Transcript Slide 1
Analyzing bones is important to identify a victim or suspect. You can find: Identity Gender Age Height Race Background A. Bones are alive 1. they grow and can repair themselves 2. they are made of cells that go through cellular respiration. 3. blood cells are made in the bone marrow 4. bones are regulated by hormones B. The cells of bone…four to consider 1. Osteoprogenitor cells a. Stem cells of bone b. divide and make more of these cells c. they are the least differentiated…they have the potential to be any kind of cell. 2. Osteoblasts a. bone forming cells…make bone by producing extracellular matrix (secreting minerals) around themselves. 3. Osteocytes a. these are osteoblasts that cannot make any more matrix so they differentiate into a cell that can maintain it 4. Osteoclast a. break down bone matrix to repair it, or release the minerals we store in the bone if they are needed in the body C. You can determine the age of a bone as well as what the bone came from by analyzing the Haversian systems (aka…Osteon) in bone. 1. Functional unit of compact bone (hard bone) 2. Osteocytes are arranged in concentric layers around a central canal that contains one or more blood vessels. 3. In animals, osteons are arranged in a pattern. In humans, they are more chaotically arranged. This Old Bone Lab Introduction: Can make measurements from a microscope using an “ocular Micrometer” (the eyepiece lens in the microscopes in the back have been replaced by this “ocular micrometer lens). What you will see: Measurement from microscope 1.0 mm = 5 micrometers Measurement from slide Use a consistent magnification….use 100X You will analyze bone fragments to determine the age The younger you are, the larger the Haversian system. With age, the Haversian systems and canals get smaller. Calculate the average number of concentric lamellae in a given bone sample to determine the age of the person at death. This Old Bone Lab Introduction: How many Osteons (Haversian systems) are shown here? You will be measuring the Haversian CANAL. From this picture, what will you measure? A story of a life told by the bones Examples: Gender Age Height Race right or left handed diet and nutrition (esp. lack of vitamin D and calcium) diseases and genetic disorders (arthritis, osteoporosis, scoliosis) previous injuries surgical implants childbirth C. What bones can tell us 1. Gender a. Overall appearance Female–“gracile”– smoother Male – “robust” – thicker, rougher and more bumpy b. Skull differences c. pelvis differences You would compare the following: subpubic angle length, width, shape, angle of sacrum width of the ileum angle of the sciatic notch *surface has scars if female has borne children Male Subpubic Angle Shape of Pubis Shape of Pelvic cavity Sacrum Female d. Thigh bones (femur) • angle of the femur with respect to the pelvis is greater in females and straighter in males. • the femur is thicker in males than females 2. Age a. analysis of Haversian system (Osteon) b. Suture marks – where bones fuse (skull) -- disappear as bones mature (smoother look) c. Cartilaginous lines – where cartilage is replaced by bone as a human grows. The line is called an epiphysis. When the replacement is complete, a line is no longer present. Age for completion for each bone varies. d. Long bones – femur (thigh) and humerus (upper arm) -- when the long part of the bone has completely fused to the rounded end part. Epiphyseal Plate 3. Height a. measure femur and/or humerus b. refer to databases (separate tables for males/females and different races) 4. Race a. difficult (intermarriages) b. skull shape of eye sockets absence or presence of a nasal spine measurements of the nasal index (ratio of the width of the nasal opening to the height of the opening, times 100) projection of the upper jaw (maxilla) beyond the lower jaw width of the face Angle of the jaw and face Caucasoid Shape of Eye Orbits Nasal Spine Nasal Index Prognathism Femur Negroid Mongoloid