Living Tissue in bone
-bone tissue; cartilage; dense connective tissue;blood;nervous tissue.
Organs support and protect softer tissues, provide points of attchment for muscles, house blood-producing cells, and store inorganic salts.
Classification of Bones
Classification based upon shape-long, short, flat, or irregular.
Have long longitudinal axes and expanded ends.
Ex. forearm; thigh bones
Cubelike, with roughly equal lengths and widths.
Ex. wrists; ankles
Platelike structures with broad surfaces.
Ex. ribs, scapulaie, some bones of skull
Have a variety of shapes; are usually connedted to several other bones.
Ex. vertebrae; facial bones
Fifth group of bones
Sesamoid bones or round bones
Sesamoid bones or Round bones
Usually small and nodular; are embedded in tendons adjacent to joints, where tendons are compressed.
Ex. Kneecap (patella)
The end of a long bone that articulates (or forms a joint) with another bone.
The articulating end of the bone is coated with articular cartilage.
thin hyaline cartilage layer that covers epiphyses of bones in synovial joints
the main (mid) section of a long bone, between the epiphyses.
a dense fibrous membrane covering the surface of bones (except at their extremities) and serving as an attachment for tendons and muscles; also helps to form & repair bone tissue.
Bony projections provide sites for attachment of ligaments and tendons.
Grooves and Openings
Passageways for blood vessels and nerves
Allows one bone to articulate with another
A dense, hard type of bone constructed from osteons (at the microscopic level). Compact bone forms the diaphysis of the the long bones, and the outer shell of the epiphyses and all other bones.
A looser, more porous type of bone tissue found at the inner core of the epiphyses in long bones and all other bone types. Spongy gone is filed with red bone marrow, important in blood cell formation.
the irregular latticework of thin bony plates in spongy bone tissue; these plates help reduce the bone's weight; most highly developed in bone region subjected to compressive forces.
A semigrid tube with a hollow chamber formed by compact bone in the diaphysis of a long bone; is continuous with the spaces of the spongy bone.
A thin membrane containing bone-forming cells that lines areas, and bone marrow.
Specialized type of soft connective tissue
Ex. red and yellow
mature bone cells
small spaces between the lamellae which contain osteocytes
Central Canals (Haversian canals)
surrounded by lamellae, run lengthwise through the bony matrix, carry blood vessels and nerves to all areas of bone
small hair-like canals extending from the central canal. Allow for diffusion of nutrients, waste products, hormones, etc. to lacunae.
The unit of combact bone, also called a Haversian system. Osteons are essentially long cylinders of bone; the hollow center is called the central canal, and is where blood vessels, nervs, and lymphatic vessels are found. Compact bone is laid down around the central canal in rings (lamellae).
Bone development & growth
Parts of skeletal system begin to form during first few weeks of prenatal development; bony structures continue to grow and develop into adulthood
Formation of Bone
Bones form by replacing existing connective tissue.
2 ways bone replaces connective tissue
1. Bones originate within sheetlike layers of connective tissues (ex.intramembranous bnes)
2. Others begin as mssas of cartilage later replaced by bone tissues (ex. endochondra bones)
Broad, flat bones of the skull.
During development are membranelike layers of undifferentiated connective tissues that appear at sites of future bones.
Make bone; synthesize and secrete the organic constituents of the bone matrix; once surrounded by the matrix they mature into osteocytes
the process of bone formation in the flat bones of the skull and mandible, where bone forms directly within mesenchyme arranged in sheetlike layers that resemble membranes
Bones that originate as hyaline cartilage and are subsequently replaced by bone tissue.
method of endochondral bone formation in which cartilage is replaced by bone
cartilaginous area at the ends of long bones where lengthwise growth takes place in the immature skeleton.
4 layers of epiphy-seal plate
1. zone of resting cartilage
2. zone of proliferating cartilage
3. zone of hypertrophic cartilage
4. zone of calcified cartilage
Zone of resting cartilage
This layer is nearest the epiphysis and consists of small, scattered chondrocytes. The term "resting" is used because the cells do not function in bone growth. Rather, they anchor the epiphyseal plate to the epipyhysis of the bone
Zone of proliferating cartilage
chondrocytes are slightly larger and undergoing rapid mitotic cell division, aligned like a stack of coins
Zone of hypertrophic cartilage
The rows of older cells, left behind when new cells appear, form the third layer enlarging and thickening the epiphyseal plate still more. Consequently, the entire bone lengthens. At the same time, invading osteoblasts, which secrete calcium salts, accumulate in the extracellular matrix adjacent to the oldest cartilaginous cells, and as the extracellular matrix calcifies, the cells begin to die.
Zone of calcified cartilage
The final zone of the epiphyseal plate is only a few cells thick and consists mostly of chondrocytes that are dead because the extracellular matrix around them has calcified.
large cells that reabsorb or break down bone matrix
simultaneous process of adding new bone and removing previously formed bone
Factors that influence bone develpment, growth, & repair
nutrition; exposure to sunlightr; hormonal secretions; physical exercise
hormone secreted by anterior pituitary gland that stimulates growth of bones
Absence of growth hormone results in failure of limb bones to develop.
Condition resulting from too much growth hormone is secreted resulting in height in excess of 8 feet.
Secretion of excess growth hormone resulting in enlarged hands, feet and jaw.
Glands that affect bone growth & development
pituitary gland; thyroid gland; parathyroid glands; ovaries or testes
formation and development of red and white blood cells from stem cells. Occur in bone marrow.
specialized protein that carries oxygen on red blood cells
Occupies the cavities of most bones; found in spongy bone of skill, ribs, sternum, clavicles, vertebrae & hip bones in adults; with increasing age, yellow marrow replaces most of it.
Stores fat and is inactive in blood cell production; if blood cell supply is deficient, some yellow marrow may change back into red marrow and produce blood cells.