8 – OUR SKELETAL
AND THE SKIN
Q 1 Fill in the blanks.
Ans 1) The place where two or more bones are connected in
called a joint.
2) Cells of the epidermis contain a pigment called melanin.
3) Epidermis and dermis are the two layers of the human skin
4) The human skeletal system is divided into two parts
Q. 2. Match the pairs.
Ans 1) Ball and socket joint - Shoulder
2) Hinge joint - Knee
3) Gliding Joint - Wrist
Q. 3. What will
happen if ......
(1) There are no joints in our body.
Ans. If there are no joints in our body, we will not be able
to move. The bones cannot Show movements without joints
(2) There is no melanin pigment in our skin.
Ans. If there is no melanin pigment in the skin, our skin
will look absolutely white The harmful ultraviolet rays of the sun will damage
our internal organs due to absence of melanin. Melanin gives characteristic hues
of colour and glow to our body, this will not be seen in the absence of melanin
(3) Instead of 33 vertebrae in our body we have one single
and straight bone
Ans. Due to individually joined vertebrae we are able to
move, bend, walk, sit and we in any possible way. But if all the vertebrae are
replaced by just one continuous bone we will not be able to perform all these
movements.
Q 4 Put a mark
at the proper places! (Note: Answers are given directly)
1)
The system which gives a definite
shape to our body.
Excretory
system Respiratory
system
√ Skeletal
system Circulatory
system
2)
The ____________Joint is seen in
fingers and toes
√ Hinge
joint Ball
and socket joint
Immovable
joint Gliding joint
3)
The layer of skin below the network
of blood vessels and nerve fibres is called___________.
Epidermis Dermis
√ Subcutaneous
layer Glandular
layer
4) The main
function of sweat is to ______________________
√ Reduce the body temperature Keep the skin moist
Remove the
excess water Making
the body hot
Q. 5. Answer the following questions in your own words:
(1) What are the functions of your
skin ?
Ans. Functions of the skin: (1) Skin protects the internal
parts of the body, such as bones, muscles, organ systems, etc. (2) Skin helps
to preserve the moisture in the body.(3) Synthetic of vitamin D is done by the
skin in the presence of sunlight. (4) Skin helps to regulate the body
temperature by realising sweat, (5) protection of body during heat or cold is
done by the skin by regulation of body temperature. (6) The skin is one of the
sensory organs which helps in sensation of touch.
(2) What should you do to keep your bones strong and healthy?
Ans For keeping the bones strong and healthy we need to the proper diet.The
diet should contain Vitamin D and minerals like calcium and phosphorus. For
obtaining these nutrients, milk, milk products, fruits green leafy vegetables,
eggs and meat should be
consumed regularly. Regular exercise, walking, cycling, etc.
will keep the bones strong.
(3)What are the functions of the human skeletal system?
Ans . (1)Bones
support the body.(2) The Shape is given
by the bones (3) Internal and vital organs are protected due to bones.(4)
Movements of the body are possible due to bones and cartilages which are
attached to muscles. (5) Minerals like calcium and phosphorus are stored inside the bones.
(4) Which are the various reasons due to which our bones
might break?
Ans. Bones may break due to accidents and injuries Falling
from height or impact of hard object upon colliding can easily break the bones.
The fracture can also occur during playing carelessly in old age, the bones
become brittle due to lack of calcium and other nutrients. In such cases, there
is more chance of having fractures.
(5) What are the different types of bones? How many types
are there?
Ans. There are four main types of bones according to their
shapes. They are (1) flat bones (2) Irregular bones 131 Small bones (4) Long
bones
Q 6 Right or
wrong? If wrong , write the correct sentence.
(1)
Bones are soft. (Wrong) Bones are hard.
(2)
The human skeleton protects the
internal organs. (Right)
(3)
All the bones of the body from the
skeletal system. (Wrong) All the bones
of the body along with cartilages from the skeletal system.
