Question

Mrs. Debbie Morgan is a 45-year-old female who works as a stocking clerk for a local home improvement store. While she was at work today a large box of metal rivets fell from a 20-ft.-high overhead shelf, striking her outstretched arm and knocking her to the ground. The ambulance personnel reported that she had lost quite a bit of blood at the accident scene and was “knocked out” when they arrived. To minimize further hemorrhage, the paramedics applied a pressure bandage to her arm.

You meet the paramedics as they bring Mrs. Morgan into the emergency room and begin to assess her for injuries. She is awake and alert, but complaining of severe left arm and back pain, plus she has a “killer headache.” To fully examine her injuries you remove four blood-soaked bandages from her arm. You notice a large open wound on her arm with what appears to be bone tissue sticking out of the skin. She also has bruises covering her left shoulder, left wrist, and lower back. To determine the extent of her injuries Mrs. Morgan undergoes several x-rays, which reveal the following:

1. In the final stage of bone repair, some of the osseous tissue must be broken down and removed. What term is used to define the breaking down of osseous tissue (1 point)? Which bone cell would be best suited for this task (1 point)?

2. The extracellular matrix (ECM) of bone is considered to be a composite material made up of organic and inorganic matter. What makes up the organic and inorganic portions of the matrix (2 points)? Describe the cellular mechanism involved in breaking down this matrix; include the bone cell required for the process (2 points).

Answer 1

1.Breaking down of osseous tissue is called Bone resorption. This process is a part of bone remodelling. It removes the damaged bone tissue.

2.The bone cell associated with resorption is Osteoclast. They are large multinucleate cells. They have clear zones and ruffled borders for bone resorption.

3.The Extra cellular matrix is formed of organic and inorganic parts. The organic part is formed of collagen and ground substance. Type l collagen is secreted by osteoblasts and osteocytes.The ground substance is formed of glycoproteins, proteoglycans and glycosaminoglycans.Inorganic part is formed of calcium hydroxy apatite .

4.Cellular mechanism involved in breaking down of matrix is resorption. It is done by osteoclast. They secrete collagenase which breaks down and digests complex proteins.