NPB 101L: Lab #1 Quiz

Lab Summary

Goal #1:

Sampling a SquareWave in order to become more familiar with the BioPac system and stimulator.

-Can adjust the frequency, magnitude and duration with multiplier knobs

-Switch stimulator from off to repeat

Goal #2:

Altering the wave shape by changing the settings of the stimulator

-Increase duration of wave -> increased wavelength

-Increase voltage -> increased amplitude

-Increased delay -> each wave occurs later at the same duration

Goal #3:

Using the function generator and recording signals

-Connect red and black cable into the wall outlet

-Open the sine wave program

Data window:

-adjust horizontal scale by adjusting the "scale" value (i.e. 3 seconds/div)

-adjust vertical scale click on vertical axis on right and enter value in volts for the "midpoint" and a value in volts for the "scale"

Analyzing waveforms using BioPac software:

-Ch 1: three measurements should be in delta, p-p, and value; use I-bar to select from upper to lower peaks

-Ch 2: select an area that extends from peak to peak; change measurement toolbox to frequency -> the value will be given in Hertz (Hz)

x-axis

time (seconds)

y-axis

force (grams)

Tool used to tell force present in the first obvious response?

Value

Tool used to tell maximum force value within the first train of responses?

Max

Tool used to tell difference between baseline force and value at the peak of the first responses?

P-p or delta

Tool used to record the "heart rate" of the first recording period if this was an ECG and units of measurement?

Tool used to get a similar answer but in different time units?

BPM tool and beats per minute (bpm) unit of measurement

Frequency

Requirements of using the BPM or frequency tools to measure to measure the "heart rate"?

Must select one period from peak-to-peak, or select more wave forms as long as you multiply the BPM/frequency by number of waves selected

Tool used to determine at what time in recording does the third recording train begin?

Time

What happens to the sine wave if frequency is increased?

The wavelength becomes shorter

Calibrate

to correlate the readings of an instrument through comparison with a standard of known accuracy

Why is calibration important in laboratory settings?

-Accurate measurements in data collections

-Valid findings in research

-Reproducible experiments (standardization)

-Quality and safety

Transducer and components

Converts energy from one form into another

Made up of:

-Input (sensor): converts physical energy to a readable electrical signal

-Output (actuator): converts readable electrical signal to physical energy

GRAS stimulator

this stimulator is used to produce an electrical impulse that can be recorded by the BioPac system

Voltage

delivers the power of the impulse, or current, delivered by the stimulator. The higher the voltage, the higher the amplitude, or difference between the peaks and trough (or baseline); or amplitude, will be on the reading

Duration

controls how long the current will be applied for, increasing this dial will increased the width of the wavelength

Delay

sets the amount of time between stimulation and wave onset, adjusting the position of the wave left or right on the x/y-axes

Frequency

controls how many times the stimulus goes off in a set time frame (usually minutes or seconds), increasing this will increase the number events within a time frame, or decrease the wavelength of a wave

Snapshot mode

Makes it easier to see and analyze one wave form at a time

Can observe the finer details of a single impulse, but can only observe one impulse at a time

Useful to determine best stimulus

Chart recorder mode

can be used to analyze an average over a longer period of time, used to visualize patterns

Allows analysis for larger data volumes to determine averages and eliminate outliers, but doesn't allow for as much emphasis on detail as snapshot mode

Useful to determine understand how an organism reacts to repeated stimuli

Delta

measures on y-axis

in grams (volts)

method to use: I beam -> delta

measures the differences in amplitude between the last point and first point of the selected area (final - initial)

P-p

y-axis

grams (volts)

I beam -> p-p

finds the max and min values, subtracts the min from max in selected areas

Frequency

x-axis

Hertz (Hz)

I beam -> frequency

measures the inverse of the amount of time selected, if only one waveform is highlighted, that is the frequency; can be used as an alternate method to find heart rate by mutiplying out of Hz (BPM) and then by number of waves to determine the heart rate

BPM

x-axis

beats per minute

I beam -> BPM

same as frequency, but also multiplies by 60 seconds/minute, if more than one wave is highlighted multiply by number of waves highlighted, highlight from lowest peak to lowest peak

Mean

y-axis

grams

I-beam -> mean

tells average force (in grams) of the selected area

Lab Purpose

To introduce us to the Biopac system and its basic functions such as measuring frequency and amplitudes of the waveforms.

General Outcomes

Measure amplitude by using I-bar and dragging peak-to-peak or peak-to-trough of one of the waveforms. Divide this value by 2 to get value with respect to 0. Value measured in force units or grams

Measure frequency by selecting "freq" channel and selecting a single value with the I-bar. This value is measured in Hertz.