1. The Excretory System

2. Excretory System  Homeostasis is the regulating of a stable internal environment.  This includes removing a build-up of harmful substances in your body  Excretion – the removal of metabolic wastes from body cells to release them to the environment  The skin, lungs, and kidneys as well as their accessory organs make up your excretory system

3. Lungs  Remember  Aerobic respiration is the process of producing energy from fuels in your body cells C 6 H 12 O 6 + O 2  H 2 0 + CO 2 + ATP  H 2 0 and CO 2 are waste products that must be removed from your cells

4. Lungs  Blood transports wastes to lungs  In your lungs CO 2 and H 2 O diffuse through capillaries into the alveoli  These wastes are then expelled when your exhale

5. Liver  Your liver plays a role in recycling worn out red blood cells  Liver also produces urea  Urea – toxic waste product that results from the breakdown of amino acids  Deamination – the chemical breakdown of amino acids

6. Sweat Glands  Believe it or not, but your sweat is a form of excreting wastes from your body!  Excess water, salts, and even urea from your blood stream are excreted as perspiration

7. Sweat Glands  Sweating also helps to remove excess heat from your body  Heat is a by-product of metabolism  Without perspiration to help remove heat your body cells could overheat  Regents question!  Give one specific reason why overheating would be detrimental to a body cell.

8. Kidneys  The main organs of the excretory system!  Your kidneys are about the size of a clenched fist and located on either side of your spine in your lower back

9. Urinary System  Ureter – a tube leading from each of the kidneys to the bladder that carry urine  Urinary bladder – collects urine from the kidneys are temporarily stores it.  Urethra – small tube that allows urine to be released from the bladder to the outside of the body

10. Kidneys  Kidneys help to regulate the chemical composition of the blood  If you regulate the blood, you regulate the body!  Blood flows to the kidneys to be “filtered”

11. Kidney Structure  Glomerulus – specialized capillary networks within the kidneys  Bowman’s capsule – cup-shaped structure surrounding glomerulus  Here soluble blood components are absorbed through diffusion  Water, salts, urea

12. Kidney Structure  Nephron – functional unit of the kidney  In the nephron loop, beneficial substances are reabsorbed by active transport  Nutrients, some water, minerals  Good components are returned to the blood  Wastes, salts, and urine remains is called urine