Bone Growth and Fractures

BONE GROWTH - hGH

• 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

1.hGH- (from Pituitary Gland)

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

BONE GROWTH

BONE GROWTH

Bone GrowthAcromegaly- 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 -

Causes elongation of bones through chondrocytes cell division at the epiphyseal plate and stimulates osteoblast activity

2. Thyroid Hormone (from Thyroid Gland)

• 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)

BONE GROWTH

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

(10-15 mins 2X/week on face, arms + hands)

(4 glasses milk/day or 1 serving fatty fish)

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

A. DIET

VITAMIN A balance between deposition and resorption, stimulates osteoblast activity liversweet potatoscarrotsmangoesspinachcantaloupedried apricotsmilkegg yolksmozzarella cheese

FACTORS AFFECTING NORMAL BONE GROWTH

A. DIET• VITAMIN C necessary for collagen synthesis,

normal bone growth, maintenance, & healing

SCURVYSymptoms – spots on skinspongy gumsbleeding 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 REMODELINGA. BONE DEPOSITION: osteoblasts build

bone & deposit Ca2+ and collagen

BONE REMODELINGB. 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 RESPONSEGLANDULAR 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

Blood Calcium Level

Low

Calcitonin

High

Parathyroid hormone

Ca2+ added to blood

Ca2+ remains in bones Osteoclasts inhibited

Osteoclasts stimulated

AGINGloss 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• 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

OSTEOPOROSISRISK 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

1. If it is a fracture, what type is it? If it’s not a fracture, what’s the injury?

2. List ALL of the bones present in the x-ray and underline which, if any, are the fractured bone

Answer these questions for each patientCan work in groups of 1-3

Bone Healing Stages