Excretory System Honors Biology Powerpoint #5

Excretory System Function: The excretory system eliminates nonsolid wastes from the body. 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. skin lungs kidneys ureters urinary bladder urethra

Excretory System The ureters are tubes that carry urine from kidneys to urinary bladder. The urinary bladder temporarily stores urine until released from body. The urethra is the tube that carries urine from 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

Excretory System Function of the Kidney filter blood to remove cellular waste products from the body. At any given time, 20 % of blood is in the kidneys. Humans can function with one kidney. If one ceases to work, the other increases in size to handle the workload.

Excretory System The kidneys help to maintain homeostasis by filtering the blood. The kidneys are fist-sized, bean shaped structures. –two layers: medulla and cortex –filtering units called nephrons –renal artery and renal vein cortex medulla renal artery renal vein ureter (to bladder)

Excretory System The kidney can also excrete other waste products, such as : 1) urea a nitrogenous waste produced in the liver from the breakdown of protein. It is the main component of urine 2) uric acid usually produced from breakdown of DNA or RNA 3) creatinine waste product of muscle action.

Excretory System Kidneys have three basic functions in maintaining homeostasis. –remove waste from blood –help to maintain electrolyte, pH, and fluid balances –release key hormones

Excretory System Nephrons clean the blood and produce urine. Nephrons are the filtering units in the kidneys. They clean and rebalance the blood to produce urine. There are approximately 1 million nephrons in each kidney from body to body from other nephrons loop of Henle

Excretory System 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 Bowman’s capsule Glomerulus: Network of capillaries Bowman’s Capsule: Encases the glomerulus The body’s entire volume of blood is filtered every 45 min

Excretory System 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 Filtrate enters the rest of the tubule most materials are reabsorbed into blood. Materials not reabsorbed make up the urine, which flows into the loop of Henle. 2

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

Excretory System Injury and disease can damage kidney functions. A kidney transplant can replaced damaged kidney. –recipient and donor tissue must match –drugs prevent tissue rejection The daughter and son in this photo donated a kidney and liver tissue to their mother.

Excretory System Dialysis can be used to filter and clean the blood.