Ch 6 SKELETAL SYSTEM

How many bones do you have in your body?

Label what you can

FUNCTIONS1. SUPPORT– provides framework for body, support for

soft tissues, attachment for tendons of skeletal muscles

FUNCTIONS2. PROTECTION– of internal organs (brain,

heart and lungs, spinal cord)

FUNCTIONS3. LEVERAGE– muscles contract and

pull on bones to provide movement

FUNCTIONS4. 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)

FUNCTIONS5. BLOOD PRODUCTION– red marrow

produces blood cells

Functions6. ENERGY STORAGE– yellow marrow

stores lipid (Energy reserve)

Types of BonesA. LONG BONES– longer than they are wide; curved;

strong-absorb stress at several different pointsEXAMPLES: femur, tibia, ulna, humerus, fingers, toes

Types of BonesB. SHORT BONES– as wide as they are tall;

EXAMPLES: wrist and ankle bones

TYPES OF BONESTYPES OF Short bonesSESAMOID 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 BONESC. 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 BONESD. IRREGULAR BONES– complex shapes

EXAMPLES: vertebrae, some facial bones, heel, ischium

TYPES OF BONESE. 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

Connective Tissue

Cells Matrix

Fibers Ground Substance

Histology (Osseous Tissue): Cell Types:1. Osteoprogenitor (Osteogenic) Cells: stem cells (only

bone cells that divide), precursors of osteoblasts2. Osteoblasts: Bone building cells (secrete collagen;

mineral salts deposited in collagen framework = calcification)

3. Osteocytes:– mature bone cells that maintain daily cellular activities of bone; most numerous

4. 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=0dV1Bwe

2v6c

• 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

1.FIBROUS OUTER LAYER: OUTER LAYER: tendon (muscle) and ligament attachment and provides route for vascular and nervous tissue2. 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