Osmoregulation and Excretion quiz #2 Flashcards
Osmoregulation and Excretion quiz #2
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Why must marine bony fishes drink large amounts of seawater?
Marine bony fishes drink large amounts of seawater to compensate for water loss due to osmosis, as they live in a hyperosmotic environment. What is the primary function of the excretory system?
The primary function of the excretory system is to regulate osmoregulation and eliminate nitrogenous waste from the body. How does the loop of Henle contribute to water reabsorption?
The loop of Henle establishes osmotic gradients that facilitate water reabsorption by creating a salty environment in the medulla. What role does antidiuretic hormone (ADH) play in osmoregulation?
ADH increases the permeability of the distal tubule and collecting duct to water, enhancing water reabsorption and reducing blood osmolarity. What is the difference between osmoconformers and osmoregulators?
Osmoconformers maintain an internal environment that is isoosmotic with their surroundings, while osmoregulators actively regulate their internal osmolarity. How do kidneys filter blood and form urine?
Kidneys filter blood plasma in the renal corpuscle, reabsorb valuable solutes in the proximal tubule, and secrete waste to form urine. What is the function of aquaporins in the kidney?
Aquaporins are water channels that facilitate the efficient transport of water across cell membranes in the kidney. How does the renin-angiotensin-aldosterone system (RAS) regulate blood pressure?
RAS increases blood pressure by promoting salt and water reabsorption in the kidneys and causing vasoconstriction. What is the role of aldosterone in the kidney?
Aldosterone stimulates the reabsorption of sodium in the distal tubules and collecting ducts, which indirectly increases water reabsorption. What is the significance of the countercurrent multiplier system in the loop of Henle?
The countercurrent multiplier system creates a strong osmotic gradient that facilitates water reabsorption in the kidney. What are the main forms of nitrogenous waste excreted by animals, and how do their properties relate to the animal's habitat and water availability?
The main forms of nitrogenous waste are ammonia, urea, and uric acid. Ammonia is highly toxic and requires a lot of water to excrete, so it is used by aquatic animals. Urea is less toxic, requires less water, and is used by terrestrial animals like mammals. Uric acid is the least toxic, requires minimal water, and is excreted by animals in very dry environments, such as reptiles and birds. How do antidiuretic hormone (ADH) and the renin-angiotensin-aldosterone system (RAS) regulate kidney function to maintain blood pressure and volume?
ADH increases water reabsorption in the distal tubule and collecting duct by making them more permeable to water, reducing blood osmolarity and increasing blood volume. The RAS system is activated by low blood pressure or volume; it leads to the production of angiotensin II, which causes vasoconstriction and stimulates aldosterone release. Aldosterone increases salt (and thus water) reabsorption, raising blood volume and pressure.
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