Evening star., 1938-11-01
OF STARS, @
MEN AND ATOMS
Notebook of Science Prosress
in Field, Laboratory
and Study.
By THOMAS r. HENRY.

By THOMAS r. HENRY.
The heat of the body upon the con-
stancy of which the life of warm
blooded animal depends is regulated
within narrow limits by a very tiny
"thermostat" in the brain.
This automatic heart-controlling de-
vice Is a bit of brain tissue, probably
less than third of an inch in diam
eter, located in the hypothalamus, a
part of the brain near the front and
buried under the cerebral cortex, or
many-layered blanket of gray matter"
which Is the organ Of conscious life.
1t Is extremely sensitive to the temp
erature of the blood washing past it and
through it. So long as this blood re-
mains at 98.6 the thermostat does not
operate. AS soon as there is little
variation above or below the figure it
goes into action. It Is wired up with
the sympathetic nervous system. This
has nerve fibers extending to all parts
OF the body. When the temperature
rises the thermostat sends impulses to
the blood vessels on the outside of the
give on more heat, to the sweat glands,
and to the heart and lungs, causing a
faster pulse rate and breathing. When
the temperature falls a different set of
sympathetic impulses are sent out which
cause contraction of the blood vessels
and shivering.
IT anything should go wrong with this
tiny bit of brain tissue the individual
would be in bad way. One theory of
neat shock has been that the thermostat
tissue itself suffers irreparable damage
When the blood which flows through it
IS greatly over-heated, and then is un-
able to bring the compensatory mechan-
isms into play.
This is probably all wrong, Capt. E. H.
Parsons Of Walter Reed Hospital ex-
pert on the heat therapy of various dis
eases, explained to members of the
academy OF Physical Medicine meeting
mere the other day. For one thing, the
extremely small amount of tissue in
VOWED serves as protection. It is
no more likely to become damaged bv
neat than any other nerve tissue in the
oody. specified effect on such minute
organ is highly unlikely.
The actual causes OF heat shock are
matter OF grave interest to the Walter
Feed physicians who have now Cant
PARSONS reported, devised system of ad-
mlhlstering fever therapy which seems
10 90 away with at least one danger
one OF the ways by which the body tries
to throw off excess heat is bv sueatina
inns Is taking water out of the system
ana thlckening the blood to a dangerous
extreme. The water must be replaced as
II is depleted. The amount lost can be
measured rather accurately. The prob
lem has been to keep the water content
OF tne TISSUES constant and at the same
time elevate the temperature to the re-
quired level.
The temperature can first be raised
ana then the required amount of va.
ter-a very large amount-given the pa-
tlent TO drink. The difficulty here is
tnat tissues have limited capacity for
water absorption. The stomach NAV
act simply as a hot-water bag in which
the liquid remains without doing anv
good. If cold water is given in smaller
amounts during the time the tempera-
ture Is being raised the process itself is
delayed.
1ney have gotten around this by CIV
ing warm water during the first hour
wien tne temperature is going up in
just sufficient amounts to balance tho
loss from sweating and slowly enough
for the body to make use of the lio,,id
Approximately 90 per cent of the
oooys normal heat loss, Capt. Parsons
explained, occurs below the neck. Sew
enty per cent Is by radiation from the
SKIN, IA per cent by the evaporation of
sweat, and per cent by vaporization
from the lungs. About 3.5 is absorbed in
the liberation Of carbon dioxide from
solution in the lungs and 25 in vorn,-
ing INSPIRED air. If the surrounding
temperature is warmer than the BODY
Ihere naturally can be no loss through
radiation because heat does not flow IN
MIL. The only other really important
source OF heat loss is evaporation. If
tnls can be controlled the Temperature
OF the body, constantly generating heat
which it cannot get rid of. natrra11y
rises rapidly.
Inc system, naturally, has been SUBJ
Jected TO radical change in internal
environment which is full of danger IN
less all the changes which are likely
can be anticipated and some sort of
compensation made for them. Changes
IN the condensation Of the blood and
IN Its oxygen-carrying capacity under
various temperatures must be known
with considerable accuracy.
IT is upon some of these problems
that the Army doctors are working in
order that form of treatment which
has proved invaluable for large num-
Der OF pathological conditions, some of
which respond to no other form Of
therapy, may be made entirely safe for
the average individual,