Exploring the Mammalian Dive Reflex in Humans

Mammalian Dive Reflex

Purpose

The purpose of this experiment is to observe the mammalian dive reflex in 2 subjects’ measuring their heart rate, blood pressure, and % arterial oxygen saturation (SpO2).

Introduction

All mammals, including humans, have the physiological means to survive the submersion of cold water for a greater period of time. This is called the mammalian dive reflex. Taking the subjects heart rate, blood pressure, and percentage of arteriole oxygen saturation shows the cardiac and vascular changes within the sympathetic and parasympathetic nervous system. In this study two human subjects underwent experiments showing how the body responds when the face is submerged in various temperature waters (room temp, warm and cold water).

When mammals are submerged in cold water the body responds by shutting down selective parts of the body including the brain, heart, and adrenal glands to store energy for their survival with a specific combination of, bradycardia (slowing of the heart rate), apnea (suspension of breathing), and peripheral vasoconstriction (DUJS 2012). In order for cardiac and vascular changes to occur there are nerves within the autonomic nervous system that triggers this physiological response. Once the trigeminal nerves in the face senses cold temperature, it sends a signal to the parasympathetic nervous system instructing the vagus nerve to cause bradycardia (slowing of the heart) so that the sympathetic nervous system can output limb vasoconstriction, which shunts blood away form the limbs and redirect it to the brain and heart. By this occurring it causes the heart to use less energy and divert blood to selective organs, in order to maintain body heat at a normal temperature.

Procedure
Six water baths were set at 3 different temperatures, 2 at 21° C, 2 at 15° C, and 2 at 35° C. Two male subjects volunteered to conduct the experiment. Subjects had a blood pressure cuff, and a sphygmomanometer attached to their arm, along with a pulse oximeter on their finger, in order to have an accurate reading, or their measurements at all times. Measurements included are heart rate (b/min) blood pressure (mm Hg), and % arterial oxygen saturation (SpO2). In any instance of a subject’s hyperventilated procedure, it is defined as breathing in and out and the releasing of CO2. 1st trial subjects just took baseline readings. In the 2nd trial, they hyperventilated, and held breath for 45 sec. With the 3rd trial, two subjects hyperventilated (breath at rapid rate) and submerged face in water along with snorkel and held breath for 45 sec. Then in trial 4, the two subjects with mask and snorkel on, paused until their heart rate went down and submerged face in water while breathing for 45 sec. In the 5th trial the subjects breathed through snorkel only and held breath in water for 45 sec. Next was the 6th trial, the 2 subjects with mask submerged face in water and held their breath for 45 sec. In the 7th trial they held their breath in water without mask for 45 sec. Then continuing on with the 8th trial the two Subjects submerged face only in a water temperature of 35° C for 45 sec. Lastly, in the 9th trial the two subjects submerged their face only, in water at a temperature of 10° C. The measurements were immediately taken after each trial, and the data was recorded, to get an accurate reading of blood pressure, heart Rate, and SpO2.

Results
Subject’s % arterial oxygen saturation (SpO2) saturation did not change throughout the trial. However, heart rate in both subjects 1 and 2 had a definite change that showed the Mammalian Dive Reflex. In trials 1 to 4 a decrease in heart rate was observed in both of the subjects. Subject 1’s heart rate in trials 1 to 4 fluctuated and then decreased form 96 b/pm to 65 b/pm. Then in subject 2 trials 1 to 4, although just a slight change compared to subject 1, was a continuous decrease in heart rate that went from 67 b/pm to 53 b/pm. Then in Trials 5 to 9 in both subjects heart rate increased and then decreased. Subjects 1 Heart Rate went up and down, which went anywhere from 77 b/pm to 102 b/pm, and then decreased in trial 9 to the lowest heart rate throughout all of the trials to 63 b/pm. Last of all, in subject 2, with just a small change compared to subject 1, the heart rate alternated in trials 1 to 8 between 59 b/pm to 69 b/pm and then in trial 9 decreased to 60 b/pm.

Mention BP…..

Table 1-1: % Oxygen Saturation, Heart Rate (b/min) and Blood Pressure (mm Hg)
Trial (water immersion) % Oxygen
Sub1 Sub2 Heart rate
Sub1 Sub2 Blood Pressure
Sub1 Sub2

1. No immersion (at rest) 99% 99% 63 67 130/70 131/79
2. No immersion (breath hold) 99% 98% 70 65 125/70 122/64
3. No immersion (breath through snorkel) 99% 99% 76 57 119/70 121/79
4. Mask and snorkel (breathing) 99% 99% 65 53 140/70 150/70
5. Snorkel only (breathing) 97% 98% 77 59 150/70 130/81
6. With face mask (breath hold) 99% 99% 102 70 140/60 145/78
7. Without face mask (breath hold) 96% 98% 89 69 145/78 140/78
8. Face only 35o (breath hold) 99% 96% 79 66 130/70 150/80
9. Face only 10o (breath hold) 99% 98% 63 60 130/78 140/71

Figure 1-1: Heart Rate vs Trial

Figure 1-2: Systolic Pressure (mmHg) vs Trial

Discussion
The outcome of this experiment on Mammalian Dive Reflex was most apparent when both subjects immersed their face in cold water. Although the three variables including water, position, and apnea were able to activate the diving reflex. It was the water alone that primarily triggered the result. Tables 1-3 shows that just breathing alone
tiggered the diving reflex with the heart rating having a slight decrease. However in table 9 when the face was submerged in water, you could see a considerable decrease in the body’s physiological response. This response suggests that when the trigeminal nerve was activated, it relayed a signal to the brain stem within the parasympathetic nervous system, which caused bradycardia (slowing of the heart rate). This data shows that the cold water was the primary source in this reaction of the diving reflex. Although, subject 2’s heart rate only changed slightly, this could be due to either internal or external factors including, students making to much noise, the subject not being familiar with using a mask, or not feeling well that day. Some room for improvements could have been to have younger or older volunteers, work in smaller groups, or to have students be in a less distracting environment.

Mammalian Dive Reflex
Purpose
The purpose of this experiment is to observe the mammalian dive reflex in 2 subjects’ measuring their heart rate, blood pressure, and % arterial oxygen saturation (SpO2).
Introduction
All mammals, including humans, have the physiological means to survive the submersion of cold water for a greater period of time. This is called the mammalian dive reflex. Taking the subjects heart rate, blood pressure, and percentage of arteriole oxygen saturation shows the cardiac and vascular changes within the sympathetic and parasympathetic nervous system. In this study two human subjects underwent experiments showing how the body responds when the face is submerged in various temperature waters (room temp, warm and cold water). When mammals are submerged in cold water the body responds by shutting down selective parts of the body including the brain, heart, and adrenal glands to store energy for their survival with a specific combination of, bradycardia (slowing of the heart rate), apnea (suspension of breathing), and peripheral vasoconstriction (DUJS 2012). In order for cardiac and vascular changes to occur there are nerves within the autonomic nervous system that triggers this physiological response. Once the trigeminal nerves in the face senses cold temperature, it sends a signal to the parasympathetic nervous system instructing the vagus nerve to cause bradycardia (slowing of the heart) so that the sympathetic nervous system can output limb vasoconstriction, which shunts blood away form the limbs and redirect it to the brain and heart. By this occurring it causes the heart to use less energy and divert blood to selective organs, in order to maintain body heat at a normal temperature.

Procedure
Six water baths were set at 3 different temperatures, 2 at 21° C, 2 at 15° C, and 2 at 35° C. Two male subjects volunteered to conduct the experiment. Subjects had a blood pressure cuff, and a sphygmomanometer attached to their arm, along with a pulse oximeter on their finger, in order to have an accurate reading, or their measurements at all times. Measurements included are heart rate (b/min) blood pressure (mm Hg), and % arterial oxygen saturation (SpO2). In any instance of a subject’s hyperventilated procedure, it is defined as breathing in and out and the releasing of CO2. 1st trial subjects just took baseline readings. In the 2nd trial, they hyperventilated, and held breath for 45 sec. With the 3rd trial, two subjects hyperventilated (breath at rapid rate) and submerged face in water along with snorkel and held breath for 45 sec. Then in trial 4, the two subjects with mask and snorkel on, paused until their heart rate went down and submerged face in water while breathing for 45 sec. In the 5th trial the subjects breathed through snorkel only and held breath in water for 45 sec. Next was the 6th trial, the 2 subjects with mask submerged face in water and held their breath for 45 sec. In the 7th trial they held their breath in water without mask for 45 sec. Then continuing on with the 8th trial the two Subjects submerged face only in a water temperature of 35° C for 45 sec. Lastly, in the 9th trial the two subjects submerged their face only, in water at a temperature of 10° C. The measurements were immediately taken after each trial, and the data was recorded, to get an accurate reading of blood pressure, heart Rate, and SpO2.

Results
Subject’s % arterial oxygen saturation (SpO2) saturation did not change throughout the trial. However, heart rate in both subjects 1 and 2 had a definite change that showed the Mammalian Dive Reflex. In trials 1 to 4 a decrease in heart rate was observed in both of the subjects. Subject 1’s heart rate in trials 1 to 4 fluctuated and then decreased form 96 b/pm to 65 b/pm. Then in subject 2 trials 1 to 4, although just a slight change compared to subject 1, was a continuous decrease in heart rate that went from 67 b/pm to 53 b/pm. Then in Trials 5 to 9 in both subjects heart rate increased and then decreased. Subjects 1 Heart Rate went up and down, which went anywhere from 77 b/pm to 102 b/pm, and then decreased in trial 9 to the lowest heart rate throughout all of the trials to 63 b/pm. Last of all, in subject 2, with just a small change compared to subject 1, the heart rate alternated in trials 1 to 8 between 59 b/pm to 69 b/pm and then in trial 9 decreased to 60 b/pm.

Mention BP…..

Table 1-1: % Oxygen Saturation, Heart Rate (b/min) and Blood Pressure (mm Hg)
Trial (water immersion) % Oxygen
Sub1 Sub2 Heart rate
Sub1 Sub2 Blood Pressure
Sub1 Sub2

1. No immersion (at rest) 99% 99% 63 67 130/70 131/79
2. No immersion (breath hold) 99% 98% 70 65 125/70 122/64
3. No immersion (breath through snorkel) 99% 99% 76 57 119/70 121/79
4. Mask and snorkel (breathing) 99% 99% 65 53 140/70 150/70
5. Snorkel only (breathing) 97% 98% 77 59 150/70 130/81
6. With face mask (breath hold) 99% 99% 102 70 140/60 145/78
7. Without face mask (breath hold) 96% 98% 89 69 145/78 140/78
8. Face only 35o (breath hold) 99% 96% 79 66 130/70 150/80
9. Face only 10o (breath hold) 99% 98% 63 60 130/78 140/71

Figure 1-1: Heart Rate vs Trial

Figure 1-2: Systolic Pressure (mmHg) vs Trial

Discussion
The outcome of this experiment on Mammalian Dive Reflex was most apparent when both subjects immersed their face in cold water.

Although the three variables including water, position, and apnea were able to activate the diving reflex. It was the water alone that primarily triggered the result. Tables 1-3 shows that just breathing alone

tiggered the diving reflex with the heart rating having a slight decrease. However in table 9 when the face was submerged in water, you could see a considerable decrease in the body’s physiological response. This response suggests that when the trigeminal nerve was activated, it relayed a signal to the brain stem within the parasympathetic nervous system, which caused bradycardia (slowing of the heart rate). This data shows that the cold water was the primary source in this reaction of the diving reflex. Although, subject 2’s heart rate only changed slightly, this could be due to either internal or external factors including, students making to much noise, the subject not being familiar with using a mask, or not feeling well that day. Some room for improvements could have been to have younger or older volunteers, work in smaller groups, or to have students be in a less distracting

environment.