Reading 1: Intro 3-18 Flashcards
Name the 6 General Lab outcomes
- Calibrate and operate scientific equipment by following detailed lab manual
- Obtain informed consent from subject prior to exp
- Conduct physiology exp while recording experimental observation in notebook. Identify potential sources of error in scientific exp
4.
Characteristics of a Good Lab Course
- Lab environment should be perceived as attractive by students
Purpose of BPK 407 Project
Gain experience conducting human physiology exp
What week do u submit project proposal that briefly outlines purpose of project
Week 8
What week to present exp and findings to other student
Week 13
How is the project report structured
Scientific journal article, 4-6 pages length, Times new roman 12 point font
What is the purpose of the abstract (200-250 words)
Provide short summary of article so reader can determine if should read entire article
Purpose of intro (2-3 paragraphs)
”- Provide reader w/info regrading WHAT physiologic question being answered, WHY important to answer”
- Summarize theoretical background to the question
- Explain why problem interesting
- Summarize project n explain HOW it answers question
- State hypothesis
- Explain how hypothesis verify/support physiologic concept in question
Purpose of procedure (2-4 paragraphs)
”- Describe exactly how exp conducted”
- Sufficient detail so as to replicate exp
- Describe subjects used
- List make n model of equipment
- Describe detailed procedures followed
What is the purpose of results (2-4 paragraphs, tables, point form can be used)
- Present results from exp
- Use tables where appropriate
- Use graphs where appropriate
- Inc statistical analysis performed
- Explain significance of results
- Explain if hypothesis supported by results
What is purpose of discussion (2-3 paragraphs)
“-Compare results to other similar studies, n to recommend further research that’ll help u answer proposed q”
- Discuss whether u obtained results u expected
- Explain unexpected results
- Is further research required to support hypothesis?
Purpose of conclusion (1 paragraph)
- Summarize exp, briefly describe how results helped solve research q proposed
References (min 5 max 10)
- Use APA style for all references and in-text citations
Purpose of 407 project PRESENTATION (20-25 min)
Gain experience presenting research findings to audience
What is the presentation graded on
Quality n effectiveness
How much is presentation worth
10% grade
What is the structure of the project proposal submitted in week 8
- Clear n concise, summarizes hypothesis n methods used
- 3-6 double spaced pages in length
How many labs and lab reports performed in course
8 labs 8 reports
In ur lab report, what are the 9 different headings required?
- Raw data and observations made during lab
- Title and date (this begins formal report)
- Procedures
- Results
- Discussion
- Sources of error
- Questions
- Citations
- References
What is the late penalty? When is the last day reports will be accepted?
5% a day, no longer accepted after one week
What kind of abbreviations are accepted?
- SI units like kg for kilogram
2. If defined first e.g. electrocardiograph (ECG)
Past tense or present tense
Past
Is the word “significant” acceptable? If not, what instead?
No, use “dramatic” or “substantial”
What happens when u miss a lab session where there’s a required lab report
u get 0 for that lap report
What do tables need to have
- Title
- Headings for each column
- Units
What do graphs need to have
- Title
- Labelled axes
- Units
- Error bars
What indicates the accuracy of a measurement
of significant digits
8V implies how many significant digits and what is the actual output
- 1 significant digit
- output btwn 7.5-8.5V
With sums and differences, how is the number of decimal places determined?
The # w/the least number of digits following the decimal point determines it
2997 + 104.6 + 0.135 = 3101.735… how many decimal places roundoff
3101.735 -> 3101
With products and quotients how much significant digits in result?
- Equal that in the component measurements with least # of significant digits e.g. 6 mm / 25 mm/s = 0.24 -> round to 0.2s or 2x10^-1 ms
What are errors in this context
Degree of uncertainty associated w/all experimental measurements.
What do random errors cause
The result to spread in both directions/cluster about the true value
What do systemic errors cause?
Causes measured values to be consistently greater than or lower than true value. Also causes variability in measured value
What are random errors caused by
- Variation in quantity being measured e.g. calf girth changes w/posture
- Variation in measurement location
Example of how systemic errors made
Meter stick might be divided into 100 equal divisions but 101 ong so length of objects measured w/stick consistently overestimated by 1%
What are paradox errors
Occurs when position of needle on scale is read incorrectly e.g. from one side, resulting in systemic error
e.g. needle at 5cm read straight on correctly vs. needle read from side resulting in read as 4cm
Is it appropriate to add two or more independent errors? Why or why not?
No, causes overestimation of error cause addition presumes 2 errors will b maximal and in same direction simultaneously
What is the combined error formula (for 2 or more independent errors in single measurement)?
E = square root (E1^2 + E2^2 + … En^2)
What is the result of the combined error? Less or more than sum?
Greater than separate errors but less than their sum
How are dependent errors different from independent?
When error from one source affects error from another source, errors are dependent
Eqn to combine errors in calculations (sum and differences) when using values obtained from other measurements to derive other values
ΔX = square root ( (ΔA)^2 + (ΔB)^2+ (ΔC)^2 + (ΔD)^2 )
- A and B are values obtained by measurement
- X is derived value
- DA and DB and DX are actual errors associated with A, B, and X respectively
Calculate error for calorimeter if A= 20 degrees, B=24 degrees, DA= 0.2, DB= 0.2,
X = B - A
X = 24-20 = 4 ΔX = sqrt ( ΔA^2 + ΔB^2) ΔX = sqrt (0.2^2 + 0.2^2)
For errors involving products and ratios combining calculations, what is the eqn
ΔX / X = sqrt ( [ΔA/A]^2 + [ΔB/B]^2
What is DX if A= 100m B = 5s ΔA = 1m ΔB = 0.2s X = 100m / 5s = 20 m/s
ΔX/X = sqrt ( (ΔA/A)^2 + (ΔB/B)^2 )
ΔX/ 20m/s = sqrt (1m/s / 100m/s)^2 + (0.2s/5s)^2
ΔX = 0.8 m/s
Velocity is 20m/s +/- 0.8 m/s
How many sig figs are errors presented to?
1 sig fig
Equation for powers e.g. if X (derived value) = A^n where A is obtained from measurement
ΔX = Xn(ΔA/A)
What is biometrics
Branch of science that includes measurement of physiological variables n parameters
In the design or specification of medical instrumentation systems, what factors should be considered?
- Range
- Sensitivity
- Linearity
- Hysteresis
- Frequency Response
- Accuracy
- Signal to Noise Ratio
- Stability
What is the range of an instrument
All lvls of input amplitude and frequency over which the device is expected to operate
What is the sensitivity of an instrument
Determines how small a variation of a variable/parameter can be reliably measured
- results in nonlinearities or instability
What is the linearity of an instrument
Degree to which variations in output of instrument follow input variations
- in linear system sensitivity would be same for all absolute lvls of input, whether high, middle, or low portion of range
What is the hysteresis of an instrument
When a given value of measured variable results in different reading when reached in an ascending direction from that obtained when it is reached in a descending direction
What can cause hysteresis
Mechanical friction
What is the frequency response of an instrument
Its variation in sensitivity over the frequency range of measurement
What is the term when an instrument system responds rapidly enough to reproduce all frequency components of the waveform w/equal sensitivity
Flat response
What is accuracy
Measure of systemic error
What are the 6 errors to be considered
- Errors due to tolerances of electronic components
- Mechanical errors in meter movements
- Component errors due to drift or temp variation
- Errors due to poor frequency reponse
- Errors due to change in atmospheric pressure or temp
- Reading errors due to parallax, inadequate illumination, or excessively wide ink traces on pen recording
- Zeroing of instrument
- Effect of instrument on parameter to be measured n vice versa
Signal to noise ratio should be as ____ as possible
High
Interference due to electromagnetic, electrostatic, or diathermy equipment is likely due to ___
poor grounding
How does thermal noise and interference differ
Thermal noise limiting factor in detection of signals in other fields of electronics vs. interference is problem in biomedical system
What is stability
Ability of system to resume steady-state condition following disturbance at input rather than be driven to uncontrollable oscillation
What is baseline stability
Maintenance of constant baseline value w/out drift
Give an example of a common DC voltage source and an example of an AC voltage source
- DC: a cell/battery
- AC: wall outlet
List several materials which have a high resistance to electric current flow
Rubber, glass
List several materials which have a low resistance to electric current flow
Copper, silver
What is the relevance of this info to the recommended rescue procedure for a victim who has been electrocuted by a broken power line falling on him/her
Wearing rubber soles can protect you from being electrocuted cause high resistance so current hard to flow
Explain how adding a resistor to a parallel circuit inc current which flows thru that circuit
Adding individual resistors dec total resistance. Since current = voltage/resistance, dec resistance means inc current flow. Adding resistor path draws current so total current inc beyond capacity of fuse. Fuse blew to protect circuit from excess current causing overheated wires and house fire
What is the purpose of amplifying biological signals? Is it desirable to have high gain or low gain on a biological amplifier?
- enlarge signals that are normally hard to detect like skeletal muscle contractions
High gain which means giving greater amplification to an input signal
Why is it dangerous to touch internal components of an electrical instrument even when instrument powered off?
Some capacitor can be charged to extremely high voltages. If current flow thru you, u can be electrocuted
What is AC
current that reverses its direction of flow
What is a wall outlet
Ac voltage sources
What is resistance
Limits or controls flow of current
What is resistance and its units
- Limits or controls flow of current
- Ohms
What are good conductors and give example
Give up electrons more easily than atoms of other material and offer less resistance to current flow e.g. copper
What is ohms law
Current in a circuit (I) = Voltage applied to a circuit (V) / resistance of a circuit (R)
What is a simple device used to determine whether or not current is flowing thru a circuit
Lamp
What are switches
Used to control when a circuit is closed (complete) or open. Current flows when switch is closed
What are switches
Used to control when a circuit is closed (complete) or open. Current flows when switch is closed
When devices r connected like knots in string this is called
Series
What happens when 2 lamps connected in series w/voltage source and one lamp removed or burnt
other lamp will not light cause circuit not complete
What is the total resistance in a series circuit equal to
Sum of resistance of each of its parts
What is the total resistance in a series circuit equal to
Sum of resistance of each of its parts
What is total resistance in parallel
1/total resistance = sum of inverse of each of all the individual resistances
1/RT = 1/5 + 1/3 = 8/15 –> RT = 15/8 = 1.9 ohm
What is total resistance in parallel
1/total resistance = sum of inverse of each of all the individual resistances
1/RT = 1/5 + 1/3 = 8/15 –> RT = 15/8 = 1.9 ohm
Why does adding individual resistances in parallel circuit dec total resistance
Total resistance in parallel circuit less than smallest of individual resistances
Why does adding individual resistances in parallel circuit dec total resistance
Total resistance in parallel circuit less than smallest of individual resistances
What is eqn for gain
gain = output voltage/input voltage
What is a capacitor (aka condensor)
- device which controls electricity by regulating flow of AC current
- stores electrical charge
What is capacitance and units?
- Opposes any change in current
- Farads (C)
How is a capacitor made
Sandwich insulating material e.g. glass between 2 conductors (metal plates)
How is a capacitor charged
When voltage across capacitor reaches same potential as that of the cell, current stops flowing in this circuit
How can a capacitor be discharged
By providing path for electrons to return to positive plate
What does it mean when electric circuits are grounded
Pathway provided for electrons to flow into earth or ground
Define ground
q
Why is it dangerous to use monitoring instruments which have a 2-prong plug rather than a 3-prong plug
q
Describe effects of 60 Hz electrical shock on heart muscle
In case of electric shock, current density thru heart reaches critical rang, and desynchronization process occurs sending heart into ventricular fibrillation
Define “let-go current”
If victim comes into contact w/power source thru gripping, 9-20ma is distressing, cause he can’t “let-go” due to the skeletal muscle contractions
With 60 Hz current in range of 50 milliamps to 3 amps can cause ventricular fibrillation. Defibrillation machines produce currents in the 6 to 10 amp range. Why can these higher currents reverse ventricular fibrillation rather than cause it?
W/high currents, all ventricular muscle fibres depolarize at once producing sustained contraction of whole organ, and then when shock removed, normal HR can resume
Defines Ohms law and differentiate btwn series circuits n parallel circuits
I = V/ R or V = IR or Voltage = current x resistance
Current is the movement of electrons.
Voltage is the force which causes current to flow.
Resistance limits or controls the flow of current.
What is leakage current n why is it dangerous
Series: devices are connected like knots in a string. If 2 lamps are connected in series w/a voltage source, the same current flows thru both of one and if one lamp removed or burnt out the other bulb won’t light as circuit is not complete
Parallel: open switches will disconnect 2nd land but the 1st lamp will still be lighted as there’s a complete circuit flowing thru it
If u were in charge of EMG lab, what precautions would u take to ensure electrical safety of patients being tested
- Make sure subject wearing electrode out of reach of electrically operated devices or metallic conductors
- Integrity of ground system regularlly checked
- Avoid storing flammable liquids near electrical equipment
Explain “the victim is capacitively coupled to power source”
aa
Why is it good idea not to handle electrical equipment when standing on wet floor
V=IR, when skin wet, ur skin resistance will be much lower than normal thus given voltage will drive much more current into ur body
Define electrode wrspt human physiology recordings
A type of transducer which changes ionic current into electric current
What underlies myocardial DEfibrillation
Passing of high currents e.g. 6 amps thru the heart. W/high currents all the ventricular muscle fibers will be depolarized at once producing sustained contraction of whole organ, then when shock removed, normal HR resumes
What is the most common form of leakage current
60 Hz
Effect of 6-10 amps
Extreme heating effects, bruns
50 ma-2.5 amps
Lethal zone (can cause heart to produce fibrillations)
20 ma
Fainting, muscle paralysis
10 ma
painful to most
5 ma
one present standard of max safe current lvl
1 ma
avg min threshold to pain
500 ua
threshold of feeling - perceived as tingling
How can victim receive electric shock
- Interposing oneself in path of current in series
2. Capacitively coupled to power source
What are some factors to DECREASE resistance
Wetting skin, cleansing it, enlarging contact area, apply electrolytes
What are some factors to DECREASE resistance
Wetting skin, cleansing it, enlarging contact area, apply electrolytes
What are 6 prevention measures to insure integrity of ground system in room
- Check all 3 wire plugs, repair broken insulation
- Dispose 2 wire cord or polarize them so that neutral is continuous in all outlets
- Beware of using any adaptor for converting a 3 wire to 2 wire system
- Set up periodic checkout procedure to measure leakage current lvls on all electrical devices
- Hospitals n human subject labs should consider isolation of electrically sensitive areas
- Incorporate use of ground-fault circuit interruptors (perform like circuit breaker or fuse), and line unbalanced detectors in schools n homes
What are general electrical safety rules
- When subject attached via recording electrodes to recording device, should b out of reach of electrically operated devices
- Equipment properly grounded
- Use only one hand when working with energize circuit
- Use back of hand to touch electrical equipment
What kind of equipment should be taken out and serviced repaired
- Wet or subject to liquids
2. Dropped or abused or loose internal/external parts
