PNB 2250 Lecture Notes - Lecture 22: Nephridium, Metabolic Water, Salt Gland
24 Oct 2016
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Green gland: crustaceans have a more advanced haemococlic circulatory system, nephridia would drain blood directly outside, green glands. Malpighian tubules: blind tubules from blood to gut wall. Collect both fluid and solutes, carry to gi tract: filtrate is moved to gut, tubule does little modification of filtrate, gut reabsorbs solutes and water, excretory and osmoregulatory. Evaporation: trachea are covered with chitin- little water loss. Chitin- super polymer with tough protein and wax exterior: cutide is permeable to water, underlying layer of wax. Waste products: very concentrated, uric acid, little water loss, requires a different type of kidney capable of producing a very concentrated urine. Water uptake: active transport, drinking, water w/food, metabolic water. Invertebrates: see the development of osmoconformers to osmoregulators, see the development of a vertebrate-like kidney. Blood osmolarity equaled paleozoic ocean: oceans became more saline, because of rock weathering and climates changes. Need to respond to changing osmolarity: animals became more complex.
