Cartilage and BoneStructure and Function

Bones

Bone Characteristics

Vascular (has own blood supply)Regenerates well Contains calcium and hydroxyapatiteForms mostly after birthIs not flexible

Bone Cells

Osteoblast (makes bone)Osteocyte (mature bone cell)Osteoclast (reabsorbs bone)

Formation of Endochondral Bone

Hyaline cartilage develops in the general shape of the future bone.

Periosteum forms on the outside of the developing bone.

Osteoblasts deposit bony tissue in place of disintegrating cartilage.

Types of Ossification

Primarystarts in diaphysis from cartilage

Secondarystarts in epiphysis from cartilage

Types of Bones

Long BonesArms and legs

Sesamoid BonesDevelop inside tendons and near joints

Flat BonesSkull bones and scapula

Irregular Bonesvertebrae

Cartilage

What are the three types of cartilage? Hyaline cartilage (most of the joints) Fibrocartilage (vertebral discs, pubic symphysis) Elastic cartilage (ears)

Where in the body can each of these three types of cartilage be found?

What type of cartilage does an embryonic skeleton have? Hyaline

Cartilage Characteristics

Avascular (no blood supply)Does not regenerate wellContains no calcium or hydroxyapatiteBegins conversion to bone before birthIs flexible

Joint Disorders and Joint Injuries

Structure of joints makes them prone to traumatic stress Function of joints makes them subject to friction and wear Affected by inflammatory and degenerative processes Sprains – ligaments reinforcing a joint are stretched or torn Dislocation – occurs when the bones of a joint are forced out

of alignment Torn cartilage – common injury to meniscus of knee joint

Inflammatory and Degenerative Conditions

Bursitis – inflammation of a bursa due to injury or friction Tendonitis – inflammation of a tendon sheath Arthritis – describes over 100 kinds of joint-damaging

diseases Osteoarthritis – most common type – “wear and tear” arthritis Rheumatoid arthritis – a chronic inflammatory disorder Gouty arthritis (gout) – uric acid build-up causes pain in joints

Lyme disease – inflammatory disease often resulting in joint pain; Lyme disease is caused by a bacterium and is transmitted to humans by the bite of infected blacklegged ticks. Typical symptoms include fever, headache, fatigue, and skin rash. If left untreated, infection can spread to joints, the heart, and the nervous system.

Osteoporosis: loss of minerals

Figure 6.15

Normal Bone

Osteoporosis

Stages of Healing a Fracture

Figure 6.14

Blood escapes

Fibrous callous

Spongy Bone callous

Osteoclasts remove excess bone

Categories of Fractures

Simple: Skin is not broken Compound: Bone sticks out through skin, often

gets infected

Complete: Both sides of diaphysis broken through

Incomplete: One side of diaphysis is broken

Stress: Just a crack in the surface

Types of Fractures

ComminutedCompressionSpiralEpiphysealDepressedGreenstick

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