Name ______
Looking Inside Bone – 75 Informal Points (& 2 Formal for Bone Dissection)
Introduction
Bones are a remarkable example of engineering, combining lightness, flexibility and incredible strength. Bone provides a tough, flexible frame for the human machine. Pound for pound, bone is actually stronger than concrete. But remember, bone is living tissue. Cells and protein fibers are wrapped inside layers of hard mineral salts. These cells are hard at work, constantly remodeling and replacing old or damaged bone. Blood vessels and nerves bring needed nutrients and signals to the cells in this hard matrix. All of these structural components allow bone to withstand tremendous amounts of stress and protects the internal organs from damage and injury.
To understand how bone is able to protect our body, we must look at the anatomy of this calcified tissue. How does the structure of bone relate to its ability to withstand stress? In this activity, you willdissect a long bone and observe the key structures that contribute to bone’s unique architecture. You will then look deeper into the chemical structure of this tissue as you view prepared slides of both compact and spongy bone.
Procedure
- Research the four main types of bone – long, short, flat and irregular. Fill in the table below with your findings.
Bone Type / Description / Example(s)
Long / Hard, dense (compact) bones that provide strength, structure, and mobility. / Femur
Short / Bones that are as wide as they are long. They provide support and stability with little to no movement. / Patella, Tarsus
Irregular / Serve various purposes in the body, such as protection of nervous tissue (such as the vertebrae protect the spinal cord), affording multiple anchor points for skeletal muscle attachment (as with the sacrum), and maintain pharynx and trachea support, and tongue attachment (such as the hyoid bone) / Examples given in blue
- Use the internetto help you research and then identify the external features of long bone listed below. Fill in the table with your findings.
External Bone Feature / Description
Epiphysis / Spongy cancellous bone covered by a thin layer of compact bone.
Diaphysis / The main part, or shaft, of a long bone. It usually contains the one marrow and adipose tissue (fat.)
Cartilage / Firm, yet soft and flexible connective tissue found between bones or between bones and joints.
Periosteum / Dense, fibrous, membrane covering the surface of a bone.
Compact (Cortical) Bone / Solid bone with only tiny spaces.
Spongy (Cancellous) Bone / A network of irregularly shaped sheets of bone (trabeculae). The trabeculae are only a few cell layers thick. The spaces between the trabeculae contain the bone marrow.
Medullary Cavity / The central cavity of a bone shaft where the red bone marrow and yellow bone marrow (adipose tissue (fat)) is stored; also known as the marrow cavity.
Red Bone Marrow / Bone marrow where red blood cells, platelets and most of the white blood cells are made.
Yellow Bone Marrow / Some white blood cells are made here, but the yellow bone marrow is mostly fat (adipose tissue)
- In the space below draw a cross section of a bone. Include and label all parts listed in the table in #3.
- Long Bone Dissection: In groups of three obtain a section of cow long bone and a set of dissecting tools from your teacher. Place the bone in a dissecting tray or on a covered lab bench. Cow and human long bones have a similar general structure.
- Use the forceps to remove a piece of the periosteum from the outer surface of the bone. You may find fragments of tendon, ligament or muscle adhering to the periosteum. In the space below, describe the composition of this membrane as well as its function.
- Use the dissecting probe to compare the texture of compact and spongy bone. Poke into each tissue and feel the composition of each type of bone. Describe the difference in the space below.
- Note the location of spongy and compact bone in the epiphysis and the diaphysis.
- Examine the epiphysis and find the articular cartilage; this tissue is slippery.
- Carefully scoop out the fat from the medullary cavity. In the space below describe the composition of this marrow as you remove it from the bone. Make sure to note the presence of any blood vessels or nerves.
- Identify where red bone marrow would be located in your cow bone in the space below.
- Get a closer look at compact and spongy bone structures by viewing each type of tissue under the microscope. (Note: you may also use the internet to look up images for each.) Compact bone may appear rock solid, but it actually contains many holes for cells, nerves and blood vessels. Draw each in the table below:
Compact Bone / Spongy Bone
Magnification: ______/ Magnification: ______
- Observe a cross-section of calcified compact bone. Use colored pencils to draw and label the following structures as they appear using the 40X objective, or by looking at an image from the internet. Label the Haversian canal, osteocyte (mature bone cell) in lacuna, and canaliculi. Then, fill in the table below to describe each.
Calcified Compact Bone
Magnification: ______
Calcified Bone Feature / Description
Haversian Canal / Part of the bone that contains the blood vessels
Osteocyte / Scientific term for a bone cell
Canaliculi / Small channels or ducts found in bone
- Observe a cross-section of spongy bone. Draw and label the following structures as they appear using the 10X objective, or by viewing an image from the internet. Label the bone marrow and the bony trabeculae.
Spongy Bone
Magnification: ______
Spongy Bone Feature / Description
Bone Marrow / Red bone marrow makes red blood cells, platelets, and most white blood cells; white bone marrow makes some white blood cells but is mostly fat
Bony Trabeculae / A network of irregularly shaped sheets of bone (trabeculae). The trabeculae are only a few cell layers thick. The spaces between the trabeculae contain the bone marrow.
Conclusion Questions
- Matt was playing football when he was tacked, knocked to the ground, and piled upon, knocking him unconscious. What properties of bone prevented Matt from breaks and damage to internal organs?
Bones are hard so that they form a sturdy protection around internal organs. When the body is hit or under pressure the bones absorb the shock or break instead of the internal organs that would be more severely damaged.
- What role did Matt being knocked unconscious play in his body’s ability to resist damage? (Ie, why might being knocked unconscious be beneficial in this case?)
When unconscious the muscles relax and are not tense. If Matt was unconscious before falling his relaxed muscles would allow him to fall more gently and not hit the ground so hard. Also, being unconscious reduces the panic and anxiety that go along with getting injured, calming the body systems and allowing them to rest and heal.
- What type of fibers or minerals do you find in the extracellular matrix of bone? How does this composition relate to the properties of bone?
Calcium makes them strong.
- What aspects of bone’s structure make it stronger than concrete? Think about the engineering design of bone. Use the terms tensile strength and compressional strength in your answer.
Similar in that steel rebar allows concrete to resist stretching forces, while the cement resists compression
Bone structure is somewhat similar to reinforced concrete that contains structural metal reinforcement rods or bars. These metal reinforcements are commonly called rebar. Protein strands make up the rebar of bone. Calcium and phosphorus mineral crystals deposited around the protein strands are somewhat like the concrete poured around the rebar in reinforced concrete. The protein strands provide the tensile strength that holds everything together and the minerals provide the solid structure. If bones were made only of protein, they would be too flexible. If bones were made solely from minerals, the skeleton would be too brittle.
- How do red bone marrow and yellow bone marrow differ in function?
Red bone marrow makes red blood cells, platelets and most white blood cells. Yellow bone marrow makes some white blood cells but is mostly adipose tissue (fat.)
- Explain how the structure of spongy bone helps reduce the overall weight of bone.
It is less dense so it less compact, making it lighter.
- Describe at least two ways bone functions in protection of the human body.
Ribs protect lungs and heart. Skull protects brain.