Skeletal System
Key Terms/Concepts
Unicellular Organisms: Organisms made up of a single cell that carry out all life processes within that cell (e.g., bacteria, amoeba, yeast).
Multicellular Organisms: Organisms composed of multiple cells that are organized into tissues, organs, and systems (e.g., humans, animals).
Skeletal System: The framework of bones that provides support, movement, and protection to the body.
Key Anatomy
Type of Bone | Where is it Present? | Description |
|---|---|---|
Long Bones | Upper and lower limbs | Long and narrow bones that support body weight and facilitate movement. |
Short Bones | Wrist and ankles | Cube-shaped bones that provide stability with little or no movement. |
Flat Bones | Skull, ribs, breastbones, hips | Thin and flat bones that provide a broad surface for muscle attachment and protect internal organs. |
Irregular Bones | Spinal column, hips | Vary in shape and structure, protecting internal organs like the spinal cord. |
Sesamoid Bones | Tendons | Small, round bones found in tendons of hands, knees, and feet. |
Key Functions of the Skeletal System
Support: Provides structure and shape to the body.
Movement: Facilitates movement by serving as attachment points for muscles.
Protection: Protects vital organs (e.g., skull protects the brain).
Key Structures
Axial Skeleton: Comprises the skull, rib cage, and vertebral column.
Appendicular Skeleton: Includes bones of the upper and lower limbs, shoulders, and hips.
Key Components of Joints
Cartilage: Reduces friction at joints during movement.
Ligaments: Tough connective tissues that connect bones at joints.
Tendons: Connect muscles to bones and control joint movement.
Facts to Memorize
Cells are the basic unit of life.
Unicellular organisms consist of a single cell (e.g., bacteria, amoeba, yeast).
Multicellular organisms consist of more than one cell (e.g., humans, animals).
Adult humans have 206 bones.
Bones are primarily made of proteins and minerals such as calcium and phosphorus.
The axial skeleton includes the skull, rib cage, and vertebral column.
The appendicular skeleton includes the bones of the upper and lower limbs, shoulders, and hips.
Reference Information
Cartilage is a soft and flexible tissue that is gradually replaced by bone as a person grows.
Calcium is a mineral that helps strengthen bones.
Joints are where two bones meet and have cartilage to reduce friction.
Concept Comparisons
Concept | Unicellular Organisms | Multicellular Organisms |
|---|---|---|
Definition | Made up of a single cell | Made up of multiple cells |
Examples | Bacteria, amoeba, yeast | Humans, animals |
Life Processes | All processes occur within one cell | Processes are divided among specialized cells |
Size | Mostly microscopic | Can be large and complex |