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12 Cards in this Set
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Within each kidney are an estimated one million microscopic nephrons. Filtering of the blood takes place within these areas. Each nephron contains a cluster of CAPILLARIES called a GLOMERULUS. A cup-shaped sac called a BOWMAN’S capsule surrounds each GLOMERULUS. The blood that flows through the GLOMERULUS is under great pressure. This causes GLOMERULUS, WATER, GLUCOSE andUREA TO ENTER into the BOWMANS capsule. WHITE BLOOD CELLS, RED BLOOD CELLS AND PROTEINS remain in the blood. |
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As the blood continues through the blood vessels, it winds around the RENAL TUBULA During this time, reabsorption occurs. Glucose and chemicals, such as potassium, sodium, hydrogen, magnesium and calcium, are reabsorbed into the blood. Almost all the WATER removed during filtration returns to the blood during the reabsorption phase. The kidneys control the amount of liquid in our bodies.Now only wastes are in the nephron. These wastes are called URINE and include WATER, UREA and inorganic SALTS The cleansed blood goes into VEINS that carry the blood from the kidneys and back to the heart. |
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1. What are the differences between excretion, secretion and defaecation? |
The excretory system is responsible for eliminating metabolicwastes from the body. |
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2. The urinary and respiratory systems as well as the skin are regarded as excretory. What does each excrete? |
Lungs, kidneys, liver, and skin |
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3. Briefly describe the path of a molecule of urea from its formation in the liver to its excretion in the urine. |
If the wastes aren’t eliminated, then there isn’t room forfresh food and oxygen in living cells |
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4. What substances are present in normal urine? |
The lungs exhale carbon dioxide from the body. |
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5. What substances may be present in greater or lesser amounts than normal in the urine of ill people? |
The kidneys filter blood through the use of millions oftiny nephrons which work at the capillary level. Water,urea, glucose, and minerals move into a hollow tube calledthe renal tubula. Capillaries wind around the renal tubulaand reabsorb most of the water back into the circulatorysystem. The wastes removed become a fluid called urineand move into the bladder and then are released from thebody through the urethra. |
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6. Describe how a nephron functions. |
The liver removes poisonous substances from our bodies,such as mercury from fish, poisonous fumes from paint,and chemicals sprayed on food. |
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7. Why do desert animals have a thicker medullary region in their kidneys than do animals in less arid areas? |
Perspiration is released out of the skin where it evaporatesor changes from a liquid to a gas. The heat energyrequired to change from a liquid to a gas comes from thebody. So the body loses heat and cools off. |
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8. How does excess coffee affect the functioning of the kidneys? |
Perspiration contains water, urea, and inorganic salts. |
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9. Artificial kidneys called dialysis machines have been devised for patients critically ill with kidney disease. How do you think they work? |
Urea is a nitrogen compound released when amino acidsare changed into sugars, glycogen, or fats. The nitrogenis changed by the liver into urea which is then sent tothe kidneys. |
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10. What are the various forms in which nitrogenous wastes can be excreted by animals? |
The bladder is the storage sac for urine before eliminationfrom the body. |
