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Osmoregulation is the active regulation of the osmotic pressure of an organism's body fluids, detected by osmoreceptors, to maintain the homeostasis of the organism's water content; that is, it maintains the fluid balance and the concentration of electrolytes (salts in solution which in this case is represented by body fluid) to keep the body fluids from becoming too diluted or concentrated.
An osmoreceptor is a sensory receptor primarily found in the hypothalamus of most homeothermic organisms that detects changes in osmotic pressure.Osmoreceptors can be found in several structures, including two of the circumventricular organs – the vascular organ of the lamina terminalis, and the subfornical organ.
Urinary water loss, when the body water homeostat is intact, is a compensatory water loss, correcting any water excess in the body. However, since the kidneys cannot generate water, the thirst reflex is the all-important second effector mechanism of the body water homeostat, correcting any water deficit in the body.
Fluid balance is an aspect of the homeostasis of organisms in which the amount of water in the organism needs to be controlled, via osmoregulation and behavior, such that the concentrations of electrolytes (salts in solution) in the various body fluids are kept within healthy ranges.
Most tubules are normally highly convoluted. The number of tubules varies between species although most occur in multiples of two. Tubules are usually bathed in hemolymph and are in proximity to fat body tissue. They contain actin for structural support and microvilli for propulsion of substances along the tubules. Malpighian tubules in most ...
The CV does not exist in higher organisms, but some of its unique characteristics are used by them in their osmoregulatory mechanisms. Research on the CV can therefore help us understand how osmoregulation works in all species. Many issues regarding the CV remain, as of 2010, unsolved: Contraction.
Homeometric autoregulation, in the context of the circulatory system, is the heart's ability to increase contractility and restore stroke volume when afterload increases. [6] Homeometric autoregulation occurs independently of cardiomyocyte fiber length, via the Bowditch and/or Anrep effects.
The heart pumps the blood in a single loop throughout the body. In most fish, the heart consists of four parts, including two chambers and an entrance and exit. [ 20 ] The first part is the sinus venosus , a thin-walled sac that collects blood from the fish's veins before allowing it to flow to the second part, the atrium , which is a large ...