bone - Bone: Introduction A bone is a rigid organ that...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Bone: Introduction A bone is a rigid organ that forms part of the endoskeleton of vertebrates. ? Bones function to: • move, support, and protect the body, • produce red and white blood cells, • store minerals. ? Bones have a complex internal and external structure, allowing them to be lightweight yet strong and hard, while fulfilling their many other functions. ? Bone tissue, or mineralised osseous tissue, gives bones their rigidity and honeycomb-like three-dimensional internal structure. ? Other tissue types found in bones include marrow, the periosteum, nerves, blood vessels and cartilage. ? The primary tissue of bone, osseous tissue, is a relatively hard and lightweight composite material, formed mostly of calcium phosphate in the chemical arrangement termed calcium hydroxylapatite (this is the osseous tissue that gives bones their rigidity). ? It has relatively high compressive strength but poor tensile strength, meaning it resists pushing forces well, but not pulling forces. ? While bone is essentially brittle, it does have a significant degree of elasticity contributed chiefly by collagen. ? All bones consist of living cells embedded in the mineralised organic matrix that makes up the osseous tissue. Bone is not a uniformly solid material: • The hard outer layer of bones is called compact bone tissue due to its minimal gaps or spaces. Also known as dense or cortical bone. • This tissue gives bones their smooth, white, solid appearance, and accounts for 80% of the total bone mass of an adult skeleton. • Filling the interior is the hole-filled spongy bone tissue (also called cancellous or trabecular bone) which is comprised of a network of flat or needle-shaped trabeculae which makes the overall organ lighter and allows room for blood vessels and marrow. • Spongy bone accounts for the remaining 20% of total bone mass, but has nearly ten times the surface area of compact bone. • The exterior of bones (except where they interact with other bones through joints) is covered by the periosteum, which has an external fibrous layer, and an internal osteogenic layer. The periosteum is richly supplied with blood, lymph and nerve vessels, attaching to the bone itself through Sharpey's fibres.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Bone: Functions ? There are five main functions of bones: 1. Shape — Bones provide a frame to keep the body supported. 2. Protection — Bones can serve to protect internal organs, i.e. skull protecting the brain or ribs protecting the abdomen. 3. Blood production — The marrow, located within the medullary cavity of long bones and the interstices of cancellous bone, produces blood cells in a process called haematopoiesis. 4. Mineral storage — Bones act as reserves of minerals important for the body, most notably calcium and phosphorus. 5. Movement — Bones, skeletal muscles, tendons, ligaments and joints
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/25/2012 for the course ECO 101 taught by Professor Staff during the Fall '10 term at Texas State.

Page1 / 13

bone - Bone: Introduction A bone is a rigid organ that...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online