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Report on Human Physiology: Cardiovascular and Respiratory System

7 pages
1701 words
George Washington University
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1. Explain in detail how physiologically the cardiovascular and respiratory systems adapt to a short term exercise stimulus. Specifically consider the heart, blood pressure and ventilation.

All human movements, irrespective of intensity and duration, are characterized by the requirement of energy above resting values. Most of this energy is generated through the use of oxygen hence the central role played by the cardiovascular and respiratory systems during exercise. The bodys response to short term exercise comprises of a series of integrated changes in most if not all physiological functions aimed at availing the energy for the exercise and controlling and sustaining the movement. The cardiorespiratory response is paramount for the body to sustain movement over extended periods of time.

Cardiorespiratory function is usually monitored using such variables as heart rate, blood pressure and ventilation. Changes in these variables during exercise define the cardiorespiratory response to the short-term exercise stimulus. Immediately before the onset of exercise the individual experiences an increase in the heart rate. This is attributable to the release of adrenaline from the adrenal medulla which is under sympathetic control (Scott Michael, 2017). The increased heart rate causes a corresponding increase in the cardiac output seeing as the cardiac output is a result of the heart rate and the stroke volume. When exercising, the heart rate increases with each corresponding increase in the intensity of the activity. It continues to increase until the intensity approaches maximal effort. Here the heart rate plateaus any changes in exercise intensity notwithstanding (Scott Michael, 2017). The plateau level is indicative of the heart rate attaining its maximal value. Post exercise, adrenaline production ceases and the heart rate returns to baseline levels.

Before the onset of exercise blood pressure remains near baseline levels because despite the increase in heart rate and corresponding increase in cardiac output, adrenaline also causes a decrease in the vascular resistance through vasodilation. During exercise, blood pressure increases mainly owing to increases in the systolic pressure. Diastolic blood pressure remains at near baseline levels during the duration of exercise. In normotensive people, systolic pressure increases linearly with increases in the intensity of the activity to achieve peaks of between 200 and 240 mm of mercury. Post-exercise, the blood pressure goes back to baseline levels. Before exercise, the ventilation rate is near baseline levels. Ventilation increases abruptly at the onset of exercise which is then followed by a more gradual growth. The initial abrupt increase is attributable to motor center activity while the gradual growth is thought to be triggered by the increasing bodily metabolic needs during exercise as reflected by the growing need for oxygen and the increasing levels of carbon dioxide.

2. Define the following terms, and the units for each.

Tidal Volume

This refers to the volume of air that is displaced during quiet breathing. It is the volume of air put out of place between a normal inhalation and a normal exhalation without the application of extra effort. It is measured in milliliters.

Pulse pressure.

This is the distinction between the systolic blood pressure and the diastolic blood pressure. The measurements are in millimeters of mercury (mmHg)


In this experimentation I am going to investigate the effects of short-term exercise stimulus on the cardiovascular and respiratory systems of healthy individuals by measuring and comparing the changes in heart rate, blood pressure and ventilation before, during and after the exercises.

3. Suggest a suitable aim and hypothesis for this experiment

Cardiorespiratory activity of healthy individuals increases right before and during exercise and is restored to normal levels as soon as the exercise is stopped.

4. Consider the raw data collected during this practical, as provided on Blackboard. Should any of the data be excluded? If any participants are excluded, justify specifically your reason why.

Since the experiment was querying the normal physiological response to exercise stimulus, there is need to exclude data points that lie outside the acceptable physiologic statistical range. Such data points may be indicative of an underlying pathology in the individual hence precluding a normal physiological response to exercise in the subject. An example would be individuals whose resting blood pressure lie above the normal physiological level of 120/80.

5. Using excel or a similar programme, produce a single table of means and standard deviation from the raw data, summarizing the following respiratory variables by time.

Breath rate (BR)

Expired O2 (FiO2)

Expired CO2 (FeCO2)

Volume expired (Ve)

Tidal volume (Vt)

Time/min Breath rate B/m Oxygen % Carbon IV oxide % Tidal volume L/m

1 19.37(7.3) 2 19.27(7.9) 3 19.32(9.3) 4 19.61(9.8) 5 20.01(11.2) 18.42 2.77 16.14

6 23.56(13.7) 7 26.77(15.3) 8 28.69(17.1) 9 29.92(17.6) 10 30.63(20.2) 17.6 4.09 32.52

11 27.07(20.2) 12 26.23(22.1) 13 23.83(23.2) 14 22(23.86) 15 22.71(25.26) 6. Draw two figures, properly labeled and captioned, showing mean +/- standard deviation of the following cardiovascular variables

Heart rate (HR) every minute

Time/min Mean heart rate (B/m) Standard Deviation

Before exercise 1 75.29 16.69

2 72.64 16.0

3 72.82 16.82

4 72.61 16.48

5 72.75 15.59

During exercise 6 76.40 16.97

7 81.57 20.03

8 83.05 23.10

9 88.50 23.40

10 93.09 26.15

After exercise 11 90.01 25.40

12 84.75 21.89

13 80.33 20.16

14 76.99 18.55

15 75.34 17.96


Pulse pressure (PP, in mmHg) prior to, during, and post exercise

Mean pulse pressure (mm/Hg) SD

Before exercise 43.87 17.87

During exercise 52.18 19.06

After exercise 41.33 16.50


7. Describe what each figure shows in words. Included a brief comment on why you think these figures are the most useful manner to understand the results.

The first table in question 6 shows heart rate per minute before, during and after exercise. The average heart rate of all participants is taken in each minute. Itis between 73 and 75 before exercise, which is well within the normal range of adults during rest (normal is between 60 to 100 beats per minute) During exercise, the rate goes up steadily in each minute and is highest at the tenth minute which registers the highest average figure during the experiment. The mean heart rate is from 76 to 93 which is entirely way higher than heartbeat per minute during rest. After exercise the mean heart rate lowers every minute all the way from 90 to 75 beats in a minute at the beginning of rest to the last minute it was recorded. The figures are obtained across a considerably large sample size. They produce a predictable pattern and therefore are beneficial.

The second table documents mean pulse pressure before, during and after exercise. A reading was taken once for each participant in each of these durations. The results show figures of 43.87, 52.18, and 41.33 as the average figures for average pulse pressure prior, during, and following exercise. The figures are obtained across a considerably large sample size as well. They also produce a predictable pattern and therefore are reliable.

Discussion (~1 000 words, 35 %)

8. Do the results collected here meet your hypothesis?

The hypothesis that cardiorespiratory activity in healthy individuals is increased during exercise and restored to normal levels after exercise has been met by the collected results. This is the case for all variables involved, including the heart rate, pulse pressure and breathing rate.

9. What (physiologically) controls breath rate? Do you have evidence for this occurring here?

Ventilation is controlled by the cardiorespiratory centre in the medulla, which moderate how air goes into and out of the lungs based on input from chemoreceptors distributed all over the circulatory system. Breathing is useful for respiration, the process by which the body, in its entirety and at the cellular level, uses oxygen and produces carbon dioxide

In a healthy individual, the partial pressure of carbon dioxide is most responsible for determining respiratory rate. The concentration of oxygen is also crucial for the same purpose. The sensors that detect oxygen partial pressure are in the aortic and carotid bodies which carry arterial blood. The brainstem at the lateral and anterior surfaces of the medulla oblongata, measure the carbon dioxide concentration and pH in cerebrospinal fluid, therefore, in arterial blood.

The data measured by these sensors is transported along neurons toward the respiratory centers in the brain stem, at the pons and the medulla oblongata. The pneumotaxic center in the pons and the apneustic center in the medulla oblongata are the inspiratory and expiratory centers. The respiratory centers control the muscles that take part in breathing, including the diaphragm and whose activity causes air to go into and out of the lungs by inhalation and exhalation.

The trends in the breathing rate and the composition of air exhaled, through oxygen and carbon dioxide partial pressures has been supported in the experiment. It is expected that low oxygen partial pressures and high carbon dioxide partial pressures would increase breathing rate. That seems to be the case during exercise when oxygen consumption is high and carbon dioxide release is high within the body, thus supporting the description of how breathing is controlled (Parkes, 2013).-

10. Suggest how individual participants exercising on bikes might vary in terms of their cardiac and respiratory responses, and physiologically why these responses may occur.

A group of participants doing a similar exercise might vary in their cardiorespiratory responses. That is a result of individual factors some of which include age, gender, body mass, exercise tolerance. Other factors would be duration, intensity, and frequency of the workout and also environmental state (Kaminsky, Arena, & Myers, 2015, p. 1518).

Most of the responses that occur in exercise are due to increased energy demand in the body. The body shifts so as to maintain homeostasis. The muscles involved in exercise need efficient delivery of nutrients and oxygen as well as effective disposal of carbon dioxide and heat. The responses work in tandem, like a single machine as they all attempt to maintain homeostasis in the body. The cardiovascular responses are coordinated by neural and endocrine systems.

In the cardiovascular system, responses such as heart rate, stroke volume, cardiac output, blood pressure, and blood flow. When an individual starts exercising, the neuroendocrine system influences the frequency and force of the heartbeat. The heart rate hence raises predictably according to the intensity of exercise, in this case, bike riding. The heart rate is higher as the heart needs to work faster to supply enough oxygen to tissues in the state of increased demand as it collects waste products of respiration. Heart rate changes depending on individual needs. Those who are more fit will increase their heart rates by smaller margins than those who are less fit. Fitness means the heart is more tolerant to exercise and therefore can deliver sufficient oxygen to tissues with a slightly increased rate. Stroke volume is the amount of blood leaving the heart in each beat. It is the maximum volume of blood in the left ventricle minus the minimal volume there. During exercise, it may rise from...

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