Understanding Vital Body Functions
1-3. Respiration and Blood Circulation
Respiration (inhalation and exhalation) and blood circulation are vital
body functions. Interruption of either of these two functions need not be
fatal IF appropriate first aid measures are correctly applied.
a. Respiration. When a person inhales, oxygen is taken into the
body and when he exhales, carbon dioxide is expelled from the body--this
is respiration. Respiration involves the--
- Airway (nose, mouth, throat, voice box, windpipe, and
bronchial tree). The canal through which air passes to and from the lungs.
- Lungs (two elastic organs made up of thousands of tiny
air spaces and covered by an airtight membrane).
- Chest cage (formed by the muscle-connected ribs which
join the spine in back and the breastbone in front). The top part of the
chest cage is closed by the structure of the neck, and the bottom part is
separated from the abdominal cavity by a large dome-shaped muscle
called the diaphragm (Figure 1-1). The diaphragm and rib muscles, which are under the control of the respiratory center in the brain, automatically
contract and relax. Contraction increases and relaxation decreases the size of the chest cage.
When the chest cage increases and then decreases, the air pressure in the
lungs is first less and then more than the atmospheric pressure, thus
causing the air to rush in and out of the lungs to equalize the pressure.
This cycle of inhaling and exhaling is repeated about 12 to 18 times per
b. Blood Circulation. The heart and the blood vessels (arteries,
veins, and capillaries) circulate blood through the body tissues. The heart
is divided into two separate halves, each acting as a pump. The left side
pumps oxygenated blood (bright red) through the arteries into the
capillaries; nutrients and oxygen pass from the blood through the walls
of the capillaries into the cells. At the same time waste products and
carbon dioxide enter the capillaries. From the capillaries the oxygen poor
blood is carried through the veins to the right side of the heart and then
into the lungs where it expels carbon dioxide and picks up oxygen. Blood
in the veins is dark red because of its low oxygen content. Blood does not
flow through the veins in spurts as it does through the arteries.
(1) Heartbeat. The heart functions as a pump to circulate
the blood continuously through the blood vessels to all parts of the body. It contracts, forcing the blood from its chambers; then it relaxes,
permitting its chambers to refill with blood. The rhythmical cycle of
contraction and relaxation is called the heartbeat. The normal heartbeat
is from 60 to 80 beats per minute.
(2) Pulse. The heartbeat causes a rhythmical expansion and
contraction of the arteries as it forces blood through them. This cycle of
expansion and contraction can be felt (monitored) at various body points
and is called the pulse. The common points for checking the pulse are at
the side of the neck (carotid), the groin (femoral), the wrist (radial), and
the ankle (posterial tibial).
(a) Neck (carotid) pulse. To check the neck (carotid)
pulse, feel for a pulse on the side of the casualty's neck closest to you by
placing the tips of your first two fingers beside his Adam's apple (Figure 1-2).
(b) Groin (femoral) pulse. To check the groin (femoral) pulse,
press the tips of two fingers into the middle of the groin (Figure 1-3).
(c) Wrist (radial) pulse. To check the wrist (radial) pulse, place
your first two fingers on the thumb side of the casualty's wrist (Figure
(d) Ankle (posterial tibial) pulse. To check the ankle
(posterial tibial) pulse, place your first two fingers on the inside of the
DO NOT use your thumb to check a casualty's
pulse because you may
confuse your pulse beat
with that of the casualty.
1-4. Adverse Conditions
a. Lack of Oxygen. Human life cannot exist without a
continuous intake of oxygen. Lack of oxygen rapidly leads to death. First
aid involves knowing how to OPEN THE AIRWAY AND RESTORE BREATHING
AND HEARTBEAT (Chapter 2, Section I).
b. Bleeding. Human life cannot continue without an adequate
volume of blood to carry oxygen to the tissues. An important first aid
measure is to STOP THE BLEEDING to prevent loss of blood (Chapter 2, Section II).
c. Shock. Shock means there is inadequate blood flow to the
vital tissues and organs. Shock that remains uncorrected may result in
death even though the injury or condition causing the shock would not
otherwise be fatal. Shock can result from many causes, such as loss of
blood, loss of fluid from deep burns, pain, and reaction to the sight of a
wound or blood. First aid includes PREVENTING SHOCK, since the
casualty's chances of survival are much greater if he does not develop
shock (Chapter 2, Section III).
d. Infection. Recovery from a severe injury or a wound depends
largely upon how well the injury or wound was initially protected.
Infections result from the multiplication and growth (spread) of germs
(bacteria: harmful microscopic organisms). Since harmful bacteria are in
the air and on the skin and clothing, some of these organisms will
immediately invade (contaminate) a break in the skin or an open wound.
The objective is to KEEP ADDITIONAL GERMS OUT OF THE WOUND. A good
working knowledge of basic first aid measures also includes knowing how
to dress the wound to avoid infection or additional contamination
(Chapters 2 and 3).
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