composed of elastic cartilage that covers the respiratory tract during swallowing.

Fibrocartilage

A cartilage type intermediate between hyaline cartilage and dense regular connective tissue, featuring rows of chondrocytes alternating with thick collagen bundles to resist compression and absorb shock.

Perichondrium

A layer of dense irregular connective tissue surrounding cartilage that contains blood vessels for nutrient diffusion and resists outward expansion during compression.

Lacuna

A small cavity or hollow space within the extracellular matrix of cartilage or bone that houses a chondrocyte or osteocyte.

Appositional Growth

Cartilage growth occurring when chondrogenic cells within the perichondrium secrete new matrix onto the external surface of existing cartilage tissue.

Interstitial Growth

Cartilage growth from within, occurring when chondrocytes trapped within lacunae divide and secrete new extracellular matrix.

Long Bones

Bones that are cylinder-like in shape and longer than they are wide, acting as levers to facilitate movement (e.g., femur, humerus, radius, phalanges).

Short Bones

Bones with a cube-like shape that are approximately equal in length, width, and thickness, providing stability and support with limited motion (e.g., carpals and tarsals).

Flat Bones

Thin, flattened, and curved bones that serve as attachment points for muscles and shield internal organs (e.g., sternum, ribs, scapulae, cranial bones).

Irregular Bones

Bones characterized by complex, non-uniform shapes adapted to protect internal organs (e.g., vertebrae and facial bones).

Sesamoid Bones

Small, rounded bones embedded within tendons to protect them from excessive compressive forces and wear, such as the patellae.

Femur

The longest and largest bone in the human body, measuring approximately $50\,\text{cm}$ in length.

Stapes

The smallest bone in the human body, located in the middle/inner ear and measuring approximately $3\,\text{mm}$ in size.

Joint

The anatomical junction or articulation site where two or more bones meet.

Compact Bone

The dense, smooth, and solid outer layer of bone tissue organized into osteons to provide high compressive strength.

Spongy Bone

A porous internal network of bone tissue, also called cancellous or trabecular bone, containing spaces filled with red or yellow bone marrow.

Trabecula

An individual small, needle-like or beam-like projection of bone forming the lattice meshwork of spongy bone.

Periosteum

A double-layered membrane enveloping the outer surface of bones, composed of an outer fibrous dense connective tissue layer and an inner osteogenic layer.

Endosteum

A delicate internal connective tissue membrane lining the medullary cavity, canals, and trabecular surfaces of bone.

Diaphysis

The tubular shaft forming the long axis of a long bone, consisting of a thick compact bone collar surrounding a central medullary cavity.

Epiphysis

The expanded, prominent end section of a long bone, typically wider than the shaft and composed internally of spongy bone capped by compact bone.

Medullary Cavity

The central space located within the diaphysis of long bones that houses bone marrow.

Nutrient Foramen

An opening in the compact bone of the shaft through which the nutrient artery, vein, and accompanying nerves pass to supply internal bone tissues.

Epiphyseal Plate

A band of hyaline cartilage located between the epiphysis and diaphysis in children and adolescents, serving as the active site of longitudinal bone growth (growth plate).

Epiphyseal Line

A bony remnant visible between the diaphysis and epiphysis in adult bones after the epiphyseal plate cartilage ceases division and becomes completely ossified.

Diploë

The central sandwich layer of spongy bone found between two thin layers of compact bone in flat, short, irregular, and sesamoid bones.

Osteogenic Cells

Mitotically active stem cells derived from embryonic mesenchyme that reside in the periosteum and endosteum and differentiate into osteoblasts.

Osteoblasts

Non-mitotic, bone-forming cells that synthesize and secrete organic collagen fibers and mineral salts to produce the extracellular bone matrix.

Osteocytes

Mature bone cells derived from osteoblasts trapped inside lacunae that maintain structural matrix integrity and bone tissue health.

Osteoclasts

Large multinucleated cells formed from the fusion of stem cells that resorb and dissolve bone matrix using acids and enzymes during bone remodeling and growth.

Osteon

The fundamental structural unit of compact bone, also known as the Haversian system, consisting of concentric lamellae arranged around a central canal.

Canaliculi

Microscopic, hair-like canals radiating between lacunae in bone that allow osteocytes to communicate and exchange nutrients and wastes with the central canal.