Chapter Review: Short Answer
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What is the bone composed of? Bone is primarily composed of a matrix made up of collagen fibers and inorganic mineral salts, predominantly calcium phosphate. This combination provides bone with both flexibility and strength. Additionally, bones contain specialized cells such as osteoblasts (which build bone), osteoclasts (which break down bone), and osteocytes (mature bone cells embedded within the matrix).
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List six functions of the skeletal system:
- Support: Provides structure and support for the body.
- Protection: Shields vital organs, such as the brain, heart, and lungs.
- Movement: Serves as attachment points for muscles, enabling movement through leverage.
- Mineral Storage: Stores essential minerals, particularly calcium and phosphorus.
- Blood Cell Production: Produces red and white blood cells in the bone marrow (hematopoiesis).
- Energy Storage: Stores lipids in the yellow bone marrow, which can be used as an energy source.
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Describe the structure of the spinal column, and list the sections that make up the spinal column. The spinal column, also known as the vertebral column or spine, consists of a series of vertebrae aligned in a vertical manner. It has a natural curvature that provides balance and support. The sections that make up the spinal column are:
- Cervical Vertebrae (C1-C7): The uppermost portion of the spine, supporting the neck.
- Thoracic Vertebrae (T1-T12): The middle section, attached to the ribs.
- Lumbar Vertebrae (L1-L5): The lower back section, characterized by larger vertebrae to bear the body's weight.
- Sacral Region (S1-S5): Composed of five fused vertebrae forming the sacrum.
- Coccygeal Region (C1-C4): The tailbone, made up of fused vertebrae.
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How is a long bone constructed? A long bone is composed of several key parts: the diaphysis, which is the long shaft made of compact bone providing strength; the epiphyses, which are the ends of the bone made of spongy bone for shock absorption; and the metaphysis, the area where the diaphysis meets the epiphysis, containing the growth plate (epiphyseal plate) in growing individuals. The outer layer of the bone is covered by a dense connective tissue called the periosteum, while the inner cavity is filled with bone marrow.
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How do long bones grow? Long bones grow in length through a process called endochondral ossification. This process occurs at the growth plates (epiphyseal plates) located at the ends of the bones, where cartilage cells divide and enlarge. As the cartilage expands, it is gradually replaced by bone tissue. Additionally, long bones can thicken through appositional growth, where new bone is added to the outer surface and old bone is reabsorbed on the inner surface.
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Identify three kinds of synovial joints, giving examples of each.
- Hinge Joint: Allows movement in one direction, like a door; example: the elbow joint.
- Ball-and-Socket Joint: Allows for a wide range of motion in multiple directions; example: the shoulder joint.
- Pivot Joint: Allows for rotation around a single axis; example: the atlantoaxial joint, which allows the head to turn side-to-side.