Principle of Osmosis and Diffusion Basics

Study Notes

Principle of Osmosis and Diffusion

Osmosis: Movement of water across membranes from high to low concentration.
- Passive process.
- Dynamic equilibrium.
- Fast over short distances.
- Dependent on temperature, concentration gradient, and particle size.
Diffusion: Movement of particles across membranes from high to low concentration.
- Passive process.
- Dynamic equilibrium.
- Fast over short distances.
- Dependent on temperature, concentration gradient, and particle size.

Terms and Measures of Fluid and Electrolytes

Molarity: Concentration of a purified compound in a volume of water (mol/L).
Millimolar (mM): 1/1000 of a mole.
Osmolality: The quantity of dissolved particulate matter in the water portion of plasma.
- Measured in milliosmoles (mOsm).
- Range: 270-290 mOsm (average: 286 mOsm).
Equivalents: Reflects the ion charge in a solution.
- Measured in milliequivalents (mEq/L).
- Used for individual ions in cell membranes and protein structures.

Cell Membranes: "The Fluid Mosaic Model"

Composed of phospholipids.
- Hydrophilic head: Attracts water.
- Hydrophobic tail: Repels water.
Membrane structure: phospholipid bilayer.
Fluid Mosaic Model:
- Dynamic, moving phospholipids.
- "No Flip Flop": Phospholipids move within their own bilayer.
- Cholesterol helps maintain membrane fluidity.
- Unsaturated fatty acids increase membrane fluidity.

Protein Structures in the Membranes

2 Major Categories:
- Extrinsic, Peripheral, Associated Proteins:
  - Located on the surface of the membrane.
  - Examples: Structural proteins.
- Intrinsic, Transmembrane, Integral Proteins:
  - Extend through the membrane.
  - Categories:
    - Structural:
      - Tight Junctions: Found in skin, small intestine, and blood-brain barrier (BBB).
      - Gap Junctions: Found in cardiac cells.
    - Enzymes
    - Receptors
    - Transporter Proteins:
      - Channels: Allow passive movement of molecules across the membrane.
        
        Open Pore Channels: No gates or barriers.
        
        Gated Channels: Open and close in response to stimuli.
        
        Voltage-Gated Channels (VGC's): Open in response to changes in electrical potential.
      - Carriers: Bind to molecules and transport them across the membrane.
        
        Require energy for transport.
    - Carrier Proteins: Bind to and move molecules across the membrane.
      - Require energy for transport.

Description

Explore the fundamentals of osmosis and diffusion, focusing on their mechanisms and the conditions that affect these processes. This quiz will also cover essential terms related to fluid and electrolyte concentration measurements, such as molarity and osmolality.