Anatomy: Levels of Organization

Study Notes

Anatomy investigates the structure of organisms and their parts.
It forms the foundation for medicine and pharmacy, explaining how drugs interact with the body.

Chemical Level: Atoms combine to create molecules, which are the building blocks of cells.
Cellular Level: Cells are the basic functional units of the body, each type performing specific tasks.
Tissue Level: Similar cells group together to form tissues with specific functions. There are four main tissue types:
- Epithelial: Covers surfaces and lines cavities.
- Connective: Provides support, protection, and binds tissues together.
- Muscle: Responsible for movement.
- Nervous: Transmits signals throughout the body.
Organ Level: Organs are composed of multiple tissue types working together for specific functions.
Organ System Level: Multiple organs working together to carry out a larger, unified function. Examples include:
- Digestive
- Respiratory
- Circulatory
Organism Level: All organ systems together form a complete organism, such as the human body.

Integumentary System: Includes skin, hair, nails, and glands. It protects the body from external threats and regulates temperature.
Skeletal System: Composed of bones, cartilage, ligaments, and tendons. Provides support, protection, and enables movement.
Muscular System: Muscles, tendons, and ligaments. Responsible for movement, stability, and heat generation.
Nervous System: Brain, spinal cord, nerves, and sensory organs. Controls and coordinates body functions, responding to both internal and external stimuli.
Endocrine System: Glands like the pituitary, thyroid, and adrenal glands. Produces hormones that regulate various physiological processes.
Cardiovascular System: Heart and blood vessels. Transports nutrients, oxygen, hormones, and waste products throughout the body.
Respiratory System: Facilitates oxygen and carbon dioxide exchange between the body and the environment through breathing.
Digestive System: Stomach, intestines, liver, and pancreas. Breaks down food, absorbs nutrients, and eliminates waste.
Urinary System: Kidneys, ureters, bladder, and urethra. Filters blood, eliminates waste, and regulates electrolyte balance.
Reproductive System: Produces offspring. Includes organs like ovaries, testes, and associated structures.

Anatomical Position: A standardized position for describing body parts.
- Body is standing erect, looking forward.
- Upper limbs hanging by the side, palms facing forward.
- Feet together.
Supine Position: Body is lying on its back.
Prone Position: Body is lying on its face.

Anterior (Ventral): Nearer to the front of the body.
Posterior (Dorsal): Nearer to the back of the body.
Superior (Cephalic/Cranial): Nearer to the head.
Inferior (Caudal): Nearer to the feet.
Proximal: Nearer to the root of a structure (usually the root of a limb or vessel).
Distal: Away from the root of a structure.
Medial: Nearer to the midline of the body.
Lateral: Away from the midline of the body.
Superficial: Nearer to the skin.
Deep: Away from the skin.
Middle (Medius): Between superior and inferior or anterior and posterior.
Intermediate: Between medial and lateral.
Internal: Nearer to the interior of the body.
External: Away from the interior of the body.