Bones and Bone Tissue: Structure, Function, and Physiology

The Skeletal System

Overview of the Skeletal System

The skeletal system is a complex organ system that provides structure, protection, and support for the human body. It consists of bones, joints, and supporting tissues.

• Bones: The main organs of the skeletal system. Adults typically have 206 bones.

• Each bone includes:

  • Bone (Osseous) Tissue

  • Dense regular collagenous tissue

  • Dense irregular connective tissue

  • A tissue called Bone Marrow

Functions of the Skeletal System

Major Functions

The skeletal system performs several vital functions necessary for survival and homeostasis.

• Protection: Bones such as the skull, sternum, and ribs protect underlying organs from mechanical damage.

• Mineral Storage and Acid-Base Homeostasis: Bones store minerals including calcium, phosphorus, and magnesium salts. These minerals are electrolytes and are critical for maintaining electrolyte and acid-base balance in the blood.

• Blood Cell Formation: Red bone marrow is the site of hematopoiesis, the formation of blood cells.

• Fat Storage: Yellow bone marrow contains adipocytes that store triglycerides, serving as an energy reserve.

• Movement: Bones serve as sites of attachment for skeletal muscles. Muscle contraction pulls on bones, generating movement around joints.

• Support: The skeleton supports the weight of the body and provides its structural framework.

Summary Table: Functions of the Skeletal System

Function	Description	Example
Protection	Shields vital organs from injury	Skull protects the brain
Mineral Storage & Acid-Base Homeostasis	Stores minerals and helps regulate blood pH	Calcium and phosphate storage
Blood Cell Formation	Produces blood cells in red marrow	Hematopoiesis in long bones
Fat Storage	Stores energy as fat in yellow marrow	Triglyceride storage in femur
Movement	Acts as levers for muscles	Arm and leg movement
Support	Provides structural framework	Vertebral column supports trunk

Key Terms

• Hematopoiesis: The process of blood cell formation, occurring in red bone marrow.

• Electrolyte: A substance that conducts electricity when dissolved in water, essential for nerve and muscle function.

• Triglyceride: A type of fat stored in yellow bone marrow, serving as an energy reserve.

Example

• When a person runs, the skeletal system provides the rigid framework for muscle attachment, stores calcium needed for muscle contraction, and protects internal organs from impact.