Complex organ systems are the integrated networks of organs, tissues, and cells that work together to carry out specific functions in the human body. These systems are essential for maintaining homeostasis and allowing the body to carry out various physiological processes.

Study Guide:

Cardiovascular System: This system consists of the heart, blood vessels, and blood. It is responsible for transporting oxygen, nutrients, and hormones to cells, and removing waste products from the body.
Respiratory System: Comprised of the lungs, airways, and respiratory muscles, this system facilitates the exchange of oxygen and carbon dioxide between the body and the environment.
Digestive System: This system includes the mouth, esophagus, stomach, intestines, liver, and pancreas. Its function is to break down food and absorb nutrients for energy and growth.
Endocrine System: Consisting of glands such as the pituitary, thyroid, and adrenal glands, this system regulates bodily functions through the production and secretion of hormones.
Nervous System: Comprised of the brain, spinal cord, and nerves, this system controls and coordinates body activities through electrical impulses and chemical signals.
Urinary System: This system includes the kidneys, ureters, bladder, and urethra. Its primary function is to eliminate waste products from the body and maintain fluid and electrolyte balance.
Reproductive System: Involving the sex organs, this system is responsible for the production of gametes (sperm and eggs) and the perpetuation of the species through reproduction.
Immune System: Comprising white blood cells, lymph nodes, and the spleen, this system defends the body against pathogens and foreign substances, and helps to maintain overall health.