excretory system

• The excretory system removes wastes and helps maintain homeostasis.
• Nonsolid wastes are eliminated through lungs, skin, and kidneys.
• Lungs exhale carbon dioxide and water vapor
• Sweat glands in skin release excess water and salts.
• Kidneys filter and clean the blood to produce urine.
• The kidneys help to maintain homeostasis by filtering the blood.
• Kidneys are a pair of bean-shaped organs that include:

  –two layers: medulla and cortex

  –filtering units called nephrons

  –renal artery and renal vein
• Kidneys have three basic functions in maintaining homeostasis:

  –remove waste from blood

  –help to maintain electrolyte, pH, and fluid balances

  –release key hormones
• Nephrons clean the blood and produce urine
• Nephrons are the filtering units in the kidneys; They clean and rebalance the blood to produce urine
• Nephrons clean the blood in a three-step process:

  •The first step is filtration of the blood.

  •The second step is reabsorption of materials.

  •The third step is excretion of materials.
• A kidney transplant can replace a damaged kidney.

  –recipient and donor tissue must match

  –drugs prevent tissue rejection
• Dialysis can be used to filter and clean the blood.
• When oxygen-poor blood travels to the lungs, what is the waste product it is dropping off? What is it picking up?

  Carbon Dioxide (CO2) and water vapor and picks up Oxygen