2. The excretory system consists of:

The excretory system is largely associated with the urinary, or renal, system. This system consists of various organs that produce and then excrete the urine out of the body: the kidneys, ureters, the bladder, and the urethra. They include the kidneys, large intestine, liver, skin, and lungs. The kidneys filter blood and form urine. They are part of the urinary system, which also includes the ureters, bladder, and urethra. Each kidney has more than a million nephrons, which are the structural and functional units of the kidney.

Explanation:

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what do the different brain waves do?

explanation:

brainwaves are produced by synchronised electrical pulses from masses of neurons communicating with each other. brainwaves are detected using sensors placed on the scalp. brainwave speed is measured in hertz (cycles per second) and they are divided into bands delineating slow, moderate, and fast waves.