Water & the Membrane Barrier Flashcards
What is Extracellular Fluid? (ECF)
- The internal environment of the body.
- Stuff that surrounds cells.
What are intracellular fluids? (ICF)
Fluid in cells.
Define homeostasis.
The maintenance of stable, ideal conditions in the internal environment.
Ideal Condition’s include: osmolarity, pH, temperature, ion concentrations, nutrient, concentrations, volume.
What are the 4 important ions for this class?
Na+, Cl-, K+, and Ca++
What is a cation?
Positively charged ion. Ex. Na+, K+, or Ca++
What is an anion?
A negatively charged ion. Ex. Cl-, or large organic anions (mainly proteins)
What molecules are hydrophilic? And what does that mean?
Polar molecules: they dissolve readily in water.
This is because polar molecules can interact with the polar regions on water through H-bonding.
What molecules are hydrophobic. And what does that mean?
Non-polar molecules: they dissolve poorly in water. This is due to the lack of hydrogen bonding interactions as they don’t have polar atoms to interact with water.
What is an Amphipathic molecule? What’s the main example of this in this class?
Molecules with both a polar and nonpolar side. Ex. Phospholipid’s.
What are the 3 behaviors of amphipathic molecules in physiological contexts?
- Bilayer (Ex. Phospholipid bilayers/cell membrane)
- Spherical Micelle (Ex. Fat absorption/lipoprotiens)
- Monolayer at air/water interface (Ex. Surfactant in lungs)
What molecules can pass through the cell membrane through diffusion? And why?
Hydrophobic molecules and some small polar molecules. Because they are the ones able to either be small enough they can squeeze through without too much repulsion from the hydrophobic tails of the phospholipids, or they are hydrophobic themselves so they have no problem going through the tails.
