Biol 1301 - Bone Health

What is the structure of Bone?

35% Collagen - a protein made of Amino Acids

• if collagen is low, bones become more brittle

65% Hydroxyapatite crystals - Inorganic minerals including calcium, phosphorus, oxygen and hydrogen

• provides the hardness of bone and teeth

What is Bone growth?

increase in bone size; completed by age 14 in girls and age 17 in boys

What is Bone modeling?

shaping of bone; completed by early adulthood

What is Bone remodeling?

removal of old or damaged bone and replacement with new bone; occurs throughout life

What is the function of OsteoClasts?

cells that degrade bone to initiate normal bone remodeling and release minerals

• regulate blood calcium

What is the function of OsteoBlasts?

produce the collagen-containing component of bone

• regulate calcium and phosphate ions in developing bone

Why is Vitamin K important for Bone health?

menaquinone (K2), a longer form of Vit K is required for bone health

• promotes bone growth by increasing osteoclast formation and increasing mineral deposition

food sources: Think green! Kale, broccoli, brussels sprouts

Why is Vitamin D important for Bone health?

cholecalciferol - a hormone, which is converted into the hormone calcitriol

• calcitriol is the activated form of vitamin D, which helps the body absorb calcium and phosphate from food

synthesized in the skin from cholesterol using UV light from the sun

What occurs from a Vitamin D deficiency?

Rickets in children

• softening of bones usually leading to fractures or

  deformities

Osteomalacia (soft bones) in adults

Neurodegeneration in elderly

Who is at risk for Vitamin D deficiency?

• People with dark skin

• People living at high latitudes

• Breast fed infants who are not exposed to sunlight

  • Breast milk has no vitamin D

risk of cancer increases with UV exposure

What is the function of Calcium?

Provides structure for bones and teeth

• Hydroxyapatite is the crystalline structure formed by Ca, P, H, O

How is Calcium absorbed?

Requires activated vitamin D (calcitriol)

• Calcitriol “turns on” cell uptake of calcium from food an into the intestinal cells

What is caused by Calcium deficiency?

Hypocalcemia (low blood calcium)

• can cause osteoporosis

What are the Minerals crucial for bone health?

• Calcium (essential for collagen production)

• Phosphorus

• Magnesium

• Fluoride

What are the Vitamins crucial for bone health?

• Vitamin K for mineralization and osteoclast formation

• Vitamin C for collagen synthesis

• Vitamin D for calcium absorption

Why is the proper balance of phosphorus and calcium important?

Calcium and phosphate levels are inversely related

• when free blood calcium levels rise, phosphate levels fall

excess phosphorus lowers calcium levels

• this can pull calcium out of bones

What are the Functions of Vitamin D?

• Regulates calcium absorption from the small intestine

• Stimulates osteoclasts to release Ca from bone when it is needed elsewhere in the body