A survey of the literature regarding the vasodepressor
and cardiodepressor reflexes is given.
Evidence is put forward that the impulses which
arise from the cardioaortic and carotid sinus regions
control not only the normal vagus restraint of the
heart but also the capacity of the circulation. Loss
of these impulses not only causes cardiac acceleration
but results in an increased return of venous blood
to the heart.
It is shown that conditions which are believed
to be produced in exercise and which are known to
reduce the vagus restraint of the heart at the same
time reduce the effect of the carotid sinus impulses
upon the vessels.
The view is therefore put forward that an
important function of the vasodepressor reflxes
is to control the capacity of the circulation in
order to provide a reserve of blood for use in
physical exercise, just as is provided a cardiac
reserve to deal with such blood maintained by
similar reflex mechanisms.
The possible clinical significance of the
findings is indicated, and a bibliography of the
literature referred to in the text is given.