Skeletal System

Skeletal System

The framework of bones, cartilage, and joints that provides structure and support to the human body.

Support, protection, movement, storage, and blood cell production.

Functions of the Skeletal System

Support

A function of the skeletal system that provides a structural framework for the body and supports soft tissues.

Protection

A function of the skeletal system where bones enclose and guard vital internal organs from injury.

Movement

A function of the skeletal system where bones act as levers for skeletal muscles to produce motion.

Storage

A function of the skeletal system involving the storage of essential minerals like calcium and phosphorus.

Blood Cell Production

A function of the skeletal system where blood cells are produced within the bone marrow.

Collagen

A structural protein found in bone matrix and connective tissues that provides flexibility and tensile strength.

Hydroxyapatite

A mineral complex composed mainly of calcium phosphate that provides hardness and strength to bone matrix.

Proteoglycans

Molecules in connective tissues and cartilage matrix that consist of a core protein with attached glycosaminoglycan chains, helping to retain water and cushion joints.

Glucosamine

A compound found naturally in cartilage that helps build and repair cartilage tissue.

Calcium

An essential mineral stored in bones that contributes to bone density and hardness.

Diaphysis

The main shaft or central long portion of a long bone.

Epiphysis

The enlarged end portion of a long bone that articulates with another bone.

Epiphyseal Plate

The layer of hyaline cartilage located at the end of a long bone where growth in length occurs.

Compact Bone

The dense, hard outer layer of bone tissue that provides strength and protection.

Spongy Bone

The porous, lattice-like inner bone tissue that contains trabeculae and red or yellow bone marrow.

Categories of Bones

The four main structural classifications of bones: long bones, short bones, irregular bones, and flat bones.

Long Bones

Bones that are longer than they are wide, consisting of a shaft and two ends.

Short Bones

Bones that are roughly cube-shaped, having similar length and width.

Irregular Bones

Bones with complex, varied shapes that do not fit into other categories.

Flat Bones

Thin, flattened, and usually curved bones that offer protection and extensive points for muscle attachment.

Ossification

The process of bone formation.

Chondrification

The process of cartilage formation.

Osteoblast

A bone-forming cell responsible for secreting new bone matrix.

Osteocytes

Mature bone cells derived from osteoblasts that maintain the bone tissue matrix.

Osteoclast

A bone-resorbing cell responsible for breaking down and reabsorbing bone matrix.

Parathyroid Hormone (PTH)

A hormone that acts as a bone breakdown or withdrawer, increasing blood calcium levels by stimulating bone resorption.

Calcitonin

A hormone that acts as a depositor, lowering blood calcium levels by promoting calcium deposition into bone.

Vitamin D

A nutrient that regulates calcium and phosphate absorption in the body, essential for healthy bone growth and maintenance.

Types of Bone Formation

The two primary processes by which bone is formed: endochondral ossification and intramembranous ossification.

Endochondral Ossification

A type of bone formation where bone replaces a pre-existing hyaline cartilage model, characteristic of long bones.

Intramembranous Ossification

A type of bone formation where bone develops directly from fibrous connective tissue membranes, characteristic of flat bones.