Current Voltage characteristic of biological tissue: Body resistance

Transcription

1 6_Current Voltage characteristic of biological tissue.xlsx/work procedure Study group: Year of study: Current Voltage characteristic of biological tissue: Body resistance Objective: Establish the mean body resistance (of your classmate) in a hand hand configuration from repeated measurements using Ohm's law. Determine selected anthropometric parameters of students using body composition monitor: body mass, body fat percentage, visceral fat level, skeletal muscle percentage and calculate the BMI index of classmate Tasks:. Record Current Voltage (VA) characteristics of human body (classmate) in hand hand configuration.. Establish the mean body resistance using the model of VA characteristics.. Explain obtained results. Recommended tools and devices: electric module for VA characteristics measurement, ampere meter, electrodes, gauze, distilled water or physiologic solution (saline), bandage, body composition monitor Omron Procedure:. Work in pairs.. Measure the microclimatic characteristics.. Check the connection of all elements of the electrical circuit. 4. Set the scale of the ampere meter to the lowest possible value. 5. Moisten the wrists of the examined person (use physiological solution) and fasten the electrodes onto them. 6. Connect the electrodes into the electric circuit according to the scheme in Figure. 7. Switch on the soure of electric current (the ON switch on the front panel on the left side). 8. Toggle the next switch to the position V. 9. Set the applied voltage by the tuner on the right side of the front panel. This voltage appears on the display on the left side of the front panel.. Read the current flowing through body of the examined person on the display of the ampere meter. Write both values (real value of voltage and current) into table.. Repeat items 8 9 with increasing the applied voltage by.5 V until you reach the highest possible value of voltage.. Turn on the power of the body composition monitor and wait for device calibration, until. kg is displayed (do not touch the display unit).. Remove the display unit and start the guest mode (button GUEST ). Set your personal data: age, gender and body height (use keys SET and, ). 4. Step on the main unit. When START appears on the display, extend your arms straight at a 9 angle to your body. (Fig.) 5. Wait for finishing of measurement (progress of measurement is displayed in the bottom of display). 6. Write down obtained results (body mass, BMI, body fat percentage, skeletal muscle percentage, resting metabolism, visceral fat level) into table. 7. Calculate the body mass index using the undermentioned formula. 8. Draw a graph representing the dependence of the electric current on the applied voltage (graph ). 9. Calculate the resistance according to the Ohm's law for each measured pair of voltage and current /7

2 6_Current Voltage characteristic of biological tissue.xlsx/work procedure Study group: Year of study:. Calculate the mean resistance as the average value and standard deviation of all measured values.. *Calculate the linear regression between the real applied voltage and measured electric current.. Fill in all entries in "Results".. Interpret all obtained results. Applied equations: Ohm's law R U I BMI (Body mass index) where m is the body mass and h is the body height, both in basic units. Figure : Simplified model of tissue resistance, where: R m is resistance of cell membranes, R e is resistance of extracelular liquid (Re << Rm) C m is capacity of cell membrannes and E m is membrane potential Figure : Electrical circuit equivalent used for the experiment (V is voltmeter, ma is ampere meter) Figure : Use of the body composition monitor Note Orange painted cells have to be filled in BEFORE your arrival on practical training. Green painted cells have to be filled during the measurement, or later during protocol processing. Parts of the procedure denoted in italics designate your homework processing measurement results at home /7

3 6_Current Voltage characteristic of biological tissue.xlsx/measurement sheet Study group: Year of study: Current Voltage characteristic of biological tissue: Body resistance Date of the measurement: Time of the measurement: I have studied the theory for practical training from: (specify a complete bibliographical reference including appropriate chapter and page designation) Used devices and tools: Microclimatic conditions of measurement: atmospheric pressure p = mmhg = kpa air temperature t = C relative humidity ϕ rel = % Object of measurement (schoolmate): Initials: Age: Sex: Body mass: kg Body height: cm Measurement results: Table : Applied voltage and measured current (examined person classmate). Measurement no. Assumed applied voltage Real applied voltage U Measured current I [µa] ,5,,5,,5,,5 4, 4,5 5, 5,5 6, 6,5 7, 7,5 8, Table : Body composition analysis of the examined person. Add correct units /7

4 6_Current Voltage characteristic of biological tissue.xlsx/measurement sheet BMI (according to the body composition monitor) Body fat percentage Skeletal muscle percentage Basal metabolism Visceral fat level Study group: Year of study: Your own values: Initials: Age: Sex: Body mass: kg Body height: cm Table : Applied voltage and measured current (your own). Measurement no. Assumed applied voltage Real applied voltage U ,5,,5,,5,,5 4, 4,5 5, 5,5 6, 6,5 7, 7,5 8, Measured current I [µa] Table 4: Body composition analysis of your body. Add correct units. BMI (according to the body composition monitor) Body fat percentage Skeletal muscle percentage Basal metabolism Visceral fat level Date and teacher's signature: /7

5 6_Current Voltage characteristic of biological tissue.xlsx/results processing Study group: Year of study: Current Voltage characteristic of biological tissue: Body resistance Date of the measurement: Time of the measurement: Used devices and tools: Microclimatic conditions of measurement: atmospheric pressure p = kpa room air temperature t = C relative air humidity: ϕ rel = % Object of measurement: Initials: Age: Sex: Body mass: kg Body height: cm Mesurement results: Table : Applied voltage and measured current at examined person. 5 Measurement no. Assumed applied voltage Real applied voltage U Measured current I [µa] Calculated resistance R [MΩ] Mean Standard Deviation,5,,5,,5,,5 4, 4,5 5, 5,5 6, 6,5 7, 7,5 8, Calculated mean resistance: MΩ ± MΩ *Calculated linear regression:. U /7

6 6_Current Voltage characteristic of biological tissue.xlsx/results processing Study group: Year of study: Table : Body composition analysis of the examined person. Complete values and correct units. BMI (according to the body composition monitor) Body fat percentage Skeletal muscle percentage Basal metabolism Visceral fat level Discussion: Physical principle of the measurement of a biological tissue electric resistance Evaluation of measurement conditions, impact of microclimatic factors and possible sources of measurement errors. Reference values, comparison of obtained values with reference values (human body resistence, BMI, body fat percentage, sceletal muscle percentage, basal metabolism, visceral fat level) /7

7 6_Current Voltage characteristic of biological tissue.xlsx/results processing Study group: Year of study: Conclusion: Results summary and their biophysical interpretation. The importance of measurement of biological tissue electric resistance in medicine and its applications. References: Cite references in the correct form. NOTE: Obligatory protocol attachment is a hand drawn graph of current voltage characteristics (* with 5 regression line). *Optional protocol attachment is a comparison of the slope of the straight put through the graph to the slope of the straight line calculated by linear regression. *Optional protocol attachment is a computer processed graph of Current Voltage characteristics. Grade: Date and signature of the teacher: Overall max. Bonus max /7