Register for FREE to remove ads and unlock more features! Learn more. The renin-angiotensin-aldosterone system (RAAS) is a hormone system that regulates blood pressure and water (fluid) balance . This system proceeds through several steps to produce angiotensin II, which acts to stabilize blood pressure and volume.
A fish is any member of a paraphyletic group of organisms that consist of all gill-bearing aquatic craniate animals that lack limbs with digits.Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups.ish do not represent a monophyletic group, and therefore the evolution of fish is not studied as a single event. Early fish from the fossil record are represented by a group of small, jawless, armored fish known as Ostracoderms. Jawless fish lineages are mostly extinct.
The body of all living organisms (bacteria, blue green algae, plants and animals) except viruses has cellular organization and may contain one or many cells. The organisms with only one cell in their body are called unicellular organism (e.g., bacteria, blue green algae, some algae, protozoa etc).The organisms having many cells in their body are called multicellular organisms (plants and animals).he organisms with only one cell in their body are called unicellular organism (e.g., bacteria, blue green algae, some algae, protozoa etc). The organisms having many cells in their body are called multicellular organisms (plants and animals).