Tissue hydration

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Tissue hydration is the process of absorbing and retaining water in biological tissues. [1]



Land plants maintain adequate tissue hydration by means of an outer waterproof layer. In soft or green tissues, this is usually a waxy cuticle over the outer epidermis. In older, woody tissues, waterproofing chemicals are present in the secondary cell wall that limit or inhibit the flow of water. Vascular plants also possess an internal vascular system that distributes fluids throughout the plant.

Some xerophytes, such as cacti and other desert plants, have mucilage in their tissues. This is a sticky substance that holds water within the plant, reducing the rate of dehydration. Some seeds and spores remain dormant until adequate moisture is present, at which time the seed or spore begins to germinate. [2]


Animals maintain adequate tissue hydration by means of (1) an outer skin, shell, or cuticle; (2) a fluid-filled coelom cavity; and (3) a circulatory system.

Hydration of fat free tissues, ratio of total body water to fat free body mass, is stable at 0.73 in mammals. [3]

In humans, a significant drop in tissue hydration can lead to the medical condition of dehydration. This may result from loss of water itself, loss of electrolytes, or a loss of blood plasma. Administration of hydrational fluids as part of sound dehydration management is necessary to avoid severe complications, and in some cases, death.

Some invertebrates are able to survive extreme desiccation of their tissues by entering a state of cryptobiosis.

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<span class="mw-page-title-main">Drinking</span> Ingestion of water or other liquids

Drinking is the act of ingesting water or other liquids into the body through the mouth, proboscis, or elsewhere. Humans drink by swallowing, completed by peristalsis in the esophagus. The physiological processes of drinking vary widely among other animals.

<span class="mw-page-title-main">Tissue (biology)</span> Group of cells having similar appearance and performing the same function

In biology, tissue is a historically derived biological organizational level between cells and a complete organ. A tissue is therefore often thought of as an assembly of similar cells and their extracellular matrix from the same origin that together carry out a specific function. Organs are then formed by the functional grouping together of multiple tissues.

Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance's molecules, adsorbing substances can become physically changed, e.g., changing in volume, boiling point, viscosity or some other physical characteristic or property of the substance. For example, a finely dispersed hygroscopic powder, such as a salt, may become clumpy over time due to collection of moisture from the surrounding environment.

<span class="mw-page-title-main">Dehydration</span> Deficit of total body water

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<span class="mw-page-title-main">Fluid replacement</span>

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In physiology, body water is the water content of an animal body that is contained in the tissues, the blood, the bones and elsewhere. The percentages of body water contained in various fluid compartments add up to total body water (TBW). This water makes up a significant fraction of the human body, both by weight and by volume. Ensuring the right amount of body water is part of fluid balance, an aspect of homeostasis.

<span class="mw-page-title-main">Embryophyte</span> Subclade of green plants, also known as land plants

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<span class="mw-page-title-main">Plant cuticle</span> Waterproof covering of aerial plant organs

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<span class="mw-page-title-main">Evolutionary history of plants</span> History of plants

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This page provides a glossary of plant morphology. Botanists and other biologists who study plant morphology use a number of different terms to classify and identify plant organs and parts that can be observed using no more than a handheld magnifying lens. This page provides help in understanding the numerous other pages describing plants by their various taxa. The accompanying page—Plant morphology—provides an overview of the science of the external form of plants. There is also an alphabetical list: Glossary of botanical terms. In contrast, this page deals with botanical terms in a systematic manner, with some illustrations, and organized by plant anatomy and function in plant physiology.

Poikilohydry is the lack of ability to maintain and/or regulate water content to achieve homeostasis of cells and tissue connected with quick equilibration of cell/tissue water content to that of the environment. The term is derived from Ancient Greek ποικίλος ..

<span class="mw-page-title-main">Mucilage</span> Thick, gluey substance produced by nearly all plants and some microorganisms

Mucilage is a thick gluey substance produced by nearly all plants and some microorganisms. These microorganisms include protists which use it for their locomotion. The direction of their movement is always opposite to that of the secretion of mucilage. It is a polar glycoprotein and an exopolysaccharide. Mucilage in plants plays a role in the storage of water and food, seed germination, and thickening membranes. Cacti and flax seeds are especially rich sources of mucilage.

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 to keep the body fluids from becoming too diluted or concentrated. Osmotic pressure is a measure of the tendency of water to move into one solution from another by osmosis. The higher the osmotic pressure of a solution, the more water tends to move into it. Pressure must be exerted on the hypertonic side of a selectively permeable membrane to prevent diffusion of water by osmosis from the side containing pure water.

A xerophyte is a species of plant that has adaptations to survive in an environment with little liquid water. Examples are typically desert regions like the Sahara, and places in the Alps or the Arctic. Popular examples of xerophytes are cacti, pineapple and some Gymnosperm plants.

<span class="mw-page-title-main">Plant stem</span> Structural axis of a vascular plant

A stem is one of two main structural axes of a vascular plant, the other being the root. It supports leaves, flowers and fruits, transports water and dissolved substances between the roots and the shoots in the xylem and phloem, stores nutrients, and produces new living tissue. The stem can also be called halm or haulm or culms.

A cuticle, or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non-homologous, differing in their origin, structure, function, and chemical composition.

Desiccation tolerance refers to the ability of an organism to withstand or endure extreme dryness, or drought-like conditions. Plants and animals living in arid or periodically arid environments such as temporary streams or ponds may face the challenge of desiccation, therefore physiological or behavioral adaptations to withstand these periods are necessary to ensure survival. In particular, insects occupy a wide range of ecologically diverse niches and, so, exhibit a variety of strategies to avoid desiccation.


  1. Kemp, Arika D.; et al. (December 2012). "Effects of tissue hydration on nanoscale structural morphology and mechanics of individual Type I collagen fibrils in the Brtl mouse model of Osteogenesis Imperfecta". Journal of Structural Biology. 180 (3): 428–438. doi:10.1016/j.jsb.2012.09.012. PMC   3685442 . PMID   23041293.
  2. Nobel, Park S.; Cavelier, Jaime; Andrade, Jose Luis. "Mucilage in Cacti: Its Apoplastic Capacitance, Associated Solutes, and Influence on Tissue Water Relations". Journal of Experimental Botany. 43 (250).
  3. Heymsfield, Steven B.; Baumgartner, Richard N.; Pietrobelli, Angelo; Wang, Wei; Deurenberg, Paul; Wang, ZiMian (1999-05-01). "Hydration of fat-free body mass: review and critique of a classic body-composition constant". The American Journal of Clinical Nutrition. 69 (5): 833–841. doi: 10.1093/ajcn/69.5.833 . ISSN   0002-9165. PMID   10232621.