Notes to/6 4- ( ea/2

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1 Notes to/6 4- ( ea/2 PART Two FACTORS AFFECTING BONE DEVELOPMENT & GROWTH Nutrition There must be adequate intake of certain nutrients, such as: 1. Calcium 2. Vitamin C : Necessary for collagen synthesis as well as all connective tissues 3. Vitamin A: Important for development and proper functioning of osteoblasts and osteoclasts 4. Vitamin D: Neccesary for absorption of CalCiurn in the small intestine. Must be "activated" by sunlight in the skin. When kids have Vitamin D deficiency it is called RICKETS... in adults it is called OSTEOMALACIA. Sunlight Exposure See Vitamin D (above) (UV Light) Hormones 1. Pituitary Gland 4 Growth Hormone : Stimulates growth of bones at the e.g epiphyseal plates. Too much? ifreac4tig4wpituitary GIGANTISM (child) or ACROMELAGY (adult). Too little? HYPOPITUITARY DWARFISM U 0

2 2. Testes and Ovaries 4 Sex Hormones: Stimulate new growth in bones, but also stimulate closure of the epiphyseal plates. Issues after MENOPAUSE include OSTEOPOROSIS. Estrogens have a more pronounced effect than Androgens. That is why girls grow faster and sooner than boys! 3. Thryoid Gland 4 Calcitonin: Inhibits osteoclasts. Not important in adult humans. I( Thryoid Gland - Thyroid Hor o Stimulates osteotlasts and Calcium and ossification of the epiphyseal plates. Too little? HYPOTHYROIDISM causes stunted growth (DWARFISM) S. Parathyroid Gland 4 Parathyroid Hormone: Stimulates osteoclasts and inhibits osteoblasts. g-eacarto Ca lf i Ni) Lotav-d- 4, Kidney 4 Calcitriole: Stimulates osteoblasts. COP - b t Exercise Mechanical stress is really important for maintaining bone strength and thickness through increased calcitonin release and the piezoelectric effect. Weight-lifters have much heavier and thicker bones! Astronauts in zero gravity? Loss of bone mass. Aging Women (particularly after menopause) and elderly men can have OSTEOPOROSIS from a loss of Calcium in the bones.

3 Blood Cell Formation Hematopoeisis: production of blood cells... Red Bone Marrow makes red blood cells, white blood cells, and platelets. (Infants) most bones (Adults) spongy bone of skull, ribs, sternum, clavicle, vertebrae, pelvis Yellow Bone Marrow stores fat.

4 r1/4f-301 CALCIUM HOMEOSTASIS julation of Calcium Levels in the Bod cola4.4- TPA e4"-ke The small intestine is the site whey dietary calcium is absorbed. Importantly, efficient absorption of calcium in the small intestine is pendent on expression of a calcium-binding protein in epithelial cells and the presence of activated Vitamin D. ot your ath c.a..a. a 12 sai- la ivt are- ar it. 5- C a z+ ie,4a-ai A C-a 01. YUU4-. 0'1. RurvAk'w ' logar Bone serves as vast reservoir of calcium. However, Only 1% of the Ilcium in the is readily "exchangeable". Calcium and phosphate can be released into the blood through osteoclast activity = resorption, and it can be deposited in bone by osteoblast activity= deposition. The constant building up and breaking down of bone is called remodeling. Icriedi 4-e caft.q to c (-7) ) (+2) ( 6 I he kidney is critically important in calcium homeostasis. Under normal blood calcium concentrations, almost all of the calcium that enters the kidney ends up back into blood, which preserves blood calcium levels. If kidney "reabsorption" of calcium decreases, calcium is lost by excretion into urine. T 12- kr-r4- ( ; / 11. (16

5 Importance of Calcium It would be very difficult to name a physiologic process that does not depend, in nne way or another, on calcium. It is critical to maintain blood calcium.l.,.,1,entrations within a tight normal range. Deviations above or below the normal range frequently lead to serious disease and muscle/nerve problems. "-Ivnocalcemia refers to low blood calcium concentration. Clinical signs of this Jer reflect increased neuromuscular excitability and include muscle spasms, tetany and cardiac dysfunction. 5 raall Wes-k^i,eostatic Response to a small amount of hypocalcemia: Increased absorption, decreased seeze..t.4,n. ic.40 gy Homeostatic Response to a great amount of hypocalcemia: Increased PTH 1,20n.c 12-e_leaces Hypercalcemia indicates a concentration of blood calcium higher than normal. The normal concentration of calcium and phosphate in blood and extracellular fluid is near the saturation point; elevations can lead to diffuse precipitation of calcium phosphate in tissues, leading to widespread organ dysfunction and damage. 5.r, Homeostatic Response to a small amount of hypercalcemia: Decreased absorbtion, increased secretion. Homeostatic Response to a great amount of hypercalcemia: (Increased Calcitonin) Calcitriole Defes-;4.5 ;, by Igwo, Bone Fractures & Repair Types of fractures (see book page 192) 1. Greenstick 2. Fissured 3. Communicated 4. Transverse Thlique spiral

6 Fracture repair 1. Fracture Hematoma comes from blood in broken blood vessels in bone L. Fibrocartilaginous Callus: (days to weeks) new blood vessels bring in osteoblasts and masses of fibrocartilage form from fibroblast cells. Phagocytes clear out the blood clot and debris. Boney Callus: Trabeculae of spongy bone formed by osteoblasts. Cartilage is replaced by bone 4. Remodeling: Osteoclasts remove excess bone tissue and restore the bone back to how it was before the break. Joints see book for details i Fibrous Cartilaginous Synovial Dense connective tissue holds them together. Hyaline or fibro-cartilage holds them together. Ball and Socket Syndesmosis 1 Synchondrosis 1 Condyloid (Ellipsoid) Suture ISymphysis 2 Gliding Gomphosis 3 Hinge 4 Pivot S Saddle Types of Joint Movement define these from your book Flexion Extension Hyperextension Du,,iflexion Plantar flexion Abduction Adduction Rotation Circurnduction Supination Pronation Eversion sion Protraction Retraction Elevation Depression