6.1 2.2.2 human skeleton  (Page 4/4)

Structure of a long bone

Parts of a long bone

Epiphysis: The head of each end of a long bone covered with hyaline cartilage and consisting largely of spongy bone .

Diaphysis: Cylindrical shaft of a long bone composed of hard compact bone on the outside

Periosteum: The membrane of dense fibrous connective tissue which surrounds the outside surface of the shaft of a long bone. It has blood vessels which enables it to nourish the bone and repair injuries. It also provides a surface for the attachment of muscles, by means of tendons and ligaments.

Marrow cavity: This is filled with yellow marrow which consists largely of fat.

Endosteum: The delicate connective tissue layer lining the inside surface of compact bone.

Cancellous/spongy bone : Found in the epiphysis of long bones and contain red marrow.

Trabeculae: The struts in the network of irregular bony plates in the epiphysis of bones which transfer stresses from the epiphysis to the diaphysis which has a much thicker layer ofcompact bone and resists stress better.

Red bone marrow: Found in the spaces between the trabeculae in spongy bone. This is where the red blood cells are made at the rate of 2 -3 million per second. White blood celltypes are also produced here.

TYPES OF BONES

• Long bones have a central shaft and two heads, one at each end. An example is the femur , which is the largest bone in the body.
• Flat bones have two layers of compact bone covering a layer of spongy bone on the inside, for example the shoulder blades .
• Irregular bones and short bones have a thin layer of compact bone covering spongy bone on the inside, for example vertebrae of the spine and the small bones in the hands and feet.

Practical investigation

Experiment A:

Aim: To investigate the role of the inorganic and organic components of bone

Apparatus: Exp A.: 2 small chicken bones

2 test tubes

Dilute hydrochloric acid

Towel

Method:

1. Label 2 test tubes with your initials and A and B. Put a bone in each tube.

2.Cover Bone A with water and Bone B with dilute hydrochloric acid. Leave for a few days. The acid will dissolve out the mineral component of the bone leavingbehind the organic part

3.Take out Bone A and dry it.

4.Use tweezers to take Bone B out of the acid. Rinse it under the tap and dry it.

5.Compare the two bones and not down how they appear and whether they are soft or hard, flexible or brittle

Experiment B

Apparatus: 1 small chicken bone

Pipe clay triangle or wire gauze on a tripod stand

Bunsen burner or Methylated spirits burner

Method:

1. Place the chicken bone (Bone C) on a pipe triangle or wire gauze on a tripod stand

2.Roast the bone strongly for 10 minutes. Roasting will burn off the organic component of bone ( mainly the protein collagen) leaving behind the mineralpart

3.Allow the bone to cool down completely before you touch it.

4.Describe the appearance of Bone C stating whether it is soft or hard, flexible or brittle

Questions

1.What are the main inorganic components of bone?

2.What changes have occurred in Bone A?

3.What properties have been removed from the bone with the loss of it inorganic components?

4.Which deficiency disease can give similar results on bones in children?

5.What is the role of Bone B in this experiment?

6.What protein makes up the main organic component of bone?

7. What changes took place in Bone C during the roasting process?

8. What properties have been removed from Bone C with the loss of its organic component?