Bone and Skeletal Tissue

3 Types of Cartilage

• Hyaline: support and flexibility• Articular cartilage• Costal cartilage• Laryngeal cartilage• Tracheal cartilage• Nasal cartilage• Epiphyseal plate

Elastic : repeated bending

External ear Epiglottis

• Fibrocartilage: highly compressible• Discs between the vertebrae•Meniscus of knee• Pelvic symphysis

Five functions of bone

1. Support2. Protection3. Movement4. Mineral storage5. Blood cell formation =

hematopoiesis

Hematopoesis

•Infants have red marrow in medullary cavity

•Adults have red marrow in spongy bone and yellow marrow in medullary cavity

Parts of a Bone• Periosteum- a 2 layer membrane around the

diaphysis contains nerves and blood vessels

The outside periosteum is tough protectionThe inside periosteum is osteogenic cells

osteoblasts- bone germinators (builders) osteoclasts- bone breakers

• Endosteum- inside lining of the marrow cavity• Also lines all the canals in bone

Type of bone (compact vs spongy)

• Compact bone- made of long cylinders called osteons

• Supplied with blood by Haversian canals up & down

• Linked by Volkmann’s canals across

Structure of Bone

Spongy bone- trabeculae resist stress in adults, it contains

marrow produces blood

Longer than they are wide

Diaphysis- shaft, surrounds medullary cavity

Mostly compact bone

Epiphysis- ends, spongy bone inside

Compact bone outside

Joint surface = articular cartilage

Epiphyseal line = growth plate

• 2. Short Bones- roughly cube like• Ex: wrist, ankle, sesamoid•Mostly spongy, thin compact

cover

•3. Flat bones- flat, thin, curved• Ex: ribs, skull•Parallel compact bone

surface, spongy inside

Irregular Bones

4.complicated shapesEx: vertebrae, hipMostly spongy bone enclosed by thin compact

Bones are made of organic and inorganic components

• Organic- • cells:• osteoblasts, osteoclasts, • Osteoids:• proteoglycans, collegen, fibers• Inorganic-• hydroxyapatites/ mineral salts

Calcium• Calcium is necessary for:• Nerve impulses• Muscle contractions• Blood coagulation• Secretion of glands• Cell division

• Calcium is obtained in your diet and absorbed in the intestine under the control of vitamin D

• Diet should contain: Proteins, Vitamin C, Vitamin A, Vitamin B12, calcium, phosphorus, magnesium, and manganese for bone health

• Vitamin D is synthesized in skin

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High Calcium Levels

• Change in plasma calcium homeostasis• Detected by Thyroid Gland• Which secretes Calcitonin• Affects osteoblasts in bone tissue• Which builds bone by depositing calcium• Removes calcium from plasma• Reduces plasma calcium levels

Low Calcium Levels

• A change in plasma calcium homeostasis• Detected by the Parathyroid Gland• Which secretes Parathyroid Hormone PTH• Affects osteoclasts in bone tissue• Which breaks down bone by removing calcium• Deposits the calcium I the plasma• Increases plasma calcium levels

Osteogenesis-bone creation

• Bone is always changing, growing, remodeling, and repairing

• Wolff’s Law- a bone will remodel in response to demands or forces placed on it

ex: ballet dancer, weight lifter

Prenatal to Young Adult

Steps in ossification• 1. starts as hyaline cartilage• 2. bone replaces cartilage at periosteum• 3. bone replaces cartilage at medulla• 4. bone replaces cartilage at ends• 5. only cartilage remaining is at ends (articular cartilage) and epiphyseal plate (growth plate)

Steps in Ossification

• Calcium is absorbed from the intestine under control of Vitamin D• Low calcium causes failure of

many systems• High calcium causes salt

deposits in kidney, blood vessels

Fractures

• 1. Simple- clean closed break• 2. Compound- broken ends break skin• 3. Comminuted- fragmented (aged)• 4. Compression- crushed• 5. Depressed- pressed inward (skull)• 6. Impacted- ends forced into each other ( the result of a fall) 7. Spiral- ragged twisted (sports)8. Greenstick- break incomplete (child)

Steps in Repair• 1. Hematoma• 2. Fibrocartilaginous callus

formation splints the broken bone• 3. Bony (hard) callus• 4. Remodeling

Osteoporosis –bone loss due to hormonal changes that interfere with calcium deposits in bone,

leads to spine problems and breaks occurs at menopause

RicketsChildhood disorder caused by the lack of calcium and vitamin D in the diet. The bones are soft and do not support the weight, so they bend -bowed legs

Pagets Diseasecaused by the uneven deposit of

calcium C