Water and Osmotic Regulation

Most animal body fluids have an osmolarity relative to another solution is said to be....

"Hyperosmotic" to the solution with lower osmolarity. "Hyposmotic" to the solution with higher osmolarity. "Isomotic" to the solution with same osmolarity

1m OsM

0.001 OsM

There are 5 general types of excretory organs

1. Concractile vacuoles - Found in protozoans and cells of sponges. Function is to eliminate excess water from individual cells 2. Nephridial-type organs - Found in flat works, roundworms, annelids, and mollusks. Function is to filter body fluids from a cavity in the animal's body called the coelome 3. Malpigian tubules of insects 4. Antennal glands of crustaceans 5. Vertebrate kidneys

What is 1 of the 4 adaptive strategies to avoid dehydration for Terrestrial insects and arachnoids?

1. Cover their exoskeleton with a waxy secretion that minimizes water loss across their body surface. Waxy covering melts at 30 degrees C. Rate of desiccation increases as waxy covering melts

2 broad categories of excretory organs

1. General excretory organs 2. Specialized excretory organs

What 2 characteristics do marine mammals have in regards to their skin and respiratory system?

1. Have skin relatively impermeable to water 2. Use lungs to breathe, so respiratory surface is not exposed to seawater

For living in marine or fresh water, there are two general rules regarding osmoregulation of body fluids:

1. If the animal's body fluids are hyperosmotic to the water they are in, they will gain water from the environment + lose solutes to the environment 2. If the animal's body fluids are hyposmotic to the water the are in, they will lose water to the environment and gain solutes from the environment

3 environments that animals live in with regard to osmolarity

1. Marine 2. Freshwater 3. Terrestrial

2 advantages of being an osmoregulator

1. The osmolarity of your body fluids is independent of that of the environment. So don't have to rely on stability of the environment to maintain body fluid osmolarity within normal physiologic range 2. Can exploit a wider range of habitats

Why is water loss to the sea usually not a major problem for marine reptiles and birds?

1. Their skin is relatively impermeable to water, so they don't lose much water across their skin. 2. They breathe using their lungs, so their respiratory surface is not exposed to seawater. So the respiratory surface is not a major site of water loss

Animals that live in freshwater have body fluids that are hyper osmotic to freshwater. So.........

1. They gain excess water from the freshwater they live in. 2. They lose salts to the freshwater they live in.

There are 2 additional ways to reduce water loss:

1. They reabsorb water from their feces as it passes through the rectum 2. Nasal counter - current system that minimizes water loss across their respiratory tract

4 functions of excretory organs

1. To maintain proper solute concentrations in the body fluids. This is achieved by selective secreting or reabsorbing solutes 2. To maintain a proper water volume in the body. This is achieved by retaining or excreting water as necessary 3. To remove metabolic waste products from the body 4. To remove toxic substances from the body

All excretory organs carry out their functions using one or both of the following processes:

1. Ultrafiltration 2. Active transport of solutes

How is dehydration a problem for terrestrial animals?

1. Water loss occurs across the skin (integument) 2. Water loss occurs across the respiratory surface 3. Water loss occurs through urine + feces

2 disadvantages of being an osmoconformer

1. You have to rely on the stability of the environment to maintain the concentration of your body fluids within normal physiologic range 2. You are limited in terms of the habitats you can exploit. Can't exploit habitats where osmolarity fluctuates too much

1M NaCL dissolved in water =

2 osmolar solution

Blood has an osmolarity of

300 mOSM

What is urea?

A by-product of protein metabolism + is normally excreted in the urine

Water loss across body/respiratory surface is not....

A major problem for marine mammals

What is Euryhaline water?

A mix of fresh water and salt water

Kangaroo rat can produce....

A urine with a concentration of 5,500 mOSM.

Kangaroo Rat has an...

Ability to produce a concentrated urine. This is a particular value for a desert animal

Where does ultrafiltration of the blood occur?

Across the walls of the glomerular capillaries + wall of Bowman's capsule. So filtrate has same constituents as blood except no cells or large proteins

How do cartilaginous fishes gain salts?

Across their gills and from food

Chloride cells in gill epithelia....

Actively transport Cl- from freshwater into the body, pulling Na+ across the epithelium passively

Hypotonic solutions

Add water to cells because they have a lower osmolarity than intracellular fluids. 1. Causes cell to swell up with water

Nasal cavity

After air has been inhaled, the surface of nasal cavityy is dry and cool. Outside air is approximately 28 degrees C and water picked up from nasal cavity is approximately 38 degrees C.

To live in these water, what do cartilaginous fishes reduce?

Amount of urea reabsorbed from their urine and reduce synthesis of methyl amines by liver. However they are still isosmotic to the water

Osmoconformers

Animals that match the osmolarity of their body fluids so that they are isosmotic to the solution they are living in Ex: Most marine invertebrates are osmoconformers: their body fluids are isosmotic to the sea water.

The water permeability of the walls of the collecting ducts is regulated by a hormone called?

Antidiuretic Hormone (ADH)

Proximal convoluted tubule

As filtrate moves along proximal convoluted tubule, all glucose, amino aids, some Na+ and Cl- ions are transported out of the filtrate and back into the blood. Also, most of theater in the filtrate is reabsorbed back into the blood. 75 - 80% of original filtrate volume is reabsorbed in proximal convoluted tubule

What is the main goal for terrestrial animals?

Avoid dehydration

Nephron

Basic functional unit of kidney

Know the loop diagram

Blood osmolarity rises above 300 mOsM -> osmoreceptors in hypothalamus sense this -> osmoreceptors increase signal rate to posterior pituitary -> posterior pituitary responds by increaseing release of ADH -> blood levels of ADH rise -> increases water permeability of walls of collecting duct --> water is pulled out of filtrate in collecting duct (concenrated urine produced) -> blood osmolarity drops below 300 mOSM -> osmoreceptors in hypothalamus sense this -> osmoreceptors decrease signal rate to posterior pituitary -> Posterior pituitary responds by decreasing release of ADH -> ADH blood levels fall->decrease water permeability of walls of collecting duct -> less water pulled out of filtrate (less concentrated urine) -> blood osmolarity rises above 300 mOSM, etc.

What is the function of a nephron

Carries out filtering of the blood + processing of the filtrate into urine

Gill secretion

Chloride cells, transport chlorine out across gills. Na+ ions follow passively

Malpighian tubules of Insects

Consist of long tubes that extend throughout the insects body and connect to the digestive system. Function is to remove uric acid from the hemolymph and excrete it into the intestinal tract with as little water as possible

If your body needs to get rid of excess water, your body _______ the water permeability of the walls of the collecting duct so ______ water is pulled out of the filtrate as it passes down through the osmotic gradient in the medulla.

Decreases, less

What is a main problem for terrestrial animals?

Dehydration

What kind of mammals have the longest loops of Henle? How does this help them in excreting excess salts?

Desert mammals and marine mammals have the longest loops of Henle. This way they can produce highly concentrated urine to excrete salts

Specialized excretory organs

Designed to rid the body of specific substances Ex: Rectal glands in cartilaginous fishes that concentrate and excrete salts (specifically Na Cl) from the body

Hypertonic solutions

Draw water out of the cells because they have a higher osmolarity than intracellular fluids. 1. Causes cell to crenate (shrivel) as water is drawn out

__________ of tubule actively transport K+ and uric acid into the tubule from the hemolymph

Epithelial cells

Marine teleosts use their kidneys to....

Excrete excess Mg++ and SO4 ions. This allows for net gain of water from drinking seawater

Antennal gland of crustaceans

Excrete magnesium and SO4, reabsorb Na+ to maintain solute concentration gradients between body fluids + seawater

The ability to produce a concentrated urine allows kangaroo rates to

Excrete their nitrogenous wastes with as little water as possible

Advantage of being an osmoconformer is that you don't have to...

Expand energy to maintain the water content of your body fluids

Osmolarity

Expression of the number of dissolved particles (ions, atoms or molecules) per liter of solution

Cells actively transport K+ and Cl- ions out of _____ in _____. Creates osmotic gradient that draws ____ across wall of rectum. ______ ______ is left behind and precipitates. The _____ _____ _____ is expelled through the anus with the feces

Fluid, rectum. water, Uric acid, Uric acid paste

The vertebrate kidney

Functioning involves ultrafiltration and active transport of solutes into or out of the filtrate

Osmoconformers do not have to worry about...

Gaining or losing water because they are isosmotic to the seawater

Osmoconformers have to deal with ...

Gaining salts from the seawater and lose water to the seawater

Isotonic solutions

Have the same osmolarity as intracellular fluids 1. "Isotonic saline" has the same osmolarity as fluid inside cells

Ultrafiltration

Hydraulic pressure created by the circulatory system forces body fluid across a semi-permeable membrane. The resulting solution (filtrate) contains the same constituents as the animals blood or hemolymph with the exception of the blood cells + larger proteins. So ultrafiltration is the result of the same forces that are responsible for capillary exchange: Hydraulic pressure pushes water + solutes outward across the walls of the capillaries. Osmotic pressure pulls water and solutes inward across the walls of the capillaries

Osmotic gain in freshwater teleosts gills are due to...

Hyper osmotic body fluids

The body fluids of osmoregulators are either

Hyperosmotic or hyposmotic to the environment. Ex: Freshwater teleosts maintain body fluids that are hyperosmotic to fresh water Ex: Marine teleost maintain body fluids that are hyposmotic to seawater

Cartilaginous fishes have body fluids that are ____ to freshwater. They ________ similar to stratrgy used by freshwater teleosts

Hyperosmotic, osmoregulate

Marine teleosts have body fluids that are _____ to seawater

Hyposmotic

ADH synthesized by ________ hypothalmus and is released through the posterior ________________ ______________ .

Hypothalamus, pituitary gland

Where do some frogs and toads store water?

In their urinary bladder, which they can reabsorb the water when needed.

If you need to reabsorb water from the filtrate, your body ______ the water permeability of the walls of the collecting duct so _____ water can be pulled out of the filtrate as it passes down through the osmotic gradient in the medulla.

Increases, more

Active transport of solutes

Involves membrane-bound protein pumps powered by ATP that actively secrete or actively reabsorb solutes from the filtrate. As a rule: If a solute is more concentrated in the urine of an animal than it is in the anima;s bloods, then that solute is being actively secreted into the urine. If a solute is less concentrated in the urine than it is in the blood, then that solute is being actively reabsorbed from the urine.

Marine mammals can excrete salts through their urine, so they could drink seawater. however...

It is believed that marine mammals don't drink seawater. These animals get their water from food they eat and they aerobic pathway for ATP synthesis.

Hindgut is AKA

Large intestine and rectum

Uric acid is _____ toxic than ____, and can be excreted with little water

Less, urea

Marine mammals use their highly efficient kidneys to produce a highly concentrated urine to excrete excess salt with as _____ water as possible

Little

There may be hundreds of ______ connecting to the gut

Malpighian tubules

Where are the salt glands located in a marine snakes? Marine crocodiles?

Marine snakes have salt glands located that open into the oral cavity. Marine crocodiles have salt glands on their tongue.

Upper part of ascending limb actively transports Na+ and CL- out of filtrate. The blood carries the NaCl down into the _____ creating the ______ _______.

Medulla, osmotic gradient

What is 2 of the 4 adaptive strategies to avoid dehydration for Terrestrial insects and arachnoids?

Minimize the opening of the spiracles or close their spiracles when they become dehydrated

Reptiles, birds and mammals have relatively dry skin. But water loss across the skin is still a major route of water loss from their body. How do they minimize water loss?

Minimizing water loss through the urine is the primary strategy for avoiding dehydration.

Lung fishes

Most are freshwater fish and use the same strategy as freshwater teleosts for osmoregulation

Where do most of coelacanths food come from? What do they contain a high content of?

Most of their food come from the sea and it is high in salts

Glomerulus

Network of capillaries

Vast majority of marine invertebrates are...

Osmoconformers

Marine teleosts' kidneys cannot....

Produce urine more concentrated than their body fluids

Absorbing their urea (cartilaginous fishes) does what?

Raises their osmolarity of their body fluid so they are isosmotic to the seawater

What is 3 of the 4 adaptive strategies to avoid dehydration for Terrestrial insects and arachnoids?

Reabsorb water from their excretory products as they pass through the rectum: Both feces + urine pass through the rectum in these animals. Reabsorbing water from these excretory products reduces water loss from the body. Some can store excretory products in their fat or waxy cuticle, so no water loss occurs due to excretion

So the water is _____ during each breath and the animal doesn't have to add ____ to the _____ during each inhalation

Recycled, water, air

Water moves across semi-permeable membranes from....

Regions of lower solution concentration to regions of higher solution concentration

Osmoregulators

Regulate the osmolarity of their body fluids

Osmoregulation

Regulation of the concentration of an animal's body fluids

Cartilaginous fishes achieve isosmotic body fluids by...

Retaining urea in their body fluids

Many have specialized patches of skin called... How do are these specialized patches used?

Seat patches. They are able to take up water quickly. So after a rain they will sit in water puddles and absorb water across their seat patches.

Midgut is AKA

Small intestine

What is 4 of the 4 adaptive strategies to avoid dehydration for Terrestrial insects and arachnoids?

Some are able to take up water vapor from the air through their rectum or mouth Ex: Desert cockroach Extrude bladder-like extension of their digestive tract through their mouth. The extension is filled with a salty solution that creates as osmotic gradient that draws water from the air

What does TMAO do?

Stabilize proteins under high urea concentrations

What is the function of the liver in cartilaginous fishes

Synthesizes + secretes methyl amines into the blood.

To be most effective...

The ambient air temp must be below the animal's body temp

Molarity

The concentration of dissolved atoms or molecules in a solution

Tonicity

The effect of a solution on a living cell -> Does the solution pull water out of the cell or into the cell?

What is the strength of the osmotic gradient in the medulla determined by?

The length of the loop of Henle

with exception of amphibians, all 7 lineage of vertebrates have representatives that live in, or make their living off of....

The marine environment

Marine reptiles and birds that live near the ocean get all their food from where?

The ocean

How do hagfish achieve isosmotic body fluids relative to seawater

The same way marine invertebrates do

The movement of water + solutes continue to move until...

The two solutions are isomotic

During exhalation...

The warm, wet air passes across the dry, cool surface of the nasal cavity. The water in the exhaled condenses on the dry, cool surface of nasal cavity

Where do Cartilaginous fishes absorb some of the urea from?

Their urine + concentrate in their body fluids

Earthworms and amphibians have a thin, moist skin used as a gas exchange surface. So the skin is a major site for water loss. How do they avoid dehydration?

These animals live in habitats that are cool + wet. Toads and some frogs have reduced use of their skin for gas exchange so they don't have to keep their skin moist.

Why can't cartilaginous fishes excrete salts through their urine?

They can't produce urine more concentrated than their body fluids

How do cartilaginous fishes get rid of excess salt?

They have evolved a special gland, called the rectal gland, that concentrates NaCL from their body fluid and secretes it into the large intestine for elimination through the anus

Since coelacanths' kidneys cannot produce urine more concentrated than their body fluids, how do they excrete excess salts?

They have evolved salt glands that concentrate and excrete excess salts from their body fluids

Marine mammals have to deal with gaining excess salts because they get all their food from the sea. How do they deal with the excess salts and how do they excrete it?

They have highly efficient kidneys. Their kidneys can produce urine more concentrated than their body fluids so they can excrete the excess salts in their urine.

Where do coelacanths live and what strategy do they use to maintain body fluids to seawater?

They live in the seawater and use the cartilaginous fish strategy to maintain isosmotic body fluids to seawater

How do teleosts that spend part of their life in freshwater and part of their life in seawater adjust?

They switch between the marine teleost osmoregulatory strategy and freshwater teleost osmoregulatory stategy. Ex: Salmon

Why don't freshwater teleosts drink water?

To minimize water gain

Primary methylamine is....

Trimethylamine oxide (TMAO)

Malpighian tubules do NOT carry out....

Ultra filtration

Osmole (OsM)

Unit of osmolarity

What kind of effects does urea have?

Urea has toxic effects in the body and it destabilizes proteins

Mammals excrete their nitrogenous wastes as....

Urea, which must be diluted with water for excretion

Reptiles and birds excrete their nitrogenous wastes in the form of..

Uric Acid

The walls of the collecting duct have a _________ _______ to water

Variable permeability

1 disadvantage of being an osmoregulator

You have to expend energy in order to maintain the osmolarity of your body fluids

The longer the loops of Henle in the kidney, and the ______ they extend in the medulla, the ______ the concentration gradient in the medulla.

deeper, greater

ADH release is regulated by a _______ _____ that involves osmoreceptors in the hypothalamus that monitor the blood osmolarity

feedback loop

The greater the concentration gradient in the medulla, the ________ the concentration of the urine that can be produced

greater

Presence of K+ and uric acid creates osmotic gradient that draws water from _________ into the ________

hemolymph, tubule

The ______ the levels of ADH in the blood, the higher the water permeability of the walls of the collecting duct, and the _______ water that is reabsorbed from the filtrate from the collecting duct

higher, more

All marine vertebrates, except hagfish and cartilaginous fish (Osmoconformers), have body fluids that are ______ to seawater

hyposmotic

Walls of ascending limb are ____ to water and _____ to NaCl. NaCl moves out of the ____ into the _________ _________ as filtrate moves up ascending limb.

impermeable, impermeable, filtrate, interstitial fluids

Freshwater teleosts produce...

large amounts of dilute urine, This also minimizes loss of salts from the body

Marine teleosts constantly ____ water and _____ salts across gills and in food eaten

lose, gain

Concentration of salts in cartilaginous fishes' bodies is _____ relative to the concentration of salts in seawater

low

Walls of descending limb are _____ to water and _____ to salts. The osmotic gradient pulls water out of the _____ into the _____.

permeable, impermeable, filtrate, blood

Freshwater cartilaginous fishes have lost ability to

reabsorb urea and their liver doesn't synthesize methyl amines

Marine teleosts drink seawater to......

replace water lost. Gain lots of salts from drinking seawater, primarily Na Cl, Mg++, and SO4

These animals excrete uric acid as a....

somewhat dry paste, minimizing water loss through the urine.

Osmosis

the movement of water across a semi permeable membrane

If air temp is at or above body temp...

the nasal cavity will not be cooled during inhalation. This is why these animals remain in their burrow during the hottest time of the day

In some cases, the presence of _____ and ______ makes the body fluids of these fishes ______ to seawater so they ____ water from the seawater instead of ____ water.

urea, methylamines, hyperosmotic, gain, lose

Classification of animals are based on..

whether or not they regulate the osmolarity of their body fluids