All
information from our environment is detected by the specialised tips of some
nerve cells. Gustatory receptors will detect taste while olfactory receptors
will detect smell.
the
process of detecting the signal or the input and responding to it by an output
action might be completed quickly. Such a connection is commonly called a
reflex arc
Nerves
from all over the body meet in a bundle in the spinal cord on their way to the
brain. Reflex arcs are formed in this spinal cord itself, although the
information input also goes on to reach the brain.
The
communication between the central nervous system and the other parts of the
body is facilitated by the peripheral nervous system consisting of cranial
nerves arising from the brain and spinal nerves arising from the spinal cord.
There
is another set of muscle movements over which we do not Have any thinking
control. Many of these involuntary actions are Controlled by the mid-brain and
hind-brain. All these involuntary actions Including blood pressure, salivation
and vomiting are controlled by the Medulla in the hind-brain.
Cerebellum
is responsible for precision of voluntary actions and maintaining the posture
and balance of the body.
Muscle
cells have special proteins that change both their shape and their arrangement
in the cell in response to nervous electrical impulses. When this happens, new
arrangements of these proteins give the muscle cells a shorter form.
Some
plants like the pea plant climb up other plants or fences by means of tendrils.
The
upward and downward growth of shoots and roots, respectively, in response to
the pull of earth or gravity is, obviously, geotropism
gibberellins
which, like auxins, help in the growth of the stem. Cytokinins promote cell
division, Abscisic acid is one example of a hormone which inhibits growth. Its
effects include wilting of leaves.
Iodine
is necessary for the thyroid gland to make thyroxin hormone. Thyroxin regulates
carbohydrate, protein and fat metabolism in the body so as to provide the best
balance for growth. Iodine is essential for the synthesis of thyroxin. In case
iodine is deficient in our diet, there is a possibility that we might suffer
from goitre. One of the symptoms in this disease is a swollen neck.
Next Topic:-Science Class 10 NCERT Textbook- Lesson-8
Next Topic:-Science Class 10 NCERT Textbook- Lesson-8
