Ausscheidens

Ausscheidens, in biological contexts, refers to the substances produced by metabolism that are eliminated from an organism as waste. The term corresponds to excretions in English. Excretion is essential for maintaining internal chemical balance and preventing the accumulation of harmful compounds. It involves coordinated activity across specialized organs, tissues, and cellular processes that transport, transform, or release waste products from the body.

Major excretory pathways include the kidneys, lungs, skin, and the digestive system. Kidneys filter blood to form urine, performing filtration, selective reabsorption, and secretion to remove water-soluble wastes. The lungs expel carbon dioxide and some water vapor. The skin sheds sweat, carrying water, salts, and trace wastes. The liver processes toxins and bilirubin; wastes are then eliminated in bile and, ultimately, in feces via the digestive tract.

Common excretions vary among organisms. Humans primarily excrete water, salts, urea, creatinine, and CO2; many reptiles and birds convert nitrogen to uric acid, which reduces water loss. Aquatic animals often excrete ammonia directly. Feces also represent elimination of indigestible matter and microbial by-products through the digestive tract. Together with urine, sweat, bile, and breath, these products sustain homeostasis.

Impaired excretion can lead to toxin buildup, electrolyte imbalance, or fluid overload. Diseases of the kidneys, liver, or lungs can disrupt excretion, highlighting the excretory system’s role in health and physiology.