Removes cellular wastes from the body Excretory System Removes cellular wastes from the body

Excretion is: the removal of metabolic wastes Main Excretory organs involved are: kidneys liver lungs skin

Major metabolic wastes: carbon dioxide and water CO2 and H2O are from cellular respiration certain nitrogen compounds Breakdown of amino acids from proteins produces nitrogen compounds Urea Ammonia Uric acid mineral salts from metabolism Sodium chloride (NaCl) Potassium sulfate (K2SO4)

Liver Detoxification changes harmful substances into inactive or less poisonous substances These inactive substances are returned to blood and are filtered by kidneys. liver

Formation of Urea in Liver: Amino acids are broken down. amino group, NH2→ changed to ammonia, NH3 → changed to urea (less poisonous) Urea diffuses back into bloodstream and is filtered out by the kidneys.

Urinary System Kidneys ureter urinary bladder urethra

Kidneys Two main functions: 1. Filters the blood (removes wastes from cellular metabolism) 2. Reabsorbs water ***If kidneys cannot perform these functions a person will die due to toxins building up.

Kidney Structure 3 layers of the kidney Cortex- outer layer blood is filtered to remove waste and excess substances Medulla- middle layer made up of tubes called collecting ducts that carry the filtered substances (filtrate) to the innermost layer of the kidney Pelvis- cavity that collects the filtrate and connects the kidney to the ureter which exits the kidney

Nephrons waste filtering unit of the kidney found in the cortex and the medulla 1.25 million nephrons in each kidney Contains glomerulus, Bowman’s capsule and a renal tubule

Filtration in Nephrons Blood enters kidney through renal artery, Small substances and wastes diffuse from the glomerulus capillaries into the Bowman’s capsule collecting cup and into the renal tubule of the pelvis, Water and some dissolved substances are reabsorbed into the blood through the capillary Clean blood leaves the kidney through the renal vein

So where does the waste go??? Urine- final waste fluid excreted made up of water, urea and various salts 1-1.5 liters of urine are produced every 24 hours Ureter- tube connects kidney to urinary bladder; urine travels from kidney to bladder Urinary Bladder- collects and stores urine for excretion Urethra- during urination urine travels from the bladder to the outside of the body

Skin Excretion- Small amounts of urea and salts in sweat Removal of excess heat Blood vessels dilate bringing more warm blood to skin surface Sweat is produced by sweat glands Sweat absorbs body heat and evaporates to water vapor and body heat leaves the body in the water vapor Body cools as a result of the evaporation

Lungs Excretion- Removes CO2 and water from cellular respiration

Excretion Disorders Renal Failure- kidneys stop filtering the blood and wastes and fluid build up in the body and death can result Treatment- dialysis- artificial machine filters and cleans the blood (works because of diffusion) *Presence of protein, sugar, or other needed substances indicates other conditions such as diabetes or cardiovascular disease