Ash, humans to remain submerged in water and

  

 Ash, S. (2015).

DIVING
REFLEX PRACTICAL

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ANNIE
OMOREGIE (U1674367) | PHYSIOLOGY: CONTROL AND COORDINATION | 14/12/2017

INTRODUCTION

Diving
reflex is a physiological mechanism that allows animals including humans to
remain submerged in water and it comprises of three independent reflexes that
cause physiological changes that counter homeostatic control (Michael
Panneton, W. 2013) and they are bradycardia which is the slowing down of the
heart rate, peripheral vasoconstriction, and hypertension. It is a very
powerful collection of reflexes that allow the preservation of oxygen for
aerobic metabolism and function of the heart and brain (Panneton, W. M., Gan, Q.,
& Juric, R. 2010). Aquatic and marine mammals such as sea otters,
platypus, hippotamus, whales, dolphins, and seals exhibit this reflex as they
can remain submerged for extended periods of time (Hempleman, H. V., &
Lockwood, A. P. M. 1978) because they are able to conserve oxygen as a means of
survival, this is the main physiological purpose of the diving reflex. The
level at which humans use this reflex is limited in terms of time compared to
the aquatic and marine mammals as they can’t remain submerged for long periods
of time. The aim of the diving reflex practical is to assess the cardiovascular
changes in heart rate and mean arterial pressure during simulated diving in
different conditions to identify the key stimuli for the diving reflex. It was
therefore hypothesized that facial immersion in water will lead to a decrease
in heart rate and an increase in mean arterial pressure, if so what effect does
the temperature of the water have on the extent of the diving reflex in humans.

METHOD

PARTICIPANTS

Twenty
healthy participants in groups of two, aged 19-25 years took part in the
experiment voluntarily after signing a consent form which was in line with the
Health and Safety guidelines of the School of Applied Sciences, University of
Huddersfield.

Experimental
Procedure

Heart
rate, systolic and diastolic pressure were measured using a blood pressure (BP)
monitor during each of the conditions. The cuff of the monitor was positioned
on the right arm at the same level as the heart for each participant and the
participants were seated comfortably upright and breathing normally before the
rest reading was taken twice to ensure a steady heart rate and blood pressure
at the start of the investigation. The first condition required the
participants to hold their breath in air until a BP/HR reading is obtained, the
second condition required the participants to submerge their faces in warm
water at 25?c after a 5 minutes’ rest to allow the participant’s cardiovascular
values return to a steady baseline. Their faces are kept submerged until a
reading is obtained. The same procedure is carried out in the third condition
except that the temperature of the water is 10?c. A bowl, towel, thermometer
and tap water were required for the experiment.

Data
Analysis

Data
analysis was carried out using the Statistical Package for the Social Sciences
(SPSS). Normality tests and descriptive analysis which included the measures of
central tendency and variability were used to describe the results of the four
conditions the participants were subjected to. To test the hypothesis, the
repeated measures ANOVA test was used to compare and test the differences
between the results of the conditions. The same participants were used throughout
the experiment and the conditions and results are related also the data fit the
assumptions necessary to run the repeated measures ANOVA (Laerd
Statistics. Lund Research Ltd. 2013). The Mauchly’s test of Sphericity was used to test for
unequal variances between all the combinations of the conditions as a violation
of this would make the repeated measures ANOVA to become too flexible (Laerd
Statistics. Lund Research Ltd. 2013).

RESULTS

Results from the normality test and graphical representation of the
frequency distribution of the heart rate and mean arterial pressure during each
condition suggested that the data was parametric because the data samples were