Osmoregulation and Excretion Flashcards
What is osmoregulation?
This is the homeostatic process by which animals control their solute concentrations and balance water gain and loss.
What is the general adaptation of freshwater mammals to osmoregulate?
Reduction in uptake of water and conservation of solutes.
What is the environment that desert and marine animals live in described as?
DESICCATING ENVIRONMENT - it can quickly deplete them of their body water.
What is excretion?
This is the process animals use to remove nitrogenous wastes from their bodies.
What is osmosis?
This is the movement of water across a selectively permeable membrane from a region of low solute concentration to an area of high solute concentration.
OR
from a region of HIGHER FREE WATER CONCENTRATION to a region of LOWER FREE WATER CONCENTRATION.
What is osmolarity?
The solute concentration in a solution, this determines the direction of water movement across a selectively permeable membrane.
When two solution differ in osmolarity, what is the net flow of water?
What happens if the solutions are isoosmotic?
Hypoosmotic (lower solute concentration) to the hyperosmotic (higher solute concentration).
If isoosmotic: water movement is equal in both directions.
What are the two ways that an animal can maintain its water balance? Example?
- Osmoconformer - these are isoosmotic to their environment and do not regulate their osmolarity. All osmoconforming animals are marine, NOT ALL MARINE ARE OSMOCONFORMERS.
- Osmoregulators - expend energy to control water uptake and loss in environments with varying osmolarity. These include freshwater and terrestrial animals.
What is meant when i say that most animals are stenohaline?
This means that they cant tolerate substantial changes in external osmolarity.
What is meant when I say that some animals are euryhaline?
This means that the animal can survive large fluctuations in external osmolarity. Such as barnacles that can handle tidal fluctuations or salmon that live in oceans but travel up freshwater rivers to reproduce.
How do most marine invertebrates osmoregulate?
Osmoconformers
Even though marine invertebrates (osmoconformers) dont face any substantial challenges in water balance, do they still need to be able to transport certain solutes to maintain homeostasis?
YES
How do most marine vertebrates osmoregulate?
Osmoregulation
some marine invertebrates are osmoregulators as well.
In comparison to sea water, what is the solute concentration of bony fishes?
hypoosmotic.
Since marine bony fish are hypoosmotic to their sea water environment, what happens to their body water? How do they balance their water loss? How do they regulate their body salt?
Their body water is lost via osmosis to the hypertonic sea water.
They gain their water back by drinking seawater and excreting the salts and small amount of water via urine.
Salt is gained by drinking sea water and is also diffused via food.
What is the osmolarity of sharks? How does sea wter act with sharks?
Sharks have an osmolarity that is very close to seawater.
The sea water will slowly enter the sharks body and is disposed via their kidneys.
What is the osmolarity of a freshwater animal (fish) to its environment? Where does water move? How do they lose their salts? How is salt replaced?
Euryhalines?
They are hyperosmotic. They take in water from environment via osmosis, excrete large amounts of water via urine to maintain water balance.
Salts are lost by diffusion and are replaced via foods and uptake across gills.
Salmon and other euryhaline fishes that migrate between seawater and freshwater undergo dramatic changes in osmoregulatory status.
What is anhydrobiosis, what is one exxample of an organism that undergoes this? What molecule aids in this process?
This is when some aquatic invertebrates in areas like temporary ponds lose almost all of their body water and survive in a dormant state.
Trehalose is a disaccharide that essentially replacing water that is normally associated with proteins.
What is a major problem in terrestrial plants and animals?
Dehydration
What are two ways in which we get our water? Look at this picture and see the differences in water uptake and water loss between a human and a desert animal.
Drinking and eating moist foods
Ultilizing metabolic water
How much of the resting metabolic rate goes to maintain osmotic gradients in osmoregulators? What does the cost depend on?
About 5-30% of resting metabolic weight
- Difference in animals osmolarity and its surroundings
- Ease of water moving across animals surface
- Work required to pump solutes across its membranes
What is transport epithelia?
These are specialized epithelial cells that regulate solute movement.
These are essential components of osmotic regulation and metabolic waste disposal.
Look at transitional epithelium and its role in salt secretion in the nasal glands of a marine bird.
Do animals tend to make different nitrogenous wastes depending on their environment? What are the 3 nitrogenous wastes we discuss? Which is the most toxic? Least toxic?
YES
Urea, ammonia, and uric acid
Ammonia is the most toxic of the nitrogenous waste products.
Urea is the least toxic.
What is gout?
This is when uric acid deposits into the joints and causes pain and inflammation.
Look at this picture and understand what animals tend to excete which notrogenous waste.
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Describe the protonephridia of a planarian. What does it consist of? Do these function in osmoregulation or nitrogenous waste removal?
These are filtration units of planarias. Consisting of a tubule cell and cap cell, there is cilia inside and all of these components together are what a “flame bulb” consists of. These tubulues end at an opening in the body wall to empty into the environment.
Mostly control osmoregulation, nitrogenous wastes are primarily removed through the mouth.
Describe the metanephridia of an earthworm. Osmoregulation or nitrogenous waste removal?
These are located two in each segment of the earthworm.
Collect fluid from the coelom, to filter and excrete it through opening in body wall per each metanephridia.
These earthworms absorb nutrients and water directly through their skin, these metanephridia allow for them to control osmoregulation and excrete nitrogenous wastes
Describe the Malpighian tubes of insects. Osmoregulation or nitrogenous waste removal?
These function in both osmoregulation and nitrogenous waste excretion.
Each tubule extends into the body cavity surrounded by hemolymph and absorbs salts, water, and nitrogenous bases and drains into the intestine where the urine and feces are both excreted through the anus.
Which of the regions is outer and which is inner between the renal cortex and the renal medulla? What is the function of the renal pelvis?
Cortex - outer
Medulla - inner
The renal pelvis collects the urine before draining into the ureter.
What are the functional units of the kidney called? What are the two types of these and their differences?
Nephrons.
Cortical - About 85% of nephrons, componenents only reside in the renal cortex.
Juxtamedullary - loop of henle descends into the renal medulla.
What deos a nephron consist of?
A single long tubule and a ball of capillaries called a GLOMERULUS.
What is the difference between an afferent and an efferent arteriole? What is the peritubular capillary? Vasa recta? How do the vasa recta function with the loop of henle?
Afferent - leads to the glomerulus.
Efferent arteriole - leaves the glomerulus
Peritubular capillaries - form the the efferent arteriole and surround the proximal and distal tubules.
Vasa recta - These serve the loop of henle, function as a countercurrent system.
Look at this picture and understand what is going on in each area of the kidney, note the active and passive transportation.
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What is the countercurrent multiplier system?
This is the type of countercurrent system in which energy is expended to establish a concentration gradient.
Look at this picture to understand the countercurrent multiplier system.
What part of the brain detects changes in the osmolarity? What is secreted in response to a increase in osmolarity? Where is this secreted from? Where does this hormone act on? What does it cause?
Hypothalamus
ADH is released
Secreted from the posterior pituitary
Acts on the collecting duct, stimulating the insertion of aquaporins so water can be reabsorbed at a higher rate.
Take a brief look at this picture of the pathway ADH action within a collecting duct cell.
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