The second manned mission of the Chinese space station
That is, Shenzhou XIII
After 183 days in space
Returned today and successfully landed at the Dongfeng landing field
The 3 astronauts were in good physical condition
The Shenzhou XIII manned mission was a complete success
Astronaut Zhai Zhigang exited the capsule safely
Wang Yaping, who picked the stars, is back
Astronaut Ye Guangfu exited the capsule safely
What are the effects of long-term space travel on an astronaut's body? What measures can medical staff do to help astronauts get back to health?
01 Effects on the skeletal system
Astronauts who have been in a weightless state for a long time will inevitably change their bone structure and function and affect the health of astronauts, and cosmic rays and other unknown factors may also affect bone metabolism. So let's look at these two aspects specifically.
Weightlessness and bone mass loss
The space station is located 393 kilometers above the ground, still within the gravity range of the Earth, but with the blessing of the first cosmic speed, the space station orbits the earth at a speed of about 7.9 km / s, thus creating a weightless environment. Astronauts live in a weightless environment for a long time, and the muscles of the body will atrophy and the bone will be lost.
When humans live on earth, many parts of the muscles will be stretched for a long time, such as the back and legs. However, when astronauts are in the weightless environment of the space station, they no longer need to maintain a "standing position", and the muscles in the back and legs no longer have to fight against gravity.
And they don't have to move the animal body with much force, which will cause the astronaut's muscle tissue to deteriorate. The data shows that after astronauts enter space, they will lose 20% of their muscles in 5 to 11 days. Second, bone growth requires stimulation by external forces, and when muscles contract or expand, bones are subjected to squeezing or torsional stress, which stimulates the growth of bone tissue to reduce the risk of fracture. During this process, the bones are remodeled, achieving a dynamic balance between bone resorption and bone formation.
However, the stress on the bones in the weightless environment is greatly reduced, disrupting this balance, which causes astronauts to lose 1.5% of bone tissue per month, the largest loss of which is the pelvis and lower spine.
Shenzhou 13 docked with the four-cabin (ship) combination configuration behind the Tiangong space station
Effects of cosmic rays on bone health
At an altitude of about 400 kilometers from the ground, it is a high vacuum, strong radiation environment. Although the space station shell shields almost all of the cosmic radiation, when solar radiation and high-energy cosmic rays collide with the space station shell, a large number of secondary particles will also be released, entering the space station and causing damage to astronauts.
The method of mechanical vibration is a measure to prevent osteoporosis. In addition, different types of low-frequency electromagnetic fields have the effect of combating osteoporosis after weightlessness and are safe and reliable. Electromagnetic fields have been developed in many types, including low-frequency pulsed electromagnetic fields and sinusoidal alternating electromagnetic fields, which are widely used in research due to their significant efficacy.
02 Cardiovascular effects
Weightlessness, ionizing radiation, claustrophobic environments and circadian rhythm disturbances are important threats to health from spaceflight. Among them, the change of cardiovascular function caused by weightlessness is the primary factor affecting the health and work efficiency of astronauts.
Poor neutral endurance, reduced exercise capacity, and remodeling of the structure and function of the heart and blood vessels are important manifestations of the dysfunction of the cardiovascular system caused by long-term spaceflight, which is not only one of the limiting factors for the astronaut's extravehicular activities, but also poses a potential threat to the emergency exit capability immediately upon return to the ground.
Fluid transfer
Fluid transfer is the most important driving factor for changes in the circulatory system during space flight. After the body enters the microgravity environment, as the gravity and hydrostatic pressure disappear, the cross-wall pressure distribution and local blood flow of each part of the artery change, resulting in rapid transfer and redistribution of body fluids.
There are two main ways of fluid transfer caused by microgravity, one is that the body fluids of the lower limbs and abdomen are transferred to the center and head, and about 2 liters of body fluids are transferred from the lower body to the upper body; the other is that the intravenous pressure and capillary fluid static pressure in the upper part of the body increase, and the body fluids are transferred from the inside of the capillaries to the outside of the blood vessels.
Fluid transfer and pressure changes will affect fluid volume and cardiovascular structure and function. Compared with the ground position, the transfer of blood to the center in the early stages of spaceflight leads to an increase in cardiopulmonary blood volume, and the amount of strokes and cardiac output are significantly increased.
In addition, after entering the weightless state, due to the lack of the normal confluence mechanism produced by gravity confrontation, bodily fluids rush to the brain, and astronauts will have a swelling of the head.
Wang Yaping standing on a robotic arm
Changes in the structure and function of the heart
Weightlessness and simulated weightlessness caused by cardiac structural remodeling and/or mass alteration have been reported in humans and mice. The mechanism of cardiac atrophy due to long-term weightlessness is not fully understood, and may be related to adaptive changes in the volume and stress load of the heart due to reduced gravitational load, reduced physical activity and reduced metabolic demand.
Heart atrophy, volume reduction, long-term decline in the amount of blood return to the heart together led to the weakening of cardiac reserve capacity, coupled with skeletal muscle atrophy, thereby affecting the astronauts' athletic ability and work efficiency.
Vascular remodeling and dysfunction
In the state of microgravity, the disappearance of hydrostatic pressure causes different changes in the internal pressure of blood vessels in different parts of the human body, resulting in corresponding adaptive structural remodeling and functional changes. Studies have shown that spaceflight increases the thickness of the median membrane in the carotid arteries of astronauts.
Changes in heart rhythm and cardiovascular regulation
Weightless cardiovascular dysfunction involves multiple aspects of system regulation, and volume reduction, decreased sensitivity to carotid sinus baroreceptors, increased venous compliance in the lower extremities, and muscle atrophy are all involved in its occurrence, and these adverse effects may be more serious as astronauts extend their flight time in orbit.
For the protection of cardiovascular dysfunction caused by weightlessness, the measures currently used mainly include active exercise, auxiliary equipment protection, drug protection and pre-flight adaptation training.
In 2013, Wang Yaping gave his first space lecture
The "three-step" strategy of manned spaceflight has taken a solid step
China's aerospace industry has entered the era of the space station
Pass the national space laboratory through the space station
Medical staff and related scientific and technological workers
We can work together on some major medical issues
Thumbs up for the Space Trio
Shenzhou 13 crew astronauts group photo, from left Ye Guangfu, Zhai Zhigang, Wang Yaping
EDIT: Wen Knife
This article is edited from: Fruit Shell, Tadpole Stave
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