the parts of the human respiratory system represented by
(Straw = windpipe; balloon = lung; balloon skin = diaphragm,
cup = rib cage of lung cavity)
is this model fundamentally different from the human system?
(Humans have two lungs that are operated by the action
of the diaphragm, rather than the one lung modeled here.)
happens to the balloon inside the cup when the rubber skin
wrapped around the base of the cup is pulled down? Why
(The balloon inflates. The volume of the artificial lung
is increased, so the pressure of the air inside is decreased.
Outside air pressure pushes air into the cup to equalize
the pressure, inflating the balloon.)
happens when the rubber skin is pushed upwards? Why?
(The balloon deflates. The volume of the artificial lung
is decreased, so the pressure on the air inside is increased.
Air is released from the cup to equalize the pressure, deflating
upon this model, where would you insert the FES electrodes
on a person who was unable to breathe on his own? Why?
(The electrodes should be inserted into the diaphragm
since this is the muscular wall that creates changes in
the size of the chest cavity, just as the rubber skin changed
the size of the "cup cavity.")
you were in charge of programming the electronics that would
trigger an FES signal to the diaphragm. How often would you
send this signal to a person who normally experiences 7 inhalations
and 7 exhalations in a one-minute period? Explain.
(You'd send about 7 signals per minute. Since only the
inhalation needs to be "triggered", you need to send an FES
signal to initiate these actions. The exhalations are passive
and will automatically occur when the inhalation contraction
Have you ever seen advertisements for electrical pad muscle
toners, used most often to tone the appearance of abdominal
muscles? These pads cause muscles to contract as a response
to surface electric stimulation. Think about it. How are the
mechanics of this device similar to FES?
(Both devices rely upon electrical signals to stimulate
How are the different?
(One is for cosmetic use, the other for more necessary life
A reflex action is an automatic and involuntary response during
which a motor signal is sent, not from the brain, but from
a lower level of the spinal column. Think about it. What type
of disorders or injuries would interfere with the knee-jerk
reflex? Would a person who has a spinal injury maintain this
reflex response? Why or why not?
(A reflex action takes place at a certain slice of the
spinal column. No message needs to travel up the spinal cord
to the brain. Therefore, if the spinal cord is damaged above
this reflex arc, the intact nerves will still produce a reflex
response even though the individual may not have awareness
of the movement. If, however, the spinal damage also compromises
the activity of nerves below the injury point, then the reflex
may be lost.)