PARKINSONISM
r e l e a s e m
o r e P T H
( s e e
f e e d b a c k ).
T h i s
r e s p o n s e
c a u s e s
t h e
b o n e s
t o
r e l e a s e
m o r e
c a l c i u m
i n t o
t h e
b l o o d ,
t h e
i n t e s t i n e s
t o
a b s o r b
m o r e f r o m
f o o d ,
a n d t h e k i d n e y s t o c o n s e r v e c a l c i u m ; a s
a r e s u l t , c a l c i u m l e v e l s r i s e r a p i d l y . I f t h e
b l o o d l e v e l o f c a l c i u m i s t o o h i g h , t h e
g l a n d s r e d u c e t h e i r o u t p u t o f P T H .
S o m e p e o p l e h a v e o n l y o n e p a r a t h y -
r o i d g l a n d o r h a v e e x t r a g l a n d s i n t h e
n e c k
o r
c h e s t .
R a r e l y , t h e
p a r a t h y r o i d
g l a n d s m a y b e c o m e o v e r a c t i v e ( a c o n d i -
t i o n c a l l e d
h y p e rp a ra t h y ro id is m ),
w h i c h
c a u s e s e r o s i o n o f t h e b o n e s a n d s t o n e s
i n t h e k i d n e y s , u r e t e r s , o r b l a d d e r
( s e e
c a lc u lu s , u r in a r y tra c t).
A l t e r n a t i v e l y ,
t h e
g l a n d s
m a y
b e c o m
e
u n d e r a c t i v e
( s e e
h y p o p a ra t h y ro id is m
) ,
r e s u l t i n g
i n
te ta n y
( p a i n f u l m u s c l e s p a s m s ) o r
s e iz u re s .
p a ra th y ro id tu m o u r
A g r o w t h w i t h i n a
p a ra t h y ro id g la n d . T h e
t u m o u r m a y c a u s e e x c e s s s e c r e t i o n o f
p a r a t h y r o i d h o r m o n e ( P T H ) , l e a d i n g t o
h y p e rp a ra th y ro id is m .
P a r a t h y r o i d c a n c e r s
a r e v e r y r a r e ; m o s t p a r a t h y r o i d t u m o u r s
a r e n o n c a n c e r o u s
a d e n o m a s .
A n a d e n o -
m a
t h a t
c a u s e s
h y p e r p a r a t h y r o i d i s m
w i l l b e s u r g i c a l l y r e m o v e d ( s e e
p a ra th y -
r o id e c to m y ).
T h i s u s u a l l y p r o v i d e s a c u r e .
p a ra ty p h o id fe v e r
A n i l l n e s s i d e n t i c a l i n m o s t r e s p e c t s t o
t y p h o id f e v e r,
e x c e p t t h a t i t i s c a u s e d b y a
d i f f e r e n t b a c t e r i u m ,
S
a l m o n e l l a
pa ra typ h i,
a n d i s u s u a l l y l e s s s e v e r e .
p a ra u m b ilic a l h e rn ia
A
h e rn ia
o c c u r r i n g
n e a r
t h e
n a v e l
.
P a r a u m b i l i c a l h e r n i a s m a y o c c u r i n o b e s e
w o m e n w h o h a v e h a d s e v e r a l c h i l d r e n .
p a re n c h y m a
T h e f u n c t i o n a l ( a s o p p o s e d t o s u p p o r t -
i n g ) t i s s u e o f a n o r g a n .
p a re n te ra l
T h e
a d m i n i s t r a t i o n
o f d r u g s
o r
o t h e r
s u b s t a n c e s b y a n y r o u t e o t h e r t h a n v i a
t h e g a s t r o i n t e s t i n a l t r a c t
( f o r e x a m p l e ,
b y i n j e c t i o n i n t o a b l o o d v e s s e l ) .
p a re n te ra l n u tritio n
I n t r a v e n o u s f e e d i n g ( s e e
fe e d in g , a rtific ia l).
p a re s is
P a r t i a l
p a r a ly s is
o r
w e a k n e s s
a f f e c t i n g
o n e o r m
o r e m u s c l e s .
p a rie ta l
A m e d i c a l t e r m t h a t i s u s e d t o r e f e r t o
t h e w a l l o f a p a r t o f t h e b o d y .
p a rity
A t e r m u s e d t o i n d i c a t e t h e n u m b e r o f
p r e g n a n c i e s
a
w o m a n
h a s
u n d e r g o n e
t h a t h a v e r e s u l t e d i n t h e b i r t h o f a b a b y
c a p a b l e o f s u r v i v a l .
p a rk in s o n is m
A n y n e u r o l o g i c a l d i s o r d e r t h a t i s c h a r -
a c t e r i z e d b y
t re m o r
( t y p i c a l l y , t h i s i s a
“ p i l l - r o l l i n g ”
t r e m o r ,
w h i c h
o c c u r s
w h e n
t h e
t h u m b
i s
r u b b e d
o v e r
t h e
i n d e x
f i n g e r ) ;
s l o w
m o v e m e n t s ;
a n d
r i g i d i t y . T h e o t h e r c h a r a c t e r i s t i c f e a t u r e s
o f t h e d i s o r d e r o f p a r k i n s o n i s m r e s u l t
f r o m t h e s l o w n e s s o f m o v e m e n t . T h e s e
f e a t u r e s i n c l u d e a m a s k l i k e f a c e , a
fe s ti-
n a tin g g a it
( a s h u f f l i n g , u n b a l a n c e d s t y l e
o f
w a l k i n g ) ,
a
m o n o t o n o u s
s t y l e
o f
s p e e c h , a n d r e d u c e d b l i n k i n g . T h e m o s t
c o m
m o n t y p e o f p a r k i n s o n i s m i s k n o w n
a s
P a r k in s o n ’s d is e a s e .
T h e
k n o w n
c a u s e s
o f p a r k i n s o n i s m
i n c l u d e
c e re b ro v a s c u la r d is e a s e
( p r o b -
l e m s i n v o l v i n g t h e b l o o d v e s s e l s i n t h e
b r a i n ) ; t h e u s e o f
a n tip s y c h o t ic d ru g s ,
o r
t h e a b u s e o f c e r t a i n
d e s ig n e r d r u g s
;
c a r -
b o n m o n o x id e
p o i s o n i n g ; a n d , r a r e l y , t h e
i n f e c t i o n
e n c e p h a lit is le th a rg ic a .
CAUSE OF PARKINSON’S DISEASE
This disorder results from damage, of unknown origin, to the basal ganglia (nerve
cell clusters in the brain). The difference between the healthy state and that of
Parkinson’s disease is shown in the diagrams below.
B a s a l
g a n g l i a
M o t o r
c o r t e x
B a s a l
g a n g l i a
M o t o r
c o r t e x
Controlled muscle activity
Increased muscle tension
and tremor
Healthy state
During movement, signals pass from the brain’s
cortex, via the reticular formation and spinal
cord (pathwayA), to muscles, which contract.
Other signals pass, by pathway B, to the basal
ganglia; these damp the signals in pathwayA,
reducing muscle tone so that movement is not
jerky. Dopamine, a nerve transmitter made in
the basal ganglia, is needed for this damping
effect. Another transmitter, acetylcholine,
inhibits the damping effect.
Parkinson’s disease
In Parkinson’s disease, degeneration of parts
ofthe basal ganglia causes a lack of dopamine
within this part ofthe brain. The basal ganglia
are thus prevented from modifying the nerve
pathways that control muscle contraction.
As a result, the muscles are too tense, causing
tremor, joint rigidity, and slow movement.
Most drug treatments increase the level of
dopamine in the brain or oppose the action
of acetylcholine.
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