The 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

The Parts: The kidneys are organs that serve to filter the blood. The ureters are tubes that carry urine from the pelvis of 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 the Urethral Sphincter. skin lungs kidneys ureters urinary bladder urethra

Function of the Kidney The principal function of the kidney is to filter blood in order 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 and gains assistance from the Liver.

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

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.

Kidneys have three basic functions in maintaining homeostasis. 1.remove waste from blood 2.help to maintain electrolyte, pH, and fluid balances 3.release key hormones

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 approximately 1 million nephrons in each kidney from body to body from other nephrons loop of Henle

Nephrons clean the blood in a three-step process. 1.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

2. 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

3. The third step is excretion of materials. 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 from body to body collecting duct from other nephrons loop of Henle

Injury and disease can damage kidney functions. 1.A kidney transplant can replaced damaged kidney. 2. Dialysis can be used to filter and clean the blood.

UTI (Urinary Tract Infection) Is a very common disorder. If the bladder has become infected, it is known as cystitis. If the urethra is infected., it is called urethritis. Symptoms include painful urination (burning sensation), frequent urination (even if no urine present) and bloody/brown urine. This can lead to chills, fever, nausea, vomiting and upper abdomen tenderness. Disorders of the Excretory System

Kidney Infections Result when an infection reaches the kidneys and becomes known as pyelonephritis. Common causes can be infection from elsewhere in the body or obstruction of the prostate gland (usually in older men). For children, infection can be caused by the tube that drains urine from the kidneys and the bladder.

Kidney Stones 80% of those stricken are males. Crystals formed from minerals in urine. They can be found in the kidney, ureter or bladder.

Kidney Stones (continued…) Symptoms include severe back or abdomen pain, blood in the urine, nausea and vomiting. Diagnosis involves a complete medical examination, including X-rays. Treatment may vary from letting the stones pass through the urinary tract, to ultrasound shock (or lithotripsy) to disintegrate the stones to a small size that can be passed through the urinary tract. Really large stones require surgery for removal.

Kidney Stones (continued…) Ways to avoid kidney stones: Increase liquid intake (1/2 your body weight in oz.) Limit sodium intake Limit animal proteins and dairy (link shown in men) Limit foods high in oxalate (spinach, strawberries, nuts, dark chocolate, brewed tea)