AP1+Chap+6-+Bone+Tissue

Skeletal System: Tissues

Four Components of the Skeletal System

  • Cartilage

  • Bone

  • Tendons

  • Ligaments

Functions of the Skeletal System

  • Produce Blood Cells

  • Protect Internal Organs

  • Stores and Releases Fat

  • Stores and Releases Minerals

  • Supports the Body

  • Facilitates Movement

Support and Protection

  • Bones provide a rigid framework that supports the body's weight and shape.

  • They protect vital organs, including:

    • Brain

    • Heart

    • Lungs

    • Spinal cord

Movement

  • Bones function as levers for muscles to attach to.

  • They enable movement by providing a stable base for muscle contraction.

  • Important to know at least three types of movement that bones facilitate.

Lever Mechanics

  • Levers can amplify a small force into a much larger one, characterized by the term mechanical advantage.

  • In the body:

    • Bones act as lever arms

    • Joints act as pivots

    • Muscles provide force for moving loads.

Key Terms Related to Levers

  • Effort: The force applied to the lever.

  • Pivot: The point about which the lever rotates.

  • Load: The weight or resistance that the lever acts against.

Torque

  • Torque: A measure of the force that can cause an object to rotate about an axis.

  • Example explanation of torque: When a load tries to turn the lever clockwise, the effort tries to turn it anticlockwise. Factors influencing torque include:

    • Distance from the pivot: e.g., pushing a door is easier near the handle than by the hinge.

  • In the context of the leg:

    • The load and weight of the lower leg produce a clockwise torque around the knee.

    • When the hamstring contracts with a strong force, it produces an anticlockwise torque that holds the leg up.

Types of Joints

  • Condyloid

  • Saddle

  • Pivot

  • Gliding

  • Hinge

  • Ball and Socket

Mineral Storage in Bones

  • Bones store substantial amounts of:

    • Calcium: Essential for bone health, muscle contraction, nerve function, and blood clotting. Bones store approximately 99% of the body's calcium. It releases calcium into the bloodstream when levels drop to maintain homeostasis.

    • Phosphorus: Essential for bone formation, cell growth, and energy metabolism. Bones contain about 85% of the body's phosphorus. It is released during low calcium levels or high energy demand.

    • Other minerals such as magnesium, sodium, and potassium.

Regulation of Mineral Storage

  • The regulation involves a complex system comprising:

    • Hormones: Influence deposition and release of minerals.

    • Enzymes

    • Cells:

    • Osteoblasts: Bone