# The human body

The body is composed of multiple independent systems that work with each other.

- These systems are highly interconnected, but can be parsed based on the [purpose](purpose.md) they accomplish.

1. Breathing (respiratory)
   - Releases carbon dioxide and exchanges it for oxygen
   - Nose, mouth, paranasal sinuses, pharynx, larynx, trachea, bronchi, lungs, thoracic diaphragm
2. Food (digestive + excretory)
   - Takes in nutrients, excretes solid waste
   - Teeth, tongue, salivary glands, esophagus, stomach, liver, gallbkadder, pancreas, small intestine, large intestine, rectum, anus
3. Blood (circulatory)
   - Transports nutrients, waste, hormones, oxygen, carbon dioxide, assists in maintaining pH and temperature
   - Blood, heart, arteries, veins, capillaries
4. Peeing (urinary)
   - Maintains fluid and electrolyte balance, purifies blood, excretes urine
   Kidneys, ureters, bladder, urethra
5. Exterior (integumentary)
   - Protects the body and regulates heat
   - Skin, hair, fat, nails
6. Structure (skeletal)
   - Structurally supports and protects the body, produces blood cells
   - Bones, cartilage, ligaments, tendons
7. Movement (muscular)
   - Moves the body, produces heat
   - Skeletal muscles, smooth muscles, cardiac muscle
8. Signals (endocrine)
   - Communicating with hormones created by endocrine glands
   - Hypothalamus, pituitary, pineal, thyroid, parathyroid, adrenal, ovaries/testicles
9. Lubrication (exocrine)
   - Ceruminous, lacrimal, sebaceous, mucus
10. Internal protection (lymphatic)
    - Returns fluid from tissues for recirculation, aids immune responses, makes white blood cells
    - Lymph, lymph nodes and vessels, tonsils, spleen, thymus
11. Information (nervous)
    - Senses and processes information, controls body activities
    Brain, spinal cord, nerves, sensory organs
12. Reproduction
    - Sex organs involved in reproducing life
    - Ovaries, fallopian tubes, uterus, vagina, vulva, penis, testicles, vasa defentia, seminal vesicles, prostate

Almost all of these systems runs through [the central flow of the spine](body.jpg).