Osmoregulation Maintaining homeostasis in solute concentrations

Water is better

Osmoregulation VIDEO!!!

Osmoregulation At a cellular level the balance of water supply and demand is critical. Why is it so important?

Osmoregulation Water dissolves solutes and is the medium in which everything happens Chemical reactions, transport of nutrients, gases and wastes.

Osmoregulation It is crucial that the solute concentration of the blood remains at a stable level. The solute concentration of the blood affects the diffusion of water across capillary walls and across cell membranes.

Osmoregulation For Example: - A relatively low concentration of water in the blood and tissue fluid can affect the functioning of cells. - This can be caused by excessive fluid loss or increased salt concentration.

Osmoregulation Mark Dorrity Story

Osmosis Define Osmosis The movement of water across a semi permeable membrane from a place of low solute concentration to a place of high solute concentration

Osmoregulation

Osmosis

Osmoregulation Where do you think these changes in concentration in the blood will be detected? HYPOTHALAMUS

Osmoregulation

If the hypothalamus detects that the concentration in the blood is too high. It releases a hormone that stimulates the pituitary gland to release ADH ADH in turn stimulates the kidney to absorb more water.

Osmoregulation

The Loop of Henle is crucial for this process It can reabsorb more water if needed and be used to excrete salts.

Osmoregulation

A thirst response is also initiated which forces animals to seek water.

Osmoregulation What are some ways in which water can be lost from the body?

Osmoregulation Water Loss Exhaling Sweating Urinating Faeces Tear Ducts

Osmoregulation Vertebrates have evolved effective ways in which to maintain the balance of water and solutes Can you think of any examples?

Osmoregulation Thirst response: Seeking water

Osmoregulation Waterproof (impermeable) outer layer [aka – integument]: Reduce water loss – e.g. scales on reptiles, hair of mammals, feathers, keratin in skin, skin, hard exoskeleton.

Osmoregulation Reabsorption: Some animals reabsorb water from their faeces.

Osmoregulation Burrowing: The temperature is cooler underground so less water is lost. Burrows also have high humidity therefore water loss is reduced.

Osmoregulation Some animals stay underground fro extended periods of time while it is extremely dry. For example: the Cyclorana burrows deep and covers itself in a cocoon. The cocoon creates humidity.

Osmoregulation Changing waste products: Some animals excrete nitrogen in different ways to conserve water.

Osmoregulation Concentrating urine: By concentrating their urine animals can conserve water (e.g. Notomys).

Osmoregulation Gets all its water from cellular respiration and conserves water by concentrating its urine. 1 gram of carbohydrates supplies 0.56 grams of water.

Osmoregulation Camels do a similar thing however they metabolise the fat in their hump to produce water. High tolerance to low water conditions.

Osmoregulation What do you do if you are surrounded by water?

Osmoregulation Some organisms don’t have to worry. These animals, mainly invertebrates, have the same internal solute concentration as their external environment. Meaning they are isotonic with the sea water.

Osmoregulation These animals are referred to as osmoconformers

Osmoregulation Other animals are not so lucky. Marine vertebrates have internal environments that are hypotonic to their surrounding environment. Their body fluids are less concentrated than the surrounding sea water.

Osmoregulation These animals must find ways in which to stabilise their internal environments. These animals are referred to as osmoregulators

Osmoregulation Water is lost by osmosis to the surrounding environment. To replace this water marine fish drink lots of sea water. However this also means they take in salts. They use secretory cells in the gills to get rid of excess salts. Production of concentrated urine also helps

Osmoregulation

Fish in freshwater environments have an internal environment that is hypertonic to their surroundings Their internal environment is more concentrated than their surroundings This mean water continually moves in to their body.

Osmoregulation Freshwater fish produce large amounts of dilute urine. Actively absorb salts via cells in their gills Do not drink much water

Osmoregulation

REVIEW Describe the difference between osmoregulators and osmoconformers Describe the different methods of maintaining stable solute concentrations used by freshwater and saltwater fish. List and describe the different adaptations animals use to conserve water. Describe why the kidney is so important in osmoregulation