Ch.8: Our Skeletal System and the Skin

Our Skeletal System and the Skin | Class 6 | Science | Chapter 8 | Maharashtra State Board

In this educational video, we'll explore the fascinating world of the human body's skeletal system and skin. First, we'll learn about the bones that make up our skeleton, including their structure, function, and importance. We'll cover topics such as the different types of bones, how bones grow and change over time, and how our skeletal system helps us move and protect our organs. Next, we'll delve into the skin, the largest organ in the human body. We'll discuss its structure and function, including the different layers of skin, how skin protects us from the environment, and how it helps regulate our body temperature. We'll also explore common skin conditions and ways to take care of our skin to keep it healthy and functioning properly. Throughout the video, we'll use engaging visuals and animations to help illustrate complex concepts and make learning about the skeletal system and skin fun and accessible. By the end of this lesson, you'll have a deeper understanding of the incredible systems that make up our bodies and how they work together to keep us healthy and thriving.

Questions & Answers

1. Fill in the blanks with the proper word.

1. The place where two or more bones are connected is 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.

2. Match the pairs.

'A'	Answer	'B'
Ball and socket joint	Shoulder	Knee
Hinge joint	Knee	Wrist
Gliding joint	Wrist	Shoulder

3. Right or wrong? If wrong, write the correct sentence.

(a) Bones are soft.

Ans. Wrong: Bones are hard.

(b) The human skeleton protects the internal organs.

Ans. Right.

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

(b) The _______ joint is seen in fingers and toes.

✅ Hinge joint

⬜ Ball and socket joint

⬜ Immovable joint

⬜ Gliding joint

5. Answer the following questions in your words.

(a) What are the functions of your skin?

Ans. The functions of the skin are:

1. Protects the internal parts of the body like muscles, bones, organ systems etc.

2. Help to preserve the moisture in the body.

3. Synthesizing Vitamin D.

4. Regulates body temperature by releasing sweat.

5. Gives protection from heat and cold.

6. Functions as the sensory organ of touch.

(b) What should you do to keep your bones strong and healthy?

Ans. To keep the bones strong and healthy:

1. We should include calcium and phosphorus rich food in our diet.

2. We also include vitamin D rich food in our diet.

3. We get these from milk, milk products, leafy vegetables, meat and exposure to sunlight.

4. We should exercise regularly.

(c) What are the functions of the human skeletal system?

Ans. The functions of human skeletal system are:

1. Gives a definite shape to the body.

2. Provides support to the body.

3. Protects the delicate organs inside the body.

(d) Which are the various reasons due to which our bones might break?

Ans. The bones in our body might break due to:

1. Lack of calcium and phosphorous.

2. Due to fracture because of an accident or a fall.

3. Lack of proper nutrition.

4. Due to deficiency of Vitamin D.

(e) What are the different types of bones? How many types are there?

Ans. There are four types of bones in our body:

	Types of Bone	Example
1.	Flat bones	Sternum in the chest
2.	Small bones	Stirrup in each ear
3.	Irregular bones	Vertebra posterior (back side) of the body
4.	Long bones	Femur or thigh bone

6. What will happen if-?

(a) There are no joints in our body.

Ans. If there are no joints in our body, we will be standing like a tree without any movement, we can move only because of joints.

(b) There is no melanin pigment in our skin.

Ans. We will not have protection from ultraviolet rays. Our skin will become whitish.

(c) Instead of 33 vertebrae in our body, we had one single and straight bone.

Ans. We cannot bend down at our will.

7. Draw diagrams.

(a) Types of joints:

(b) Structure of the skin:

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E X T R A

1. Fill in the blanks.

1. The skull protects the brain.

2. The bones of skull are immovable.

3. We can move the bones of shoulder in a 360° angle.

4. Our body temperature usually remains constant at 37 °C.

5. The part of the skin which maintains body temperature is Subcutaneous layer .

6. Except for the lower jaw, none of the bones of the skull can move.

7. The spinal cord originates from the brain.

8. The longest and the strongest bone in the human body is femur .

9. Stirrup is the smallest bone in our body.

10. The vertical, flat bone in the chest is called the sternum.

11. The hinge joint moves in a 180° angle.

2. Answer the following.

(a) What is a fracture? How will you help a friend who has met with an accident and fractured his leg?

Ans. Fracture is a crack or break in a bone. Fracture may occur due to accident or fall from height or injury. If my friend’s leg is fractured, then. I would –

1. Ask him to prevent any movement of the fractured part.

2. Get immediate medical help.

3. Take the x-ray image of the fractured or swollen part.

4. An x-ray image shows the exact spot where the bone is broken. This will help in providing proper treatment.

(b) What are the properties of bones?

Ans. The properties of bones are:

1. Bones are hard and not flexible.

2. Bone cells are composed of two main constituents:

• Bone cells are biotic components.

• Calcium carbonate, calcium phosphate, minerals and salts are abiotic components.

3. Calcium imparts strength to bones.

4. As we grow the size and length of bones increases upto a certain limit.

(c) What is human skeletal system? How is it divided?

Ans. All the bones together form a framework or a skeleton.

1. All the bones of the body along with cartilage together form the skeletal system.

2. The human skeletal system can be divided into two parts – the axial skeleton and the appendicular skeleton.

3. The axial skeleton consists of the skull, the spine and the rib cage. These are situated symmetrically along the central axis.

4. The appendicular skeleton consists of the bones of arms and legs on either side of the central axis.

(d) What is a joint? What are it’s types?

Ans. Joints are places where two or more than two bones are connected to each other. There are 3 types of movable joints.

1. Hinge joint : This type of joint allows the movements of bones only in one direction. It moves in a 180-degree angle. Example: the elbow and knee joints.

2. Ball and socket joint: In this type of joint, the bones can move in two or more directions - in a 360-degree angle. Examples: shoulder and hip joints.

3. Gliding joint: In this type of joint, the bones can only slide over each other. Examples: wrist and ankle joints.

(e) Describe the structure of skin.

Ans.

1. Human skin is made up of two main layers- outermost layer, epidermis and layer below it called dermis.

2. Below dermis there is a network of blood vessels and nerve fibers.

3. Under this layer there is a subcutaneous layer, which maintains body temperature.

4. The epidermis has various layers.

5. There are sweat glands in the skin which secrete sweat.

(f) Write a short note on melanin.

Ans.

1. Melanin is a pigment present in the cells of epidermis.

2. Melanin is synthesized in certain glands in the skin.

3. The percentage of melanin decides the fairness or darkness of the skin.

4. Melanin protects our skin and the inner parts from ultraviolet sunrays.

3. Give scientific reasons.

(a) We are able to bend down at our will.

Ans.

1. 33 bones of the spine are placed straight one above the other.

2. They are arranged flexibly.

3. Their flexibility allows us to bend down at our will.

(b) Calcium is an important mineral.

Ans.

1. Calcium imparts strength to our bones.

2. If we are calcium deficient, possibility of bone fracture during a fall or an accident increases.

Hence, calcium is an important mineral.

(c) Sweating helps to lower the body temperature.

Ans.

1. In the hot sun, the temperature of the body rises.

2. The sweat is released.

3. The heat required for the evaporation of sweat is drawn from the body itself.

Hence, sweating lowers the body temperature.

(d) Some people have jet black hair, while others have brown or reddish hair.

Ans.

1. It is melanin that determines the colour of our hair.

2. Jet black hair is due to pure melanin.

3. Brown hair is due to sulphur in the melanin.

4. Reddish hair is due to iron in the melanin.

(e) Grandmother has wrinkles on her skin.

Ans.

1. As we grow older, the proportion of fat beneath the skin reduces.

2. However, previously tout skin does not shrink.

3. This causes wrinkles on the face of older people.

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