Electricisy And Electrical Safety Flashcards
What is electricity?
The effects produced by moving charges
What types of charges are there?
Positive: contain more protons than electrons
Negative: contain less protons than electrons
*like charges repel, opposite charges attract
Coulomb’s Law
Like charges repel, opposite charges attract. The magnitude of the electrostatic force of attraction or repulsion
What is SI unit of charge?
The coulomb
What is electrical potential energy?
If we put a “test charge” into an electric field and hold it still
What is current?
Electrical current is the amount or charge flowing per unit time
And amp (ampere) of current corresponds to 1 coulomb of charge per second
What are conductors?
Materials in which charges can easily move
- to be a good conductors, electrons must be able to move easily from one atom to the next
- metals are good electrical conductors
What are insulators?
Most are non-metals and generally are not good conductors
What is the molecular orbital approach to bonding?
Atomic orbitals from individual atoms are added together to form molecular orbitals that extend over the entire moleule
What is resistance?
The energy required to push electrons through a material
*measured in ohms
Conductance is the ____________ of resistance
Reciprocal
Conductance is measured in mhos
Electric circuit
The closed path through which a charge flows
Direct current (DC) circuit
An electrical circuit in which the current flows in one direction only
Alternating current (AC) circuit
An electrical circuit in which the current reverses its direction in a periodic fashion
Short circuit
A situation in a circuit where the normal resistance of the circuit is bypasses by a low resistance path resulting in a large current
*if current from a short circuit is not limited by a fuse or circuit breaker, the resulting heat from the high current can lead to a fire
Series circuits
When batteries or resistors are connected in a series, the voltages and resistances are added
Parallel circuits
When resistors are connected in parallel, current flows through each resistor independently of the other
Electrical power is the product of what 2 things?
Volts and amps
What is the difference between electrical energy and electrical power?
Power = energy/time
Energy = power x time
*we pay for electrical energy, not electrical power
What are semiconductors?
A moderately good conductor of electricity
P-Type Semiconductor
Positive type
The crystalline lattice thinks it’s a few electrons short or has “positive holes”
N-Type semiconductor
Negative
The crystalline lattice thinks it has extra electrons
What types of diodes are there?
Forward bias: when current passes through, electrons move towards eachother
Reverse bias: when current passes through, electrons move away from eachother. Provides a high level of resistance
What are diodes?
2 semi-conductors put together (N and P).
Used to control current direction
What are triodes?
Transistors
-another way of manipulating the current to get it to do what you want it to do
What is spectroscopy?
The branch of science concerned with the investigation and measurement of spectra produced when matter interacts with or emits electromagnetic radiation
How are electrical shocks possible?
If you come in contact with an external source of electricity
Also possible from stray capacitance and inductance
Macroshock
Large amounts of current conducted through a pts skin or other tissues.
The extent of injury will depend on the amount of current and duration of exposure
Micoshock
The delivery of small amounts of current directly to the heart
Very small currents (=50 micro amps) can produce v-fib
What is the threshold of human perception of a shock?
1 milliamp
What does a ground wire on a piece of equipment do?
Provides a low-resist case pathway for leakage current and constitutes the major source of protection against microshock in the electrically susceptible pt
*never simultaneously tough an electrical device and saline-filled CVP catheter or external pacing wires. * wear rubber gloves
Pt monitors are designed to electrically ___________ all direction pt connections from the power supply of the monitor.
Isolate
Polarized plugs
New electrical devices have plugs with one narrow prong an done wide prong.
Ensures that the plug may be only inserted into the outlet in one orientation
Three-pronged grounded plug
Some electrical devices have a rounded third prong that is connected to the ground when plugged into a three-pronged receptacle.
If for some reason a high-potential wire comes in contact with the case, the current will flow directly through the third prong instead of through your body
Ground fault circuit interrupter (GFCI)
Used in circuits near water sources.
Immediately disrupts the flow of current in the circuit if a change in current is detected
*disadvantage of using in OR is that it interrupts power without warning.
Modern electrical circuits are typically _____________
Grounded
To further decrease the risk of electrical shock in ORs, electrical systems are ___________ from the grounded electrical supply through the use of __________ _____________
Isolated
Isolation transformers
Isolation transformers
Rely on magnetic inductance to transfer a current from the grounded electrical system to an ungrounded secondary system without the two systems physically contracting each other
Lessens the risk of shock
____________ systems i the OR prevent accidental shocks resulting from simply touching a single live wire
Ungrounded
If live wires make contact with tea ground, the ungrounded system now becomes a ground system. Thus we say a ______ has occurred resulting in a grounded system
Fault
Line isolation monitor
A device that alarms when a fault in an ungrounded system occurs
Located between live wires and a ground to that the impedance to current flow can be measured
If contact is made between a live wire and a ground, current will flow, resulting in an alarm
The alarm set point for a line isolation monitor is usually__________
Between 2 and 5 mA
How do you determine if there is a true fault when the line isolation monitor alarms?
- If the gauge reads between 2-5 mA, there is probably too much electrical equipment plugged into the circuit
- If the gauge reads > 5 mA, it is like that a faulty piece of equipment is present in the OR
- Equipment may be identified by unplugging each piece of equipment until the alarm is silenced
- If the faulty piece of equipment is not essential, it should be removed from the OR
T/F: the line isolation monitor is not designed to proved protection from microshock.
True
This organization sets fire standards from health care facilities
National Fire Protection Association (NFPA)
What 2 factors determined the need to install isolated power in the OR?
Is the OR a wet location? (Presence of blood, fluid, saline solutions)
If so, is an interruptible power supply acceptable?
All health care facilities are required to have what if the even of a power outage?
Emergency power: electrical generators, battery operated light sources including laryngoscopes, etc
The main objective of electrical safety
Make it difficult for electrical current to pass through people
Dynamic equilibrium
Most chemical reactions are reversible
Reactants combine to give products
Products can fall apart to give reactants
Le Chatelier’s Principle
When a system in a state of dynamic equilibrium is disturbed, it will enact to re-establish the equilibrium condition
When is a system in a state of equilibrium?
When there is a balance between reactants and products
Equilibrium constant: K. Provides a numerical description of that balance
As K increases, the reaction tends to increasingly favor_________
Products
As K decreases, the reaction tends to increasingly favor________
Starting materials
What are these? Keq Ka kb Ksp
(All subscripts of K)
Keq: generic equilibrium constant
Ka: weak acids
Kb: weak bases
Ksp: solubility
Why do concentrations of solids or liquids do not appear in the equilibrium constant expression?
Because concentrations of pure solid or liquid, and liquid solvent are nearly constant. These constant values are included with the equilibrium constant
If you ADD products, the equilibrium will shift towards________
If you REMOVE products, the equilibrium will shift towards _______
Reactants
Products
Changing volumes only impacts equilibrium reactions when at least one of the reactants or products is a ___________
Gas
*solids and liquids are not compressible
What is the most generally used definition of an acid?
Bronstead definition
- an acid is a proton donor
- a base is a proton acceptor
What are conjugate acid-base pairs?
When an acid donates a proton, it’s converted into its conjugate base
When a base accepts a proton, it’s converted into its conjugate acid
Amphoteric species
Can behave as either an acid or a base
H20 is an example
H + H2O = H3O+ -> becomes a base
H2O = H +OH+ -> becomes an acid
The stronger the acid, the _________ the conjugate base
Weaker
And vise versa
Stronger acids/bases are more or less determined to give/take a proton
More
Strong bases are:
Soluble ionic hydroxides
The pH scale is based on what?
Self-ionization of water
What is a pH buffer?
A solution that resists changes in pH
May contain a weak acid and its conjugate base
When concentrations of a weak acid and its conjugate base are equal, the pH is equal to ________
-pKa
Are nonionized drugs lipid soluble>
Yes
They readily penetrate the blood brain barrier and placental barriers
Ionized form of a drug is______
Water soluble
What are the 3 steps to determining the ionization/nonionization of a drug?
- Is the drug a weak acid or a weak base?
- What is the pKa of the drug?
- What is the pH of the target solution is placed in? (Usually the body which is 7.4)
Acid + acid = increased nonionized
Base + base = increased nonionized
Acid + base = decreased nonionized
Base + acid = decreased nonionized
What is a solution?
Homogenous mixture tats consists of one or more solutes
Solvent: present in larger amount
Solute: present in smaller amount
Molality and molarity
Deals with units of concentration
Molality is more useful when dealing with physical chemistry
Solubility
The amount of solute that will dissolve in a given amount of solvent
What is a saturated solution?
Contains the maximal amount of a solute as defined by its solubility
What is supersaturated?
A solution contains more solute than allowed by the solubility
Miscible
Two liquids are miscible if they are soluble in each other at all proportions
Solubility guidelines
Like dissolves like
Lattice energy
The energy released when molecules or ions settle into crystalline lattice
Solvation (hydration) energy
The energy released when an ion (or molecules) settles into a sphere of solvent molecules
For a gaseous solute, as partial pressure increases, solubility ___________
Increases
Henry’s Law
The amount of a non reaction gas which dissolves in liquid is directly proportional to the partial pressure of the gas, provided the temperature remains constant
For a gas solute, as temperature increases, solubility ____________
Decreases
*think of a warm can of pop, turns flat
The amount of gas dissolved is inversely or directly proportional to the temperature?
Inversely
The colder the liquid, the more gas that will dissolve in the liquid
If pt colder, anesthetic gas is harder to come off
Colligative properties include what 4 things?
- Vapor pressure decreasing
- Boiling point elevation
- Freezing point depression
- Osmotic pressure increase
*colligative property depends only on the number of solute particles, not the identity of solute particles
Raoult’s Law
Describes vapor pressure of a solution
As vapor pressure goes down, boiling point goes______
Up
Means boils at a higher temp
Des has a high vapor pressure and boils at almost room temp
Why is salt added to the ice when homemade ice cream?
It lowers the freezing point
Osmosis
Diffusion of water through semipermeable membrane
Solute particles are too big (or too polar) to make it across the membrane
This is how water gets moved around cells
Isotonic solutions have _______ concentrations of solute particles
Hypertonic solution has a ________ concentration of solute
Hypotonic solution has a _________ concentration of solute
Equal
Greater
Lower
Osmotic pressure results from what?
The potential drive for the concentration of water to equalize
Fun facts about colloids
- they are not true solutions
- colloidal particles cannot be filtered and do not settle out of solution
- exhibit the Tyndall effect (light scattering)
