Our body has a supporting frame work made of bones. This
frame work is known as skeleton. It is the skeleton which
gives the body its firmness. Without- the skeleton our body
will be as supple as that of a worm. There is another great
advantage of the skeleton. It protects some of the most
delicate parts of the human body form external injury. Thus
the brain is kept safe in a bony box. This box safeguards
the heart and the lungs. Also by its very nature of
formation, it helps body movement with the help of muscles
attached to it. The main parts of the skeleton are the skull
and the spinal column.
An example of this kind of joint is the
movement of the wrist. At the wrist there are a number of
small boned which glide one over the other, when we turn our
palm upwards or downwards.
When a part is capable of making an
all round movement ?up and down and sideways- this is
possible by a joint of this kind. The leg can be moved in
any direction, sideways, up and down
The place of attachment between two or more bones is known
as a joint. All the joints of the body are capable of
movement except for the joints of the bones of cranium,
which houses the brain.
There are various kinds of movable
joints depending upon the movements they perform. Thus the
knee joint is like a hinge, which allows the lower keg to
move up or down, but not sideways. Following are different
kinds of joints
3. Ball and socket joint
4. Gliding joint
(1)Hinge- joint :-This allows the movement of the part of
body in one direction ?up or sown but not sideways. Example
of this joint are knee-joint, elbow-joint, movement of the
(2)Pivot joint :-As the name suggests, this kind of joint
permits pivotal movement of the parts of body this joined.
Movement of the skull is an example. A man can turn his head
from one side to the other by rotating the skull, which is
joined to the backbone at its top in such a way that a
pivotal movements is possible
(1) To regulate body temperature. The skin which is exposed
to the cooling action of the air outside, plays an important
part in regulating the loss of heat and maintaining uniform
temperature of body. This is dine by the mechanism if
dilation and contraction of superficial blood vessels and by
the evaporation of water from the body surface. In fact
this function if the skin can be compared to that of the
radiator of a car
(2)To act as a sense organ. Pain heat, pressure, cold,
touch, etc.. are all felt by the skin and conveyed to the brain
(3)To protect internal organs against external injury and
infection. Many an injury is limited to the skin. But for
skin, our bones would be cracking too often. In fact this
function of the skin can be compared to that of the radiator
of a car.
(4)To eliminate waste products through sweat glands
(5)To protect the body form harmful rays of the sun by means
of pigments of the outer skin
Skin plays an important part in a man?s life. It makes his
appearance attractive. He gets a distinctive appearance
because of his skin. There are race conflicts because of the
colour of the skin.
There covering if the human body. Is known
as the skin. Two layers of akin cover the body. The lower
layer known as dermis is made up of fibrous tissues having
blood vessels , glands, hair follicles, sweat glands, etc.
It is very essential that the skin is kept clean. Dust and
dirt collect on the skin and become mixed with salts and
the scales of the outer skin. They thus from fertile soil
for the growth of germs.
Lungs are the principal organs of respiration.Ty lie in thoracic cavity. Right lung is 3-lobed and left lung two-lobed. The cone shaped space between two lungs is called mediastinum. Each lung is covered by a two-layered membrane. Its outer membrane is called parietal pleura and inner visceral pleura. The space between these two membranes is called pleural cavity which is filed with a serous fluid. This fluid lubricates the lungs and protects them from friction.
Each bronchus enters the lungs of its side. The right bronchus gives up four branches while the left has two.Inside each lung these branches go on ramifying till a bronchial tree is formed. The terminal bronchioles open into a space called vestibule which gives rise to one to three respiratory bronchioles. The wall of respiratory bronchioles form thin walled sac-like alveoli.
The wind pipe, trachea is 10-12cm long and 2.5 compound in diameter. Entering into thoracic cavity trachea divides into the right and left bronchi. The trachea is supported by C-shaped cartilages.
It is the anterior enlarged part of the wind pipe, made of cartilage i.e. thyroid, cricoids. Arytenoids, etc. the enlarged thyroid cartilage is called Adam's apple. A cartilaginous muscular flap, the epiglottis is attached to the top of the thyroid cartilage. It can close the glottis while swallowing food. Vocal cords are stretched between thyroid and arytenoids cartilages. Vibrations of vocal cords produce sound. Rima glottidis is the opening between the cords.