Is the ability of the kidneys to maintain a relatively constant gfr despite changes in blood pressure without the input of nervous or hormonal control. the process whereby the flow of filtrate through the distal tubule results in changes in gfr is termed .the three components of the are the jg cells, the macula densa, and the mesangial cells. epithelial cells found where the distal tubule passes between the afferent and efferent arterioles are called the .the afferent arteriole contains cells called that secrete the enzyme renin. the afferent arteriole reflexively contracts in response to a rise in blood pressure, thus preventing a rise in gfr. this form of regulation is called the .an increase in the rate of filtrate flow through the distal tubule results in contraction of the and a decrease in gfr. when blood pressure drops, renin is released into the blood, resulting in an increase in the hormone , which acts to decrease gfr while simultaneously raising blood pressure

Hunting in the darksome fish rely on senses beyond sight. in the darkness of the marianas trench, a fish called the rattail has an extremely sensitive sense of smell. the fish uses scent, rather than sight, to steer toward food. once it's near food, the rattail uses a special organ on the bottom of its chin to guide itself by feel.marine snowone staple of the deep sea diet is "marine snow," flakes of organic, edible substances that sink down from the upper ocean. animals at the ocean's bottom find sustenance in everything from the bodies of dead creatures to fecal matter. marine snow is diverse enough to support numerous species. for instance, several species of snails and worms feed exclusively on deceased whales.microorganismsthe deep sea is an intricate ecosystem, and even the ocean floor itself plays a part. hydrothermal vents are cracks in the sea floor where erupting magma mixes with ocean water to produce plumes of hot, sulfur-rich chemicals. some microbes can use these chemicals for energy, sustaining their existence and that of the animals who depend on their roles in the deep sea food chain.