Space Physiology Love of Extremes: Space Physiology

¶ … Space Physiology Love Of Extremes: Space Physiology About the effect of gravity on the human being in space Early milestones in space exploration and space physiology Gravity The effects of microgravity on human physiology Physiological changes during a space flight The effects of microgravity on the human body The Vestibular System Orientation in space Space Adaptation Syndrome (SAS) and Space Motion Sickness (SMS) The effects of radiations on astronauts in space DNA damage mechanisms by radiations The biological effects of radiations Acute effects of ionizing radiations on health The effects on the immunologic and hematological system The late effects of radiations on human health Cardiopulmonary System (CVS) Heart, circulation and body fluids Countermeasures The effects of microgravity on bone physiology The structure and function of muscles Effects on the muscles The effects of microgravity on the immune and hematopoietic systems Effects of microgravity on the nervous system In-flight acclimatization with time Foremost animals initially sent to space Fruit flies Dogs Cats Spiders Bullfrogs The Russian tortoise Rabbits Newts Chimpanzees Water Bears The first man to enter space Yuri Gagarin's career When scientists thought of exploring space The Felix jump Conclusion References Introduction The human body undergoes considerable changes that are sometimes usually harmless while exposed to an environment without the aspect of gravity.

Without consideration of the gravity, there is no longer the pressure to keep the fluids of the body on the specified normal course. The fluid travelling up to the head and the chest causes the face to puff up finally with the organs enlarged, the veins located in the neck bulges out. This is because of the accumulation of an extra fluid.

The foremost problem affecting the humans since beginning to carry out expeditions into the outer space connects to the respective physiological effects that the environment lacking gravity poses to the body (Stellman & International Labour Office, 2008). The realization that the lack of gravity results to physical changes to the respective human body comes following the step NASA took sending astronauts into the orbit for a shorter period.

Upon returning to the ground, the experience disorientation with the inability to walk hence resulting to research on what actually happens to the general body of human. Following the prolonged space flights, scientists have managed to discover the changes in the human body. One of the principal findings is that the body becoming enlarged with the bones deteriorating within the body. The body muscles begin to atrophy with extreme circumstances because of lack of use (Stellman & International Labour Office, 2008).

The astronauts spend more time in the environments having no gravity enabling for more studies in relation to the problems arising in the course of the long-term space travel (Stellman & International Labour Office, 2008). The majority of the space machines constitutes of elastic straps anchored at one of the ends and then to the specified astronaut. The aspect of the astronaut stretching it out keeps the bones and muscles from deteriorating as opposed to its normal standards (Stellman & International Labour Office, 2008).

Prior to human beings setting out into space, some animals preceded in spaceships as surrogates to enhance the understanding if really a living being could endure and survive an expedition beyond the protective environment of the Earth. The foremost spaceflight carrying live creatures successfully departed from the Earth in September 1951, when the U.S.S.R. sent a sounding spaceship carrying a monkey together with eleven mice within the rocket's nose cone.

This though was not a flight round the orbit, but rather, a simple up-and-down flight within the rocket, and amazingly, the animals were able to withstand the expedition. Before then, unsuccessful attempts to fly animals had been, initiated since 1948. The attempts were, purposely meant to analyze the implications of contact with the radiations of the sun at such a high altitude, as well as determining the impacts of weightlessness on the various physiological systems (National Aeronautics and Space Administration, 2008).

About the effect of gravity on the human being in space Fluid accumulation in the body when in space poses a threat to the functional system of the human body. The spinal discs begin to encounter enlargement from gravity albescence. This causes the respective person to experience growth of about two inches. Another relative problem that occurs is the sudden impairment of the direction sense. The human body entirely depends on the fluid situated in the inner ear for the determination of balance and direction.

Without the aspect of gravity, the fluid no longer stays at the inner era bottom causing the body to be mildly disoriented (Stellman & International Labour Office, 2008). The space environment without gravity can also result to psychological changes accompanying the respective physical changes. The body is likely to suffer from the aspect of insomnia with severe depression with irritation with the other respective people.

All the relative symptoms that the body is likely to undergo usually alleviate having no lingering effects following the reintroduction of the body to gravity (Stellman & International Labour Office, 2008). The other relative changes that the body undergoes in space as opposed to the environment of the earth can be potentially harmful. Without the aspect of gravity, significant muscles use is no longer significant. The muscles atrophy at a higher rate incredibly.

Following the return from the outer space flights in reflection to the length of a period of one month, the muscles usually have no mass to function as before (National Research Council (U.S.), 2012). This depicts on the fact that the body sometimes no longer have the ability to handle other seemingly effortless specified actions. The set rehabilitation time for the situation in some cases extends to more than two years. The other related potential harmful change the respective body undergoes are the aspect of extreme osteoporosis.

In space, the respective human body loses the bone mass in one to two percent each month. That amount corresponds to the average of what postmenopausal women lose every year. The amount of the bone loss can result to severe osteoporosis in the body of the astronaut. The respective skeletal system of the specified astronauts exposed to the outer space atmosphere would be susceptible to breakage and stress fractures on the ground and space respectively (National Research Council (U.S.), 2012).

Early milestones in space exploration and space physiology The advent of orbital flight eventually started in 1957 during which the former USSR launched Sputnik 1 rocket to space. Important to note is the fact that Sputnik 1 was not a manned space flight. However, during the same year, in November 1957, Sputnik 2 was, sent into space with the foremost living thing to enter the orbit; the dog bore the name Laika. They carried her in a compartment within the satellite that was pressurized. Unfortunately, she died in a span of few days.

Thereafter Sputnik 2 once again entered space in April 1958. While the animals went into space, scientific instruments were useful in monitoring different physiological changes as these animals became, subjected to the strain of the launch of the spaceflight, reentry, as well as the weightlessness surroundings. As scientists continued to gather more knowledge with the spaceflights, animals sent to space could thereafter return to the Earth in a sound state of health, refuting the then predictions that alleged the failure to function of some crucial organs upon exposure to microgravity (Sunny, 2008).

This valuable experience with the help of animals opened up the leeway for expeditions by human beings. In April 1961, a Soviet cosmonaut named Yuri Gagarin took the credit for being the first man to enter space. He used Vostok 1 to go 24,800 miles round the Earth thus experiencing weightlessness for approximately 89 minutes. After orbiting once, he entered back to the earth's atmosphere and secured a safe landing. In May 1961, Alan B.

Shepard, Jr., entered space in Freedom 7 Mercury spaceship for approximately 15 minutes of a suborbital flight but was, removed from water approximately 300 miles downrange (National Aeronautics and Space Administration, 2006). Following the astronauts' safe return, medical scientists refuted most concerns centered on the human space explorer's frailty. Nonetheless, the Mercury spaceflights clarified the fact that the human body underwent significant modifications during as well as following a space flight, including measurable loss of weight as well as redistribution of body fluids.

Astronauts embarked on completing more intricate, in-flight medical evaluations during the subsequent Gemini missions that acted as precursors to the missions to the moon. All the scientific studies, conducted up to then became vital in the preparation of the space suits as well as the additional equipment essential to ensure survival during the initial space walk that took place in June 1965 during the Gemini 4 mission by the United States.

Additionally, doctors noted other physiological alterations like significant loss in the density of the bone as well as the muscles, but confirmed no significant health challenges that would otherwise hinder humans from exploring the moon (Peter, 2003). In total, 11 Apollo flights were, then sent into space between the period 1968 and 1972. Twelve astronauts proceeded to work on the moon following Neil Armstrong's first walk on the lunar surface that happened on 20 July 1969, in the 11th Apollo mission.

The missions demonstrated that indeed astronauts could do very productive work on the lunar surface that had only a sixth of the Earth's gravity. While these missions entailed simple observations on physiological adjustments within the spaceflight, doctors conducted an in depth examination of crewmembers primarily prior as well as upon completion of their missions. During these flights, the crewmembers described some minor physiological changes like space motion sickness (SMS).

Nevertheless, human beings were now able to exist as well as do some work effectively while in space with minimal physiological challenges (National Aeronautics and Space Administration, 2004). Throughout the early missions of Gemini, Mercury, as well as Apollo, the scientists started learning concerning the responses by human beings to microgravity; on the other hand, the small spacecrafts used in Gemini, Mercury, as well as Apollo spaceships had minimal space for installation research equipment.

This took a different turn in 1973 during which the United States launched the Skylab program as the maiden space station by the United States. Finally, scientists could then make comprehensive measurements throughout the three space missions that lasted 28, 59 and 84 days. Each of the missions involved three human beings on board of the spacecrafts. The most significant input of these space missions was in proving the fact that humans could survive and work within space for many months.

The former USSR's space station as well as the American Spaceship gave experiences to the subsequent generation on human beings' survival within space. The Spaceship thus allowed frequent opportunities to carry out investigations aiming at fostering a widened understanding of adaptations of humans in space. Gravity Sir Isaac Newton came up with the universal laws of gravity as well as those of motion that form the foundation for knowledge of spaceflight as well as planetary motion.

As thus, a given object of a given mass on the Earth's surface accelerates towards the Earth's centre at a speed of about 9.8m/sec2. Such acceleration is, known as 1-G. A spaceship orbiting round the Earth generates centrifugal acceleration, which counteracts the gravitational acceleration of the Earth present at its mass centre. Therefore the spaceship is in a "free" fall round the Earth as the two contrasting forces of acceleration give rise to the resultant forces of gravity, which from 10-3 to 10-6G.

Gravity falls by approximately 10% at the altitude of low Earth orbit, however the most significant reality is that acceleration of gravity is essentially, annulled by the centrifugal acceleration. Weight remains as the factor that drives several chemical, biological, as well as ecological processes on the Earth's surface. Given these evidence, it is safe to conclude that lack of gravity can produce significant changes to life even though it is a weak physical force of nature (Roger B., 2003).

The effects of microgravity on human physiology Various severe patho-physiological alterations take place when astronauts go into space. These alterations entail redistribution of fluids, raised glomerular filtration, changes in neurotransmission, deconditioning of the cardiovascular system, deterioration of the bones, muscle wasting, as well as impairment of the immune system. Adequate counteraction of the pathophysiological changes through nutrition as well as performance of physical exercises is usually impossible. This strongly indicates that the changes arise as due to extra mechanisms with a molecular basis.

As such, an in-depth understanding of the implications of microgravity on human physiology remains essential (National Aeronautics and Space Administration, 2008) Several pathways involved in metabolism as well as signal transduction undergo alteration in environments with microgravity thus causing changes the functions of cells especially cellular proliferation, cellular differentiation, cellular maturation, as well as survival of the resultant cells. Recently, the levels of mRNA became the backbone of studies related to the regulatory effects of the genes within the cells during their acclimatization to environments with microgravity.

This study is a review of recent milestones that identify changes in the genetic makeup as well as expression of proteins in muscle cells, bone cells, immune cells, as well as the nerve cells when subjected to microgravity environments (Roger H., 2006). Physiological changes during a space flight Protection of human beings from unbearable environments calls for knowledge in the fundamental physiologic modifications arising from such exposure as well as the medical risk degree coupled to that exposure.

Regardless of the fact that considerable limitations, like operational challenges, making use of countermeasures, as well as wide variability between subjects, humans can adapt effectively and function efficiently in space provided adequate medical assistance is, accorded. The main problem during space missions revolves around the harmful consequences of weightlessness exerted on the body of human beings.

The effects comprise of a reduction in the density of bones; muscles mass as well as the red blood cells, shifting of body fluids from the lower compartments to the uppermost body compartments, cardiovascular as well as deconditioning of the sensory-motor system, and immune system alterations (National Aeronautics and Space Administration, 2006). Following the four decades of experience by humans in spaceflights, various countermeasures have, been advanced. These measures include saline "loading," pharmacological manipulations as well as resistance training, and intermittent venous pooling (with lower body negative pressure, LBNP).

Despite the wide range of in-flight exercises, many astronauts experience challenges associated with orientation, balance, faintness as well as a bone fractures, and muscle tears following the initial days subsequent to their landing (Sunny, 2008). The effects of microgravity on the human body Weightlessness is the main significant and the most apparent impact of gravity on the life human beings in space.

Though the feeling of being free from gravity is thrilling, especially when one adapts to the novel environment, weightlessness has enormous complications on man's activities of daily living such as sleeping and eating. Space adaptation entails complex short-term as well as long-term human body alterations. These modifications may cause health related problems while in space, or upon return to Earth (Buckey, 2006). The ubiquitous gravity shapes the process of evolution of all the biological systems present on the Earth's surface.

Growth and development, function, structure, orientation as well as motion take the advantage of the forces of gravity. Remarkable structural alterations take place in the absence of gravity. Notably, astronauts are taller during flights and the posture assumed in weightlessness is akin to that of a fetus in-utero. Shifting of body fluids further corroborate the inevitable effects that arise because of weightlessness (Buckey, 2006). Existing evidence suggests cellular-level modifications within the tissues of the body.

Some endocrine as well as metabolic changes observed during a flight occur in relation to the alterations in the process of mechano-transduction within the body when there is no or minimal force of gravity. Despite the fact that weightlessness remains the key factor contributing towards the observable physiological modifications, other contributing factors also do exist. Launching as well as re-entry into the atmosphere of the Earth involves contact to increasing G-forces as well as vibrations, which may confer distinct physiological influences (Douglas & Pickering, 2008).

The Vestibular System The sense of balance is, pegged upon a complex sensory system, which provides a continuous flow of data to the central nervous system. Motion sensors are mainly composed of the vestibular system situated in the innermost ear. In cases of lack of gravity, the signals arising from the vestibular system as well as the proprioceptors are very misleading.

Consequently, immediate disorientation takes place: several astronauts abruptly feel themselves being in an upside-down position, for instance, or even experience difficulties in feeling where their arms, and legs are located (Clement, 2007). This kind of disorientation mainly triggers Space Motion Syndrome (SMS), which as described by Wryly, is "a fancy term for throwing up." Most space travelers experience SMS that manifests through headaches, poor concentration, and nausea as well as vomiting. However, these problems subside within a matter of days as the astronauts begin to adapt to the surroundings.

Vision is the principal source of balancing information because of the assumption of the confusing impulses sent by the inner ear to the brain. On reentry into the Earth's atmosphere, many astronauts experience challenges in maintenance of balance. Due to the impacts of weightlessness exerted on the bones as well as the muscles, it may be very difficult to stand at all. This disorientation usually lasts a short period of time, after which no long-term impacts are experienced. The CNS' plasticity helps astronauts in adapting to alterations in sensory stimuli.

Contact with low gravity re-orientates the existing relationships among the signals from the vestibular, vision, joints, and skin as well as muscle receptors (Buckey, 2006). Unless acquisition of some adaptation to the new sensory states experienced in this weightlessness surrounding of the spaceflight takes place, individuals experience illusory self or surrounding motions, SMS, impairment of coordination of the eye and the head, and disturbances in the control of equilibrium. The same disturbances are, experienced during the re-adaptation period after returning to the Earth's surface.

For proper orientation in space, astronauts rely on the interplay of the entire sensory system (Chertok, 2005). Orientation in space Spatial orientation refers to the association instituted between the external frame of reference, and the body. It comes from integration of the sensory signals from all the relevant inputs, and from comparing them with the motor-command signals emanating from the brain. In a weightlessness environment, the otoliths are no longer able to carry out their usual function of graviception.

Consequently, visual as well as proprioception information becomes very significant in establishment of spatial orientation within a weightlessness environment (Buckey, 2006). According to figure 1, the interpretation of the gravireceptor signals received from the otoliths is as linear motion. Figure 1 With the aspect of spatial orientation, visual as well as proprioception information becomes very significant in establishment of spatial orientation within a weightlessness environment In regions with microgravity, the CNS reinterprets signals arising from the otoliths.

Following the return to the Earth, the CNS interprets signals from otoliths as emanating from translational movements of the head, instead of combining those movements of the head together with altitude changes with a vertical reference. Following a flight, the detection threshold for linear acceleration tends to change. At the same time, visual effects on orientation tend to be stronger than they were prior to the flight. Tilting head movements may trigger a sense of abrupt linear translation into the contrary direction.

Moreover, various perceptual changes are, reported commonly, and they include a heaviness feeling, disorientation upon making quick movements of the head, an impaired ability of moving in a dark environment as well as illusions of a moving floor during vertical movements of the body (Clement, 2007). Figure 2 The picture is an indication of the mechanisms responsible for the alterations in osteoblastic activity mainly regulates the involved transcription factors.

Lack of stimulation to activate several parts of that comprise the musculoskeletal system in an environment of microgravity arises from the inevitable absence of biological needs Space Adaptation Syndrome (SAS) and Space Motion Sickness (SMS) Approximately 67% of astronauts as well as cosmonauts who enter space become subjects of Space Adaptation Syndrome (SAS). This condition sets in during the initial weightlessness days, but occasionally follows a return to the surface of the Earth. The main symptoms include dizziness, cold, headache, sweating as well as nausea, fatigue, and vomiting.

The consequences of SMS include discomfort, incapacitation, and creation of potential problems on reentry as well as upon emergency exits from spaceships. SAS arises from conflicting sensory information from the visual as well as tactile senses with that from vestibular system (Chertok, 2005). The effects of radiations on astronauts in space Space presents conditions of radiation that can never be, experienced elsewhere. These conditions are not uniform but are, influenced by parameters such as the sun's activity, geographical latitude, and altitude. Evidence obtained from previous space missions.