Subatomic Processes Flashcards
What makes up an atom?
Protons (+ charge) neutrons (neutral charge) electrons (negative charge).
Protons and neutrons are in the nucleus and are made up of sub atomic particles called quarks.
How do electrons behave
The arrangement of electrons in orbitals determines how an atom will react with another atom. When e- drops an energy level this energy is relased as a photon of light.
This photon has a specific energy and wavelength for each species of atom known as a spectral line.
Atomic wt v atomic number
What is an isotope
Atomic number is number of protons in nucleus. Atomic weight is number of protons and neutrons.
Isotopes have same atomic number but different atomic weight
- Covalent bonds
- Ionic bonds
- Share electrons
- Transfer electrons
- Hydrogen bonding
- Hydrophobic bonding
- Van der walls forced
- Hydrogen atom covalently charged to negatively charged atom (dipolar force).
- Exclude water molecules between two non polar molecules.
- Attractions between electron clouds of neighbouring atoms
Electrostatic binding
Binding of oppositely charged MOLECULES. Ie drug to protein binding.
Hydroxyl
Amino
Carboxyl
Methyl ether
Benzene
Phenol
OH
NH2
COOH2
OCH3
Six carbon atoms in a ring
Benzene ring with hydroxyl group (add two carbon chains to make propofol!)
What is isomerism
Molecules composed of the same number of atoms in the same proportions but with variations in the arrangement of the atoms.
What is tautomerism
Give an example.
Migration of a hydrogen atom and switching single and adjacent double bond.
Midazolam open ring form is water soluble at lower pH
At physiological higher pH is closed ring and lipid soluble to cross CNS.
Aromatic isomer
Give an example.
Chemical group positioned on a different part of benzene ring.
Aspirin
Stereoisomer definition.
Give two types of stereoisomer.
Same number of molecules in same order but different 3D arrangement.
Optical and geometric.
Chiral centre
Carbon atoms attached to 4 different chemical species
Racemic mixture
Equal enantiomers of left (S) and right (R) configurations
Geometric conformer isomersim
Give an example.
Rotation about one or more single bonds.
Hindrance of rotation around bond - vancomycin
What is the venturi principle
Example
When fluid flows through a tube with a constriction in it, the kinetic energy energy increases. Due to the conservation of energy this means that there is a fall in potential energy and a drop in pressure. This can be used to entrainment a second fluid.
Nebuliser
What happens if a compressed gas expands adiabatically?
Example
Which law is this?
It will cool because the energy required to over come the van der walls forces can only come from the molecules themselves there is no heat transfer from surroundings.
Cryoprobe
First
First, second and third law of thermodynamics
- Energy is not created or destroyed
- Law of increased entropy (unavailable entropy)
- As a system approached 0 Kelvin all processes cease and the entropy is minimal
What is pH
Negative logarithm to base 10 of hydrogen ions
What is a strong ion
Give 4 examples
Compound which completely dissociates in water
K, Ca, Mg, LACTATE
What is a weak ion
Example
What is K
Partially dissociated
Carbonic acid
Dissociation constant - rate of forward reaction into ions
What is dissociation constant equation
K = [H+] x [HCO3-] / [H2CO3]
What is a strong acid
Weak acid
Example of strong
Acid completely dissociated in solution
Does not completely dissociate
Lactic acid
What is a strong or weak base
Example of weak base
Compound with does or does not dissociate into its hydroxyl ion and cation
Ammonia, LA
What is pKa
The pH at which a compound and its dissociated ions exist in equilibrium.
Acids ionise above their pKa
Bases ionise below their pKa
What is a buffer, give 3 examples
Solution able to resist changes in H and OH
Bicarbonate, phosphate, proteins
How does temperature affect pH
Increases disassociation and hydrogen ions conc therefore lowers pH
How does EM radiation originate
Generated by oscillations of charged particles (either protons or electrons) and attract opposite charge on electrical field lines
Frequency definition
Frequency equation
Frequency units
Number of wavelengths passing a fixed point in 1 second
Lamba (wavelength) = f x c (speed of light 2.98x10⁸)
Hertz
Energy of EM radiation equation
E = v (frequency) x h (Plancks constant)
How does EM waveforms exist
As an oscillating sine wave travelling at the speed of light in longitudinal and transverse fields. Longer wavelengths ie radio waves exist as waves and shorter ie gamma have more particle properties
How does a side stream analyser work and advantages (3)/ disadvantages (2)
Removes 150ml/ min through sample line, water removed and remaining gas sent to analyser
Lightweight, robust, allows multiple gas sampling
Lag time, can be affected by O2, N2O and water vapour
Reasons sats probe may be unreliable? (Three categories)
- Pulsatile component - AF, Met and COHb, surgical dyes, vasoconstriction
- Non pulsatile component - external lighting interference, nail varnish
- Electrical interference - diathermy
What is total internal reflection
Angle of incidence is greater than the critical angle required that would refract the light
How does fibre optical laryngoscope work
Two layers of glass, outer layer has a lower index of refraction to ensure total internal reflection
Wavelength of maximal absorption of CO2
4.3 micro metres
Definition of laser
Light amplification of stimulated emission of radiation
Three properties of laser
- Monochromatic (one specific wavelength)
- Coherent (in phase)
- Collimated (highly directional)
What is stimulated emission
When energy provided to electrons to reach higher state this acts as an energy source to neighbouring atoms to achieve the same state. When it relaxes it releases two in phase photons of light.
How do lasers work
A lasing medium is pumped with energy to create stimulated emission. Mirrors allow amplification to achieve population inversion and a small gap let’s out light energy.
Examples of 2 infrared lasers
- CO2 - 10600nm far IR
1mm tissue surface
Bloodless cutting and vaporisation - Nd:YAG - 1064nm near IR
3-5mm depth
Absorbed by Hb, melanin and water
Example of visible light laser
Argon - 500nm blue green
2mm
Coagulation
Laser classification
1 low power
2 < 1mw
3 < 500mw hazardous if directly viewed
4 >500mw
Name two types of isomerism with examples
Constitutional (structural) - Identical chemical formula, order of atomic bonds differ.
Enflurane and isoflurane.
Stereoisomers - same atoms same order different 3D arrangement.
Definition of optical isomers
Give two examples
Non superimposable mirror image
(left/ right) (R/S)
- S-ketamine (less psych s/e)
- Levo-bupivicaine (less cardio toxic)
Cis-trans geometric isomerism definition
Give an example
Variable molecule on same or opposite side of double bond
Cisatracurium (more CVS stable)
pH equation
pH = pKa log10 ([HCO3-] / [CO2])
Risks of lasers
- Flammable
- Laser tracheal tubes, balloon with saline
- Reflection if light therefore use matt black instruments
- Visual - goggles, door screens
- Personell - specific person in theatre responsible
