The document discusses the effects of heat on the human body, highlighting how cell metabolism increases with temperature and the body's cooling mechanisms become ineffective above 42°C. It explains methods of heat transfer such as convection and perspiration, and includes calculations on waste heat generated by students during a lecture. Additionally, it addresses the diagnostic and therapeutic uses of heat and cold, including their impact on infections and muscle relaxation.

1. HEAT AND
THE
HUMAN
BODY
REPORTED BY
MARVIN B. GONZAGA

2. EFFECTS OF HEAT ON THE HUMAN BODY
Cell metabolism
increases with
increasing temperature
If body temperature
rises above about 42○ C
(108 ○ F), the body’s
cooling mechanisms
cannot keep up, and
external intervention is
necessary

3. BODY MECHANISMS TO GET RID OF EXCESS HEAT
Once heat reaches the surface, all 3 methods
of heat transfer remove heat, provided that the
external temperature is lower than body
temperature.
Convection – blood circulation;
increased blood flow to the skin to
help remove heat. When body
temperature drops, blood flow to
the surface is reduced.
Perspiration - keeps temperature
from rising uncontrollably when
surrounding temperatures are high.

4. EXAMPLE
(a) Using data from Table 4.5, calculate the power in waste
heat put into a classroom by 30 students. (b) How many
calories of energy do the students put into the room during
a 50-min lecture?
Solution
(a.)Using the value of 210 W from Table 4.5, the power in
waste heat is simply
Pheat = (210 W/person)(30 persons)
= 6300 W
Pheat = 6.3 kW

5. (b.) The number of calories can be calculated by
multiplying the power by time, or by using the value of 3.0
kcal/min per person from Table 4.5
Q = 3.0 (kcal/min) (30 persons)(50 min)
person
= (4500 kcal)(103 cal/kcal)
Q = 4.5 x 106 cal
= 3.0 (kcal/min) (30 persons)(50 min)
person
= 30 kcal (50 min)
min

6. Physical activity produces thermal
energy since the body is not 100%
efficient in converting food energy
to work
Severe shivering results in little
work and a lot of thermal energy
80 W
425 W

7. Diagnostics
DIAGNOSTIC AND THERAPEUTIC USES
OF HEAT AND COLD
Temperature can indicate the presence and seriousness of an infection. Raising
body temperature is one of the body’s defense mechanisms.

8. Thermography
Gives an indication of
blood supply. Depressed
skin temperature means
deficiency in blood flow.
Measures infrared radiation
and maps body
temperature. The picture is
called a thermograph.

9. THERAPEUTIC USES OF HEAT
Applying heat to a part of the body brings
relief through muscle relaxation and
increased blood flow
Conduction
Microwave Diathermy
Radiation

10. THERAPEUTIC USES OF COLD
Cryosurgery Organ freezing
Pain relief
If the temperature of the entire body is
lowered, the metabolic rate drops and most
bodily functions are slowed.

11. THANK
YOU!