The act of respiration (breathing) is to supply O2 to the tissues and to remove CO2 from the tissues। To achieve respiration, four major actions must be regulated: pulmonary ventilation, diffusion of O2 and CO2 between the alveoli and the blood, transport of O2 and CO2 into the blood and body fluids to and from cells, regulation of ventilation (exercise subjects these factors to change, but the body is designed to maintain homeostasis)। When an individual goes from a state of rest to a state of maximal intensity of exercise, O2 consumption, CO2 formation, and total pulmonary and alveolar ventilation increase by about 20 times. A linear rapport exists between O2 consumption and ventilation. At maximal exercise, pulmonary ventilation is 100-110 L/min., whereas maximal breathing capacity is 150-170 L/min. Therefore, the maximal breathing capacity is about 50% greater than the actual pulmonary ventilation during maximal exercise. This extra ventilation is there for safety, so that it can be called on if the situation demands it (ex. high altitudes, abnormality in the respiratory system). Therefore, the respiratory system itself is not usually the most limiting factor in the delivery of O2 to the muscles during maximal muscle aerobic metabolism.
VO2 (max) is the rate of oxygen consumption under maximal aerobic metabolism. This rate was found to increase by only 10% with the effect of training. However, that of a person who runs in marathons is 45% greater than that of an untrained person. This is believed to be partly genetically determined (stronger respiratory muscles, larger chest size in relation to body size) and partly due to long-term training. Oxygen diffusing capacity is a measure of the rate at which oxygen can diffuse from the alveoli into the blood. An increase in diffusing capacity is observed in a state of maximal exercise. This results from the fact that flow through many of the pulmonary capillaries is sluggish in the resting state. In exercise, increased blood flow through the lungs causes all the pulmonary capillaries to be perfused at their maximal level, providing a greater surface area through which oxygen can diffuse into pulmonary capillary blood. Athletes, who require greater amounts of oxygen per minute, have been found to have higher diffusing capacities. Although one would expect the oxygen pressure of arterial blood to decrease during strenuous exercise and carbon dioxide pressure of venous blood to increase far above normal, but this is not the case. Both of these values stay close to normal. Stimulatory impulses from higher centers of the brain and joint and muscle stimulatory reflexes account for the nervous stimulation of the respiratory and vasomotor center that provides almost exactly the proper increase in pulmonary ventilation to keep the blood respiratory gases almost normal. If nervous signals are too strong or weak, chemical factors bring about the final adjustment in respiration required to maintain homeostasis.
The cardiovascular system helps transport oxygen and nutrients to tissues, transport CO2 to the lungs and kidneys, distribute hormones throughout the body, and assist with thermoregulation. Regular exercise makes the cardiovascular system more efficient at pumping blood and delivering O2 to muscles. The release of adrenaline and lactic acid into the blood results in an increase of the heart rate. Exercise increase some different components of the cardiovascular system such as the stroke volume, cardiac output, systolic blood pressure, and mean arterial pressure. A greater percentage of the cardiac output goes to the exercising muscles. At rest, muscles receive about 20% of the total blood flow, but during exercise, the blood flow increases to 80-85%. To meet the metabolic demands of skeletal muscle during exercise, 2 major adjustments to blood flow must occur: there must be an increase in CO2, their must be a redistribution of blood flow from inactive organs and tissues to active skeletal muscles. The longer the duration of exercise, the greater the role the cardiovascular system plays in metabolism and performance during exercise. An example would be a 100-meter sprint (little or no cardiovascular involvement) versus a marathon (maximal cardiovascular involvement).
The pumping of blood by the heart requires two mechanisms to be efficient: alternate periods of relaxation and contraction of the atria and ventricles, coordinated opening and closing of the heart valves for unidirectional flow of blood. Most of the work of the heart is completed when ventricular pressure exists. The greater the ventricular pressure, the greater the workload of the heart. Increases in blood pressure dramatically increase this workload, and this is why hypertension is so harmful to the heart. Exercise is accomplished by alteration in the body’s response to physical health. These responses to exercise include increase in the heart rate, blood pressure, stroke volume, cardiac output, ventilation, and VO2 (rate of oxygen consumption under maximal aerobic metabolism). The metabolism at cellular level is also modulated to accommodate the demands of exercise.
Methods
Sphygmomanometer (blood pressure cuff) – device for measuring blood pressure (automatic sphygmomanometer/brachial artery)
Spirometer – device for measuring respiratory capacity
Results
(See attached Cardiovascular/Pulmonary Adjustments in Exercise)
Discussion
I want to start the discussion by indicating that unfortunately I am a smoker, and I always had a slightly low blood pressure. When an individual goes from a resting state to maximal intensity of exercise, CO2 formation, O2 consumption and total pulmonary and alveolar ventilation increase. The release of adrenaline and lactic acid into the blood results in an increase of the heart rate. These are the reasons why my BP and pulse increased slightly after walking for several minutes. My pulse did go back to normal 5 minutes after the exercise, therefore my recovery time is somewhat rapid. The body was designed to maintain homeostasis. These changes occur temporarily during exercise. My vital capacity was at 97.06%. (Considering I do smoke, it’s not too bad). www.PassNurseExams.com
Bibliography
http://www.emedicine.com/SPORTS
http://www.PassNurseExams.com
