the excretory system

• Homeostasis is the body's attempt to maintain a constant internal environment
• One major way the body achieves homeostasis is through excretion, the process of removing waste and excess water from the body
• Excretion is the removal of unwanted substances of metabolism, which are produced by many metabolic reactions in the body
• Three products of excretion are:

  • Carbon dioxide
  • Sweat
  • Urea
• Organs of excretion include the lungs, skin, and kidneys
• Carbon dioxide is produced by cells in the body through aerobic respiration and is excreted through the lungs
• Sweat is produced by sweat glands in the skin and helps regulate body temperature in hot conditions; it contains salts and urea
• Urea, formed by excess amino acids, is produced in the liver and excreted by the kidneys in urine
• Amino acids are compounds that combine to make proteins
• Kidneys are responsible for removing waste products and extra fluid from the body, balancing fluids, releasing hormones that regulate blood pressure, balancing minerals and chemicals, and aiding in red blood cell production
• The cortex of the kidney provides a space for arterioles and venules to supply blood to the nephrons

  • The medulla regulates the concentration of urine
  • The renal pelvis functions as a funnel for urine flowing to the ureter
• • Our bodies have two kidneys located at the posterior side of the abdominal cavity.
  • Ureters carry urine away from the kidneys to the bladder where it is stored. This is then expelled by the urethra