Term
| What is longitudinal bone growth and when do they grow most? |
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Definition
Bone growth in length Grow during juvienille years mostly puberty.
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Term
Describe the process of longitudinal bone growth.
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Definition
Chrondroblasts in the epiphysisal plate near the epiphysis do mitosis and increase the amount of cartilage causeing the bone to lengthen. Chondrocytes near the diaphysis hypertrophy, the matrix calicfies, the cells die, and the matrix breaks down. Osteoblasts near the diaphysis invade cartilage and replace it with bone. Osteoclasts increase the size of the medullary cavity. Epiphyseal plate stays the same size but the lenth of the bone increases
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Term
| What does growth hormone do to bones? |
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Definition
Sitmulates the mitosis of chondroblasts at the epophyseal plate in infancy and childhood.
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Term
| What happens if there is too much growth hormone? |
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Definition
| The child will be very tall and have gigantism |
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Term
| What will happen if there is too little growth hormone? |
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Definition
The child will be short but proportionate. Dwarfism.
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Term
How do estrogen and testosterone effect bone growth?
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Definition
| Promote growth spurts and complete ossification of the epiphyseal plate. |
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Term
What is appositional bone growth and when does it occur?
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Definition
Bone growth in thickness Could occur throughout your whole life.
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Term
Describe the process of appositional bone growth.
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Definition
Osteoblasts in the periosteum do mitosis and create matrix or the inside. Osteoclasts in the endosteum increase the medullary cavity to decrease weight. The result is a stronger thicker bone that is not too heavy. |
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Term
| What is bone remodeling? How often does it occur? |
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Definition
Organic materials are recycled and renewed. It invovles bone deposition by osteoblasts and bone reabsorption by osteoclasts. In non-growing healthy bone depositin and reabsorbtion are about equal; the size of bone stays the same. Occurs continually, about 4% of bone is new at anyone time and 1/5th of adult skeleton is rplaced a year. |
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Term
Why do we have bone remodeling?
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Definition
Repair injuries. Respond to growth of bone. Increase bone strength where there is stress. Release minerals saved in the bone.
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Term
Describe the process of bone reabsorbtion.
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Definition
Oseoclast secrete proteolytic enzymes that digest theorganic bone matrix. Metboloc acids like citric acid and lactic acid convert hydroxyapatie to a soluble form it goes into the blood. The osteoclasts phagocytize demineralized matrix. |
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Term
Describe the process of deposistion.
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Definition
Osteoblasts secrete bone matrix and form new osteons. The uncalcified matrix is calcified by alkine phosphotase from osteoblasts.
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Term
| Describe the process that occur when blood calcium levels are low. |
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Definition
Low blood calcium levels stimulate the release of parathyroid hormone from the parathyroid gland. Parathroid hormone stimulates osteoclast production and activity which causes bone/Ca++ reabortion into the blood. It also stimulates Ca++ absorbtion from the intestines but needs activated Vitamin D. |
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Term
| What happens when blood calcium levels are increased? |
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Definition
Parthyroid hormone release is stopped and calcitonin is release from the thyroid. This causes decrease production and activity of osteoclasts. It also stimulates deposition of Ca++ in the bone. |
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Term
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Definition
| Bone deposistion is in proportion to the stress on the bone. |
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Term
| Name a couple mechanical/physical stresses on the bone and what they do. |
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Definition
Muscle pull, gravity Help keep bone strong by addung collegen fibers and mineral salts like calcium phosphate. May change the shape of the bone. |
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Term
| List the 4 step invovled if fracture repair. |
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Definition
Formation of a hematoma Formation of a fibrocartilagenous callus Formation of a bony callus Remodeling |
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Term
| What happens with formation of a hematoma? |
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Definition
breaking bones also breaks some blood vessels which leads to bleeding. This causes swelling and eventually a clot around the fracture. Some bone cells die. |
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Term
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Definition
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Term
| How does a fibrocartilagenous callus form? |
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Definition
Capillaries start to fom a hematoma and bring phagocytic cells, fibroblasts, ect. Phagocytic cells eat/clean up dead cells and debris. Fibroblasts secrete collagen fibers to temporarily bind bone ends together. Some cells differentiate into chondroblasts that secrete cartilage matrix. Takes about 3-4 weeks. |
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Term
How does a boney callus form?
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Definition
Increased blood supply... chrondblasts--> osteoblasts--> secrete bone matrix which become woven bone. Osteoblasts and osteoclasts of periosteum and endosteum replace fibrocartilagenous callus with bone callus. Takes 2-3 months.
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Term
| What occurs in the remodeling of a fracture? |
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Definition
Excess material is removed and reshaped Woven bone becomes compact bone. |
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Term
| Describe a simple fracture |
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Definition
clean break doesn't penetrate the skin |
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Term
Describe a compound fracture.
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Definition
clean break penetrates the skin |
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Term
Describe a comminuted fracture.
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Definition
fragmented into 3 or more peices
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Term
Describe a compression fracture
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Definition
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Term
| Describe a depressed fracture. |
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Definition
Broken bone is pressed inward
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Term
Describe a spiral fracture
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Definition
Comes from excessive twisting
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Term
Describe an impacted facture
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Definition
Occurs when falling, one bone is pushed into the other.
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Term
| What is a greenstick fracture. |
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Definition
| The bone doesn't break all the way through, usually happens in children. |
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