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25 Cards in this Set
- Front
- Back
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What is the role of the kidney? |
-Removes Nitrogenous Wastes -Balances water and salts |
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Why is passive transport inadequate in removing dissolved nitrogenous wastes? |
-Too Slow -Doesn't select useful solutes -Osmosis only deals with water, not wastes |
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Where is active transport in the kidney? |
Active transport occurs when ions in the blood are transported to cells in the nephron tubule. Some poisons and drugs are removed in this way. |
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Where is there passive transport in the kidney? |
Passive transport occurs when water returns to the capillary via osmosis, after filtration. |
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What is filtration and where does it occur? |
Filtration of the blood occurs in the Bowman’s capsule where high blood pressure in the glomerulus forces all small molecules out of the blood into the capsule. |
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What is filtered into the bowman's capsule? |
Water, urea, ions (Na, K, Cl, Ca, and HCO), glucose, amino acids and vitamins are all small enough to be moved into the glomerular filtrate. |
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What is not filtered into the bowman's capsule? |
Blood cells and proteins are too large to be removed. |
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Is filtering selective in the kidney? |
This filtering process is non-selective and therefore many valuable components of the blood must be recovered by reabsorption. |
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Where does re-absorption take place? |
Reabsorption takes place selectively at various points along the proximal tubule, loop of Henle and distal tubules. |
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What is re-absorbed |
All glucose molecules, amino acids and most vitamins are recovered, although the kidneys do not regulate their concentrations. The reabsorption of the ions Na, K, Cl, Ca and HCO occurs at different rates depending on feedback from the body |
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Where is water re-absorbed? |
Water is reabsorbed in all parts of the tubule except the ascending loop of Henle. |
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What is aldosterone? |
-This is a steroid hormone secreted by the adrenal gland. -Its function is to regulate the transfer of sodium and potassium ions into the kidney. |
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When is aldosterone released? |
When sodium levels are low, Aldosterone is released into the blood, causing more sodium to pass from the nephron to the blood. Water then flows from the nephron to the blood via osmosis. This results in the homeostatic balance of blood pressure. |
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What is the anti-diuretic hormone (ADH)? |
Controls water reabsorption in the nephron |
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When is anti-diuretic hormone released? |
When fluid levels drop, the hypothalamus causes the pituitary gland to release more ADH. This increases the permeability of the collecting ducts to water, allowing more water to be absorbed from the urine into the blood. |
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What are the steps in urine formation? |
1. The Glomerulus Filters Water and Other Substances from the Bloodstream 2. The Filtration Membrane Keeps Blood Cells and Large Proteins in the Bloodstream 3. Reabsorption Moves Nutrients and Water Back into the Bloodstream 4. Waste Ions and Hydrogen Ions, drugs, Secreted from the Blood into filtrate |
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What is the renal capsule? |
Outer membrane that surrounds the kidney; it is thin but tough and fibrous |
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Renal Pelvis |
basin-like area that collects urine from the nephrons, it narrows into the upper end of the ureter |
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Cortex |
extension of the renal pelvis; they channel urine from the pyramids to the renal pelvis |
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Nephron |
Filtering units of the kidney |
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Medulla |
Inner region of the kidney contains 8-12 renal pyramids. |
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Medullary pyramids |
Formed by the collecting ducts, inner part of the kidney |
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Ureter |
collects filtrate and urine from renal pelvis and takes it to the bladder for urination |
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Renal Artery |
branches off of the aorta bringing waste-filled blood into the kidney for filtering in the nephrons |
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Renal vein |
Removes the filtered blood from the kidneys to the inferior vena cava |
