The Excretory System What Does Excretion Mean Excretion
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The Excretory System
What Does Excretion Mean? • Excretion means getting rid of wastes that could harm or poison the body • The three main wastes are Carbon Dioxide, undigested food (like fibre) and Urea
How Do We Get Rid Of Wastes? • The three mains ways are: 1. Urination : Urea is made into to urine (http: //health. howstuffworks. com/adam-200032. htm ) 2. Breathing: Carbon Dioxide is breathed out by the lungs 3. Defecation We egest food that we cannot digest through (http: //lgfl. skoool. co. uk/content/keystage 3/biology/pc/learningsteps/EGSLC/laun ch. html )
Excretory Organs • The kidneys are responsible for filtering the blood • The large intestine begins the egestion of waste food
The Kidneys • You have two kidneys, but can survive with one • They look like kidney beans
The Kidneys • Each Kidney gets it’s blood from the renal artery
The Nephron • The Nephron: there are millions found inside the kidney. They absorb useful water and salts from the blood • ADH (anti- diuretic hormone) is produced when it is a hot day and you are dehydrated. It makes your urine less watery and more concentrated
The Kidneys • How they work? • http: //www. kidneypatientguide. org. uk/site/HKWanim. php (basic) • http: //www. biologymad. com/resources/kidney. swf (excellent)
Other Excretory Organs • The lungs breathe out Carbon Dioxide, which can acidify the blood • Your skin can remove salt and water as sweat
Weird Facts • Your blood passes through the kidneys 300 times a day. • The nephrons clean all your blood in 45 minutes. • Every day the nephrons send about six cups of urine to the bladder. • If you eat lots of beetroot your urine will turn beetroot red
Questions • What are three main wastes made by the body? • Urea, Carbon Dioxide, undigested food • What are three main ways wastes are removed from the body? • Breathing, defecation and urination • Which organ filters the blood? • The kidneys • What is the most important part inside the kidney? • The Nephron • What does the kidney reabsorb into the blood? • Water and glucose