Physiology: biological systems
The major systems covered in the study of human physiology are as follows:
Circulatory system - including the heart, the blood vessels, properties of the blood, and how circulation works in sickness and health.
Digestive/excretory system - this domain charts the movement of solids from the mouth to the anus and includes study of the spleen, liver, and pancreas, the conversion of food into fuel and its consequent expulsion from the body.
Endocrine system - the study of endocrine hormones that carry signals throughout the organism, helping it to respond in concert. The principal endocrine glands - the pituitary, thyroid, adrenals, pancreas, parathyroids, and gonads - are a major focus, but nearly all organs release endocrine hormones.
Immune system - the body's natural defense system is comprised of white blood cells, the thymus, and lymph systems. A complex array of receptors and molecules combine to protect the host from attacks by pathogens. Molecules such as antibodies and cytokines feature heavily.
Integumentary system - the skin, hair, nails, sweat glands, and sebaceous glands (secreting an oily or waxy substance).
Musculoskeletal system - the skeleton and muscles, tendons, ligaments, and cartilage. Bone marrow - the site of red blood cell creation - and how bones store calcium and phosphate are included.
Nervous system - the central nervous system (brain and spinal cord) and the peripheral nervous system. Study of the nervous system includes research into the senses, memory, emotion, movement, and thought.
Renal/urinary system - including the kidneys, ureters, bladder, and urethra, this system removes water from the blood, produces urine, and carries away waste.
Reproductive system - consisting of the gonads and the sex organs. Study of this system also includes investigating the way a fetus is created and nurtured for 9 months.
Respiratory system - consisting of the nose, nasopharynx, trachea, and lungs. This system brings in oxygen and expels carbon dioxide and water.