Experiment 1 & 2


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Experiment 1 & 2

  1. 1. Heart Rate, Blood Pressure,and Exercise 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 ? -The pressure increased when introduced to cold stimulus. Blood pressure generally is higher in the winter and lower in the summer. Thats because low temperatures cause your blood vessels to narrow — which increases blood pressure because more pressure is needed to force blood through your narrowed veins and arteries. -High blood pressure is also an indicator of stress. Stress definitely affects our bodies. In addition to the emotional discomfort we feel when faced with a stressful situation, our bodies react by releasing stress hormones (adrenaline and cortisol) into the blood. These hormones prepare the body for the "fight or flight response" by making the heart beat faster and constricting blood vessels to get more blood to the core of the body instead of the extremities. Constriction of blood vessels and increase in heart rate does raise blood pressure, but only temporarily; when the stress reaction goes away, blood pressure returns to its pre-stress level. This is called situational stress, and its effects are generally short-lived and disappear when the stressful event is over. -"Fight or flight" is a valuable response when we are faced with an imminent threat that we can handle by confronting or fleeing. However, our modern world contains many stressful events that we cant handle with those options. Chronic (constant) stress causes our bodies to go into high gear on and off for days or weeks at a time. The links between chronic stress and blood pressure are not clear.
  2. 2. 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 -The class average blood pressure is normal (119/63).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. -It reached its maximum value in about 45 seconds. In normal individuals, cardiac output during maximum exercise is approx. 4.5 times greater than the resting value. During peak exercise the stroke volume is increased to approximately 150% of the resting value. The increased stroke volume is accomplished by an increase in venous return, ventricular filling, and contractility. But the most important mechanism by which cardiac output is increased during exercise is by increasing heart rate. (CO = stroke volume * HR).
  3. 3. -Increase in heart rate with exercise, in normal individuals, is accomplished by both neural and neurohumoral mechanisms. There is a rapid withdrawal of parasympathetic (vagal) tone and a slightly slower increase in sympathetic tone. There is a still slower rise in circulating catecholamine levels. There is a direct and relatively linear relationship between heart rate and exercise level and, in turn, between heart rate and cardiac output during exercise. In normal individuals, peak cardiac output can be increased to 300% of resting values simply by an increase in heart rate. - An additional point relating to rate—modulation capabilities in pacing systems is that, in normal individuals, there is a relatively rapid achievement of the appropriate heart rate for a given level of exercise. The appropriate heart rate for the exercise level is achieved within 1.0 to 1 .5 minutes after the beginning of the particular level of exercise. Thus, to recapitulate normal physiology it is important for pacing systems to respond quickly to exercise.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 ? -The rebound heart rate was 63 bpm (98 seconds). Resting pulse varies from person to person, but according to the American Heart Association, the average resting pulse should be between 60-80 beats per minute (BPM). 68-80 BPM is by no means the only place a healthy person’s pulse can be. For athletes or people who often perform cardiovascular activity, “a normal resting heart rate may be closer to 40 beats a minute” [1], with the most noted example being that Lance Armstrong reportedly had a resting pulse of 32 BPM when he was in peak conditioning.
  4. 4. -The main inputs are the sympathetic and the parasympathetic nervous system (PSNS) and humoral factors. Respiration gives rise to waves in heart rate mediated primarily via the PSNS, and it is thought that the lag in the baroceptor feedback loop may give rise to 10 second waves in heart rate (associated with Mayer waves of blood pressure), but this remains controversial. -Factors that affect the input are the baroreflex, thermoregulation, hormones, sleep- wake cycle, meals, physical activity, and stress.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 98 seconds to arrive at the rebound heart rate. Physiologic response to a stimulus would be your heart rate increasing during exercise or stress. The speed of mechanisms would be how fast it returns to normal. Homeostasis is the bodys attempt to maintain a constant internal environment. Homeostatic regulation involves three parts or mechanisms: 1) the receptor, 2) the control center and 3) the effector. -The receptor receives information that something in the environment is changing. The control center or integration center receives and processes information from the receptor. And lastly, the effector responds to the commands of the control center by either opposing or enhancing the stimulus. This is an ongoing process that continually works to restore and maintain homeostasis. For example, in regulating body temperature there are temperature receptors in the skin, which communicate information to the brain, which is the control center, and the effector is our blood vessels and sweat glands in our skin.
  5. 5. -Because the internal and external environment of the body are constantly changing and adjustments must be made continuously to stay at or near the set point, homeostasis can be thought of as a synthetic equilibrium.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 . -When you suffer from anxiety, feeling faint is almost exclusively caused by hyperventilation. Also known as "over-breathing," hyperventilation occurs when you breathe out too much carbon dioxide as a result of poor breathing habits. -Interestingly, hyperventilation feels like the exact opposite – when youre hyperventilating, it often feels as though youre not getting enough oxygen. So those that are hyperventilating have a tendency to try to take even deeper breaths – breathing in more oxygen to compensate. -This makes it worse. The abundance of oxygen and the depletion of CO2 causes your blood vessels to constrict, which reduces blood flow to the brain. When your brain doesnt feel like its getting enough blood, it prepares you for passing out, because the easiest way to make sure blood flow reaches your brain is when youre on the floor.
  6. 6. DATA Table 1–Baseline Blood Pressure Systolic pressure Diastolic pressure Mean arterial pressure Pulse (mm Hg) (mm Hg) (mm Hg) (bpm) 117 65 83 82 Table 2–Blood Pressure After Exercise Systolic pressure Diastolic pressure Mean arterial pressure Pulse (mm Hg) (mm Hg) (mm Hg) (bpm) 166 103 149 103 Table 3–Heart Rate Condition Resting heart rate (bpm) 87.85 Maximum heart rate (bpm) 161.5 Recovery time (s) 110
  7. 7. DATA ANALYSIS1. 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.-With exercise the systolic pressure, diastolic pressure, mean arterial pressure and the pulseincreased dramatically. It took more time for the numbers to go down (relaxation period afterexercising) than for them to increase (during the exercising). The Systolic pressure remained thehighest rate during both rest and exercise.-The new cardiac output would be 7,400.2. 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 ?-While exercising the body realizes that it is being pushed to go beyond its normal limitations. As your brain tells the body to move faster and stronger the heart tries to keep up and pumps overtime. This causes the pulse to quicken and is why the pulse pressure increased during exercise from where it was when the body was at rest.-The component of the blood pressure that is most responsible for the change is the aorta because this artery is what pushes the blood that contains oxygen to the body.
  8. 8. 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.-Yes, there is hardening of the walls in Atherosclerosis. People with bad cholesterol are indanger because fat and cholesterol build up and they can block the blood flow and get hard asthey line the vessel walls. This causes the pulse pressure to slow down, or in extreme cases, stop. (B) A DAMAGED AORTIC VALVE DOES NOT SEAL PROPERLY AND ALLOWS BLOOD TO FLOW BACK INTO THE VENTRICLE DURING DIASTOLE .-The pulse pressure would increase because the heart would continue to pump more and more -- blood to make up for what is leaking out, so the systolic pressure would get bigger. The diastolic pressure on the other hand would get smaller because there isn’t much blood to pump back because of the leak.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?-The subject’s heart rate was 82 bpm. The subject’s heart rate increased by 21 bpm with exercise. This was a 26% increase.5. HOW DOES YOUR/THE SUBJECT ’S MAXIMUM HEART RATE COMPARE WITH OTHER STUDENTS IN YOUR GROUP/CLASS? IS THIS WHAT YOU EXPECTED ?
  9. 9. -Our subject’s heart rate was very similar to our classmate’s even though it was a little on the high side. We expected that the rates would be roughly the same because the subjects were about the same age and were all healthy.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?-The recovery rate of our subject was a little faster than most of the class. We expected this because she is young and very healthy. There were no signs that she would have any problems that would negatively affect the rate of her recovery.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 think that a person with congestive heart failure will have a faster heart rate with and without exercise because the heart will want to work twice as hard to make up for the amount of blood that is not being sent throughout the body.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, the average heart rate should be between 60 and 100 bpm while this patient has a dangerously high heart rate of 120 bpm.