Overview of Human Physiology in Space

Focus 1	Focus 2	Focus 3	Focus 4	Focus 5	Focus 6	Focus 7

Spacelab	Cardio- vascular System	Blood Components	Fluid Regulation	Muscular System	Skeletal System	Human Sensory & Balance System

Human Physiology in Space
Illustrations in the book were done by Howard Bartner. Bartner's work is featured on the National Institutes of Health page in an exhibit entitled "The Ultimate Portrait Painter: Howard Bartner and Forty Years of Medical Illustration." (NIH's Online Museum)

Focus 1 Space as a Laboratory for the Life Sciences

Spacelab, a reusable laboratory module inside the space shuttle, has provided space life scientists with a more regular opportunity to conduct experiments aimed at a deeper understanding of the human body. Certain dedicated missions have been designed to look more completely at the human and animal physiology. These missions have sought to determine, in detail, how space flight influences living things, so that the health and productivity of space travelers can be maintained and so that lessons in medicine and physiology learned in space can be transferred back to Earth to enrich all our lives.

Focus 2 Examining the Effects of Space Flight on the Heart, Lungs, and Blood Vessels

Scientists do not yet have enough data from space to tell exactly what causes the cardiovascular system to change during space flight. However, there is plenty of evidence to tell that it does change the way it operates, even on a short journey into space. This Focus examines an actual space flight investigation which flew in both the SLS-1 mission and the SLS-2 mission and was designed to examine how the operation of the cardiovascular system is changed in space when astronauts are at rest and when they are exercising. Prior to this investigation, a review is included covering the normal functions of the heart, lungs, and blood vessels as they exist on Earth.

Focus 3 Examining the Effects of Space Flight on Blood and its Components

Examination of the blood begins by looking at its various components and then focusing in on how the red blood cells are produced and destroyed in our bodies. Following an investigation designed by Dr. Clarence Alfrey, the principal investigator, the Focus examines how blood is affected by space flight and, more specifically, how red blood cell activity changes in space.

Focus 4 Examining the Effects of Space Flight on the Fluid Regulating Systems of the Body

On Earth, gravity affects the distribution of fluids inside the body by pulling the various body fluids down towards the feet. Upon entry into space, the virtual absence of gravity causes these fluids to redistribute upwards towards the chest and the head. This perceived increase in fluid volume in the upper part of the body causes multiple physiologic changes in the kidneys and associated fluid-regulating hormones, in the cardiovascular system, and in the red blood system. The Focus examines how your kidneys, working with certain hormones, adapt to space flight and regulate the levels of fluids and electrolytes in the body.

Focus 5 Examining the Effects of Space Flight on the Muscles

It is believed that astronaut's muscles weaken while in space because they do not have to use them as they normally would on Earth. When the astronauts return home, they experience gravity as much more of a force to reckon with than they had ever noticed before. This Focus starts with a description of the structure and mechanical action of muscles. It then looks at the chemical activities that take place in the muscles to assure that they receive the appropriate levels of energy to keep us moving. And finally, it illustrates an important space study that was carried out to see how and why the muscles of astronauts can change their very character as they adapt to the new environment of space where the natural gravitational pull is absent.

Focus 6 Examining the Effects of Space Flight on the Skeletal System

In the microgravity of outer space, the musculoskeletal system is used less intensively and in a different way than it is on Earth. The absence of gravitational force results in changes to load-bearing tissues, causing a reduction of bone and muscle. This Focus examines how muscle and bone losses contribute to a reduced fitness of astronauts when they return to Earth. In addition, the Focus examines a particular space flight experiment that was carried out to look at how bone formation and calcium metabolism change in microgravity.

Focus 7 Examining the Effects of Space Flight on the Human Sensory and Balance System

Our brain and overall nervous system work together to provide us with the direction, guidance, and impulses necessary to move about and function day to day. In this Focus, the influence of gravity on the sensory and balance centers within our brains is discussed. A space flight investigation, designed to learn more about the major effects on our senses and perceptions that result from the removal of gravity, is outlined.

Front Cover

		*Human Physiology in Space* Illustrations in the book were done by Howard Bartner. Bartner's work is featured on the National Institutes of Health page in an exhibit entitled "The Ultimate Portrait Painter: Howard Bartner and Forty Years of Medical Illustration." (NIH's Online Museum)

Focus 1		Space as a Laboratory for the Life Sciences
		Spacelab, a reusable laboratory module inside the space shuttle, has provided space life scientists with a more regular opportunity to conduct experiments aimed at a deeper understanding of the human body. Certain dedicated missions have been designed to look more completely at the human and animal physiology. These missions have sought to determine, in detail, how space flight influences living things, so that the health and productivity of space travelers can be maintained and so that lessons in medicine and physiology learned in space can be transferred back to Earth to enrich all our lives.

Focus 2		Examining the Effects of Space Flight on the Heart, Lungs, and Blood Vessels
		Scientists do not yet have enough data from space to tell exactly what causes the cardiovascular system to change during space flight. However, there is plenty of evidence to tell that it does change the way it operates, even on a short journey into space. This Focus examines an actual space flight investigation which flew in both the SLS-1 mission and the SLS-2 mission and was designed to examine how the operation of the cardiovascular system is changed in space when astronauts are at rest and when they are exercising. Prior to this investigation, a review is included covering the normal functions of the heart, lungs, and blood vessels as they exist on Earth.

Focus 3		Examining the Effects of Space Flight on Blood and its Components
		Examination of the blood begins by looking at its various components and then focusing in on how the red blood cells are produced and destroyed in our bodies. Following an investigation designed by Dr. Clarence Alfrey, the principal investigator, the Focus examines how blood is affected by space flight and, more specifically, how red blood cell activity changes in space.

Focus 4		Examining the Effects of Space Flight on the Fluid Regulating Systems of the Body
		On Earth, gravity affects the distribution of fluids inside the body by pulling the various body fluids down towards the feet. Upon entry into space, the virtual absence of gravity causes these fluids to redistribute upwards towards the chest and the head. This perceived increase in fluid volume in the upper part of the body causes multiple physiologic changes in the kidneys and associated fluid-regulating hormones, in the cardiovascular system, and in the red blood system. The Focus examines how your kidneys, working with certain hormones, adapt to space flight and regulate the levels of fluids and electrolytes in the body.

Focus 5		Examining the Effects of Space Flight on the Muscles
		It is believed that astronaut's muscles weaken while in space because they do not have to use them as they normally would on Earth. When the astronauts return home, they experience gravity as much more of a force to reckon with than they had ever noticed before. This Focus starts with a description of the structure and mechanical action of muscles. It then looks at the chemical activities that take place in the muscles to assure that they receive the appropriate levels of energy to keep us moving. And finally, it illustrates an important space study that was carried out to see how and why the muscles of astronauts can change their very character as they adapt to the new environment of space where the natural gravitational pull is absent.

Focus 6		Examining the Effects of Space Flight on the Skeletal System
		In the microgravity of outer space, the musculoskeletal system is used less intensively and in a different way than it is on Earth. The absence of gravitational force results in changes to load-bearing tissues, causing a reduction of bone and muscle. This Focus examines how muscle and bone losses contribute to a reduced fitness of astronauts when they return to Earth. In addition, the Focus examines a particular space flight experiment that was carried out to look at how bone formation and calcium metabolism change in microgravity.

Focus 7		Examining the Effects of Space Flight on the Human Sensory and Balance System
		Our brain and overall nervous system work together to provide us with the direction, guidance, and impulses necessary to move about and function day to day. In this Focus, the influence of gravity on the sensory and balance centers within our brains is discussed. A space flight investigation, designed to learn more about the major effects on our senses and perceptions that result from the removal of gravity, is outlined.