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.
In the vast majority of plants and animals, the body is made up of numerous cells. They are called multicellular organisms. A multicellular organism is actually an aggregation of cells. Here a group of cells functions in a same way to form a tissue or an organ (Example: Xylem vessels, cork cells, cells in the skin).Multicellular organisms have a great capacity to survive than unicellular organisms.n some lower forms of life (Example: Euglena, Amoeba) The body is formed of a single cell; these organism are described as unicellular. In a unicellular organism, all life activities are carried out by itself with its internal structures. The intracellular structures are called the organelles.