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Biological Temperature
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| PowerLab systems can be used for various biological temperature measurements.
ADInstruments provide three major types of temperature probes: thermocouples and thermistors. Each probe requires its own type of preamplifier which provides a signal to a PowerLab data acquisition system.
Thermocouples
Thermocouples are commonly used for temperature measurement as they are highly accurate and operate over a broad range of temperatures. They consist of two different metal wires that are welded together at one end (A). These wires generate a thermoelectric voltage between their open ends that changes according to the temperature difference between the two ends, that is, between junction (A) and the reference (R).
Thermistors
Thermistors consist of an electronic component (semiconductor material) that exhibits a large change in resistance in proportion to a small change in temperature. In comparison to thermocouples, thermistors have a limited (smaller) temperature range; however, they are highly sensitive within this range. The resistance of these devices often changes in a non-linear fashion with temperature and additional instruments required to linearize the reading.
ADInstruments Temperature Probes & Amplifiers
- The Skin and Nasal Temperature Probes (thermistors) are used to measure skin surface temperatures or nasal air temperatures (a useful indicator of respiratory rate) in the range 0-50°C. They connect to PowerLab data acquisition systems
- Using one of the following: any ADInstruments Bridge Amp, GP Amp (ML117) or Thermistor Pod (ML309)
- T-type Implantable Thermocouple Probe (IT-18): The 0.6 mm diameter implantable probe is suitable for immersion in various solutions, semi-solids and tissue. It can also be used to measure rectal temperatures of small animals and is suitable for measuring temperatures up to 150 °C.
- T-type Implantable Thermocouple Probe (IT-21): The 0.4 mm diameter implantable probe is suitable for immersion in various solutions, semi-solids and tissue. The isolated probe is totally sheathed in chemical resistant Teflon and is rugged. It can measure temperatures up to 150 °C.
- Ultra Fast T-type thermocouple probe (IT:23): A tissue implantable microprobe with an ultra fast response time of 0.005 seconds. The tip of the thermocouple is just 0.76 mm in diameter, and is inserted into tissue with a supplied 23 ga. hyperdermic needle. It is suitable for temperature measurements to a maximum of 150 °C.
- General Purpose T-type thermocouple probe (HT-1): Suitable for measuring temperature in liquids, gases and semi-solids. It has a plastic handle and a 75 mm long stainless steel shaft, and is suitable for temperature measurements to a maximum of 400 °C.
- Mouse rectal T-type thermocouple probe (RET-3): Suitable for measuring the body temperature in small animals such as mice, hamsters or rat pups. The probe consists of a thin stainless steel shaft 19 mm long, with a smooth ball tip of 1.7 mm diameter.
- Rat rectal T-type thermocouple probe (RET-2): Suitable for measuring the body temperature in adult rats. The probe consists of a stainless steel shaft 25.4 mm long, with a smooth ball tip of 3.2 mm diameter.
The T-type thermocouple probes listed above have a 2-pin T-type plug that is suitable for connection to PowerLabs using either: The Ultra-fast T-Type Thermocouple (IT-23) and T-type Implantable Thermocouple Probe (IT-21) are also suitable for use with the Cardiac Output Pod. These probes may be used to determine cardiac output using the thermodilution method. For further information, see the Cardiac Output page.
Note: The pH Amp is a dual function amplifier capable of measuring pH and temperature. The unit is supplied with an RTD Temperature Probe. |
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| PowerLab (MacLab) citations: |
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| Comparison of intracranial pressure measured in the cerebral cortex and the cerebellum of the rat. |
| S. Rooker, G. deVisscher, B. van Deuren, M. Borgers, P.G. Jorens, R.S. Reneman, K. van Rossem, J. Verlooy, Journal of Neuroscience Methods, 119, 83-88, 2002 |
| ….. the head of the rat (370-490g) was fixed in a stereotaxic apparatus (model DK1962; Ultra Precise Small Animal Stereotaxic, Kopf Instruments, Germany) and a thermistor inserted into the tip of an ear bar was used to measure the tympanic temperature, providing an accurate measurement of brain temperature. A rectal temperature probe was inserted to monitor body temperature, which was controlled with a heating pad connected to a temperature controller unit..……….. All data were collected with a MacLab computer system (MacLab/8 MK3 Version 3.5, ADInstruments, Australia). |
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| 5'-Adenosine monophosphate and adenosine metabolism, and adenosine responses in mouse, rat and guinea pig heart. |
| J.P. Headrick, J. Peart, B. Hack, B. Garnham, G.P. Matherne, Comparative Biochemistry and Physiology A, 130, 615-631, 2001 |
| Hearts were isolated from 7-12-week-old male and female wild-type C57-BL6 mice, Wistar rats and Hartley guinea-pigs ……..hearts rapidly excised into ice-cold perfusion fluid. The aorta was rapidly cannulated and the coronary circulation perfused with modified Krebs-Henseleit buffer….all hearts were perfused at an aortic pressure of 90 mmHg. …….Left ventricles were vented with polyethylene apical drains and hearts were instrumented for functional measurements……. The temperature of coronary perfusion fluid was continuously assessed by a needle thermistor located at the entry into the aortic cannula, and the temperature of the water bath assessed using a second thermistor probe. Temperatures were recorded using a three-channel Physitemp TH-8 digital Î thermometer (Physitemp Instruments Inc, Clifton, . NJ, USA)… All functional data ventricular and aortic pressures, coronary flow were recorded at a sampling speed of 1 kHz on a 4/s MacLab data acquisition system (AD Instruments, Castle Hill, Australia) connected to an Apple 7300/180 computer. |
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The material on this page is provided in good faith and believed accurate at the time of writing. No responsibility will be taken, or liability accepted, for damages arising from the use of information herein. Readers are urged to check with respective manufacturers the accuracy of all product related information.
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