Heat and Temperature in Medicine

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Questions and Answers

What is heat in medicine?

The kinetic energy of molecules in a substance

The size of the particles in a substance

The temperature of a substance

The total energy of molecular motion in a substance (correct)

What is temperature?

The average kinetic energy of molecules in a substance (correct)

The size of the particles in a substance

The kinetic energy of molecules in a substance

The total energy of molecular motion in a substance

What is the unit of temperature on the absolute scale?

oK (correct)

What is the normal body temperature in Celsius?

37oC Signup and view all the answers

How does heat travel?

By four methods: conduction, convection, evaporation, and radiation Signup and view all the answers

What is the purpose of an opaque white backing in a thermometer?

To increase the visibility of the capillary Signup and view all the answers

What is a thermistor?

A special resistor that changes its resistance rapidly with temperature Signup and view all the answers

What is the advantage of using a thermistor in medicine?

It is more sensitive to temperature changes Signup and view all the answers

What is the relationship between the temperature scales?

oK = 273.15oC Signup and view all the answers

What is the expansion of the liquid in a thermometer?

1 cm³ of mercury increases in volume by 1.8% when going from 0 to 100°C Signup and view all the answers

What is the primary purpose of using a thermocouple in medical physics?

To measure the temperature of individual cells Signup and view all the answers

What is the Stefan-Boltzmann law used for in medical physics?

To calculate the radiation power from the body Signup and view all the answers

What is the effect of heat therapy on damaged tissue?

It increases the metabolism and increases blood flow Signup and view all the answers

What is the range of wavelengths for radiant (IR) heat in medical physics?

800-40000 nm Signup and view all the answers

What is the method of short-wave diathermy that uses an oscillating electric field?

Capacitance method Signup and view all the answers

What is the purpose of keeping one junction of a thermocouple at a reference temperature?

To measure the temperature difference Signup and view all the answers

What is the unit of the Stefan-Boltzmann constant?

W/cm^2K^4 Signup and view all the answers

What is the effect of heat therapy on the capillary system?

It increases the blood flow and dilates the capillaries Signup and view all the answers

What is the method of heat transfer used in hot baths and hot packs?

Conductive method Signup and view all the answers

What is the temperature range of the core of the body?

Within ±1°F (±0.6°C) of normal body temperature Signup and view all the answers

What is the frequency of microwave diathermy usually used in physical therapy?

2450 MHz Signup and view all the answers

What is the purpose of ultrasonic waves in physical therapy?

Heating body tissue Signup and view all the answers

What is the advantage of ultrasonic heating in bones?

Bones absorb ultrasound energy more effectively than soft tissue Signup and view all the answers

What is the name of the science and technology of producing and using very low temperatures?

Cryogenics Signup and view all the answers

What is the purpose of the Dewar container?

To store and transport liquids at very low temperatures Signup and view all the answers

What is the temperature of liquid nitrogen?

-196°C Signup and view all the answers

What is the name of the method used to freeze blood at cryogenic temperatures?

Blood-sand method Signup and view all the answers

What is the advantage of using cryogenic temperatures for preserving blood and tissues?

It allows for long-term preservation Signup and view all the answers

Study Notes

Topic: Heat and Cold in Medicine

Heat is the total energy of molecular motion in a substance.
Temperature is a measure of the kinetic energy of molecules, and it is related to the temperature of a substance.

Temperature Scales

Fahrenheit (oF) scale: water freezes at 32oF and boils at 212oF, normal body temperature is about 98.6oF.
Celsius (oC) scale: water freezes at 0oC and boils at 100oC, normal body temperature is about 37oC.
Kelvin (oK) scale: absolute temperature scale, water freezes at 273.15oK and boils at 373.15oK, normal body temperature is about 310oK.

Heat Transfer

Four methods of heat transfer: conduction, convection, evaporation, and radiation.
Heat energy will always move from higher to lower temperatures.

Temperature Measurement

Thermometer: a device that measures temperature, examples include mercury thermometer and thermistor.
Mercury thermometer: contains mercury or alcohol that expands more than the glass, producing an increase in the level of the liquid.
Thermistor: a special resistor that changes its resistance rapidly with temperature, used in medicine because of its sensitivity.

Core Temperature and Skin Temperature

Core temperature remains almost constant, within ±1oF (±0.6oC), while skin temperature rises and falls with the surrounding temperature.
The Stefan-Boltzmann law is useful for calculating the total radiated power per surface area.

Heat Therapy

Heat therapy has primary therapeutic effects: increase in metabolism, relaxation of the capillary system, and increase in blood flow.
Physical methods of producing heat in the body: conduction, radiation, and short-wave diathermy.
Short-wave diathermy: uses electromagnetic energy to heat the body, two methods are used: capacitance and inductance methods.

Cold in Medicine

Cryogenic: the science and technology of producing and using very low temperatures.
Cryobiology: the study of low temperature effects in biology and medicine.
Dewar container: an insulated container developed by James Dewar in 1892, used to minimize conductive, convective, and radiative heat losses.
Cryogenic methods are used in medicine for long-term preservation of blood, sperm, and tissues at very low temperatures.

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Description

This quiz covers the basics of heat and temperature, including temperature scales and their applications in medicine. Learn about the differences between Fahrenheit, Celsius, and Kelvin scales and how they are used to measure body temperature.