The excretory system is responsible for removing waste products from the body. It includes several structures that work together to perform this function:
1. Kidneys: The kidneys are two bean-shaped organs located in the abdomen. They filter blood, removing waste products such as urea, excess water, and electrolytes.
2. Ureters: The ureters are tubes that carry urine from the kidneys to the bladder.
3. Bladder: The bladder is a muscular sac that stores urine until it is expelled from the body.
4. Urethra: The urethra is a tube that carries urine from the bladder to the outside of the body.
The main functions of these structures are:
1. Filtration: The kidneys filter waste products from the blood, including urea, excess water, and electrolytes.
2. Reabsorption: The kidneys also reabsorb useful substances such as glucose, amino acids, and water back into the bloodstream.
3. Secretion: The kidneys secrete substances such as hydrogen ions and potassium ions into the urine, helping to regulate the pH balance and electrolyte levels in the body.
4. Storage: The bladder stores urine until it is expelled from the body.
5. Elimination: The urethra carries urine from the bladder to the outside of the body, allowing for the elimination of waste products.