Ch 6: THE SKELETAL SYSTEM: Bone Tissue

Red Bone Marrow

Produces red blood cells, white blood cells, and platelets in a process called Hemopoiesis

Tensile Strength

Provided by collagen fibers and other organic molecules. Resistance to being stretched or torn apart.

Spongy Bone

Short, flat, and irregular bones and the interior of the epiphyses in long bones

Support

Skeletal Structural Framework: supports soft tissues, provide attachment points for the tendons of most skeletal muscles

Protection

Skeletal function that protects most important internal organs from injury

The ending -clasts

in a bone cell means that the cell breaks down extracellular matrices

Medullary Cavity /Marrow Cavity

A hollow, cylindrical space within the diaphysis that contains fatty yellow bone marrow in adults

Periosteal Arteries

Accompanied by nerves enter the diaphysis through many perforating (Volkmann's) canals. Supply the periosteum and outer parts of the compact bone.

Metaphyseal and Epihyseal Arteries

BOTH supply the ends of long bones, which arise from arteries that supply the associated joint

Metaphyses of a long bone and Nutrient Artery

BOTH supply the red bone marrow and bone tissue of the metaphyses.

Osteoclasts

Bone-destroying cells that contain lysosomes and phagocytic vacuoles that demineralize bone tissue. Help regulate blood calcium level. Target cells for drug therapy to treat osteoporosis. Ruffled border.

Bone Tissue

Bone (Osseous tissue), Cartilage, dense connective tissues, epithelium, adipose tissue, and nervous tissue. Makes up 18% of weight of the human body.

Calcium & Phosphorus (Minerals)

Bone Tissue mineral storage: calcium & phosphorus (strengthens bones), Stores 99% of the body's calcium

Two types of Bone Tissue

Compact Bone Tissue and Spongy Bone tissue

Skeletal System

Composed of Bones and their cartilages, ligaments and tendons

Yellow Bone Marrow

Consists mainly of adipose cells, which store triglycerides.

Lacunae

Contain osteocytes. Small spaces between lamellae.

Bone Flexibility

Depends on its collagen fibers.

Spongy Bone Tissue

Does not contain osteons, Consists of lamellae trabeculae surrounding many red bone marrow-filled spaces.

Epiphyseal Arteries

Enter the Epiphyses of long bone and supply the red bone marrow and bone tissue of the epiphyses

Metaphyseal Arteries

Enter the metaphyses of a long bone

Intramembranous (dermal) Ossification

Forming directly as a bone. (Facial bones, most cranial bones, and the clavicle)

Bone Tissue Functions

Homeostatic Contributions: Provide Support, Protection, Production of blood cells, Storage of Minerals and Triglycerides

Endosteum

Is a thin membrane that lines the internal bone surface facing the medullary cavity. Contains a single layer of cells and a small amount of connective tissue.

Blood Supply of Bone

Long bones are supplied by periosteal, nutrient, metaphyseal, and epiphyseal arteries; veins accompany the arteries.

Long Bones

Longer than they are wide, Act as levers and shock absorbers, mostly compact bone with spongy bone at the ends.

Spongy Bone tissue Trabeculae

Offer resistance along lines of stress, support and protect red bone marrow, and make bones lighter for easier movement

Mineral Storage and Release

On demand, bone releases minerals in to the blood to maintain critical mineral balances (homeostasis) and distribute the minerals to other parts of the body

Endochrondral Osssification

Ossification from primary centers occurs before birth; from secondary centers in the epiphyses, it occurs during the first 5 years.

Circumferential Lamellae

Rings of hard calcified matrix found just beneath the periosteum and in the medullary cavity

Central or Haversian Canals

Run longitudinally through the bone

Compact Bone

Strongest form of one tissue. Provide protection and support and resists the stresses produced by weight and movement. Found beneath the periosteum of all bones and make up the bulk of the diaphyses of long bones

Periosteum

Surrounds the external bone surface wherever it is not covered by articular cartilage. Protects the bone, assists in fracture repair, helps nourish bone tissue, and serves as an attachment point for ligaments and tendons

Diaphysis

The bone's shaft or body (Long, cylindrical, main portion of the bone) Contains the Medullary (Marrow) Cavity

Remodeling

The construction of new bone tissue and breaking down of old bone tissue.

Osteogenic Cells

Unspecialized stem cells derived from mesenchyme. Found along the inner portion of the periosteum, in the endosteum, and in the canals within the bone that contain blood vessels. The only bone cells that goes through cell division. Give rise to all bone cells

Epiphyseal Line

When the bone ceases to grow in length (ages 18-24), this is the replacement of the Epiphyseal Plate. Boney structure.

Blood cell production

Red bone marrow consist of developing blood cells, adipocytes, fibroblasts, and macrophages within a network of reticular fibers.

Assistance in Movement

Skeletal muscles attach to bones; upon muscle contraction they pull on bones to produce movement

Haversian Systems

perforating canals: allow blood vessels and nerves into bone tissue; Cicumferential Lamellae : layers of bone next to periosteum and endosteum

Endochrondral Ossification

Bone development first through a cartilaginous stage. Begins in a primary center in the shaft of the cartilage model with hypertrophy of chondrocytes (cartilage cells) and calcification of the cartilage matrix. The cartilage model is then vascularized, osteogenic cells form a bony collar around the mode, and osteoblasts lay down bony matrix around the calcareous spicules. The formation of most bones

Ossification

Bone formation develops by either ENDOCHRONDRAL ossification or INTRAMEMBRANOUS (dermal) ossification begins during the fourth week of prenatal development.

Osteoblasts

Bone-building cells, Synthesize and secrete collagen fibers and other organic components needed to build the extracellular matrix of bone tissue, initiates calcification, surrounds themselves within their own extracellular matrix, become osteocytes.

Periosteum Composition

Outer fibrous layer of dense irregular connective tissue Inner osteogenic layer consists of cells (Some cells enable bone growth in thickness, but not in length)

Resorption

Part of normal development, maintenance, and repair of bone

Triglyceride storage

Potential chemical energy reserve. With increasing age, much of the red bone marrow turn yellow

Types of Cells present in Bone Tissue

Osteogenic Cells, Osteoblasts, Osteocytes, and Osteoclasts

Components of Compact Bone

Osteons/ Haversian systems: Repeating structural unitis

Osteons

(resembles a stack of logs) Consists of a central (haversian) canal, with arranged lamellae, lacunae, osteocytes, and canaliculi. they are aligned in the same direction along lines of stress which helps the long bone resist bending or fracture. Changes over time in response to the physical demands placed on the skeleton

Extracellular Matrix of Bone Tissue

25% water, 25% collagen fibers, and 50% crystallized mineral salts.

Epiphyseal Growth Plate

A layer of hyaline cartilage that allows the diaphysis of the bone to grow in length.

Perforating or Volkmann's Canals

Allows blood vessels, lymphatic vessels, and nerves from the periosteum to penetrate compact bones

Nutrient Foreman

An opening in the shaft of the bone allowing an artery to pass into the one

Interstitial Lamellae

Area between osteons. Fragments of older osteons that have been partially destroyed during bone rebuilding or growth

Concentric lamellae

Around the central canals are rings of calcified extracellular matrix much like the rings of a tree trunk

Bone (Osseous) Tissue

Contains an abundant extracellular matrix that surounds widely separated cells.

Bone Hardness

Depends on the crystallized inorganic mineral salts.

Red Bone Marrow Locations

Developing fetus. Adult bones: hip bones, ribs, breastbone, vertebrae, skull, ends of bones of the arm and thigh.

Parts of a Long Bone

Diaphysis, Epiphyses, Metaphyses, Articular Cartilage, Periosteum, Medullary Cavity, Endosteum

Osteocytes

Mature bone cells, the main cells in bone tissue and MAINTAIN its daily metabolism such as the exchange of nutrients and wastes with blood

Nutrient Artery

Near the center of the diaphysis; Divides in the medullary cavity into proximal and distal branches. Supplies both the inner part of the compact bone tissue of the diaphysis and the spongy bone tissue and red marrow as far as the epiphyseal plats

Nerve Supply of Bone

Nerves accompany blood vessels in bone; the periosteum is rich in sensory neurons. Some of which carry pain sensations.

Canaliculi

Small channels filled with extracellular fluid. Inside contains slender fingerlike processes of osteocytes. Connects lacunae with one another and with the central canals, provides routes for nutrients and oxygen to reach the osteocytes and for the removal of wastes

Epiphyses

The proximal and distal ends of the bone

Metaphyses

The regions between the diaphysis and the epiphyses. Contains Epiphyseal (growth) plate (or) Epiphyseal Line

Osteology

The study of bone structure and the treatment of bone disorders.

Mesenchyme

The tissue from which almost all connective tissues are formed

Perforating (Sharpey's) Fibers

Thick bundles of collagen fibers that extend from the periosteum into the extracellular bone matrix. Provide attachment of the periosteum to the underlying bone.

Long Bones

Thighs, Legs, Toes, Upper arms, Forearms, and Fingers

Articular Cartilage

Thin layer of hyaline cartilage that covers the part of the epiphysis where the bone forms an articulation (joint) with another bone. Reduces friction and absorbs shock at freely movable joints

Osteoprogenitor Cells

bone stem cells, periosteum and endosteum

Genic

genic= producing

The ending -blasts

in the name of a bone cell or any other connective tissue cell means that the cell secretes extracellular matrix

The ending -cytes

in the name of a bone cell or any other tissue cell means that the cell maintains the tissue