REVIEW OF THE CIRCULATORY AND RESPIRATORY SYSTEMS
Some of the terms used in this subcourse are defined below.
a. Casualty. The casualty is the person with the medical problem, such as a
person who is not breathing. When being treated by medical personnel, the casualty
may be referred to as a patient.
b. Rescuer. The rescuer is the person who is assisting the casualty; for
example, the person giving mouth-to-mouth resuscitation to a casualty who is not
breathing. In this subcourse, you are the rescuer.
c. Airway. The airway consists of the body structures through which air from
the atmosphere passes while going to the lungs.
d. Sign. A sign is anything that the rescuer can tell about the casualty's
condition by using his (the rescuer's) own senses. For example, a rescuer can see the
casualty's chest rise and fall, hear the sounds made by a casualty when he breathes,
and feel the casualty's pulse.
e. Symptom. A symptom is any change from the norm which is felt by the
casualty but which cannot be directly or objectively sensed by the rescuer. Examples of
symptoms felt by the casualty include chest pain, nausea, and headache. An injury can
produce both signs and symptoms. If you bump your leg against a chair, for example, a
bruise may develop. The bruise is a sign of the injury since other people can see the
bruise. The pain you feel is a symptom since other people cannot feel your pain.
IMPORTANCE OF THE CIRCULATORY SYSTEM
The human body is composed of cells. The average adult human's body is made
up of around eighty trillion (80,000,000,000,000) living cells. Cells need energy to
survive, repair themselves, perform their functions, and reproduce. Cells obtain this
energy through cellular respiration; that is, they combine a source of potential energy
with oxygen to liberate energy. The sources of potential energy come from the food
(carbohydrates, fats, and proteins) that are processed into usable units by the body's
digestive system (stomach, small intestine, liver, pancreas, and so forth). The oxygen
comes from the air that is inhaled by the lungs. Oxygen in the lungs and food in the
intestine cannot help the muscles and other cells unless the oxygen and food can be
delivered to those cells. Delivering oxygen and food to the cells is the function of the
blood in the body's circulatory system. The circulatory system also takes waste
products (by-products of cellular respiration) from the cells and delivers them to organs
(lungs and kidneys) where the wastes can be expelled from the body.