SKELETAL & ENDOCRINE SYSTEMS MARY, LARRY, AND MELINDA

ANATOMY OF THE SKELETAL SYSTEM -“Skeleton can be defined as the hard framework of human body around which the entire body is built. Almost all the hard parts of human body are components of human skeletal system. Joints are very important because they make the hard and rigid skeleton allow different types of movements at different locations. If the skeleton were without joints, no movement would have taken place and the significance of human body; no more than a stone.” -Human skeleton is composed of three main components; Bones, Associated cartilages and Joints.

MICROSCOPIC ANATOMY OF SKELETAL SYSTEM Osteocytes - A mature osteoblast which no longer secretes matrix, yet is surrounded by it. Maintains metabolism, and participates in nutrient/waste exchange via blood. Unable to divide. -Star shaped cell -Most numerous cell found in mature bones -Capable of molecular synthesis and modification as well as transmission of signals over long distances -Regulator of bone mass and the key endocrine regulator of phosphate metabolism

ANATOMY OF THE ENDOCRINE SYSTEM -The endocrine system is the system of glands, each is a type of hormone directly into the bloodstream to regulate various functions in the body such as metabolism, growth and development, tissue function and mood. The endocrine system is in contrast to the exocrine system, which secretes its chemicals using ducts. -The field of study dealing with the endocrine system and its disorders is endocrinology, a branch of internal medicine.

HORMONES INVOLVED IN BONE STRUCTURE Calcitonin -Bone: Calcitonin suppresses reabsorption of bone by inhibiting the activity of osteoclasts, a cell type that "digests" bone matrix, releasing calcium and phosphorus into blood. Thyroid in the endocrine system produces the hormone Calcitonin, which decreases the concentration of calcium in the blood by acting with bone to inhibit its breakdown. The less bone that is reabsorbed, the less calcium moves into the blood.

HORMONES INVOLVED IN BONE STRUCTURE Parathyroid Hormone (PTH) -PTH controls calcium and phosphorus levels in the blood. -PTH is made by the parathyroid glands. -If the blood calcium level is too low, the parathyroid glands release more PTH. This causes the bones to release more calcium into the blood and reduces the amount of calcium released by the kidneys into the urine. If the calcium level is too high, the parathyroid glands release less PTH, and the whole process is reversed. -PTH levels that are too high or too low can cause problems with the kidneys and bones and cause changes in calcium and vitamin D levels.

NORMAL INTERACTIONS BETWEEN ENDOCRINE AND SKELETAL SYSTEMS -The thyroid in the endocrine system produces the hormone calcitonin. Calcitonin decreases the concentration of calcium in the blood by acting with bone to inhibit its breakdown. The less bone that is reabsorbed the less calcium moves into the blood. So the level of calcium in the blood decreases. -On the other hand, the parathyroid secretes parathyroid hormone which increases the concentration of calcium in the blood. The PTH stimulates the osteoclasts to increase the breakdown of bone.

OSTEOPOROSIS - Osteoporosis is one of the most common endocrine diseases -Normally these bone remodeling processes are tightly coordinated by a wide variety of hormones and growth factors, allowing compensation for any change. -The most common form of osteoporosis is age related

OSTEOPOROSIS -Osteoporosis may occur as a result of a reduced peak bone mass or a mismatch between bone formation and reabsorption. It has been calculated that lifetime risk of osteoporotic fracture over the age of 50 years is 40% for females and 13% for males. These fractures cost the Health Service many hundreds of millions of pounds per year. -Because of the many factors that may lead to osteoporosis, as many as 10 million Americans are already diagnosed with the said illness and 34 million more at risk.

SYMPTOMS OF OSTEOPOROSIS IN THE SKELETAL SYSTEM -Osteoporosis itself has no symptoms; its main consequence is the increased risk of bone fractures. Osteoporotic fractures are those that occur in situations where healthy people would not normally break a bone; they are therefore regarded as fragility fractures. Typical fragility fractures occur in the vertebral column, rib, hip and wrist.

SYMPTOMS OF OSTEOPOROSIS ON THE ENDOCRINE SYSTEM -Severe back pain -Loss of height is one of these symptoms of osteoporosis, as the vertebrae may compress when they break. -Other symptoms include spinal deformities, such as kyphosis or an extremely rounded upper back.

ABNORMAL INTERACTIONS BETWEEN THE SKELETAL AND ENDOCRINE SYSTEMS -Osteoporosis occurs when bone reabsorption exceeds formation this is caused by depletion of certain hormones from aging Ex) Calcitonin and Parathyroid -untreated hyperthyroid (excessive production of PTH) leads to weak/ brittle bones