Wednesday, January 30, 2013

Experiments 1 & 2

Ice Experiment
DATA

Table 1–Baseline Blood Pressure
Systolic pressure
(mm Hg)
Diastolic pressure            (mm Hg)
Mean arterial pressure      (mm Hg)
118 mm Hg
79 mm Hg
97 mm Hg

Table 2–Blood Pressure Response to Cold
Systolic pressure
(mm Hg)
Diastolic pressure            (mm Hg)
Mean arterial pressure     (mm Hg)
130 mm Hg
80 mm Hg
107 mm Hg

Table 3
Condition
Heart rate
(bpm)
Time
(s)
Resting heart rate
86 BPM
25.2 sec
Maximum heart rate
106 BPM
38 sec
Rebound heart rate
94 BPM
34.3 sec



Data Analysis
1.   Describe the trends that occurred in the systolic pressure, diastolic pressure, mean arterial pressure, and heart rate with cold stimulus. How might these responses be useful in a “fight or flight” situation?
When your heart beats, it contracts and pushes blood through the arteries to the rest of your body. This force creates pressure on the arteries. This is called systolic blood pressure. The diastolic blood pressure number or the bottom number indicates the pressure in the arteries when the heart rests between beats. (3)  Mean arterial pressure is the average pressure within an artery over a complete cycle of one heartbeat. (4) When the foot was immersed into the water, the new environment made the nerves in the foot send a signal to the central nervous system, telling it that a new and uncomfortable stimulus was introduced that may stunt or get in the way of homeostasis for that particular part of the body. The CNS sent signals to the brain, telling it to remove the foot from the cold water. The brain increased blood flow to the limbs, thus increasing the diastolic, systolic, and mean arterial pressure in the body in order to increase the amount of oxygen delivery to allow the muscles to move quicker and react faster than when in a homeostatic state. This same reaction occurs during Fight-or-Flight reactions.



2.   As a vital sign, blood pressure is an indicator of general health. A high blood pressure (140/90 or higher) increases the risk of cardiovascular disease and strokes. Collect the systolic and diastolic pressures for the class and calculate the average for each. Rate the class average blood pressure using the follow scale:
Blood Pressure
Category
140/90 or higher
High
120–139/80–89
Pre-hypertension
119/79 or below
Normal


Systolic Pressure                              Diastolic Pressure
Group 1- 131                                    Group 1- 90
Group 2- 118                                    Group 2- 79
Group3- 128                                     Group 3- 86
Group 4- 116                                    Group 4- 79
Group 5- 119                                    Group 5- 83
(131+118+128+116+119= 612/5= 122.4) (90+79+86+79+83= 417/5= 83.4)
Average BP is (122/83)

The average diastolic blood pressure for the class is . the average systolic blood pressure for the class is. Therefor the average blood pressure for the class is / which falls into the __Pre-Hypertension_ category.


3.   How long after immersion did your heart rate reach its maximum value? Explain the    physiologic mechanism that led to this change in heart rate.
Resting heart rate
86 BPM
25.2 sec
Maximum heart rate
106 BPM
38 sec
Rebound heart rate
94 BPM
34.3 sec


Fight-or-Flight reaction is a set of physiological changes, such as increases in heart rate, arterial blood pressure, and blood glucose, initiated by the sympathetic nervous system to mobilize body systems in response to stress.(5) It took the heart 38 seconds to reach it maximum number of beats per minute (BPM). During this time frame, the heart was constantly increasing blood pressure, and mean arterial pressure in order to increase reaction time to remove the foot from the water, as explained in question 1.  This entire reaction happens subconsciously, meaning the mind is not aware of what is occurring. However, the foot was not removed, which is a conscious reaction by the body. The heart rate increased by 20 BPM in 38 seconds, so for 30 seconds the subconscious and conscious mind were both at work in controlling the body’s reaction to the cold stimulus. When the stimulus was removed, it took 34.3 seconds for the heart to return to a consistent 94 BPM. The slowing of the heart rate was all subconscious.

4. Describe the changes in heart rate that occurred after the maximum value. How can you explain the minimum heart rate value? How would you explain the heart rate variations seen in the remainder of the experiment?
-Right after her heart rate reached its maximum value, it drastically decreased to almost the resting heart rate. The minimum heart rate was when the subject was resting because the heart had not yet needed to increases its rate to accommodate the body. After she put her foot in the ice water, her body reacted in a panicked manner and her heart rate shot up to reach the maximum rate. After taking her foot out of the water, her heart rate began to drop and return to its normal rate, which was only a few BPM more than the minimum/resting heart rate.


5.   How long after the maximum heart rate did it take to arrive at your rebound heart rate? What can you say about the relative speed of physiologic response to a stimulus vs. the speed of mechanisms that are designed to maintain homeostasis?
-It took her heart 34.3 seconds to return to the rebound heart rate after reaching its maximum, while it took her heart 38 seconds to reach its maximum initially. Our data suggests that the heart reacts to a stimulus slower than it reacts in order to maintain homeostasis, however we expected the heart to react much faster when the foot was initially submerged in the ice water than when the heart was attempting to achieve its rebound rate.


6.   If the heart rate is too slow there is inadequate blood pressure to maintain perfusion to the brain. This can lead to loss of consciousness (fainting). Keeping in mind the autonomic nervous system responses that you observed in this experiment, explain the sequence of events that results in a severely frightened person fainting.
-Fainting due to being startled or frightened is known as Neurocardiogenic syncope and is caused by a short-term malfunction of the autonomic nervous system. The body is in such a frightened state that the ANS begins to lower the blood pressure and heart rate, causing the brain’s supply of oxygen to be temporarily interrupted. The brain uses fainting as a survival mechanism in response to a drop in oxygen levels to shut down all the non-vital parts of the body so that resources can be focused on the vital parts of the body. To do this, the brain increases the breathing rate and heart rate to direct blood to the brain at the expense of other parts of the body. This combination of hypertension and low blood pressure in the body can cause the body to shut down, or faint.






Exercise experiment
DATA
Table 1–Baseline Blood Pressure
Systolic pressure
(mm Hg)
Diastolic pressure
(mm Hg)
Mean arterial pressure
(mm Hg)
Pulse
(bpm)
111
67
81
89



Table 2–Blood Pressure After Exercise
Systolic pressure
(mm Hg)
Diastolic pressure
(mm Hg)
Mean arterial pressure
(mm Hg)
Pulse
(bpm)
125
85
101
71

Table 3–Heart Rate
Condition
Resting heart rate (bpm)
68
Maximum heart rate (bpm)
108.7
Recovery time (s)
1 min 9 sec



DATA ANALYSIS
1.   Describe the trends that occurred in the systolic pressure, diastolic pressure, mean arterial pressure and pulse with exercise. Assume that the stroke volume increased from 75 mL/beat to 100 mL/beat. Use this information and the change in pulse with exercise to calculate the change in cardiac output (stroke volume × heart rate) that occurred per minute.
The systolic, diastolic, and mean arterial pressure increases during running along with the pulse rate. The systolic, diastolic and mean arterial pressures, and pulse rate return to normal a little over a minute because our person is in soccer and they have a faster recovery time than someone who doesn’t exercise or is active. The cardio output before running in pace is 2225 per minute and 1,775 per minute after running.

2.   Pulse pressure is the difference between systolic pressure (peak pressure during active contraction of the ventricles) and diastolic pressure (the pressure that is maintained even while the left ventricle is relaxing). Describe the change in pulse pressure seen with exercise. Which component of the blood pressure is most responsible for this change?
The pulse pressure in the beginning of the exercise is less than after running. The left ventricle ejects blood which causes aorta pressure. The change is caused by the stroke volume of the ventricle. (6)

3.   A change in pulse pressure can be seen in a variety of medical conditions. What would you expect to happen to the pulse pressure in the following examples?
  (a)  In atherosclerosis there is a hardening of the arterial walls.
It blocks the flow the blood in which decreases the amount of blood the left ventricle ejects, which lowers the stroke volume. The stroke volume determines the pulse pressure, so atherosclerosis hinders the stroke volume. (7)

  (b)  A damaged aortic valve does not seal properly and allows blood to flow back into the ventricle during diastole.
The pulse pressure increases because the aortic valve is leaky and the systolic pressure increases as the diastolic pressure decreases. (7)

4.   Normal resting heart rates range from 55−100 beats per minute. What was your/the subject’s resting heart rate? How much did your/the subject’s heart rate increase above resting rate with exercise? What percent increase was this?

5.   How does your/the subject’s maximum heart rate compare with other students in your group/class? Is this what you expected?
It is average compared to the other results. Our resting heart rate was slightly higher than the rest of the class but during exercise, the heart rate increases to supply the body with enough oxygenated blood.

6.   Recovery time has been shown to correlate with degree of physical fitness. How does your/the subject’s recovery rate compare to that of your classmates? Is this what you expected?
Our recovery time was shorter compared to our classmates because the person we tested with was a fit athlete.  This is what we expected because a person that exercises daily has a shorter recovery time than someone that does not exercise often.


7.   Congestive heart failure is a condition in which the strength of contraction with each beat may be significantly reduced. For example, the ventricle may pump only half the usual volume of blood with each beat. Would you expect a person with congestive heart failure to have a faster or slower heart rate at rest? With exercise?
I would expect that the person’s heart rate would be faster than normal at rest and much faster when the person is exercising


8.   Medications are available which can slow the heart or speed it up. If a patient complains of feeling poorly and has a heart rate of 120 beats per minute, should you administer a medicine to slow the rate?
Yes, because the average heart rate is 70-75 beats per minute under resting conditions.

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