Intro to Electricity

What is electricity?

Flow of electrons around a circuit from negative to positive

How do you measure charge?

Coulomb

How do you measure current?

Ampere

How do you measure voltage?

V

How do you measure resistance?

Ohm

What is a coulomb?

Charge transported by a current (1A/sec)

What is a joule?

Passing electric current of one ampere through a resistance of one ohm for one second

What is a Watt?

1 J/second (energy rate of transfer)

What is voltage?

Difference in electric potential energy between two points in a circuit

What is voltage equivalent to on circuit?

Pressure (Change in pressure)

What is current?

The flow of charge

Do conductors hold on to electrons loosely or tightly?

Loosely

Do insulators hold electrons tightly or loosely?

Tightly

What is current equivalent to on bypass?

Flow

What is resistance?

Opposition to the movement of electrons

What is a semiconductor?

Material that is neither conductor nor insulator

What is a good conductor that is used in medicine?

0.9% saline or electrolyte solutions

What type of wave does AC voltage display?

Sinusoidal wave

What is amplitude?

The maximum value reached by a voltage or current waveform

What is frequency?

Number of waves that pass a fixed point per unit time

What unit is frequency measured in?

Hertz (Hz)

What type of interference will we see in the operating room?

Electrical interference 60 cycle

Which type of voltage can travel far distances?

AC (Less voltage drop)

What is Ohm’s law?

I=V/R

What is Ohm’s law for our bypass system?

R=ΔP/Q

How do you calculate resistance?

L*η*8/πr^4

(length* viscosity * 8/ pi x radius^4)

What is reynolds number?

Dimensionless quantity whose magnitude gives an indication of whether flow is laminar or turbulent

What does it mean if Reynolds number is <2000?

Flow is likely to be laminal

What does it mean if reynolds number is >2500?

Flow is likely to be turbulent

How do you calculate reynolds number?

(mean velocity x density x diameter)/viscosity

How does pressure drop in a series?

It can be large due to it compounding

How does pressure drop in a parallel circuit?

Pressure drop will be constant for each branch of the circuit

What are units for resistance?

Dynes/sec/cm^5

What is unit for flow?

LPM

How do you calculate SVR? (system)

(Aorta - CVP)/Q

How to calculate PVR?

(PAP - PWP/Q)

What is happening at Phase 0?

Rapid depolarization and fast influx of Na

What happens during Phase 1?

Transient efflux of K

What happens during Phase 2?

Influx of Ca and Na

What happens during phase 3?

Efflux of K is greater than influx of calcium and sodium

What happens during phase 4?

Na and K active pump