Water Regulation – Excretory & Integumentary Systems

Water Regulation

The process by which the body maintains a proper balance of water and electrolytes to ensure stable internal conditions (homeostasis).

Homeostasis (in water balance)

The maintenance of stable internal water levels and solute concentration, despite changes in hydration or environment.

Osmoregulation

The control of water and salt balance in the body by regulating the movement of water between cells and body fluids.

Excretory System

The organ system responsible for filtering blood, removing waste, and regulating water and electrolyte levels; includes kidneys, ureters, bladder, and urethra.

Integumentary System

The body system composed of skin, sweat glands, hair, and nails; helps regulate body temperature and water loss.

Kidney

The main organ of the excretory system; filters blood to remove wastes and controls water and salt balance.

Nephron

The functional unit of the kidney where filtration, reabsorption, and secretion occur to form urine and regulate water balance.

Glomerulus

A network of capillaries in the nephron that filters blood, removing water, ions, and waste to form filtrate.

Reabsorption (in kidneys)

The process in which useful substances and water are returned from the nephron back into the bloodstream.

Antidiuretic Hormone (ADH)

A hormone released by the pituitary gland that increases water reabsorption in the kidneys, reducing urine output when the body is dehydrated.

Aldosterone

A hormone produced by the adrenal glands that increases sodium reabsorption and water retention in the kidneys.

Dehydration

A condition where water loss exceeds intake, leading to increased ADH release and reduced urine output.

Overhydration

Excess water intake that lowers solute concentration; ADH secretion decreases, leading to increased urine output.

Urine Concentration

The amount of solute in urine, controlled by kidney reabsorption and ADH levels to maintain water balance.

Sweating (perspiration)

Water and salt are released from sweat glands in the skin to cool the body; results in minor water loss.

Skin (as part of water regulation)

Acts as a barrier to prevent excessive water loss and houses sweat glands that regulate temperature and water output.

Sweat Glands

Structures in the dermis that secrete sweat to the skin surface; help regulate temperature and water balance.

Vasodilation (in skin)

Widening of blood vessels near the skin’s surface to release heat and promote sweating when the body overheats.

Vasoconstriction (in skin)

Narrowing of blood vessels to conserve heat and reduce water loss when the body is cold.

Interaction Between Systems

The excretory system controls internal water balance through urine output, while the integumentary system regulates water loss through sweat.