Life Science Curriculum K-7
Submitted by: Manda B. Teeter
Institution: Azusa Pacific University
Title of Experiment: A Study of the Composition and Structure of the Human Skeletal System
- Small or medium-sized glass jar with lid
- White vinegar
- Cookie sheet
- Aluminum foil
- 6 to 10 chicken bones
Scientific Background of Experiment:
The human skeleton is made up of over 200 bones. The skeletal system offers both support for the body and protection for important organs. The human skeleton is divided into two parts, the axial skeleton and the appendicular skeleton. The axial skeleton includes the skull, backbone, and rib cage. The appendicular skeleton has the bones of the hands, arms, shoulders, pelvis, legs, and feet. Where two bones meet, a joint is formed. The joints of the skeleton are held together by pieces of tissue called ligaments (Mader, 1996).
The two types of bone that make up the bones of the skeletal system are spongy bone and compact bone. Spongy bone is found inside of bones and has many spaces filled with marrow. Bone marrow is tissue inside the hollow parts of bone that produces new blood cells and stores fat. The second type of bone is compact bone. Compact bone makes up the outer surfaces of the bone, is harder than spongy bone, and has fewer and smaller hollow spaces than spongy bone. Canals inside the compact bone, called Haversian systems, are much like blood vessels and serve some of the same purposes. Units called lacunae that are also inside the compact bone contain the cells that produce new bone (McFadden and Keeton, 1995).
The bones of the human skeletal system store great quantities of calcium and phosphate. These two minerals, particularly calcium, make the bones strong and rigid. It is very important to get enough calcium in one's diet to keep bones strong. The recommended calcium intake is contained in 24 ounces, or about three glasses, of milk per day. One should also be sure to get enough vitamin D, because the body needs this vitamin to properly digest calcium. If one does not get enough calcium in his diet, he may develop a disease called osteoporosis (awh-stee-o-per-OH-sis) later in life. Osteoporosis causes the bones of the body to become brittle, weak, and possibly even deformed from the loss of calcium. The bones of a person with osteoporosis break much easier than the bones of a person who has strong, healthy bones (McFadden and Keeton, 1995).
The purpose of the following experiments is to show the importance of calcium in one's diet to ensure that one's bones are kept strong, to demonstrate the consequences of not getting enough calcium, and to show the effects of skeletal diseases like osteoporosis. In the first experiment, vinegar, which is a form of acetic acid (HC2H3O2), eats away and dissolves the calcium in the chicken bones (Kotz and Treichel, 1999). This simulates the effect of not getting enough calcium in one's diet. Without calcium, bones lose their rigidity and the lacunae will not be as equipped to make new bone cells. In the second experiment, the chicken bones are baked at a very high temperature, showing the danger of having brittle bones. The bones are weakened by the high temperatures; the same result may be apparent in bones affected by osteoporosis because they have not received enough calcium (Mader, 1996).
1. Obtain a small or medium sized glass jar with a lid, some white vinegar (about enough to fill the jar), and 3 to 5 chicken bones. Make sure any extra tissue is removed from the bone (the cartilage can be left on the bone).
2. Place the bones in the jar and fill the jar with enough vinegar to completely submerge the chicken bones.
3. Screw the lid on the jar and set the jar aside.
4. Check the jar after a week to observe the beginning effects of the acid on calcium loss, and the check it again after another two to three weeks. Keep the bones submerged in the vinegar until they can be bent without very much pressure (Shimmin, 1991).
5. After the bones have become soft, cut a few of the bones open and examine the inside.
1. Preheat an oven to 400oF.
2. Obtain a few of the chicken bones from experiment one, 3 to 5 other normal chicken bones, a cookie sheet, and some aluminum foil (enough to line the cookie sheet).
3. Line the cookie sheet with foil and make sure any extra tissue is removed from the bones as in experiment one.
4. Place the bones on the foil of the cookie sheet and put in the oven.
5. Bake the bones at 400oF for 6 to 7 hours (Eddington, 2000).
6. Remove and allow to cool.
7. Try breaking the bones and compare the bones that were soaked in the vinegar and then baked to those that were just baked.
Misc. Helpful Information/ Hints/ Suggestions:
- When choosing chicken bones for the experiment, drumsticks often work the best because they demonstrate the best results.
- Make sure to keep the lid on the jar of vinegar with the bones in it so that the vinegar does not evaporate.
- A clear jar is optimal for experiment one, as the effects of the vinegar may be seen through the glass, such as the bones bending as they lean against the side of the jar.
Eddington, Prof. L. E. 16 March 2000.
Personal Interview. Azusa Pacific University.
Kotz, John C. and Paul Treichel, Jr. 1999. Chemistry and Chemical Reactivity.
Saunders College Publishing, Fort Worth, pp.147.
Mader, Sylvia. 1996. Biology Laboratory Manual. WCB/McGraw-Hill, Boston,
McFadden, Carol H. and William T. Keeton. 1995. Biology: An Exploration of Life.
W. W. Norton & Company, New York, pp. 653-654.
Shimmin, Deloris. 1991. Choosing Good Health. A Beka Book Publications,
Pensacola, FL, pp. 40.