APL2 and 3 Skeletal Anatomy The evil that men do lives after them, the good is oft interred with their bones. —William Shakespeare ( ) Julius Caesar, Act III, Scene 2

Functions of Skeleton 1. Supporting framework 2. Attachment of muscles 3. Protects vital organs Cranium: Brain Thoracic: Heart & lungs 4. Reservoir of minerals Calcium & Phosphorus 5. Red bone marrow Formation of RBC

L3: add to your #4 #5 Functions of the skeleton  4. cont. Storage Site of Inorganic Salts, such as CALCIUM. Calcium may be removed from bone to maintain a normal blood calcium level, which is essentially for BLOOD CLOTTING  5. cont. Contains and Protects the Red Bone Marrow, Some White Blood Cells (Leukocytes) are also produced

Macroscopic structure of Long Bone  Epiphysis: ends of a long bone. Contains mainly spongy bone  Red Marrow fills it. Its fxn is to produce RBC  Articular Cartilage: covers ends of long bone Hyaline cartilage Creates smooth surface

Macroscopic Structure of Long bone  Endosteum : inner membrane lining MC MC contains yellow marrow (fat) Continuous with spongy bone  Periosteum : tough outer “jacket” Composed of fibrous tissue Contains BV, Nerves, and Osteoblasts Initiates growth in DIAMETER

Macroscopic structure cont’  Epiphyseal Disk: area of bone where active growth occurs.  AKA: growth plates  Initiates growth in LENGTH  When growing stops, disk is replaced by Epiphyseal line.  Diaphysis: shaft of bone Outer wall contains mainly compact bone. Strong & resistant to bending Compact bone encloses Medullary canal. MC contains yellow marrow (Fat)

Formation of Bone  Using your book as a reference, How does the skeleton seem to develop? Ossification starts at 12 wks.

Epiphyseal disk (line = adult)  Area of actively reproducing cartilage cells  Contain osteblasts  Will close approx 18yr. old  Osteoblasts: “bone builders”  Capable of producing collagen fibers (living=organic)  May “cement” themselves in Lacunae (cavity)  Osteocyte is mature osteoblast

 Femoral Epiphyseal disk: F=14-16 M=16-18  Sacral / Hip: F=21-23 M=23-25

Bone Remodeling  Osseous tissue constantly being formed and resorbed (destroyed)  3 stages: 1. Infancy to Adolescent: Osteoblastic activity dominant 2. Adolescent to Mid adult (40-50): Balance 3. Post middle age: Osteoclastic activity dominant leading to certain diseases

Microscopic Bone structure  1. Haversian (osteonic) canal : contain blood vessels & nerves  2. Canaliculi: interconnecting channels. Allow osteocytes to communicate  3. Lamellae: thin sheets of bone matrix layered in circles around the canals  4. Lacunae: spaces that contain osteocytes

Haversian(osteonic) System=canal, lamellae, osteocytes and canaliculi  Lamella: Concentric ring  Haversion’s (osteonic) canal: runs through core  Perforating canals: connect the Haversion canals  Lacuna: contain osteocytes (mature bone cells)  Types of osteocytes  osteoblasts : build bone  osteoclasts : remove bone

“Bone destroyers” Osteoclasts (microscopic)  Multi- nucleated cells  Release “digestive” enzymes to reshape or remodel bone

Nutrition Corner!  Calcium: mineral needed as primary make-up of inorganic salts of bones 99% in bone, 1% in blood  Vitamin D: needed for Ca  If a 20 year old woman consumes 400 mg of calcium a day (half of what is recommended), at age 55, she will have lost 1/3 of her calcium.  RDA Requirements for Calcium mg mg mg mg mg Pregnant 1200mg Lactating 1200 mg What is the reasoning?

Use vs. Decreased use  Increased use (exercise): increases deposition of collagen and calcium(inorganic=non-living) salts  Bones get stronger  Decreased use: compact bone in diaphysis thins out & calcium removed from bone  Bones get weak and fragile

You create the Treatment protocol  Treatment concerns of 82 y.o. elderly woman (95 lbs.)  Concerns for a 47 y.o average sized woman  Pregnant 31 y.o woman  313 lbs. 38 y.o. obese man.  200lbs. 22 y.o man  How should they differ? Be similar?

Osteoporosis  Excessive loss of bone volume & mineral content. Trabeculae of spongy bone is lost/spaces develop Spontaneous fracture as result of weakened bone  Aging reason for large % of fractures over age of 45

Common Sites of Osteoporotic fractures  Spinal column (vertebrae)  Distal Radius / Ulna  Hip fractures (actually is neck of femur NOT actual hip)  WHY DO YOU THINK?

Osteoporosis cont’  Factors which INCREASE risk 1. Low intake of dietary calcium and Vit D 2. Lack of physical exercise 3. Menopause: ovaries produce less estrogens…ceases decreases bone absorption of Calcium… Decreasing secondary sex characteristics

Prevention methods  How can someone, especially woman, prevent this? 1. Calcium supplements: 1000mg – 1500mg per day. Ex: 8oz glass milk = 275 mg 2. Regular physical exercise program. WHY? 3. What about Estrogen replacement therapy?

Homework  There are many different factors that can affect bone growth: Your homework is to research how one of these affects bone growth/what disorders can result.  1. Vitamin A  2. Vitamin C  3. Vitamin D  4. Pituitary growth hormone (too much, too little)  5. Female sex hormone (estrogen)  6. Male sex hormones (testosterone)