Overview
This lecture covers the structural organization of the human body, explaining its six levels of organization and outlining the eleven major organ systems, their primary organs, and functions.
Levels of Structural Organization
- The body’s structure is organized into six main levels of complexity.
- Chemical level: subatomic particles, atoms, and molecules make up all matter.
- Cellular level: cells are the smallest independently functioning units of life, composed of a membrane, cytoplasm, and organelles.
- Tissue level: tissues are groups of similar or related cells working together for a common function.
- Organ level: organs are anatomically distinct structures made of at least two tissue types, performing specific physiological roles.
- Organ system level: organ systems are groups of organs that cooperate to perform major body functions.
- Organism level: the human organism is a living being capable of all physiological functions required for life.
The Eleven Organ Systems and Functions
- Integumentary system: includes skin, hair, nails; protects body and senses environment.
- Skeletal system: bones, cartilage, joints; supports the body and enables movement.
- Muscular system: skeletal muscles, tendons; enables movement and helps maintain temperature.
- Nervous system: brain, spinal cord, nerves; detects/processes sensory information and controls body responses.
- Endocrine system: glands like pituitary, thyroid, pancreas; secretes hormones to regulate processes.
- Cardiovascular system: heart, blood vessels; delivers oxygen/nutrients and helps regulate temperature.
- Lymphatic system: thymus, spleen, lymph vessels/nodes; returns fluid to blood and defends against pathogens.
- Respiratory system: nasal passages, trachea, lungs; delivers oxygen and removes carbon dioxide.
- Digestive system: stomach, liver, intestines; processes food and eliminates waste.
- Urinary system: kidneys, urinary bladder; controls water balance and removes blood waste.
- Reproductive system: testes, ovaries, uterus; produces sex hormones, gametes, and supports offspring.
Biological Sex in Anatomy
- "Female" and "male" in this course refer only to typical biological sex, not gender identity.
- Most organ systems and structures are discussed in context of XX and XY individuals.
Key Terms & Definitions
- Atom — smallest unit of an element, composed of subatomic particles.
- Molecule — two or more atoms bonded together.
- Cell — smallest unit of a living organism, performing life functions.
- Tissue — group of similar or related cells with a specific function.
- Organ — body structure made of two or more tissue types with distinct roles.
- Organ system — group of organs working together to perform major functions.
- Organism — a living being with all levels of organization functioning together.
Action Items / Next Steps
- Review the eleven organ systems and memorize one organ and function for each.
- Study the six levels of structural organization and be able to list them in order.
- Read related textbook sections for further detail on each organ system.