The Skeletal System: Bone Tissue

Flashcards about the skeletal system and bone tissue.

Bone

An organ made up of several different tissues (bone, cartilage, dense connective tissue, adipose, and nervous tissue) working together.

Functions of the Skeletal System

Provides support, protects internal organs, assists body movements, mineral homeostasis, participates in blood cell production, and stores triglycerides.

Structure of a Long Bone

Diaphysis, 2 epiphyses, 2 metaphyses, articular cartilage, periosteum, medullary cavity, and endosteum

Diaphysis

Bone shaft

Epiphyses

Both ends of the bone at the joints

Metaphyses

Region between diaphysis and epiphysis

Periosteum

Connective tissue surrounding the diaphysis

Medullary Cavity

Hollow space within the diaphysis

Endosteum

Thin membrane lining the medullary cavity

Extracellular Matrix Composition

15% water, 30% collagen and 55% crystalized mineral salts

Mineral Salts that Form Hydroxyapatite

Calcium phosphate and calcium hydroxide

Four Types of Bone Cells

Osteoprogenitor cells, osteoblasts, osteocytes, and osteoclasts

Osteoprogenitor Cells

Bone stem cells able to differentiate into other types of cells

Osteoblasts

Bone-building cells that secrete matrix; initiate calcification

Osteocytes

Mature bone cells

Osteoclasts

Remodel bones and cause them to release calcium; bone resorption

Compact Bone

Provides protection and support; strongest

Spongy Bone

Lightweight and provides tissue support; also called trabecular or cancellous bone

Periosteal Arteries

Enter the diaphysis through Volkmann’s canals

Nutrient Artery

Enters the center of the diaphysis through a nutrient foramen

Ossification (Osteogenesis)

The process of bone formation

Minerals Affecting Bone Growth and Remodeling

Calcium, phosphorus, magnesium, fluoride, manganese

Vitamins Affecting Bone Growth and Remodeling

Vitamins A, C, D, K, and B12

Hormones Affecting Bone Growth and Remodeling

IGFs (stimulated by GH), T3 and T4, sex hormones (estrogen in females, testosterone in males)

Phases of Bone Fracture Healing

Reactive, reparative, and bone remodeling

Reactive Phase of Healing

Early inflammatory phase

Reparative Phase of Healing

Formation of fibrocartilaginous callus and bony callus

Bone Remodeling Phase

Bony callus is remodeled

Open (Compound) Fracture

The broken ends of the bone protrude through the skin

Comminuted Fracture

The bone is splintered, crushed, or broken into pieces at the site of impact

Greenstick Fracture

A partial fracture in which one side of the bone is broken and the other side bends; occurs only in children

Impacted Fracture

One end of the fractured bone is forcefully driven into the interior of the other.

Pott Fracture

Fracture of the distal end of the fibula with serious injury of the distal tibial articulation

Colles Fracture

Fracture of the distal end of the radius in which the distal fragment is displaced posteriorly

Vertebral Compression Fracture

The vertebral body of one or more vertebrae fractures and becomes compressed into a wedge-shape

Hormone Released When Calcium Levels Drop

Parathyroid hormone (PTH)

Bone Response to PTH

Osteoclasts are stimulated to increase bone resorption and calcium is released

How PTH Increases Calcium Absorption

By stimulating production of calcitriol by the kidneys

Osteoporosis

Bone resorption outpaces formation

Rickets and Osteomalacia

Inadequate calcification of extracellular bone matrix, rickets affects children and osteomalacia affects adults

Osteoarthritis

Degeneration of articular cartilage, leads to friction of bone against bone

Osteomyelitis

Infection of bone often caused by Staphylococcus aureus

Osteopenia

Reduced bone mass below normal

Osteosarcoma

Bone cancer that primarily affects osteoblasts

Types of Ossification

Intramembranous and endochondral

Intramembranous Ossification

Occurs in flat bones when a connective tissue membrane is replaced by bone

Endochondral Ossification

Replaces cartilage with bone in developing embryo and fetus