Body Organization and Systems

Lesson 1: Body Organization

  • Homeostasis: The state in which the internal environment of the human body remains stable.

  • Levels of Organization:

    • Cell

    • Tissue: A group of similar cells performing a common function.

    • Organ: A collection of tissues carrying out specialized functions.

    • Organ System: A group of organs working together for a specific function.

    • Organism

Types of Tissue

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  1. Epithelial Tissue: Covers and protects underlying tissues (e.g., lining of intestine).

  2. Nervous Tissue: Sends electrical signals throughout the body (e.g., brain).

  3. Muscle Tissue: Contracts and relaxes to produce movement (e.g., cardiac).

  4. Connective Tissue: Joins, supports, and protects organs (e.g., bones).

Lesson 2: The Skeletal System

  • Function: Supports, protects, and allows movement of the body.

  • Protection: Skull, ribs, and backbone.

  • Storage: Stores minerals aiding nerve and muscle function.

  • Movement: Skeletal muscles pull on bone.

  • Blood Cell Formation: Bone marrow.

Types of Bone Tissue

  • Compact Bone: Rigid and dense with no visible open spaces.

  • Spongy Bone: Bone tissue with many open spaces.

Joints and Ligaments

  • Cartilage: Strong, flexible connective tissue supporting bones.

  • Joint: Place where two or more bones meet.

  • Types of Joints:

    • Gliding Joint: Allows bones to glide (e.g., wrist).

    • Ball-and-Socket Joint: Allows movement in all directions (e.g., shoulder).

    • Hinge Joint: Allows back and forth movement (e.g., knee).

  • Ligaments: Strong elastic bands of connective tissue.

Lesson 3: The Muscular System

  • Function: Controls movement, posture, and blood circulation.

Types of Muscle

  1. Smooth Muscle: Involuntary, smooth, lacks cross stripes.

  2. Cardiac Muscle: Makes up the heart, pumps blood.

  3. Skeletal Muscle: Voluntary, controls movement, posture, and balance.

Muscle Actions

  • Voluntary Muscle: Under your control.

  • Involuntary Muscle: Not under your control.

  • Tendons: Connect skeletal muscles to bones.

  • Flexor: Bends part of the body.

  • Extensor: Straightens part of the body.

Exercise and Injuries

  • Resistance Exercise: Working against weight.

  • Aerobic Exercise: Increases heart rate.

  • Strain: Overstretched or torn muscle/tendon.

  • Tendinitis: Inflamed, swollen, or irritated tendon.

Lesson 4: The Integumentary System

  • Function: Forms a protective covering on the body’s exterior (includes skin, hair, nails).

Functions of Skin

  1. Protection

  2. Absorption

  3. Secretion

  4. Excretion

  5. Heat Regulation

  6. Sensation