Integumentary System: skin, hair nails, exocrine glands (sweat glands, oil glands)
Skeletal System: bones, joints, cartilage
Muscular System: skeletal muscles. smooth muscles, cardiac muscle
Nervous System: brain, spinal cord, nerves
Endocrine System: hypothalamus, pineal body, pituitary, thyroid, parathyroid, thymus, adrenal gland, pancreas, ovary, testis
Cardiovascular System: heart, veins, arteries, capillaries
Lymphatic System: bone marrow, spleen, thymus, lymph nodes, lymphatic vessels
Respiratory System: nose, pharynx, larynx, trachea, bronchi, lungs
Digestive System: mouth, esophagus, stomach, small intestine, large intestine, rectum, anus
Urinary System: kidneys, renal pelvis, ureters, bladder, urethra
Reproductive System: male – testes, epididymis, vas deferens, seminal vesicles, prostate, penis, scrotum
female – ovaries, fallopian tube, uterus, vagina, mammary glands
The urinary system and respiratory system are the two main modulators of pH levels in the body. The respiratory system adjusts the pH by the expiration of carbon dioxide since carbon dioxide forms carbonic acid when combined with water. The urinary system affects pH levels through reabsorption of bicarbonate and excretion of fixed acids