A&P 1, Exam 3 Review

What are sex hormones responsible for?

closing the epiphyseal plate at the end of puberty (also important in bone density maintenance during adulthood)

what do thyroid hormones do?

contribute to bone growth involving the modulation of the activity of growth hormone -ensures proper bone proportions

What is Vitamin D essential for?

healthy bones because it promotes the absorption of calcium from foods in the gastrointestinal tract into the blood.

The process of regulation serum Ca2+ levels

mineralizing bone is under hormonal control and it carefully balanced

fractures in youth

most result from trauma (hold my beer)

fractures in old age

most result of bone weakness due to thinning

Hormones

occur continuously, but regulated by genetic factors and 2 control loops -negative feedback hormonal loop for Ca2+ homeostasis *control blood Ca2+ levels, not bone integrity *Serum Ca2+ concentrations are very important for proper nervous and muscle function *Even minute changes in blood calcium are dangerous -responses to mechanical and gravitational forces

Whether skin is penetrated

open(compound)-skin is penetrated closed(simple)-skin is not penetrate

What is Vitamin C needed for?

synthesis of collagen

What is Vitamin A important for?

the activity of osteoblasts

What does the female sex hormone promote?

the female sex hormones also promote widening of the pelvis in the female skeleton

what is the 2nd step of fraction repair?

the formation of a callus -

What is the 1st step of fraction repair?

the formation of a fracture hematoma (clot) as a result of blood vessels breaking in the periosteum and in osteons (site swollen, painful, and inflamed)

Estrogen and testosterone

the sex hormones(estrogen and testosterone) cause a dramatic effect on bone growth, such as sudden "growth spurt" that occurs during adolescence

Negative feedback hormonal loop for Ca2+ homeostasis

~maintaining a normal serum Ca2+ level takes precedence over mineralizing bone *parathyroid hormone (PTH) -produced by parathyroid glands - removes calcium from bone regardless of bone integrity *Calcitonin may be involved -produced by parafollicular cells of thyroid gland -in humans, high doses lower blood calcium levels temporarily (normal human physiological serum levels not high enough to cause the above affect)

Wolffs Law Explains

-Handedness(right or left handed) results in thicker and stronger bone of that upper limb -curved bones thickest where most likely to buckle -trabeculae of spongy bone form trusses along lines of stress -large, bony projections occur where heavy, active muscles attach (even more pronounced on professional weight lifters) - bones of fetus and bedridden relatively featureless

Day to day control of calcium regulation mainly involves:

-PTH stimulates osteoclastic activity and raises blood serum calcium levels stimulates reabsorption of calcium ions in the kidneys -to a small extent, calcitonin-maybe-hGH, and the sex hormones (estrogen & testosterone) stimulate osteoblastic activity and serum calcium level -Vitamin D is produced for absortion of the Ca2+ and PO4- ions from the small intestine

What is Rickets?

-Weakening of bone hardness due to insufficient absorption of dietary calcium from lack of vitamin D or prolonged diets deficient in calcium -More common in children than adults (Called osteomalacia in adults) Increase in dietary Vitamin D or Ca intake can be used to treat

Classification of bone fractures

-also described by location of fractures -external appearance -nature of break -eponym (someones name)

Results of hormonal and mechanical influences

-hormonal controls determine whether and when remodeling occurs (bases on maintaining blood calcium levels) -mechanical/gravitational stress determines where remodeling occurs

Results of Mechanical Stress: Wolffs Law

Bone grows or remodels in response to demands placed on it

Response to mechanical and gravitational forces

Bones stress when bearing weight or pulled on by muscle -usually stress is off center so tends to bend bones -bending compresses on one side, stretches on other Bones reflect stresses they encounter -long bones thickest midway along diaphysis where bending stresses greatest

Vitamin D and Ca deficiency

Can happen in places with low sun exposure or low calcium content in diet

Completeness of break

Complete-broken all the way through incomplete-not broken all the way through

What are key contributors to normal bone growth?

Hormones

The hormones most important to bone growth

Human growth hormone(hGH) and Growth factors called IGFs (produced by the liver) they both stimulate osteoblasts, promote cell division, at the epiphyseal plate, and enhance protein synthesis

Normal bone growth depends on several factors:

Minerals are an essential component. -Large amounts of calcium and phosphorus and smaller amounts of magnesium, fluoride, and manganese are required for bone growth and remodeling.

Position of bone ends after fracture

Nondisplaced-ends retain normal position Displaced-end out of normal adjustment

What is Vitamins K and B12 needed for?

Vitamins K and B12 are needed for synthesis of bone proteins.

Fractures

breaks in bone tissue

Fracture Treatment

reduction -realignment of broken bone ends -closed reduction-physician manipulates to correct position -open reduction-surgical pins or wires secure ends Immobilization by cast or traction for healing -depends on bone severity, bone broken and age of patient