ESS 205 1st Edition Lecture 12Outline of Last Lecture I. Bone MarrowII. Intramembranous OssificationIII. Endochondral Ossification a. Secondary Ossification Centersb. MetaphysisIV. Bone Growth and RemodelingV. Physiology of Bone Tissuea. Wolffs LawOutline of Current LectureVI. 3 Hormones related to vital homeostasisVII. Other factors affecting boneVIII. Bone fracture and repairIX. Overview of muscle systemCurrent Lecture1. Calcitriol is the first of three hormones to sustain normal homeostasis in bones. Calcitriolis from vitamin D produce by the skin=>liver=>kidneys. It acts as a hormone but is technically considered a vitamin. Its function is to increase blood calcium concentrate. The second hormone is calcitonin. It is secreted by the thyroid gland when calcium concentrates rise too high. Its function is to lower blood calcium concentrates by reducing osteoclast activity or increasing number and activity of osteoblasts. This hormone plays an important role in children but do not have much effect in adults. The These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.last hormone is the parathyroid hormone. It is secreted by the parathyroid glands. It is released when the blood calcium concentrate level is too low. Its function is to raise blood calcium levels by binding osteoblasts which then causes them to release osteoclast stimulating factor that stimulates osteoclast multiplication and activity, promotes calcium resorption by the kidneys, promotes calcitriol synthesis in the kidneys,and last inhibits collagen synthesis and bone deposition by osteoblasts. 2. There are twenty or more other hormones, vitamins, and growth factors that are not well understood. Bone growth is especially rapid at puberty. The reason for this is because hormones stimulate proliferation of osteogenic cells and chondrocytes in growth plates. Another reason is that estrogen has a stronger effect making girls grow faster than boys earlier on. The growth of bone ceases when epiphyseal plate “closes.” Anabolic steroids may cause premature closure of growth plate producing short adult stature. 3. Bone fractures are an acute break caused by abnormal trauma to a bone. A pathological fracture is a break in a bone weakened by some other disease. Stress fractures are chronic overuse fractures that are caused by imbalance in minerals. Fractures are characterized by their structural characteristics-causing a break in skin, breaking in to multiple pieces, etc. The healing of fractures normally takes eight to twelve weeks. Thereare four stages of healing:a. Hematoma and granulation formation-broken vessels form a blood clot pool which forms granulated tissueb. Soft callus- fibrous tissue formed by fibroblasts and infiltrated by capillaries. c. Hard callus- a soft callus of fibrocartilage is replaced by hard callus of bone in six weeks (temporary splint)d. Remodeling- occurs over next six months as spongy bone is replaced by compact bone. There are also different treatments for fractures. The first is closed reduction. The fragments are aligned with manipulation and casted by MD. Open reduction is where surgical exposure and repair with plates, wires, and screws. Electrical simulation is used on fractures that take longer than two months to heal. 4. There are three types of muscle tissue. The first is skeletal muscle. There are about six hundred skeletal muscles in human body. The cells are striated. The second is cardiac muscle tissue. It occurs only in the walls of the heart. These cells are also striated. The third is smooth muscle tissue. It occupies the walls of hollow organs. These cells lack striations. 5. The muscles functions include movement, stability, communication, control of openings, and body heat production.6. Within skeletal muscles there are connective tissue layers. The first is fascicle which is where muscle fibers are grouped into bundles. Next is epimysium. They are dense regular connective tissue covering the entire muscle and works to separate muscles. Thethird is perimysium. They are a slightly thicker layer of CT that surrounds each fascicle. The last is endomysium. It is a fine sheath of areolar connective tissue wrapping each muscle cell and allows room for capillaries and nerve fibers. a. The two locations of fascia (fascicles) are deep and superficial. Deep fascia is found between adjacent muscles (no fat). Superficial fascia is found between skinand muscles that contain adipose tissue. 7. There are direct and indirect muscle attachments to bone. Direct (fleshy) attachments is where the epimysium is continuous with periosteum. Indirect attachments is where the epimysium continues as tendon that merges INTO periosteum as perforating fibers. The muscle attachments that attach to the dermis are facial muscles. Stress will tear the tendon before pulling the tendon loose from the muscle or