Bones Activity Packet
The adult skeleton consists of 206 bones. The skeletal system provides the framework for your body and protects delicate organs. Your bones enable you to stand upright. The marrow of certain bones makes the red cells of you blood and some of the white blood cells. The bones themselves serve as storage places for minerals, especially calcium and phosphorus. Bone itself contains living tissue. Because living issue needs a constant supply of nutrients and oxygen, blood vessels supply you bones. Your bones are also supplied with nerves.
So why do bones stick around after all the living tissue is removed through death of the creature? Calcium (Ca) is left behind which and this is the hard material that make up our bones. Skeletal remains indefinitely as long as there are no predators around. However, if the soil is very wet and rich in minerals the calcium will eventually dissolve and the bones will return to dust.
Today, we are going to do a little experiment on a chicken bone. Here are the instructions:
Hypothesis:
H1 =
H2 =
Materials:
Chicken bone
Contain with lid
Vinegar
Methodology:
1. Have a nice chicken dinner and save a bone. Leg bones work best.
2. Rinse off the bone in running water to remove any meat from the bone.
3. Notice how hard the bone is - gently try bending it. Like our bones, chicken bones have a mineral called calcium in them to make them hard.
4. Put the bone into the jar and cover the bone with vinegar. It might be a good idea to put the lid on the jar or cover it - let it sit for 3 days
5. After 3 days, remove the bone. It should feel different. Now can rinse it off and try bending it again. Is it really a rubber bone?
4. Put the bone into the jar and cover the bone with vinegar. It might be a good idea to put the lid on the jar or cover it - let it sit for 3 days
5. After 3 days, remove the bone. It should feel different. Now can rinse it off and try bending it again. Is it really a rubber bone?
6. Repeat above with another chicken bone, only use DISTILLED water in place of vinegar. This is called a control.
Observations:
Day 3 Day 4 Day 5
Jar 1
Jar 2
Conclusions:
H1 (is the hypothesis support yes or no) and discuss observations
H2 (is the hypothesis support yes or no) and discuss observations
Discussion Questions:
1. Does the length of time the bone is in vinegar affect how much the bone bends?
2. Do different types of liquids affect how bendy bones become?
So what happened? What is so special about vinegar that it can make a hard bone squishy? Vinegar is considered a mild acid, but it is strong enough to dissolve away the calcium in the bone. Once the calcium is dissolved, there is nothing to keep the bone hard - all that is left is the soft bone tissue. Now you know why your mom is always trying to get you to drink milk - the calcium in milk goes to our bones to make our bones stronger. With some effort and you can really get the bone to bend.
Bone Growth
Your bones began to form as cartilage, long before you were born. As you grow, this cartilage is gradually hardened by minerals. As you get bigger and stronger, secondary growth centers appear at both ends of your bones. Until gull growth has been achieved, areas of cartilage remain between the areas of bone growth. These are called growth plates. All growth stops when the growth plates are fully hardened into bone. In a young man, completion of growth is determined at about 18-21 years of age by a hormone from the testicles. Later a growth line remains visible on an x ray showing where the growth took place. This x-ray shows a knee of a child approximately 10 years old. You can see lines across the ends of the femur and tibia, these are the epiphyseal lines or growth plates, these are layers of epiphyseal cartilage between the body of the bone and its end. It is growth in this layer which ultimately causes increase in length of the bone. A long bone typically has a growth plate at each end. Invariably, one grows faster than the other, and this is often called the 'growing end', although growth is of course occurring at both ends. In the lower limb, the main growing ends are at the lower end of the femur and upper end of the tibia.
A B
Can you make observations the two x rays above?
1. Which picture shows a child’s hand A or B? Explain.
2. What do you predict about the growth of the person x rayed in picture B? Why?
3. Can you count the number of bones in the human hand?
4. Why does the child’s hand look like it is missing bones?
So based on an x ray picture of your bones, a Radiologist (doctor who views x rays) can determine how much growth your bones still have to grow, and therefore, how tall you’ll be!
Broken Bones
When a bone is broken, a blood clot forms between the pieces. Within a few days this clot is invaded by immature bone cells. They produce a callus – lump of immature bone that surrounds the broken area and binds it together. Gradually the callus changes shape until the bone returns to its normal shape and strength. If the broke pieces of bone are not kept in the proper position during the healing process, the healed bone will be misshapen.
Types of Broken Bones
buckle or torus fracture: one side of the bone bends, raising a little buckle, without breaking the other side
greenstick fracture: a partial fracture in which one side of the bone is broken and the other side bends (this fracture resembles what would happen if you tried to break a green stick)
closed fracture: a fracture that doesn't break the skin
open (or compound) fracture: a fracture in which the ends of the broken bone break through the skin (these have an increased risk of infection)
non-displaced fracture: a fracture in which the pieces on either side of the break line up
displaced fracture: a fracture in which the pieces on either side of the break are out of line (which might require surgery to make sure the bones are properly aligned before casting)
fracture hematoma.Due to loss of blood supply adjacent portion of broken ends die. Inflammation changes occur in the haematoma over next few hours (A reaction by the body which occurs whenever there is an insult to a part or structure. The basic purpose of the inflammation is to contain the damage and facilitate the healing and regeneration. Inflammation is responsible for redness, pain, warmth and tenderness of the wound.)
This inflammation brings in many cells that would help in regeneration of the broken bone. Periosteum plays a vital role in fracture healing. The periosteum is the primary source of precursor cells which develop into cartilage cells and bone cells that are essential to the healing of bone. As the time progresses, the fibroblasts ( A kind of cells which produce fibrous tissue in the body) get interspersed with small vessels and form a loose mesh like structure uniting the broken ends of the bone and on which the future layers of bone tissue would be added. This structure is called granulation tissue.
Over the next few days, the cells of the periosteum replicate and transform. The periosteal cells proximal to the fracture gap develop into cartilage and form hyaline cartilage. The periosteal cells next to the fracture gap develop into bone cells and form woven bone a kind of bone which is structurally different from the hard bone found in the body. These two new tissues grow in size until they unite with their counterparts from other pieces of the fracture. This process forms the fracture callus. The callus is the first sign of union visible in x-ray and generally appears around two weeks after fracture. Eventually, the fracture gap is bridged by the cartilage and woven bone, restoring some of its original strength. A picture like this is produced.
From here on slowly and steadily bone is restructured by a process called remodeling.
Naming Important Bones
(See diagram)
Make a visual comparison about the x ray pictures Group 1 and Group 2. Record your observations. Determine when Group A and Group B in relationship to the break in the bone. Support your hypothesis using the information we have discussed this week in science.
Rubric
Use of Vocabulary Words /25
Details of Visual Observations /10
Clear Explanation of Hypothesis /15
TOTAL /50
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