Transcript Slide 1
Excretory System Metabolic Waste Removal Organs of Excretory System Lungs – CO2 and water Skin - Sweat Kidneys – Urine Liver – detoxification of blood These organs work with other body systems to keep the body in homeostasis. Excretion Excretion – is the process by which waste and excess substances are removed from the body. If wastes from metabolism (metabolic wastes) are not removed from the body, the body will die. Metabolic wastes come from chemical reactions in the cells of the human body Major Metabolic Wastes Carbon Dioxide Nitrogen compounds – Ammonia – Urea – Uric acid Mineral Salts – Sodium chloride – Potassium sulfate All of these wastes are poisonous to the body in high concentrations Nitrogen wastes Nitrogen wastes are a by product of protein metabolism. Amino groups are turned into ammonia, which in turn is converted to urea, dumped into the blood and filtered out by the kidneys. Ammonia is converted to urea, a compound the body can tolerate at higher concentrations than ammonia. Role of the Liver Removes harmful substances such as bacteria, certain drugs, and nitrogenous wastes from the blood In the liver the substances are changed into inactive or less poisonous forms Inactive substances (urea) are returned to the blood stream and filtered and excreted by the kidneys. The Skin The skin performs a number of different functions one of them is excretion of wastes. In sweat there is a small amount of urea and salts. Sweat 99% water 1% Urea and Salts Lungs Excrete CO2 and Water – The end products of cellular respiration Urinary System Waste is filtered from the blood and collected as urine in each kidney. Urine leaves the kidneys by ureters, and collects in the bladder. The bladder can distend to store urine that eventually leaves through the urethra The urinary system: – – – – Kidneys Ureters Bladder urethra Urinary tract Kidneys Ureters Bladder Urethra Prostate Female Male Kidneys Bean shaped organs that are about 10cm long Main Functions: – Remove wastes of cellular metabolism (metabolic waste) – Regulate the concentrations of the substances in the blood Kidneys (1) Kidneys (2) Structure of the Kidneys Kidney is made up of 3 parts – Cortex – outer part – Medulla – middle part – Pelvis – inner part Blood is filtered in the cortex Collecting ducts extend through the medulla The filtered substances, called the filtrate, collect in the pelvis which are connected to the ureter Cross Section of Kidney Nephrons MOST important job of the kidney is to filter waste from blood The filtering is done by the nephron. There are about 1.25 million nephrons in each kidney Components of The Nephron Glomerulus: Arteriole blood is filtered under high pressure. Bowman's Capsule: surrounds the glomerulus and collects the filtrate Bowman capsule Component of Nephrons Continued Proximal Convoluted Tubule Loop of Henle Distal Convoluted Tubule – All of these nephron structures aid in the reabsorption of materials needed for the body. Nephron (1) The Nephron Function The nephron consists of a ball of blood capillaries called the glomerulus Blood flows into the kidney through the renal artery, which branches into capillaries associated with the glomerulus. The Nephron Function Continued Arterial pressure causes water and solutes from the blood to filter into the Bowmans Capsule which surrounds the glomerulus The Filtrate flows through the proximal convoluted tubule, loop of Henle, and then into the distal convoluted tubule. The distal tubule empties into a collecting duct. Which carries urine to the pelvis of the Kidney The nephron has three functions: Glomerular filtration of water and solutes from the blood. Tubular reabsorption of water and conserved molecules back into the blood. Excretion of urine from collecting tubes WOW that’s a big filter Nephrons filter 125 ml of body fluid per minute; filtering the entire body fluid component 16 times each day. In a 24 hour period nephrons produce 180 liters of filtrate, of which 178.5 (99%) liters are reabsorbed. The remaining 1.5 liters forms urine. Disruption of Kidney Function Infection, environmental toxins such as mercury, and genetic disease can have devastating results by causing disruption of kidney function. Many kidney problems can be treated by dialysis, where a machine acts as a kidney. Kidney transplants are an alternative to dialysis.