Space

Question 1

• Space in and of itself poses some very unique medical problems due to prolonged exposure to a combination of stressful stimuli, what are 3:
• _______ forces
• Rad….
• Weigh….

-in space biological changes may occur which links microgravity to..

• astronauts on early extended duration missions showed signs of symptoms in aging populations, name 6

Answer 1

• Acceleration forces (static gravitational fields)
• Radiation (no protection of atmosphere, natural shield)
• Weightlessness (reduced for against gravity)
• links between microgravity, disease onset and aging
• negative calcium balance with bone density loss, muscle atrophy, cardiovascular and hematic changes, metabolic, endocrine, and sleep disturbances

Question 2

• The majority of human spaceflights have taken place in low Earth orbit, which occurs how far for ISS and satellites
• Objects in low Earth orbit are subjected to about 90% of the Earth’s ground-level gravity, what counter balances this to make free falling/weightlessness
• what are Astronauts exposed to (2) far higher than those experienced at most locations on Earth

Answer 2

• The International Space Station = 400km away, ,ost satellites operate in low Earth orbit 200-2000km away
• the speed during orbit effectively counterbalances the force of gravity
• Astronauts are exposed to heavy ions and proton fluxes, far higher than those experienced at most locations on Earth

Question 3

• Gravity = crucial factor in fluid distribution and has played an enormous role in shaping the evolution of the cardiovascular system, what is it like on earth (upright vs supine)

In space (and low Earth orbit), this gradient does not occur (no same pull blood to feet)
- substantial reduction in ______ pressure and ______ is redistributed towards the head causes altered responses of what 3 systems

• These MSS arise because changes in gravity alter the sensory input from the _____ system
• which in turn generates a persistent conflict (i.e., mismatch) between expected and actual sensory _____ inputs during active movements

Answer 3

• In an upright posture on earth: Mean BP in the head is ~70 mmHg, heart is ~93 mmHg, feet is ~200 mmHg. In a supine posture; Mean BP for the body is ~93 mmHg
• substantial reduction in intrathoracic pressure and blood is redistributed towards the head causes altered responses of baroreceptor, nervous and endocrine systems (false readings due to increased pooling)
• These motion sickness symptoms arise because changes in gravity alter the sensory input from the vestibular system
• which in turn generates a persistent conflict (i.e., mismatch) between expected and actual sensory vestibular inputs during active movements

Question 4

• Initial hours and days of being exposed to microgravity, his shift in fluids to the head, cause the head and chest to swell as blood is redirected from lower limbs, what is this condition called
• Additionally, in a microgravity environment, large contractility of the heart is not required to send blood where against gravity and to maintain what
• Thus, the heart is atrophied by −__ to −____% after _____ days of spaceflight

Answer 4

• Change is often referred to as “Puffy Head, Chicken Legs” condition (Forehead circumference increased by 7% while tibia circumference decreases by 15%)
• Additionally, in a microgravity environment, large contractility of the heart is not required to send blood toward the head against gravity, and to maintain blood pressure
• Thus, the heart is atrophied by −8 to −10% after 10 days of spaceflight (heart doesn’t pump as hard to fight gravity)

Question 5

• What happens to blood pressure in different parts of body in space
• how do we replicate this one earth at a supine position, what is pressure at feet, heart and head
• As blood is redistributed towards the head during microgravity, these changes are detected by _______
• which activate _____ offloading and ____ _____ regulating reflexes

Answer 5

• 93mmHg all around the body leading chicken legs and puffy face
• 6 degree HDT bed rest position where legs are elevated and head is descending cause blood to pool to the head. feet = 85mmHg, 93mmHg is heart and head is 105mmHg
• As blood is redistributed towards the head during microgravity, these changes are detected by baroreceptors
• activate autonomic offloading and blood volume regulating reflexes

Question 6

• To compensate for the redistribution of blood in the early space exposure period, there is a reduction of what two things and increased _____ production
• in order to compensate for the change in blood volume in what 3 places (location of _____)
• After acclimatization, what happens to blood volume, while MAP and HR are maintained at….
• The Hb reduction reported in astronauts returning from missions 145 days may represent the completed human erythrocytic adaptation, how so

Answer 6

• To compensate for the redistribution of blood in the early space exposure period,
  there is a reduction to HR, reduced level of thirst and increased urine production (kidney trying to decrease fluid volume and relive pressure)
• in order to compensate for the change in blood volume in the head, neck and torso
  (location of baroreceptors)
• After acclimatization, there is a reduced total blood volume (increased hematocrit),
  while MAP and HR are maintained at pre-light levels
• long longer you stay in space the more dramatic the hb change (decrease) in the first 30 days, after a year you end up with positive hb change

Question 7

• Prolonged exposure to microgravity affects the musculoskeletal system, with the loss of what 2 things attributed to what 2 things
• the rate of bone mineral density loss occurring during a 6-month stay on ISS is similar on average to that occurring with someone aging from…on earth
• Bone mineral loss was higher in sites supporting the body weight in normal gravity, like lumbar spine, femoral neck, and trochanter, pelvis, calcaneus, and leg, whereas arm bones were largely unaffected, why?

Answer 7

• Prolonged exposure to microgravity affects the musculoskeletal system, with the
  loss of bone and muscle mass attributed to both reduced use and perfusion changes
• the rate of bone mineral density loss occurring during a 6-month stay on ISS is similar on average to that occurring with someone aging from 50 to 60 on Earth

-During a microgravity environment, humans do not need to support their bodies; thus the antigravity muscles become atrophied (massive unloading)

Question 8

• Muscles are needed for movement and to counteract gravity, and they must be used in
  order to maintain…(2)
• The main cause of muscular loss is the disappearance of mechanical ______ and the subsequent decrease in muscular ______

-These physiological alterations may have a major impact on _____ after injuries, especially in ______ subjects

• Highlighting the need to focus on those muscle groups more prone to _____ loss in response with ____ , what behaviours

Answer 8

• Muscles are needed for movement and to counteract gravity, and they must be used in
  order to maintain the structure and the function
• The main cause of muscular loss is the disappearance of mechanical constraints and the subsequent decrease in muscular activity

-These physiological alterations may have a major impact on rehabilitation after injuries,
especially in aging subjects

• Highlighting the need to focus on those muscle groups more prone to mass loss in response with unloading (sedentary behaviours)

Question 9

• In order to protect and maintain the health and wellness of astronauts, countermeasures designed have been designed to try and simulate Earth-like…..or _______ of gravity
• One of the most important countermeasures for space flight is ___ although consensus regarding the best type of devices and exercise protocols has not yet been reached

Answer 9

• In order to protect and maintain the health and wellness of astronauts, countermeasures designed have been designed to try and simulate Earth-like movements/ stresses or reloading of gravity
• One of the most important countermeasures for space flight is exercise although consensus regarding the best type of devices and exercise protocols has not yet been reached