Movement
, or
motion
, is the
state
of changing something's
position
or changing where something is. A
bird
that is flying is
moving
. So is a
person
who is walking. This is, because they change where they are. They "move" from one place to another. There are many forms of
science
and
mathematics
that are related to movement.
Because of the work of
scientists
including
Galilei
and
Newton
, we know that
position
is
relative
. This means that an object's position depends on where it exists in relation to other objects. For example, a ball can be 5 ft (150 cm) away from a
box
, 3 ft (91 cm) from a
chair
and 1 ft (30 cm)away from a
table
. Here, the box, chair and the table helped to define the position of the ball. They acted as the reference points for the observation of the ball. By telling someone how far the ball was from other objects, they were told its relative position.
The motion of an object is also relative. It depends on how its position changes in relation to other objects. For example:
A person is sitting inside a train (Train A). The train has not started moving yet. When that person looks out the window, they see another train (Train B) . Both trains are facing the same direction. If Train B moves backwards, it appears to the person on Train A that they are moving toward Train B. If a reference point it added this can be changed. If the person can also see a pole next to the trains they will see that train A did not move and train B moved backwards.
From this, it is shown that what the movement is can not bo known without a frame of reference. In this example the pole is the frame of reference.
The study of motion without considering its cause is called
kinematics
. Kinematics deals with terms like
speed
,
velocity
, and
acceleration
.
Dynamics
is the branch of
physics
that focuses on the causes and effects of motion. It deals with
force
,
inertia
,
work
,
energy
and
momentum
.
The movement of
animals
is controlled by the
nervous system
, especially the
brain
and
spinal cord
.
The
muscles
that control the
eye
are driven by the
optic tectum
in the midbrain. All the
voluntary muscles
in the body are controlled by
motor neurons
in the
spinal cord
and
hindbrain
.
[1]
Spinal motor neurons are controlled by neural circuits of the spinal cord, and by inputs from the brain. The spinal circuits do many
reflex
responses, and also do rhythmic movements such as walking or swimming. The descending connections from the brain give more sophisticated control.
[1]
The brain has several areas that project directly to the spinal cord. At the highest level is the
primary motor cortex
. This is a strip of
tissue
at the back of the
frontal lobe
. This tissue sends a massive projection directly to the spinal cord, through the
pyramidal tract
. This allows for precise voluntary control of the fine details of movements. There are other brain areas which affect movement. Among the most important secondary areas are the
premotor cortex
,
basal ganglia
, and
cerebellum
.
[1]
In addition, the brain and spinal cord controls the
autonomic nervous system
. this system works by secreting
hormones
and by modulating the "smooth" muscles of the gut.
[1]
The autonomic nervous system affects
heart rate
,
digestion
,
respiration
rate,
salivation
,
perspiration
,
urination
,
sexual arousal
and several other processes. Most of its functions are not under direct voluntary control. Several of them, such as respiration, can be controlled directly as well.
- ↑
1.0
1.1
1.2
1.3
1.4
1.5
Kandel, Eric R; Schwartz, James Harris & Jessell, Thomas M. 2000.
Principles of neural science
. New York: McGraw-Hill.
ISBN
978-0-8385-7701-1
[]
- ↑
Dafny, N.
"Anatomy of the spinal cord"
. Neuroscience Online. Archived from
the original
on 2011-10-08
. Retrieved
2011-10-10
.
- ↑
Dragoi, V.
"Ocular motor system"
. Neuroscience Online. Archived from
the original
on 2011-11-17
. Retrieved
2011-10-10
.
- ↑
Gurney, K; Prescott, TJ; Wickens, JR; Redgrave, P (2004).
"Computational models of the basal ganglia: from robots to membranes"
.
Trends in Neurosciences
.
27
(8): 453?459.
doi
:
10.1016/j.tins.2004.06.003
.
PMID
15271492
.
S2CID
2148363
.
- ↑
Shima, K; Tanji, J (1998).
"Both supplementary and presupplementary motor areas are crucial for the temporal organization of multiple movements"
.
Journal of Neurophysiology
.
80
(6): 3247?3260.
doi
:
10.1152/jn.1998.80.6.3247
.
PMID
9862919
. Archived from
the original
on 2021-05-09
. Retrieved
2022-01-10
.
- ↑
Miller, EK; Cohen, JD (2001). "An integrative theory of prefrontal cortex function".
Annual Review of Neuroscience
.
24
(1): 167?202.
doi
:
10.1146/annurev.neuro.24.1.167
.
PMID
11283309
.