Bone Growth and Fractures

hGH- (from Pituitary Gland) BONE GROWTH - hGH hGH- (from Pituitary Gland) Increases size of all organs (including brain) Increases Protein Synthesis: Builds up Body Affected by exercise, nutrition, sleep Increases osteoblast activity Stimulates growth of cartilage in the epiphyseal plate

BONE GROWTH Disorder: Gigantism- excess growth from too much hGH during childhood, before epiphyseal plates have closed

BONE GROWTH

Bone Growth Acromegaly- adult condition, ↑ hGH after Epiphyseal plate closure, disfigured face, pronounced jaw and brow, swelling of internal organs most common cause: benign tumor of pituitary gland treatment: surgery

BONE GROWTH - 2. Thyroid Hormone (from Thyroid Gland) Causes elongation of bones through chondrocytes cell division at the epiphyseal plate and stimulates osteoblast activity

BONE GROWTH Estrogen and Testosterone (Male and Female Sex hormones – from ovaries /testes + adrenal glands ) -at puberty released in larger quantities -increasing osteoblast activity and synthesis matrix -responsible for “growth spurts” teen yrs. - Levels of Estrogens (♀)/Androgens(♂) at the end of puberty cause epiphyseal plate to close (epiphyseal line)

FACTORS AFFECTING NORMAL BONE GROWTH A. DIET 1. Minerals CALCIUM & PHOSPHORUS (& traces of fluoride, magnesium, iron, manganese) for deposition into matrix Broccoli, Nuts, Seeds, Legumes, Grains, Dairy, Garlic, Chicken and Turkey

FACTORS AFFECTING NORMAL BONE GROWTH A. DIET 2. vitamins VITAMIN D  stimulates absorption & transport of Ca2+ into blood - can be synthesized by skin in presence of UV light or taken in through diet (4 glasses milk/day or 1 serving fatty fish) (10-15 mins 2X/week on face, arms + hands)

FACTORS AFFECTING NORMAL BONE GROWTH A. DIET VITAMIN D: Deficiency  Rickets in Children/ Osteomalacia in Adults -Affects long bones: Bowed Legs, Fragile bones, Impaired growth, Dental problems, Bone pain, Muscle weakness

Rickets

Rickets Caused by Vitamin D deficiency in childhood Vit D crucial for calcium and phosphorus absorption in digestive tract Not enough minerals so bones are too flexible During Industrial Revolution, a lot of children who worked in factories (little exposure to sunlight and malnourished) Starting to increase again in urban US because spending so much time in doors and drinking soda instead of milk

FACTORS AFFECTING NORMAL BONE GROWTH DIET VITAMIN A  balance between deposition and resorption, stimulates osteoblast activity liver sweet potatos carrots mangoes spinach cantaloupe dried apricots milk egg yolks mozzarella cheese

FACTORS AFFECTING NORMAL BONE GROWTH A. DIET VITAMIN C  necessary for collagen synthesis, normal bone growth, maintenance, & healing SCURVY Symptoms – spots on skin spongy gums bleeding from mucous membranes

BONE REMODELING - continual trading of Ca2+ between blood & bones; bones are continually remodeled with spongy bone being replaced every 3-4 years and compact bone every 10 years

BONE REMODELING A. BONE DEPOSITION: osteoblasts build bone & deposit Ca2+ and collagen

BONE REMODELING B. BONE RESORPTION: osteoclasts break down bone (acids and enzymes) & release Ca2+ into blood

BONE REMODELING *TOO MUCH Dietary Ca2+  can lead to “bone spurs” (Ca2+ deposits) and muscle weakness, heart failure *TOO LITTLE Dietary Ca2+ can lead to brittle, weakened bones, muscle spasms

BONE REMODELING - *Major Factors Influencing Remodeling: A. STRESS RESPONSE osteoblast formation stimulated by physical stress (exercise) from gravitational and mechanical forces

BONE REMODELING - *Major Factors Influencing Remodeling: A. STRESS RESPONSE CALCITONIN (thyroid gland) is released and inhibits osteoclast activity and encourages osteoblast’s activity and calcium deposition from blood into bone

BONE REMODELING - *Major Factors Influencing Remodeling: A. STRESS RESPONSE B. BLOOD CALCIUM & PHOSPHORUS CONCENTRATION HOMEOSTASIS P5+ needed for phosphates (PO43-) which contribute to ATP, DNA, & RNA

BONE REMODELING - *Major Factors Influencing Remodeling: B. BLOOD CALCIUM & PHOSPHORUS CONCENTRATION HOMEOSTASIS Ca2+ needed for normal functioning in: MUSCLES & NERVES BLOOD CLOT RESPONSE GLANDULAR SECRETIONS CELL DIVISION

Ca2+ Regulation Flow Chart: (bones = storage tank for Calcium (Ca2+)) CALCITONIN (THYROID GLAND) secreted when blood calcium inhibits osteoclasts Stimulates osteoblasts PARATHYROID HORMONE (PARATHYROID GLANDS) secreted when blood calcium stimulates osteoclasts Inhibits osteoblasts

Thyroid and Parathyroid Glands

Calcitonin High Osteoclasts inhibited Ca2+ remains in bones Blood Calcium Level Low Osteoclasts stimulated Ca2+ added to blood Parathyroid hormone

AGING loss of Ca2+ over time (mostly due to hormonal changes) -in females  age ~ 30 (accelerates 40-45) -in males  age ~ 60 loss of protein (organics) from bone matrix = overall weakening of bone tissue

Bone Density -soccer + basketball better than running Some studies show peak bone density may be reached by age 15 After age 15 bone density only slightly increases Mid 30’s bone density begins to decline 1% /year menopause ↓ (decreases osteoblast activity) impact activities stimulate osteoblasts ↑ -soccer + basketball better than running -strength training – great -swim/cycle need to do other activities if possible -walking pretty good *don’t specialize in one sport Need sex hormones for osteoblast activity

-Bones need sex hormones (stimulate osteoblasts) to maintain density OSTEOPOROSIS RISK FACTORS AGE (Dec. Hormones) -Bones need sex hormones (stimulate osteoblasts) to maintain density -estrogen drops dramatically ♀, in ♂ testosterone declines gradually  male menopause EATING DISORDERS LACK OF EXERCISE Ca2+ Deficiency VITAMIN D Deficiency DRUGS (Alcohol, Smoking, some Diuretics, etc.)

Bone Fractures and Healing

Answer these questions for each patient Can work in groups of 1-3 If it is a fracture, what type is it? If it’s not a fracture, what’s the injury? List ALL of the bones present in the x-ray and underline which, if any, are the fractured bone

Bone Healing Stages