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Ch. 8.2 The Excretory Syste m. 1. systems that form the excretory system. digestive system- undigested food leaves through large intestine respiratory system- carbon dioxide and water out skin- salt and organic substances leave through sweat
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Ch. 8.2 The Excretory System
1. systems that form the excretory system digestive system- undigested food leaves through large intestine respiratory system- carbon dioxide and water out skin- salt and organic substances leave through sweat urinary system- water, metabolic wastes, and salts out in urine
rids the blood of wastes made by the cells • controls blood volume by removing extra water made by body cells during respiration 2. urinary system
hypothalamus- in brain, monitors the amount of water in the blood • too much water in blood, hypothalamus releases a hormone that tells kidneys to return less water to blood and release more as urine • specific amount of water is important for movement of gases and excretion of solid waste • also balances the amounts of salts 3. regulating fluid levels
-filter blood that contains wastes collected from cells, all blood in body passes through in 5 minutes • made of about 1 million nephrons 4. kidneys • filtering units in the kidneys • made of a cuplike structure and a tubelike structure called a duct 5. nephrons
6. stages of filtering in kidneys • stage 1: water, sugar, salt and wastes from blood pass into cuplike structures, red blood cells and protein are left in blood, water is squeezed into a narrow tubule • stage 2: most water, sugar and salt reabsorbed and returned to blood and purified blood returned to body through renal vein, wastewater becomes urine
average sized person makes 1 liter of urine per day • leaves kidneys through ureters and go into bladder • carried out of body through urethra 7. urine 8. ureters - tubes that lead from each kidney to the bladder
9. bladder • an elastic, muscular organ that holds urine until it leaves the body • can hold about 0.5 liters of urine 10. urethra - a tube that carries urine from the bladder to the outside of the body
11. other organs of excretion • liver- filters the blood to remove wastes • extra amino acids changed to urea that leaves in urine • hemoglobin from broken down red blood cells becomes part of bile
wastes can build up and act as poison • extra water can cause ankles and feet to swell • fluid can build up around the heart, causing it to work harder to move blood to the lungs • unbalance of salts can cause kidney damage • infections in bladder can spread to kidneys • blockages in ureters or urethra 12. What happens if wastes are not removed?
13. detecting urinary diseases • change in urine color- kidney or liver problems • high levels of glucose- diabetes • high levels of protein called albumin- kidney disease or heart failure - an artificial kidney machine used to filter blood if both kidneys fail 14. dialysis