11.3 The Kidney Flashcards
How is the type of nitrogenous waste correlated with habitat?
Aquatic animals remove their waste in the form of ammonia: highly toxic, but very water-soluble
Terrestrial animals: less access to water, so it is excreted in the form of urea
Birds, reptiles, insects in the form of uric acid, even less toxic
What are the 2 purposes of excretion?
- remove toxic nitrogenous waste
- remove excess water to maintain suitable osmolarity
What is an osmoregulator?
internal conditions are always the same, regardless of environmental conditions
What is an osmoconformer?
internal conditions are equal to external osmolarity of the environment
What are advantages of being a osmoconformer and of being a osmoregulator?
Osmconformer: less energy is used to maintain internal osmotic conditions
Osmoregulator: optimal internal conditions are maintained
What is the path taken by nitregenous waste in insects?
Hemolymph (like blood system) -> Malpighian tubules -> Hindgut -> Rectum
What are the differences between the blood composition in the renal vein and in the renal artery?
In the renal vein there is less urea, less water, less solutes, less glucose, less oxygen, and more carbondioxide
What are the 3 steps in the kidney?
- Ultrafiltration (in glomerulus)
- Selective reabsorption (in proximal convoluted tubule)
- Osmoregulation (in distal convoluted tubule)
Outline ultrafiltration.
Non-specific filtration of blood under high pressure in the Bowman’s capsule. The high pressure filtrates the blood from proteins and bloodcells, which means they stay outside.
Outline selective reabsorption.
The proximal convoluted tubule selectively reabsorbs nutrients and water by active transport into the blood
Which parts of the nephron is in the cortex and which is in the medulla?
Cortex: glomerulus & bowman’s capsule, proximal convoluted tubule, distal convoluted tubule, collecting duct
Medulla: loop of henle, collecting duct
What is the collecting duct?
it collects all the urine from different nephrons, which then goes through the pelvis, to the urether
Outline osmoregulation in the collecting duct.
The loop of Henle established hypertonic conditions in the medulla by pumping salts out of the loop of henle. This will attract water to diffuse out too, back into the bloodstream. In the distal convoluted tubule, water can leak to, depending on the hydration of the person. If the person is dehydrated, their hypotalamus will secrete ADH, which will increase the permeability of water of the collecting duct and the distal convuluted tubule, and therefore more water will diffuse out and into the blood.
Animals that live in dry arid conditions, will have a… longer/shorter loop of Henle. Why?
longer
a greater concentration gradient can be built up and thus more water is reabsorbed into blood.
