Excretion – removes cellular waste Excretory System Excretion – removes cellular waste Your excretory system collects wastes produced by cells and removes these wastes from your body. The removal process is known as excretion.

Cellular Waste Heat Water – H2O Salts Carbon dioxide - CO2 Urea W/O excretion poisonous wastes build up in blood, cells, and tissues. Could lead to serious illness & eventually DEATH!

Four Organs of the Excretory System The lungs excrete CO2 as a waste products The skin rids the body of wastes through the sweat glands. The liver excretes bile and converts nitrogenous waste from the break down of proteins into urea. The kidneys are the major organ in the urinary system.

Filters nitrogen out of your blood  UREA Liver

Liver Produces Urea Functions in Excretion Forms Urea Changes toxic wastes (ammonia – from break down of amino acids) to Urea. Urea  Blood  Kidneys Filtered out & excreted in Urine

DETOXIFIES the blood (removes toxins such as drugs and alcohol) https://www.youtube.com/watch?v=FSprnYACYJI

A liver is about 3 pounds in an average human and it is rubbery to touch.

The Main Parts of the Excretory System

Kidneys & Urinary System Two Fist sized Bean shaped

Each kidney is about 4 ½ inches long Weight is 4 – 6 ounces The urine output varies from 1 to 2 liters per day.

The ureters are tubes that carry urine from the kidneys to the urinary bladder. The urinary bladder temporarily stores urine until it is released from the body. The urethra is the tube that carries urine from the urinary bladder to the outside of the body. The outer end of the urethra is controlled by a circular muscle called a sphincter. skin lungs kidneys ureters urinary bladder urethra

two layers: medulla and cortex filtering units called nephrons renal artery and renal vein cortex medulla renal artery renal vein ureter (to bladder)

Contains nephrons

Nephrons clean the blood and produce urine. from body to body from other nephrons loop of Henle There approximately 1 million nephrons in each kidney

Nephrons clean the blood in a three-step process. The first step is filtration of the blood. FILTRATION Water, electrolytes, amino acids, glucose, urea, and other small molecules diffuse out of the blood, creating the filtrate. 1 Glomerulus: Network of capillaries Bowman’s Capsule: Encases the glomerulus Glomerulus Bowman’s capsule The body’s entire volume of blood is filtered every 45 min

from body collecting duct to body from other nephrons loop of Henle The first step is filtration of the blood. The second step is reabsorption of materials. from body to body collecting duct from other nephrons loop of Henle REABSORPTION As the filtrate enters the rest of the tubule, most of the materials are reabsorbed into the blood. Materials not reabsorbed make up the urine, which flows into the loop of Henle. 2

The first step is filtration of the blood. The second step is reabsorption of materials. The third step is excretion of materials. from body to body collecting duct from other nephrons loop of Henle EXCRETION In the loop of Henle, water can be reabsorbed one final time to reduce the volume of urine. The remaining urine flows into a collecting duct that leads to the ureter. 3

Ureters Narrow muscular tubes Connect Kidney  Bladder Bladder Muscular sac Stores Urine Expand to fill Sphincter muscle relaxes Urine squeezed into Urethra

Urinary bladder http://www.youtube.com/watch?v=uAy5C2YYlbk

Urinary System - endpoint Urethra Tube leading from Bladder  outside of body

Produce URINE Water, salt and urea

2.Which organ produces urea? 1.Identify A, B, and D. 2.Which organ produces urea? 3.What is the function of D? 4.What does organ A excrete? 5.Which organ detoxifies the blood? Lungs Urea Filter urea from the blood. Liver CO2, H2O Kidney Liver

Identify structures A, B, C, and D. Which structure produces urine? What is the path of urine? What are the 2 main functions of A? 5. What stores urine? 6. What is the function of D? Kidney Kidneys Kidney, ureters, urinary bladder, urethra Ureter Filter the blood Regulate the amount of H2O in blood. Urinary bladder Urinary bladder Urethra Transport urine out of body.