Ion and Water Balance Flashcards
What are the two main body fluids?
Inttracellular and extracellular
What is intracellular fluid?
the fluid that exists
within cells
What are the three types of extracellular fluid?
- Blood plasma and lymph
- Interstitial fluid : in the spaces
between cells and tissues of the body. - Cerebrospinal Fluid
What is osmosis?
Osmosis is the diffusion of water across a membrane in response to osmotic
pressure caused by an imbalance of molecules on either side of the membrane.
What is osmoregulation?
Osmoregulation is the process of maintaining salt and water balance (osmotic balance) across membranes within the body
Why is osmoregulation important?
Without a mechanism to regulate osmotic pressure, or when a disease damages this mechanism, there is a tendency to accumulate toxic waste and water, which can have dire consequences.
What is a hypertonic solution? What happens when a cell is in a hypertonic environment?
High salt concentration. Water exits cell to balance it out. Tend to shrink.
What is a hypotonic solution? What happens to cells when placed in this environment?
Higher salt concentration within cells, water enters cell to balance. Tend to swell.
What is an isotonic solution?
Equal balance inside and outside of cell.
What is an electrolyte?
Electrolyte is a solute that dissociates into ions when dissolved
in water.
What is a non-electrolyte?
- A non-electrolyte, does not dissociate into ions during water
dissolution.
What are stenohaline organisms? What environments can they live in?
can tolerate only a relatively narrow range of salinity. Restricted to either fresh or saltwater and are incapable of osmoregulation in opposite environment.
What are euryhaline organisms?
can tolerate a relatively wide range of salinity are referred to as euryhaline organisms. This is possible because some fish have evolved osmoregulatory mechanisms to survive in all kinds of aquatic environments.
Is the diffusion of salt/ions across semi-permeable membranes facilitated or passive?
Active
What is facilitated diffusion?
Facilitated diffusion requires protein-based channels for moving the solute.
Why are salt/ions moved by facilitated diffusion?
If electrolyte ions could passively diffuse across membranes, it would be impossible to maintain specific concentrations of ions in each fluid compartment,
What is active transport? What does it require?
Active transport requires energy in the form of ATP conversion, carrier proteins, or pumps in order to move ions against the concentration gradient
Why do people die of dehydration when stranded in the ocean despite being surrounded by water?
Stranded in ocean, drinking salt water:
No matter how much they drink, they will get dehydrated as the body will try to remove as much water as possible to get the high salt concentration out of the body.
What is the relationship between freshwater fish and their environment? What does this mean?
Hyperosmotic; inside of the body contains more salt than outside, thus water tends to enter the body more readily.
What are the challenges of freshwater fish? What solutions do they have to manage this?
Challenges:
* Gaining too much water
* Losing too much salt
(because the environment is relatively hypotonic)
Solutions:
* Drink less or no water
* Osmoregulate:
* Excrete very dilute urine
* Actively transport salts back through the gills
What is the relationship between saltwater fish and their environment? What does this mean?
Hyposmotic; more salt outside the body than inside, water tends to exit the fish.
What are the challenges of saltwater fish? What solutions do they have to manage this?
Challenges:
* Losing too much water
* Too much salt in their system
Solutions:
* Drink seawater
* Osmoregulate:
* Excrete very concentrated urine
* Actively remove excess salts through gills
What relationship do marine invertebrates have with their environments? How does this work? Provide an example.
- Most marine invertebrates, maybe isotonic with sea water (osmoconformers)
- Their body fluid concentrations conform to changes in seawater concentration
- Body fluid salt concentrations comparable to those of the environment
- Ex. Sharks have rectal glands that help with this
Explain rectal glands in sharks. How is this conforming and not regulating?
glands that assist in excreting extra salt if needed (not there for osmoregulation, but to conform to the environment the shark is in)
Explain the evolutionary timeline of osmoregulation.
- Membrane channels and pumps
- Malphigian tubes
- Nephron
- Kidneys
What is a nephron?
The smallest functional unit of a kidney.
List the components of a nephron.
Renal corpuscle
Proximal convoluted tubule (PCT)
Nephron loop
Distal convoluted tubule (DCT)
Collecting duct
Papillary duct
Label this image.
I. PCT
II. Renal carpuscle
III. Nephron loop
IV. DTL
V. TAL
VI. DCT
VII. Collecting duct
VIII. Papillary duct
Use this image to countercurrent multiplication.
The loop of Henle acts as a countercurrent multiplier that uses energy to create concentration gradients. The descending limb is water permeable. Water flows from the filtrate to the interstitial fluid, so osmolality inside the limb increases as it descends into the renal medulla. At the bottom, the osmolality is higher inside the loop than in the interstitial fluid. Thus, as filtrate enters the ascending limb, Na+ and Cl- ions exit through ion channels present in the cell membrane. Further up, Na+ is actively transported out of the filtrate and Cl- follows.
