Ch 6 SKELETAL SYSTEM How many bones do you have in your body?

Label what you can

FUNCTIONS 1. SUPPORT– provides framework for body, support for soft tissues, attachment for tendons of skeletal muscles

FUNCTIONS 2. PROTECTION– of internal organs (brain, heart and lungs, spinal cord)

3. LEVERAGE– muscles contract and pull on bones to provide movement FUNCTIONS 3. LEVERAGE– muscles contract and pull on bones to provide movement

FUNCTIONS 4. MINERAL STORAGE– contribute to bone strength, stored calcium and phosphorus can be distributed to body at will (need Ca2+ for nerve impulses to cross synaptic cleft)

5. BLOOD PRODUCTION– red marrow produces blood cells FUNCTIONS 5. BLOOD PRODUCTION– red marrow produces blood cells

6. ENERGY STORAGE– yellow marrow stores lipid (Energy reserve) Functions 6. ENERGY STORAGE– yellow marrow stores lipid (Energy reserve)

Types of Bones A. LONG BONES– longer than they are wide; curved; strong-absorb stress at several different points EXAMPLES: femur, tibia, ulna, humerus, fingers, toes

Types of Bones B. SHORT BONES– as wide as they are tall; EXAMPLES: wrist and ankle bones

TYPES OF BONES TYPES OF Short bones SESAMOID BONES – small; usually located in tendons (where there is a lot of physical stress) of hands, feet and knees; variable (#, ossification) EXAMPLES: knee cap (everyone has) fabella

TYPES OF BONES C. FLAT BONES– thin spongy bone sandwiched between two layers of compact bone; protective; forms large surface area for muscle attachment; site of blood production in adults EXAMPLES: cranial, sternum, rib, scapula, ilium

TYPES OF BONES D. IRREGULAR BONES– complex shapes EXAMPLES: vertebrae, some facial bones, heel, ischium

TYPES OF BONES E. SUTURAL BONES– small bones b/w joints of some cranial bones; variable (#)

HISTOLOGY (OSSEOUS TISSUE) Composition: 1/3 COLLAGEN FIBERS (protein); function: FLEXIBILITY + STRENGTH 2/3 MINERAL SALTS (mainly Ca & P); function : HARDNESS   Connective Tissue Cells Matrix Fibers Ground Substance

Histology (Osseous Tissue): Cell Types: Osteoprogenitor (Osteogenic) Cells: stem cells (only bone cells that divide), precursors of osteoblasts Osteoblasts: Bone building cells (secrete collagen; mineral salts deposited in collagen framework = calcification) Osteocytes:– mature bone cells that maintain daily cellular activities of bone; most numerous Osteoclasts: huge multinucleated cells; break down bone & allow for growth, maintenance & repair (lysosomal enzymes + acids digest protein & minerals = resorption (reg. Blood Ca2+)

Histology (Osseous Tissue): Cell Types: Osteoprogenitor Cells  Osteoblasts  Osteocytes

What is the hardest substance in the body?

What spongy bone looks like. Video Links: Short clip of Osteoblasts and Osteoclasts http://www.youtube.com/watch?v=78RBpWSOl08 Explanation of how bone is remodeled: http://www.youtube.com/watch?NR=1&v=0dV1Bwe2v6c&feature=endscreen

Bone Remodeling: http://www.youtube.com/watch?v=0dV1Bwe2v6c Rank Ligand: http://www.youtube.com/watch?NR=1&v=GpMV197xZXc&feature=endscreen

LONG BONE GROSS ANATOMY (Ex: HUMERUS) Each bone is an ORGAN With its own osseous tissue, cartilage, dense connective tissue, epithelial tissue, adipose tissue and nervous tissue

LONG BONE GROSS ANATOMY DIAPHYSIS – long, main portion of bone (shaft)

LONG BONE GROSS ANATOMY EPIPHYSIS – proximal and distal ends of bone (heads)

LONG BONE GROSS ANATOMY METAPHYSIS – region where diaphysis meets epiphysis

LONG BONE ARTICULAR CARTILAGE– thin layer of hyaline cartilage covering ends (epiphyses) of bones that contact other bones (@ articulation/joint), reduces friction, absorbs shock @ freely moveable joints

LONG BONE GROSS ANATOMY PERIOSTEUM– dense, white fibrous covering (dense irregular conn. tissue) around surface of bone – protects, nourishes, repairs, allows for growth, allows for attachment of tendons (& muscle) and ligaments

LONG BONE GROSS ANATOMY (Ex: HUMERUS) PERIOSTEUM– dense, white fibrous covering FIBROUS OUTER LAYER: OUTER LAYER: tendon (muscle) and ligament attachment and provides route for vascular and nervous tissue 2. CELLULAR INNER LAYER: growth & remodeling; osteoprogenitor cells, osteoblasts, & osteoclasts

LONG BONE GROSS ANATOMY

LONG BONE GROSS ANATOMY (Ex: HUMERUS MEDULLARY CAVITY – cavity containing yellow marrow (fat cells – energy storage) in adults

LONG BONE GROSS ANATOMY (Ex: HUMERUS) ENDOSTEUM – lining of medullary cavity containing osteoprogenitor cells, osteoblasts, & osteoclasts