10/27 Recitation Quiz Flashcards
Diffusion
the movement of molecules across a selective barrier
Selective (semi-permeable) barrier
allows water molecules to pass through, but not most of the molecules dissolved in the water
Osmosis
the diffusion of water molecules across a selective barrier from high to low concentration
Solutes
molecules that are dissolved in water
What is the concentration of water determined by?
The concentration of solutes in the water
Solute potential (Psy sub s)
a measure of the concentration of solutes dissolved in water
Pure water
has no solute (highest value; most concentrated water molecules)
Psy sub s= 0
Relationship between Psy sub S and water molecule concentration
Linear
high Psy sub s= high water molecule concentration
- closer to 0
Relationship between solute concentration and Psy sub S and Water concenration
As solute concentration increases, Psy sub s decreases and water concentration decreases
What happens when Psy sub S is higher outside the cell?
Water will rush into the cell
- The cell will swell
- The cell could burst
What happens when Psy sub S is higher inside the cell?
Water will diffuse out of the cell
- The cell will shrink
- The cell could die
Brain capillaries
fine blood vessels that feed brain tissue
Capillary wall cells
form a tube
Intercellular junctions
physical connections between capillary wall cells
Hold capillaries together
Blood-Brain-Barrier
Strict control of molecules must pass through the plasma membrane of capillary wall cell
Breaching the Blood-Brain-Barrier
- Lower the psy sub s of blood (inject a solute)
- Water moves out of the capillary wall cells
- Capillary wall cells shrink slightly - Creates an opening between cells
Energy
the capacity to do work
What are the 2 forms of energy?
Kinetic energy and Potential energy
Kinetic energy
Energy of motion, a variety of forms
- Heat
- Light
- Mechanical
Potential energy
stored energy
- Concentration gradients
- Chemical bonds
Thermodynamics
a branch of chemistry that deals with energy transformations (changes)
- the first law
- the second law
First Law of Thermodynamics (Conservation Law)
Energy can’t be created or destroyed
Energy can only change from one form of energy to another
Total amount of energy in the universe remains constant
Second Law of Thermodynamics (energy transfer)
No energy transfer is 100% efficient
Some energy is always lost (usually as heat) and becomes unusable energy
Entropy (unusable energy) in the universe is continuously increasing
Free energy (usable energy) in the universe is continuously decreasing
Free energy (usable energy)
- G: energy available to do work
G= H-TS
