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10 Cards in this Set
- Front
- Back
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digestion |
the break down of food from large insoluble molecules into small molecules |
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structure and function of small intestine |
covered in small finger-like projections (villi) to increase surface area - the larger the surface area, the more absorption can take place. kind of like a sieve which only allows small molecules to pass through. |
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nitrogenous waste products |
urea - less toxic, waste can be more concentrated to conserve water ammonia - toxic, needs to be excreted in dilute solution (only animals living in water) uric acid - non toxic, semi-solid, need to conserve lots of water |
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3 steps in formation of urine |
filtration, reabsorption, secretion |
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sodium reabsorption |
creates the osmotic pressure to pump blood back out of the loop of Henle sodium level kept low thanks to sodium-potassium pump that constantly pumps sodium into extra cellular space. creates concentration gradient |
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glomerulus |
capillary network - high pressure forces blood into bowmans capsule - removes toxic materials from blood (first step of filtration) |
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bowmans capsule |
active transport required to move ‘clean’ blood into Bowmans capsule |
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proximal and distal tubules |
selective reabsorption - useful molecules transported back into blood |
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Loop of Henle |
2 parts (descending and ascending) - selectively permeable, active transport (sodium-potassium pump) maintains concentration gradient, draws water out through osmosis. |
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collecting duct |
all material from tubule exits body through urine collecting duct helps to further concentrate urine and therefore conserve water - gets saltier deep in the medulla, filtrate loses more and more water |
