• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Discuss the Need for Osmoregulation in animals, using specific examples and environments

Extracts from this document...


Discuss the Need for Osmoregulation in animals, using specific examples and environments All external environments fluctuate frequently. They can be relatively stable with small stochastic changes, or extremely random. So, no matter in which habitat they live, all organisms have to have the ability to survive in changeable circumstances. This is the fundamental basis of homeostasis, the process of maintaining a relatively constant internal environment. One of the major factors in homeostasis is the process of maintaining a constant osmotic pressure. Osmotic pressure is "the pressure that can potentially be created by osmosis between two solutions separated by a semi-permeable membrane"(Eckert Animal Physiology). This osmotic pressure is effectively the amount of pressure necessary to prevent osmotic flow between two solutions, and so it is important to maintain this value at a constant rate. Water entering a cell with no cell wall, as in animals, at a high rate, can cause the cell to swell until it bursts. This can be fatal. By contrast, water leaving a cell down its concentration gradient can cause the cell to become flaccid and dehydrated to such an extent that it dies, because metabolic reactions cannot occur with the diluted solutes. Osmosis is the movement of water molecules only across a semi-permeable membrane down a concentration gradient. The amount of water in a cell affects many variables that are dependent on it, because the volume of water in a solution affects its concentration. Thus is water moves out of a cell, the concentration of the solutes in the cell increases because there is less water to dilute them. ...read more.


Osmoregulation in marine elasmobranches, reptiles and teleosts does not expend much energy because most of these animals have cellular fluid compositions similar to that of the water surrounding them. They are said to be isosmotic. They can be broken into Elasmobranches e.g. sharks, which do not drink seawater, and have excrete hyperosmotic NaCl from the rectal gland. Marine teleosts such as mackerel, drink seawater and secrete salt from the gills. Freshwater teleosts such as salmon, by comparison, drink absolutely no water and absorb salt from the gills. The habitat of the animals is so important in the extent for their need to osmoregulate. In hot, arid regions, the extreme heat causes more water to evaporate from the skin and to be lost in ventilation. Cells become easily dehydrated and so in these regions, most animals have adaptations to conserve water. A salt conservation technique is also important to restore vital minerals lost in sweat. Some animals avoid the problem in the first place by not drinking much or any water, so their osmolarity is never greatly changed. For example, Desert mammals such as the desert rat, drink no water, and instead depend solely on water from the metabolism of fats. They often have special adaptations such as an extra long loops of Henle designed from the reabsorption of more water. Amphibians, which tend to live close to or in water, e.g. salamanders absorb salt through the skin. This balances the high osmolarity caused by diffusion of vast quantities of water through the integument. ...read more.


It becomes highly permeable to urea, so it leaks out by diffusion. This further adds to the osmolarity of the interstitial fluid around the bottom of the loop of Henle. In this way, it can be seen that the organs specifically designed to cope with osmolarity problems, work in a negative feedback way, without direct interception by the nervous system. When there is a lack of water, for example, more of a gradient is built up naturally because the concentration of the solutes increases if there is less volume, so this means more water is reabsorbed. This function in itself varies between species, and even between individual organisms. Although the kidney is relatively unique, osmoregulatory organs all contain similar features. For example, Malpighian tubules in insects contain similar one-cell thick tubules with brush borders and proximal and distal convoluted tubules. Osmoregulatory systems are very specific to the animal concerned because differing environments produce different needs for salts and water. The general need for a constant osmolarity in cells is a basic fundamental for all living organisms though, animals or plants. Word Count = 2517 Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2002). Molecular Biology of the Cell. 4th ed. New York: Garland Science. Jones, M., Fosbery, R. and Taylor, D. (2000). Biology 1. Cambridge, Cambridge University Press. Jones, M. and Gregory, J. (2001). Biology 2. Cambridge: Cambridge University Press. Randall, D., Burggren, W. and French, K. (2002). Eckert Animal Physiology: Mechanism and Adaptations. 5th ed. New York: W.H.Freeman and Company Widmaier, E.P. (1999). Why Geese Don't Get Obese (And We Do). New York: W.H.Freeman and Company http://www.neoucom.edu/Depts/ANAT/Osmo.html Jessica Beveridge Due 25/11/02 PoO supervisions: Dawn Muddyman ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our University Degree Zoology section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related University Degree Zoology essays

  1. Free essay

    Explain, using evolutionary arguments, why social living is common among mammals

    Tinbergen, in his book 'Social Behaviour in Animals', suggests that parent-offspring groups develop into symbiotic relationships between families, before later developing into full scale communities. (4) This further concretes the concept of gene protection and inclusive fitness mentioned previously.

  2. What organs and tissues have been successfully transplanted?

    I can identify that the number of donors have decreased over the years, there may be a reasonably explanation why it have decreased maybe it could be because of bad publicity, not enough qualified doctors or nurses, maybe it's against peoples religions or just maybe people don't know enough about organ transplants.

  1. Drawing on examples from the key concepts, discuss the extent to which animals and ...

    Lenneberg believes that whilst the brain is developing it does not specialize therefore children who lose their language ability can relearn it. This is because other, non damaged, parts of the brain take over. This is different for adults or those who suffer brain damage after puberty.

  2. The positive correlation shows that the older the molehill the higher the species diversity ...

    This means that the null hypothesis is rejected because the original hypothesis and predictions are accepted: Hypothesis The compactness of the soil of the molehill will alter with the age of the molehill. The age of the molehill will affect the species diversity of plants growing on it.

  1. To what extent we can say animals have language

    Duality is also one the defining features of language. This means that language is organised into two levels. There is physical level which enables us to produce sounds like p, i, g. These, standing by themselves, are meaningless. It is only at the second level after combining them into sequences such as p-i-g when they become meaningful.

  2. This study attempts to explore the basis of people's fear of animals.

    Classical conditioning (CC)5 focuses on the learning of involuntary emotional or physiological responses, in our case that of fear. Researchers have found it to be a useful model for explaining some of the fears and phobias that people develop. For example, people's fear of snakes can be explained by the fact that snakes (CS)

  1. Review and discuss the significance of animal cloning (such as: Dolly the sheep)

    and the capacity of that malignant genetic material to give rise to normal cell progeny. Cloning may be the most direct method of acquiring information about these two important aspects of cancer-cell biology (Nguyen, Peter). Cloning provides a means whereby scientists will be given the tools to fully understand the

  2. Compare and contrast the ways different animals respond to osmotic challenges

    The loss of salts is overcome by channel pumps such as H+ V-ATPase and Na+/K+ P-ATPase, which actively transport ions in to the skin. Aquatic insects, which also have body fluids hyperosmotic to their environment, employ a similar mechanism and so water enters through their body surface.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work