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, some of which are toxic
• Metabolism refers to the chemical reactions in the body's cells that change food into energy
• Three products of excretion are: Carbon dioxide, sweat, and urea
• Organs of excretion include the lungs, skin, and kidneys
• Carbon dioxide is produced by cells in the body through reactions of aerobic respiration and is excreted in the air we breathe out
• Sweat, produced by sweat glands in the skin, helps to keep the body cool in hot conditions and contains salts and urea
• Urea, formed by excess amino acids in the liver, is transported to the kidneys via blood plasma, where it is removed from the blood and excreted as urine
• Amino acids are compounds that combine to make proteins, and when proteins are digested or broken down, amino acids are left
• The cortex of the kidney provides a space for arterioles and venules from the renal artery and vein to supply the nephrons with blood
• The main function of the medulla in the kidney is to regulate the concentration of urine
• The renal pelvis in the kidney functions as a funnel for urine flowing to the ureter
• The two kidneys are located at the posterior side of the abdominal cavity
• The ureters carry urine away from the kidneys to the bladder where it is stored
• Urine is then expelled by the urethra
• The excretory system includes: vena cava, aorta, renal artery, renal vein, kidneys, pelvis, ureter, bladder, urethra
• Functions of the kidneys:

  • Remove waste products and extra fluid from the body
  • Remove drugs from the body
  • Balance the body's fluids
  • Release hormones that regulate blood pressure
  • Balance minerals and chemicals
  • Help with red blood cells production