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28 Cards in this Set
- Front
- Back
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What is transamination? |
The conversion of one amino acid into another |
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What is deamination and why is it needed? |
The removal of an amine group from an amino acid We can't store proteins or amino acids in our body |
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What happens to the products of deamination? |
The amine group is converted into ammonia then urea The remainder of the amino acid is fed into cellular respiration or converted into lipids |
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What is the ornithine cycle? |
When ammonia is converted into urea in a set of enzyme controlled reactions |
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What are the stages in the ornithine cycle? |
1. NH3, CO2 and ornithine combined together to create citruline in a condensation reaction 2. The NH3 is added to citruline in a condensation reaction to form arginine 3. Hydrolysis removes urea from arginine which is converted back into ornithine |
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How does the liver detoxify substances? |
It contains enzymes such as catalase which breaks down H2O2 Hepatocytes use enzymes called dehydrogenase that convert ethanol (from alcohol) to ethanal to ethanoate which can be used for respiration or stored as fatty acids in the liver |
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What is the ureter? |
A tube connecting the kidney and the bladder |
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What are the different areas of the kidney? |
The cortex where most of the blood filtering takes place The medulla contains the tubules of nephrons and collecting ducts The pelvis is the central chamber where urine is collected before entering the ureter |
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What is the function of a nephron? |
To filter the blood and removes nitrogenous waste products |
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What is bowman's capsule? |
A cup shaped structure that contains the glomerulus (a network of capillaries) |
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What is the proximal convoluted tubule and what happens there? |
The first coiled region of the tubule which is found in the cortex where many of the substances are actively, selectively reabsorbed into the blood such as glucose amino acids, water and Na+ and Cl- ions |
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What is the loop of henle? |
A long loop of tubule that creates a very high solute concentration in the tissue fluid and runs deep into the medulla |
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What is the distal convoluted tubule? |
A second coiled tubule where water balance of the blood is adjusted (it has permeable walls) |
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What is the collecting duct? |
Where urine passes down into the pelvis (the walls are also permeable to water) |
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How does glucose from the tissue fluid move back into the bloodstream? |
Substances in the tissue fluid diffuse into the surrounding capillaries which lead to the renal vein |
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What is ultrafiltration? |
When blood is filtered through the walls of the bowman capsule under pressure |
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What is the structure of the glomerulus and what does this cause? |
The afferent arteriole has a relatively wider lumen than the efferent arteriole This causes a higher hydrostatic pressure at the arterial end which forces blood plasma through the basement membrane of the bowman's capsule |
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What doesn't pass the basement membrane in ultrafiltration? |
RBC and WBC and large proteins as they are too large |
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What is the structure of podocytes? |
They have extensions called pedicels which wrap around the capillaries acting as another filter |
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What are the adaptations of epithelial cells lining the proximal convoluted tubule? |
They are covered with microvilli which increase surface area and maximise reabsorption They have many mitochondria for maximum ATP production and active transport |
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How does selective reabsorption occur? |
1. Na-K pumps actively transport Na+ out of the cell into the tubule 2. Na+, glucose and amino acids return down a conc gradient through facilitated diffusion 3. Na+, glucose and amino acid conc risers in the cell and diffuse out into the capillary then Cl- follows down an electrochemical gradient 4. Blood maintains this gradient by transporting substances away 5. Water enters the cell with a lower water potential gradient from the tubule by osmosis |
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In terms of water potential what is the fluid that enters the loop of henle and exits the loop of henle? |
Isotonic when it enters Hypotonic when it leaves |
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What does the loop of henle act as? |
A countercurrent multiplier |
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Explain what happens in the descending limb of the loop of henle |
The lower part is permeable to water and water moves out of the filtrate down a water potential gradient by osmosis into the surrounding tissue fluid. The tissue has a high solute concentration at the bottom |
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What are the capillaries surrounding the loop of henle? |
The Vasa recta |
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Explain what happens in the ascending limb of the loop of henle? |
The lower part of the limb is permeable to Na+ and Cl- ions, so they diffuse out of the tubule fluid into the surrounding tissue down a conc gradient In the upper part of the limb ions are actively pumped out into the tissue fluid creating a high solute conc in the medulla Ascending limb is impermeable to water |
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What does ADH control in terms of permeability? |
Permeability of the distal convoluted tubules and collecting duct walls |
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How is more concentrated urine created in other organisms? |
They have longer loops of henle to create higher solute concentrations |
