1. SKELETAL SYSTEM

2. Function of Bones ________________ _________________ BODY ________________ - muscles "pull" on bones __________________- hemopoiesis ' occurs in red bone marrow ___________________ of inorganic salts - especially calcium phosphate, but also magnesium, sodium, potassium, carbonates and others

3. ORGANIZATION Normally 206 bones 2 Main Divisions –AXIAL –APPENDICULAR ____________-: Head; Skull Neck HYOID BONE (upper neck, under jaw, mandible) trunk VERTEBRAL COLUM (spine/backbone) THORACIC CAGE (rib cage-12 pairs) STERNUM

4. ORGANIZATION _________________ PECTORAL GIRDLE: scapula & clavicle UPPER LIMBS: radius, ulna, humerus, carpals metacarpals, phalanges PELVIC GIRDLE: (Ilium coccyx sacrum ) LOWER LIMBS Femur tibia fibula tarsals metatarsals phalanges

5. BONE STRUCTURE “LONG BONE" = typical bone Major parts:  EPIPHYSIS - ___________________.  ARTICULATES (________________) with another bone.  DIAPHYSIS - ___________of the bone  ARTICULAR CARTILAGE - hyaline cartilage covering the ends of bone  ________________ - tough membrane- like covering over entire bone, except for articular cartilage.  Connects with tendons and ligaments. Forms bone tissue.

6. BONE STRUCTURE  ___________________________- hollow chamber within the diaphysis connects to spaces in spongy bone. Filled with soft specialized tissue called bone marrow.  " _______________- mainly in spongy bone in adults. Produces blood cells " _______________- fat storage. Replaces much of the red marrow in diaphysis through childhood  ____________________ - lining of the medullary cavity

7. BONE TISSUE  TWO TYPES OF BONE  _____________; wall of the diaphysis, solid, strong  _________________(cancellous) ; epiphysis. Honeycomb of trabeculae filled with yellow bone marrow.  Covered with a thin layer of compact bone. Many branching, bony "plates"

8. BONE TISSUE  Microscopic Structure  _______________ composed of collagen and inorganic salts  ___________________ (mature bone cells) are enclosed in tiny chambers called Lacunae  __________________ and form concentric "ring" (layers) around a passageway called the HAVERSION CANAL  The haversian canals are interconnected by passages called VOLKMANN'S CANALS. All of these canals contain blood vessels and nerve fibers  The osteocytes are connected by minute passages called CANALICULI (canaliculus) through which tiny "branches" or processes pass The circular layers of matrix material and osteocytes, along with the haversian canal, forms a unit called a HAVERSIAN SYSTEM. Compact bone tissue is formed in this way

10.  Bone formation results in two types of bones  ________________________  Broad, flat bones of the skull. These bones form from membrane-like sheets of connective tissue Occurs directly in connective tissue membranes  Flat bones of skull, mandible & clavicles  Fontanels – soft spots – still membrane  _______________________  All other bones. Bone Development and Growth

11.  ENDOCHONDRAL BONES  Bones first form as hyaline cartilage.  The cartilage then gradually changes into bone tissue - a process called OSSIFICATION, which begins near the _______________in an area called the PRIMARY OSSIFICATION CENTER.  Later the bone begins to ossify in the _____________- these areas are called the SECONDARY OSSIFICATION CENTERS.  As long as growth is occurring, a "band" of cartilage (___________________________________) remains between the diaphysis and the epiphysis.  Bones increase in length as these cartilage cells continue to reproduce and ossify  Cartilage cells form cells called _________________. These cells produce bone matrix and once the cell is enclosed in bone matrix it is considered to be a mature bone cell and called ____________________

12. Bone Development and Growth  Growth in thickness of bone occurs as osteoblasts from beneath the periosteum produce bone matrix and build compact bone just underneath the periosteum  Bone tissue is constantly being replaced as special cells called _______________  Osteoclasts dissolve bone tissue from within the medullary cavity - a process called RESORPTION.  At the same time new bone tissue is being added to the outside of the bone.

17. Growth in thickness  Appositional growth – _____________ _____________ _____________

18. Bone Remodeling  Bone is continually being broken down and reformed  _________________________________  In response to stress on bones  Balance between actions of osteoclasts and osteoblasts

19. Bone growth and maintenance  Minerals: Calcium, phosphorus, boron and manganese  Vitamins:  ________________Rickets or osteomalacia  ________________for osteoblasts and osteoclasts  ________________ for collagen synthesis

20. Hormonal control  At puberty, _________________(estrogens/ androgens) trigger osteoblasts to produce bone faster than the epiphyseal cartilage can divide.  This causes the characteristic growth spurt and closure of the epiphyseal plate.  ___________________________of the epiphyseal growth plate than do androgens.  Other hormones that affect bone growth include insulin and the glucocorticoids.  ________________________________

21.  Parathyroid hormone and calcitonin are 2 hormones that antagonistically maintain blood [Ca 2+ ] at homeostatic levels.  _____________-– secreted by thyroid – inhibits osteoclasts and stimulates osteoblasts - ↓ blood Calcium  ______________  ________ – stimulates osteoclasts and ↑ blood calcium  Increases reabsorption from kidneys  Promotes formation of vitamin D

22. Bone Remodeling  Bone is a dynamic tissue.  _______________ holds that bone will grow or remodel in response to the forces or demands placed on it.

23. The mechanism of remodeling  Why might you suspect someone whose been a power-lifter for 15 years to have heavy, massive bones, especially at the point of muscle insertion?  Astronauts tend to experience bone atrophy after they’re in space for an extended period of time. Why?

24. Fracture and Repair  Bone is set (reduction)  ________________________– blood clot, cells die  ________________________ – blood vessels and fibroblasts- granulation tissue → fibrocartilaginous (soft) callus  _________________________ – spongy bone → bony (hard) callus  Callus removal and remodeling

27. Types of Fractures  Fractures are often classified according to the position of the bone ends after the break  _____________  bone ends penetrate the skin.  _____________  bone ends don’t penetrate the skin  _____________  bone fragments into 3 or more pieces. Common in the elderly (brittle bones).  _____________  bone breaks incompletely. One side bent, one side broken. Common in children whose bone contains more collagen and are less mineralized.  _____________  ragged break caused by excessive twisting forces. Sports injury/Injury of abuse.  _____________  one bone fragment is driven into the medullary space or spongy bone of another.

29. Clinical Conditions  _________________  Literally “soft bones.”  Inadequate mineralization  Causes can include insufficient dietary calcium  Insufficient vitamin D fortification or insufficient exposure to sun light.  ___________________  Children's form of osteomalacia  More detrimental due to the fact that their bones are still growing.  Signs include bowed legs, and deformities of the pelvis, ribs, and skull.

30. Clinical Conditions  __________________  Osteo=bone + myelo=marrow + itis=inflammation.  Inflammation of bone and bone marrow caused by pus-forming bacteria that enter the body via a wound (e.g., compound fracture) or migrate from a nearby infection.  Fatal before the advent of antibiotics.

31. Clinical Conditions  _____________________  Group of diseases in which bone resorption occurs at a faster rate than bone deposition.  Bone mass drops and bones become increasingly porous.  Compression fractures of the vertebrae and fractures of the femur are common.  Often seen in postmenopausal women because they experience a rapid decline in estrogen secretion; estrogen stimulates osteoblast and inhibits osteoclast activity.

32. Clinical Conditions  ___________________  Childhood hypersecretion of growth hormone by the pituitary gland causes excessive growth.  ___________________  Adulthood hypersecretion of GH causes overgrowth of bony areas still responsive to GH such as the bones of the face, feet, and hands.  ___________________  GH deficiency in children resulting in extremely short long bones and maximum stature of 4 feet.