Introduction to Physiology: Respiration
There are a lot of factors that determine the rate and depth of human respiration. Some of the factors are influenced by the conscious control part of the brain while others are not. Different organ system functions leads to unique pattern of respiration and even though respiration is controlled by the autonomous nervous system, people play a part in the control of breathing. Respiration is affected by certain chemicals which include oxygen, carbon dioxide, acid, epinephrine and acetylcholine (Marieb e.tal 2010).
Whether or not oxygen concentration affects respiration remain a debating topic in the scientific realm. This is because the human body is as sensitive to blood oxygen concentration as other chemicals like carbon dioxide. The aortic bodies cause an increase in respiration with low oxygen concentration but there is no response with a high concentration. On the other hand, the aortic bodies and other brain parts senses both low and high carbon dioxide concentration and cause and appropriate response. Breathing can be altered by speaking, singing, emotions and even pain whereby a signal is sent via the limbic system to the sympathetic center of the hypothalamus. Exercises also cause an increase in breathing since the muscles consume lots of oxygen and releases carbons oxide in excess triggering increased respiration. Generally the rate of respiration differs according to age, gender, height, weight and whether or not the person is a smoker (Scott 2004).
Breathing was done deeply and at a fast rate for a period of 30 seconds. The number of breaths taken each minute after hyperventilating was recorded in a table.
Breathing was then done into a bag for a long time while ensuring that no air leaks occur at the bag’s edges. This ensures that one breath the same air repeatedly. The number of breathes in the first minute of recovery was tabulated.
Breath was held at the peak of a normal, gentle and quiet inspiration and the time taken to breath point (in seconds) was measured and tabulated. Hyperventilation followed for 30 seconds and the breaking point measurement was captured again into the table. After recovery, air from the bag was re-breath for 1 minute and the breaking point measurement taken.
A beaker was half filled with water and a few drops of bromothymol blue were added. The color and pH was then noted. Wearing a pair of safety glass and using a straw, air was blown into the water for a number of complete breaths. The water color and the pH were noted again.
Chart 1 Class average of breathing rate
The breathing rate at rest which is the normal condition is 15.924b/min. After hyperventilation, whereby one breathes deep and fast for 30 seconds, the rate reduces slightly below the rest condition. The rate of breathing increases tremendously during the third procedure, breathing after re-breathing using a closed bag. This reaches a rate of 22.178b/min.
The breaking point results show that the time taken to reach the breaking point at rest conditions is 43 seconds. This time increases by 20 seconds when it comes to the time taken to reach the breaking point after hyperventilation. The time it takes to reach breaking point during breathing after re-breathing reduces to almost half of the time after hyperventilating.
The chart also shows information on breathing rate among both male and female smokers and non smokers. Comparing the male and female breathing rate in general, males have a slightly lower breathing rate at rest conditions. In addition the males have a higher breaking point than the females. An analysis of the smokers shows (both male and women) that they have a higher breathing rate at rest conditions. However, the breathing rate after hyperventilation for the female non smokers is higher than that for male smokers. For non smokers, their breathing rate after hyperventilation is almost the same. Finally, the breathing rate of the smokers is lower compared to those of the non smokers with a reduced breaking point.
The general state of activity of the body determines the rate at which breathing occurs. Vigorous exercise more often leads to increase of breathing rate since the muscles consume oxygen and release lots of carbon dioxide which is a respiration stimulant (Wilburta e.tal 2009). Therefore, at normal rest conditions the breathing rate is reduced and the breathing is slow and quiet. This is seen from the table of results that at rest the rate is low at about 15b/min. The increase of CO2 in the blood stream triggers the central chemoreceptor causing an increase in rate and depth of breathing. This leads to an active removal of CO2 from the body and an increase intake of oxygen. This condition is known as hyperventilating. After hyperventilation, the rate of breathing reduces since the level of CO2 in the bloodstream is low. This is the reason why the table shows a reduced rate of breathing after hyperventilating. In addition the breaking point or the time taken till one cannot hold their breath again at the peak of inspiration is affected by the amount of CO2 in the lungs (alveoli). The breakpoint is thus inversely proportional to the CO2 in the blood stream. The lesser the amount of CO2 in the blood, the longer the breaking point. Therefore after hyperventilation the amount of CO2 in the lungs and the bloodstream will be reduced. For this reason after hyperventilation the breaking point is the longest with up to 62 seconds (Morrow e.tal 1986).
When one breathes, they use up the oxygen in the surrounding and exhale carbon dioxide from the body. In a closed of space, the amount of oxygen will deplete faster and the amount of carbon dioxide will increase. Therefore, during breathing into a bag with no air leakages the amount of oxygen gets depleted and thus one keeps on breathing in carbon dioxide and less oxygen. This leads to an increase in the amount of carbon dioxide in the lungs and blood stream triggering an increased rate of breathing. This causes an increase in breathing rate as indicated in table 1. The breaking point during breathing after re-breathing is reduced to half of that after ventilation. This is because during re-breathing, the amount of CO2 in the blood stream increases greatly. This leads to a short breaking point since it is inversely proportional to the amount of carbon dioxide in the lungs.
The chart shows the breathing rates of smokers and non smokers from both genders. The breathing rate of the smokers is seen to be high than that of smokers with a lower breaking point. Smoke from cigarettes, interferes with the cilia which keeps the lungs clean. This causes clogging of the cilia with tar and narrowing of the airwaves channels. The clogging and thickening of the airwaves eventually reduces the elasticity of the lungs and its capacity to expand and retract during breathing. Also, nicotine which is an active component in cigarettes causes the brain to trigger release of adrenaline. This causes the vessels to constrict and the heart to pump faster. As a result the blood pressure increases. The respiratory systems tries to match the increased heart rate therefore increasing the rate of breathing (Scott 2004). This is indicated in the chart above (Chart 1).
Cigarettes smoke releases carbon monoxide into the bloodstream. This is a toxic gas that prevents oxygen from being absorbed into the vital organs like the heart and lungs. Carbon monoxide also reduces the red blood cell affinity to oxygen and its effectiveness in removing carbon monoxide. Thus smokers have reduced amounts of oxygen in their bloodstream and increased amount of carbon dioxide. This reduces their breaking point since it is affected by the amount of CO2 in the lungs and blood stream (Wang L 1994).
Tests performed under different conditions indicated that breathing dynamics varied amongst different genders because of physiological differences in the brain. Under different postures, breathing dynamics were different since thoracic cavities tended to vary in size and inclination. Women breathe higher in the thorax whereas men breathe lower abdomen. Thus men have a higher capacity than women (Morrow e.tal 1986).
In conclusion, the rate of breathing is different for every individual with lots of factors coming to play. This includes the age, height, weight and gender differences. Emotions and pain also affects the rate of breathing. Breathing is controlled by the autonomous action of the nervous system and that’s the reason people don’t even notice the process going on. Oxygen is required by the vital organs of the body which use it and releases carbon dioxide as a waste product. Even though oxygen is the vital gas of the two, it is carbon dioxide which determines the respiration. Increase or decrease of carbon dioxide triggers the central chemoreceptor to either increase or decreases the rate and depth of breathing. The ability to hold ones breath for certain duration is determined by the amount of carbon dioxide in the lungs. Smokers have an increased rate of breathing and a reduced breaking point due to the harmful effects of the chemicals in the smoke that affect the respiratory system.
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