Saddleback Journal of Biology - Saddleback College

Fall 2009 Biology 3B Paper
Mean Change in Heart Rate
(BPM)
Figure 10. Mean change in heart rate was not
significantly different for first time male donors and
first time female donors (p>0.05, two-tailed,
unpaired T-test).
Mean arterial pressure also showed no
significant difference between frequent male donors
and frequent female donors, nor between first time
male donors and first time female donors. The
results of the T-test for pre- and post-donation MAP
in frequent male and female donors indicated there
was no significant difference (T-test assuming
unequal variances, t=0.09, df=18, and p>0.05)
(Figure 11). In first time male and female donors, the
T-test indicated there was no significant difference
(T-test assuming unequal variances, t=-0.83, df=18,
and p>0.05) (Figure 12).
Mean Change in MAP (mmHG)
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
-1.0
1.5
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
-2.5
-3.0
-3.5
Male
Male
Gender
Gender
Female
Female
Figure 11. Mean change in heart rate was not
significantly different for frequent male donors and
frequent female donors (p>0.05, two-tailed, unpaired
T-test).
Mean Change in MAP (mmHG)
1.0
0.0
-1.0
-2.0
-3.0
-4.0
-5.0
-6.0
-7.0
-8.0
Male
Gender
Female
Figure 12. Mean change in MAP was not
significantly different for frequent male donors and
frequent female donors (p>0.05, two-tailed, unpaired
T-test).
Discussion
The results indicate that there was not a
significant change in pre- and post-donation systolic
and diastolic blood pressures, heart rate, or MAP
between frequent donors and first-time donors, nor
between male and female donors. These findings
indicates that no matter how often a person
experiences blood loss and despite different genders,
the body does not physiologically adapt to blood loss.
Based on this result, the hypothesis and predictions of
this study were not supported.
As previously discussed, the loss of blood during
donation is enough to cause physiologic responses in
a body. One such response is a lower blood pressure
(McGuill, 1989). Another physiological response is
the activation of the baroreceptor response to changes
in blood pressure. With a decrease in blood pressure,
the baroreceptors would send a signal to cause the
heart to beat faster (Parati, 1988). If adaptation were
occurring as a result of frequent blood loss, then the
baroreceptors would reset the threshold to a lower
blood pressure. Thus, no change in pre- and postdonation
blood pressure would occur. The data
indicates that a change in blood pressure does occur.
However, the change is not statistically significant.
The data illustrates that overall there in as
increase in heart rate. However, the results indicate
that there was not a significant change in heart rate
between frequent and first time donors, nor between
males and females. If adaptation occurred, then the
heart rate for frequent donors would have a smaller
change because the baroreceptors would reset or
adjust for the blood loss.
62
Saddleback Journal of Biology
Spring 2010