The H

um

an in S

pace:

Altera

tions in H

um

an P

hysio

logy

Cla

rence F

. Sam

s, Ph.D

.

NASA/J

SC

Cardiovascular

↑ resting heart rate

↑ stroke volume early in flight

↑PACs & PVCs

↓ fluid volume

↓ orthostatic tolerance

↓ aerobic & anaerobic capacity

↓ resting blood pressure postflight

↓ central venous pressure (indirect)

↓ cardio/thoracic (CK) ratio postflight

Ocular

↑ intraocular pressure in flight

↑retinal blood vessel constriction

postflight

↓visual motor task performance

↓ contrast discrimination

↓ visual field postflight

↓ intraocular pressure postflight

Neurosensory

↑ vestibular disturbances

↑ space motion sickness

early in flight

↓ postural stability

↓ sensorimotor function

Body Fluids

↑ hemoglobin & hematocrit

postflight

↓ total body water

↓ plasma & urine volumes

postflight

Electrolytes

↑ urinary Ca, PO4postflight

↓ plasma K & Mg postflight

↓ urinary Na, K, Cl, Mg

Hormones

↑ plasma ADH, ANF

↑ urinary aldosterone

↑ urinary ADH, cortisol postflight

↓ urinary epinephrine,

androsterone postflight

↓ plasma ACTH, aldosterone,

cortisol

Metabolites

↑ plasma glucose, creatinine, BUN

postflight

↓ albumin, cholesterol,

triglycerides, uric acid

Musculoskeletal/Bone

↓ muscle mass

↓ muscle endurance & strength

↓ bone mineral content

↓ bone integrityAdaptations to Long-Duration Space Flight

Impacts

of Physio

logic

al Adapta

tion

•Space flig

ht-in

duced c

hanges c

an

affect opera

tions d

uring flig

ht or

cre

w function u

pon retu

rn to E

arth

•N

om

inal or contingency retu

rn a

nd

egre

ss

•Functional opera

tions c

apabili

ty (E

VA

,

etc

)

•R

apid

retu

rn to function in terrestria

l

gra

vity

•They m

ay a

lso b

e d

ele

terious to

long term

cre

w h

ealth

•These facto

rs m

ust be thoro

ughly

unders

tood a

nd m

itig

ate

d w

here

possib

le in o

rder to

manage

mis

sio

n a

nd c

rew

health ris

ks

Specific

Space-P

hysio

logy D

iscip

lines for

Today's

Briefing

•Bone

•Neuro

vestibula

r

•Nutritio

n

•Im

munolo

gy

BO

NE ISSU

E F

OR

SPAC

EFLIG

HT

•Weakenin

g o

f th

e b

ones d

ue to the

pro

gre

ssiv

e loss o

f bone m

ass is a

pote

ntially

serious s

ide-e

ffect of exte

nded s

paceflig

ht

•Stu

die

s o

f cosm

onauts

and a

stronauts

who

spent m

any m

onth

s o

n s

pace s

tation M

ir

reveale

d that space tra

vele

rs c

an lose (on

avera

ge) 1 to 2

perc

ent of bone m

ass e

ach

month

•Spacefa

rers

typic

ally

experience b

one loss in

the low

er halv

es o

f th

eir b

odie

s, partic

ula

rly in

the lum

bar vertebra

e a

nd the leg b

ones.

•Dim

inis

hin

g b

one m

ass a

lso triggers

a ris

e in

calc

ium

excre

tion in u

rine, w

hic

h c

an incre

ase

the ris

k o

f kid

ney s

tones.

•Bones a

re d

ynam

ic liv

ing tis

sues that consta

ntly reshape them

selv

es in response to

the s

tresses p

laced o

n them

•Tw

o c

ell

types, "o

ste

obla

sts

" and "oste

ocla

sts

" are

consta

ntly b

uild

ing o

r destroyin

g

bone. U

sually

these a

ctions b

ala

nce e

ach o

ther out.

What is

wro

ng?

•In p

rolo

nged w

eig

htlessness,

bone m

ass d

ecre

ases b

ecause

the lack o

f stress o

n the b

ones

alters

the b

ala

nce b

etw

een b

one

resorp

tion a

nd b

one form

ation.

•This

altere

d b

ala

nce favors

resorp

tion a

nd results in a

net

loss o

f bone m

ass.

Blo

od b

iochem

ical m

ark

ers

of bone m

eta

bolism

:

Used to e

stim

ate

rate

of bone loss, bone m

eta

bolis

m

Suggestth

at b

one d

egra

dation is incre

ased, fo

rmation is u

ncouple

d

from

resorp

tion.

Bone R

esorp

tion

Bone F

orm

ation

Overv

iew

of BM

D

-25

-20

-15

-10-505

10

0300

600

900

1200

1500

Days-A

fter-

Landin

g

BMD deficit (% Loss)

Tro

chante

r BM

D o

f IS

S &

Mir C

rew

mem

bers

Tro

chante

r BM

D o

f IS

S &

Mir C

rew

mem

bers

Loss0=7.4

%Loss0=7.4

%R

ecovery

Half

Recovery

Half-- life=276 d

life=276 d

Cortical Bone/ “Compact Bone”

PROXIMAL FEMUR

VERTEBRAL BODY

Cancellous “Spongy”Bone/Trabecular Bone

Trochanter

Femoral

Neck

Med o

ps takin

g s

evera

l actions b

ased o

n

these fin

din

gs:

Aggre

ssiv

e u

se o

f on-o

rbit c

ounte

rmeasure

s

Follo

win

g c

rew

for lo

nger post-flig

ht w

ith

DX

A a

nd Q

CT

Develo

pin

g a

strate

gy for FE

A m

odelin

g to

dete

rmin

e s

trength

levels

Further re

searc

h c

olla

bora

tions to d

ete

rmin

e

long term

fra

ctu

re ris

ks

•O

vera

ll bone loss rate

s o

f 1-

1.5

% p

er m

onth

in w

t bearing

bones

•Tra

becula

r bone loses m

inera

l

sig

nific

antly faste

r th

an the

cortic

al bone (appro

x 2

X)

•O

vera

ll bone d

ensity s

low

to

recover

•R

ecovere

d s

tructu

re n

ot th

e

sam

e a

s o

rigin

al and m

ay

have less tota

l strength

9

Centr

al N

erv

ous S

yste

m Inte

gra

tes

Multip

le S

ensory

Inputs

to C

ontr

ol M

ovem

ent

Sensorim

oto

r D

istu

rbances O

ccur D

uring

and A

fter G

-tra

nsitio

ns

10

Pla

neta

ry S

urf

ace

Op

era

tio

ns

Eart

h P

os

tfli

gh

tE

art

h P

refl

igh

t

Tra

nsit

Tra

nsit

OP

ER

AT

ION

AL

IM

PA

CT

:V

ehic

le c

ontr

ol

Vehic

le e

gre

ss

Pla

neta

ry E

VA

s

ISS

UE

S:

Postu

ral and g

ait insta

bili

ty

Vis

ual perf

orm

ance c

hanges

Manual contr

ol dis

ruptions

Spatial dis

orienta

tion

Motion s

ickness

G-t

ran

sit

ion

s

G-t

ran

sit

ion

s

Fu

ncti

on

al M

ob

ilit

y T

est

Data

: E

valu

ate

s L

oco

-mo

tor

co

ntr

ol

Time to Complete Course

Reco

ve

ry o

f fu

ncti

on

al m

ob

ilit

y t

o 9

5%

of

pre

flig

ht

level

too

k 1

5 d

ays.

N = 18

Mu

lava

ra A

P,

Fe

ive

son

A,

Fe

idle

r J,

Cohen

HS

, P

ete

rs B

T,

Mill

er

CA

, B

rad

y R

,

Blo

om

be

rg J

J.

Exp

erim

en

tal B

rain

Re

sea

rch.

202

(3):

64

9-5

9.

2010

.

Sensorimotor Countermeasures

Tra

inin

g for in

congru

ent stim

uli

–th

e b

rain

can learn

to

better to

lera

te m

ixed C

NS s

ignals

(A) Adapta

bili

ty T

rain

ing:

Enhance a

bili

ty to a

dapt to

novel gra

vitational

environm

ents

(B) Sensory

Supple

menta

tion:

Use a

ltern

ate

sourc

es o

f

sensory

info

rmation to p

rovid

e

feedback d

uring a

daptive

phases.

(C) Artific

ial G

ravity:

Short radiu

s, in

term

itte

nt exposure

Bone

Muscle

Card

io

Flu

id/E

lectr

oly

te

Imm

unolo

gy

Hem

ato

logy

Neuro

vestibula

r

Endocrine

GI

BH

P

Vis

ion

Energ

y

CH

O (fiber)

, Fat, P

rote

in

Fat-solu

ble

vitam

ins

Wate

r-solu

ble

vitam

ins

Min

era

ls

Flu

id

Systems

Energ

y

Am

ino a

cid

s

Pro

tein

Sodiu

m

Fatty a

cid

s

Antioxid

ants

Oth

er

Bis

phosphonate

s

KC

itra

te

Oth

er M

eds

Exerc

ise

Oth

er

Dura

tion

Food S

yste

m

Radia

tion

EV

A

Schedule

Vehicle/Mission

Space N

utr

itio

n

Nutrient

Requirements

Countermeasures

Nutr

itio

n is c

ritical fo

r any type o

f explo

ration m

issio

n, and is

multifacete

d.

Die

tary

Inta

ke

Main

tain

ing d

ieta

ry inta

ke d

uring flight is

very

im

port

ant. In

adequate

inta

kes a

re

associa

ted w

ith g

reate

r bone a

nd m

uscle

loss, altere

d c

ard

iovascula

r

perf

orm

ance, and o

ther health ris

ks. Inta

ke for IS

S c

rew

mem

bers

is tra

cked w

ith

a c

om

pute

r-based F

ood F

requency Q

uestionnaire (above).

Omega-3 Fatty Acids

Fis

h inta

ke is a

ssocia

ted w

ith low

er bone loss. Fis

h, and o

mega-3

fatty a

cid

s in

part

icula

r, m

ay m

itig

ate

bone a

nd m

uscle

loss, card

iovascula

r, a

nd c

ancer risks.

Vitam

in D

Vitam

in D

inta

ke is c

ritical fo

r astr

onauts

, w

here

the food s

yste

m d

oes n

ot pro

vid

e

adequate

am

ounts

, and the c

rew

s a

re s

hie

lded fro

m u

ltra

vio

let light.

Supple

menta

tion w

ith 8

00 IU

vit D

/day m

ain

tain

s s

tatu

s d

uring flight (left p

anel).

Anta

rctic s

tudie

s s

how

vitam

in D

, str

ess, and v

iral re

activation

are

inte

rrela

ted.

•One o

f la

rger tissues in the h

um

an b

ody

and e

xis

ts in a

hig

hly

dis

trib

ute

d s

tate

.

•Consis

ts p

rim

arily

of w

hite b

lood c

ells

(WBC

s) lo

cate

d in lym

ph n

odes a

nd the

periphera

l blo

od.

•Responsib

le for pro

tection a

gain

st viral

and b

acte

rial in

fection, la

tent viral

reactivation, tu

mor surv

eillance, w

ound

healin

g, etc

.

•Dysre

gula

tion c

an result in incre

ased

infe

ction rate

, m

alig

nancy, auto

imm

unity,

alle

rgy, etc

.

TH

E IM

MU

NE

SY

STE

M

Hu

mo

ral

imm

un

ity

-Im

mu

niz

ati

on

wit

h a

nti

ge

n

ge

ne

rate

s n

orm

al a

nti

bo

dy

resp

on

se d

uri

ng

fli

gh

t

(MIR

-18

)

Po

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lig

ht

ob

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ati

on

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ere

d c

ircu

lati

ng

le

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te

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uti

on

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ion

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tte

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ted

, in

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cell

ula

r,

Th

1/T

h2

)

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http://www.nasa.gov/exploration/humanresearch/

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