MOUTHWASH
M
A m o u t h u l c e r m a y b e a n e a r l y s t a g e o f
m o u t h
c a n c e r
.
T h o s e
t h a t
f a i l
t o
h e a l
w i t h i n a m o n t h m a y n e e d t o b e i n v e s t i -
g a t e d w i t h a
b i o p s y
.
m o u th w a s h
A s o l u t i o n f o r r i n s i n g t h e m o u t h . M a n y
o n l y l e a v e t h e m o u t h f e e l i n g f r e s h a n d
r e m o v e
l o o s e
f o o d
d e b r i s
f r o m
t h e
t e e t h .
S o m e , s u c h
a s
t h o s e
c o n t a i n i n g
h y d r o g e n p e r o x i d e
,
c a n h e l p t o c l e a n t h e
t e e t h i f t h e g u m s a r e t o o t e n d e r f o r p r o p -
e r t o o t h b r u s h i n g , a s i n s o m e t y p e s o f
g i n g i v i t i s
.
T h o s e c o n t a i n i n g
c h l o r h e x i d i n e
a r e e f f e c t i v e a g a i n s t p l a q u e w h e n r o u t i n e
d e n t a l h y g i e n e i s i m p o s s i b l e .
F l u o r i d e
m o u t h w a s h e s h e l p t o p r e v e n t
t o o t h
d e c a y ( s e e
c a r i e s , d e n t a l
) ,
a n d a
m o u t h w a s h o f w a r m s a l t w a t e r c a n h e l p
t o e a s e p a i n f u l i n f l a m m a t i o n c a u s e d b y
t o o t h d i s o r d e r s . A n t i s e p t i c m o u t h w a s h e s
i n t e n d e d t o c o m b a t
h a l i t o s i s
a r e u s u a l l y
i n e f f e c t i v e b e c a u s e t h e y d o n o t t r e a t t h e
c a u s e o f t h e p r o b l e m .
m o v e m e n t
A n y m
o t i o n o f l i m b s o r o t h e r a r e a s o f
t h e b o d y , o r a n y m
o t i o n w i t h i n s o f t t i s -
s u e s a n d b o d y
o r g a n s . A l l m o v e m e n t s
a r e
c a u s e d
b y t h e a c t i o n s
o f m u s c l e s .
T h e y m a y b e e i t h e r v o l u n t a r y ( w i l l e d ) o r
i n v o l u n t a r y ( a u t o m
a t i c ) . C e r t a i n m o v e -
m e n t s o c c u r a s
r e f l e x
a c t i o n s .
SKELETAL MOVEMENTS
T h e s e
m o v e m e n t s
i n v o l v e
t h e
b o n e s ,
t h e
j o i n t s ,
a n d
t h e
s k e l e t a l
m u s c l e s .
M
o s t
o f t h e m
a r e v o l u n t a r y . T h e y a r e
i n i t i a t e d i n a p a r t o f t h e c e r e b r u m ( t h e
m a i n
m a s s
o f
t h e
b r a i n
)
c a l l e d
t h e
m o t o r c o r t e x . S i g n a l s a r e s e n t d o w n t h e
s p i n a l c o r d
a l o n g s o m e n e r v e f i b r e s , a n d ,
f r o m t h e r e , a l o n g s e p a r a t e n e r v e f i b r e s
t o
t h e
a p p r o p r i a t e
m u s c l e s .
C o n t r o l
r e l i e s o n i n f o r m a t i o n s u p p l i e d b y s e n -
s o r y n e r v e
r e c e p t o r s
,
i n t h e m u s c l e s a n d
e l s e w h e r e ,
t h a t r e c o r d t h e p o s i t i o n
o f
d i f f e r e n t b o d y p a r t s a n d t h e d e g r e e o f
c o n t r a c t i o n i n e a c h m u s c l e . T h i s i n f o r -
m a t i o n i s i n t e g r a t e d i n s p e c i f i c r e g i o n s
o f t h e b r a i n ( i n c l u d i n g
t h e
c e r e b e l l u m
a n d
b a s a l g a n g l i a
)
t h a t
c o n t r o l
t h e
c o o r d i n a t i o n ,
i n i t i a t i o n ,
a n d
c e s s a t i o n
o f m o v e m e n t .
S k e l e t a l m o v e m e n t s c a n a l s o o c c u r a s
s i m p l e
r e f l e x e s
i n
r e s p o n s e
t o
c e r t a i n
s e n s o r y w a r n i n g
s i g n a l s . T h e s e
m o v e -
m e n t s a r e a u t o m a t i c a n d l e s s c o n t r o l l e d ,
i n v o l v i n g f a r f e w e r n e r v e c o n n e c t i o n s .
OTHER MOVEMENTS
S o m e b o d y m o v e m e n t s d o n o t i n v o l v e
t h e
s k e l e t o n .
F o r
e x a m p l e ,
e y e
a n d
t o n g u e m o v e m e n t s r e s u l t f r o m t h e c o n -
MOVEMENT
Various movements occur constantly
throughout the body. All movement is
either voluntary (willed) or involuntary
(automatic). Visible movements are
caused by the contraction of skeletal
muscles or eye muscles, usually for
only brief periods at a time.
SKELETAL MOVEMENT
This action involves the
movement of bones relative to
one another, often at the joints.
Many muscles are involved. Some
act to brace certain bones, while
others move adjacent bones.
Arm movements
A ball-and-socket joint, the shoulder
allows combined rotation and
displacement movements in all directions.
Knee movement
A hinge joint, the knee allows movement
(through an arc of about 130°) in only one
plane: forwards or backwards.
EYE MOVEMENT
A group of six muscles act together
on each eyeball to give a range of
smooth, precise movements. The
eyeball can move through an arc of
about 100° horizontally and about
80° vertically.
Eye muscles
The four rectus eye muscles run directly
from the eyeball to a tendon at the back of
the eye socket. The oblique muscles are
attached to the eyeball at an angle.
Looking from
side to side
Looking up
and down
Actions of the eye muscles
Two rectus muscles control side-to-side
movements. The other rectus muscles,
with the oblique muscles, control up-and-
down and rotational movements.
INVOLUNTARY MOVEMENT
Many movements in the body
are involuntary (automatic), and
are regulated by the autonomic
nervous system. One example
of involuntary movement is the
beating of the heart, which
automatically speeds up in
response to increased demands
for oxygenated blood by body
tissues and slows down again
when these demands decrease.
Another example is peristalsis
(see right).
Peristalsis
This is an example of movement caused by
involuntary muscle action. Waves of contraction
pass along muscles in the intestinal wall, forcing
the contents forwards and preventing obstruction.
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