Chapter 8 – Our Skeletal System and the Skin
1. Fill in the blanks with the proper word.
(a) The place where two or more bones are connected is called a ________.
Ans: joint
(b) Cells of the epidermis contain a pigment called ________.
Ans: melanin
(c) ________ and ________ are the two layers of the human skin.
Ans: Epidermis, dermis
(d) The human skeletal system is divided into ________ parts.
Ans: two
2. Match the pairs.
| ‘A’ | ‘B’ |
|---|---|
(1) Ball and socket joint | (a) Knee |
(2) Hinge joint | (b) Wrist |
(3) Gliding joint | (c) Shoulder |
Ans:
| ‘A’ | ‘B’ |
|---|---|
(1) Ball and socket joint | (c) Shoulder |
(2) Hinge joint | (a) Knee |
(3) Gliding joint | (b) Wrist |
3. Right or wrong? If wrong, write the correct sentence.
(a) Bones are soft.
Ans: Wrong
Reason: Bones are hard.
(b) The human skeleton protects the internal organs.
Ans: True
4. Put a ✓ mark at the proper places.
(a) The system which gives a definite shape to our body.
Excretory system
Respiratory system
Skeletal system
Circulatory system
Ans: Skeletal system
(b) The ……………. joint is seen in fingers and toes.
Hinge joint
Ball and socket joint
Immovable joint
Gliding joint
Ans: Hinge joint
5. Answer the following questions in your words.
(a) What are the functions of your skin?
Ans: Functions of skin are;
(1) Skin protects the internal parts of the body, such as bones, muscles, organ systems, etc.
(2) The skin helps preserve the moisture in the body.
3) The synthesis of vitamin D is done by the skin in the presence of sunlight.
(4) The skin helps regulate the body’s temperature by releasing sweat.
(5) Protection of the body during heat or cold is done by the skin through regulation of body temperature.
(6) The skin is one of the sensory organs that helps with the sensation of touch.
(b) What should you do to keep your bones strong and healthy?
Ans: To keep the bones strong and healthy, we need to eat a proper diet. The diet should contain vitamin D and minerals like calcium and phosphorus. To obtain the nutrients, milk, milk products, fruits, green leafy vegetables, eggs, and meat should be consumed regularly. Regular exercise, such as walking, cycling, etc., will keep the bones strong.
(c) 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 by bones.
(4) Movements of the body are possible due to bones and cartilage, which are attached to muscles.
(5) Minerals like calcium and phosphorus are stored inside the bones.
(d) Which are the various reasons due to which our bones might break?
Ans: Bones may break due to accidents and injuries. Falling from a height or the impact of a hard object upon colliding can easily break the bones. The fracture can also occur while playing carelessly. In old age, the bones become brittle due to a lack of calcium and other nutrients. In such cases, there is a higher chance of fractures.
(e) 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
(3) Small bones
(4) Long bones
6. What will happen if?
(a) 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.
(b) There is no melanin pigment in our skin.
Ans: If there is no melanin pigment in the skin, it will look absolutely white. The harmful ultraviolet rays of the sun will damage our internal organs due to the absence of melanin. Melanin gives characteristic hues of colour and glow to our body; this will not be seen in the absence of melanin.
(c) Instead of 33 vertebrae in our body, we had one single and straight bone.
Ans: Due to individually joined vertebrae, we are able to move, bend, walk, sit, and work 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.
7. Draw diagrams.
(a) Types of joints
Ans:
(b) Structure of the skin
Ans:
