Excretory System

Removing unwanted waste

Excretory System

• System involved in removing metabolic waste• Waste removed as urine, sweat, carbon

dioxide– Urine- water and waste produced from metabolic

processes

Organs involved• Lungs

– Remove carbon dioxide resulting from the breakdown of sugar during cellular respiration

• Skin– Removes water and urea through sweat glands

• Kidneys– Remove excess water and urea from blood stream, sending to the

bladder• Liver

– ***Site of much protein breakdown in the body, resulting in excess nitrogen

– Detoxifies harmful substances in the blood– Produces enzymes to break fat

Sources of waste

• Cellular respiration– Carbon from glucose as well as other materials

must be removed from body. Done so by sending carbon dioxide to blood, then to lungs

• Deamination (in liver)-when proteins are broken down, the amine groups (containing N) from amino acids are removed, and must exit the body– Amine group main component in urea

Route of waste in body

• Food digested• Absorbed through intestines into blood stream– Carbs broken down, sent to mitochondria for

cellular respiration• carbon dioxide

– Proteins broken down as long-term energy• Nitrogen removal through kidneys to bladder

• Nutrients not wanted pass through colon and out through rectum.

Main organ- kidney

• Kidney function-– Absorption– Active transport– Diffusion– osmosis

General system structure

Kidney structure

Renal cortex

• Outer portion of kidney• Holds most of the nephron, the functional

portion of the kidney

Renal medulla

• Inner portion of kidney, with many capillaries carrying blood to cortex– Contains lower part of nephron– Holds collecting tubes carrying excess material to

center of kidney

nephron

• Tangle of small capillaries and collecting ducts working to remove water and waste from blood

• Large amounts (4x body’s content) of water removed every day, then most reabsorbed back into blood stream

Nephron structure• Water and waste removed in glomerulus• Travels down tubules, where much of

water and salt reabsorbed in loop of henle• Excess water and metabolic waste sent

down collecting duct to be sent to ureter

glomerulus

• Area where metabolic waste is originally pulled out of blood stream along with water

• Fluid then continues down the renal tubule through the loop of Henle, then throughout the tube until reaches collecting duct

ureter

• From nephrons, all collected waste is removed from kidney through ureter– Long tube descending from kidney, leading to

urinary bladder

urethra

• Once waste has been collected in bladder, it is removed from bladder through small opening called urethra