Week 1 General chemistry, solubility, diffusion & osmosis

Atomic number

Number of protons in the nucleus

Mass number

Number of protons and neutrons in the nucleus’s

Electron arrangement determines what?

Chemical bonding, molecular behavior,

What are valence electrons?

Electrons in the outer most shell, they determine reactivity and bonding.

What do bond affect?

Stability, polarity, and solubility

Ions

Atoms that have a positive or negative charge due to gaining or losing electrons

Anion

Atom that has gained electrons and therefore has a negative charge

Cation

Positively charged ion due to the loss of electrons

What are Ions important for?

Chemical bonding and aqueous solubility

What are isotopes?

Same formula but different structure, same number of protons, different number of neutrons.

What are the different type of isomers?

Structural- Have different bonding arrangements

Stereoisomers- Have different spatial orientation

Why are isomers clinically relevant?

isomers of the same drug have different drug effect, potency, metabolism and side effects. Example is bupivicaine (high cardio toxicity) and ropivicane (less cardio toxicity)

What are Ions important for?

Chemical bonding, drug solubility, electrolyte balance, cardiac conduction, neuromuscular function, membrane potential, drug solubility.

What are the two main types of molecular bonds?

Covalent and electrostatic

Covalent bonds

Strong and stable, sharing of electrons.

What do bonds determine?

Shape stability and reactivity

In anesthesia what do bond affect?

Lipid solubility, receptor interactions, and metabolism

What are types of electrostatic bonds?

Ion-ion, ion-dipole, and dipole-dipole

Ion-ion bonds

Complete transfer of electrons, form charged ions, have strong electrostatic attraction, water soluble, disassociate in solution.

ion-dipole bonds

Ions interact with polar molecules, important in drug dissolution, essential for dissolving electrolytes (without drugs would not remain dissolved in plasma) example is sodium chloride ion interacting with water.

Dipole-Dipole

Two polar molecules (example: two water molecules),

What do dipole-dipole bonds influence?

Molecular organization and solubility

Bond breaking

Breaking bond requires energy, forming a bond releases energy, same amount of energy needed to break bond is needed to form it. Short covalent bonds are stronger and require more energy to break as opposed to longer electrostatic bonds. Bond energies are measured as enthalpy changes.

Enthalpy

The total amount of energy in a system, can be atomic or macroscopic. Includes potential and kinetic energy. This is difficult to measure so energy changes are often measured instead. Is important in metabolism and drug reactions.

What is an organic compound?

Carbon containing molecules, all biological life contain carbon.

Van der Waals forces

Temporary electron shifts, weak intermolecular forces (between molecules) that are present in molecules. Clinical applications are drug-receptor binding, volatile anesthetic affects, and protein interactions.

Bond strength

Strong bonds= structure, weak bonds = drug receptor interactions (reversible)

Covalent—ionic—-hydrogen (polar interactions)—-Van der Waals Forces

Water as a solvent

Polar molecules that dissolve in water are hydrophilic. Nonpolar molecules do not dissolve in water and are hydrophobic.

Hydrocarbons

Made of hydrogen and carbon, types are alkanes (single bond), alkenes (double bond), and alkynes (triple bond). Unsaturated are more reactive.

Why are functional groups important?

They affect drug solubility, potency, and metabolism.

Common functional groups

Alcohols, amines, ethers, carbonyl-containing groups (aldehyde, ketones, carboxylic acid, esters, amides

Solubility

The max amount of one substance (solute) that can be dissolved into another (solvent).

What factors affect solubility?

Temperature, pressure, and intermolecular interactions between the substances.

Solubility- solids and liquids

Like dissolves like..polar-polar, nonpolar-nonpolar. Increasing temperature usually increases solubility. Minimal effect from pressure changes. Breaking intermolecular forces requires endothermic (heat) energy.

Solubility-gases

Inverse relationship with temperature (decreased temp increases gas solubility. Directional relationship with pressure (increase pressure increases solubility). Clinical applications: Hypothermia increase gas solubility.

Henry’s Law

• 𝐶 = 𝑘 · 𝑃 The amount of dissolved gas in a liquid is proportional to its partial pressure above the liquid. Gases will move from higher pressure to lower pressure. Clinical example: Increased inspired anesthetic will increase blood concentration and have faster uptake. Clinical implications: Increase in Fio2 or HBO will increase dissolved O2

Henrys Law- dissolved O2 and CO2 equation?

PaO2× 0.003 mL/dL/mmHg

CO2 = PaCO2 × 0.0067 mL/dL/mmHg

What is diffusion?

Movement from area of high concentration to low concentration. Is driven by Brownian motion and kinetic energy. Smaller molecules diffuse faster.

What factors are directly proportional to diffusion?

Concentration gradient, surface area, and solubility. If any of these increase so does the rate of diffusion.

What factors are inversely proportional to diffusion?

Membrane thickness and molecular weight. Thicker membranes and larger molecules diffuse slower.

Fick’s Law

Describes the relationship between the rate at which particles move and the concentration gradient. Particles will flow from higher to lower concentrations at a rate proportional to the concentration gradient.

What is osmosis?

Movement of water across a semipermeable membrane. Water moves from areas of low concentration to high concentration

What is the opposing force to stop osmosis

Oncotic pressure. ~28mmHg

Examples of diffusion in anesthesia?

Nitrous oxide moving rapidly into air-filled spaces (second gas effect) and apneic oxygenation (O2 continues to diffuse without ventilation.

Graham’s Law

Molecular weight of a gas determines how fast it can diffuse through the membrane. Rate of gas diffusion is INVERSELY proportional to the square root of the gas’s molecular weight. Smaller molecules diffuse faster. Second gas effect is clinical application.