The Human Body Class 3 Science

• The human body consists of different living and non-living components that together form a living structure that includes a variety of cells, tissues and organs.
• Similar organised cells form tissues that work together to make an organ. Different organs working to do similar functions form organ systems.
• The human body shows specific unique structures that are very essential for the life of any human.

Facts About Human Body

Question 1:

What Are the Main Non-living Components of the Human Body?

Answer:

Non-living components of the body comprise water, gases like oxygen and carbon dioxide, and nutrients like sodium, potassium, iron etc.

Question 2:

What Causes Shivering in a Freezing Environment?

Answer:

• The sensation of shivering arises due to constant contraction and relaxation of muscles.
• It is an action of our body to produce enough heat to bring the body's temperature to an optimum level.

Question 3:

What Causes Bruising?

Answer:

• We get a bump or bruise due to the effect of the tiny blood vessels present below our skin.
• These blood vessels get ruptured and bleed under the skin, leading to a red bruise that slowly darkens and fades away in a few days.

Question 4:

What Is a Stethoscope Used for? The Doctor Places Their Stethoscope on the Chest and Back. They Also Tap the Chest and Back of the Body. Why Do They Do That?

Answer:

• A stethoscope is used to hear the changes in the sound of the heart and lungs.
• They tap the chest and back to check if there is any liquid inside the lungs, as normal lungs are filled only with air; when filled with water, they sound differently.

Body Organs and Their Functioning

Question 1:

When We Are Injured, It Starts Bleeding, but After Some Time, the Bleeding Stops. How Does It Happen?

Answer:

• Blood comprises various cells which perform different functions.
• Platelets in blood help to clot and make a dense covering at the site of injury to reduce the blood loss from our body which may otherwise prove fatal.

Question 2:

When We Touch Our Chest Part, It Feels Hard and Bony, but Why Not the Abdomen Part Feels the Same?

Answer:

• The structure of particular bones protects the chest part (thoracic region) called the rib cage.
• A bony rib cage protects the heart and lungs and allows these organs to contract and relax.
• No such bony structure is present in the abdominal region; hence we do not feel any hardness there.

Question 3:

What Is the Function of the Liver in the Human Body?

Answer:

• The liver plays an essential role in the digestion of fats.
• The blood circulated through the liver undergoes key processes like removing unwanted substances, regulating blood sugar levels, releasing nutrients or enzymes required by the body, e

Question 4:

Why Do Kids Have Less Number of Teeth Than Adults?

Answer:

• Kids start developing their teeth after the age of 7-8 months and develop their primary teeth up to the age of 3 years.
• Until now, the buccal cavity is not big enough to develop other teeth.
• As children grow, the buccal cavity size increases, enabling it to accommodate 32 permanent teeth.

Question 5:

It Does Not Pain When We Brush Our Teeth. Then Why Does It Pain Badly While the Dentist Cleans Them?

Answer:

• Teeth are dead and the hardest part of our body. But like hair and nails, the roots of the teeth are connected to the nervous system and blood vessels.
• When the germs reach the root part of the teeth, we feel pain.
• So, while the dentist cleans the teeth, we feel pain as the instruments reach the root of our teeth, where we can feel sensations.

Question 6:

What Connects Bones and Muscles Together? How Are Bones Attached to the Other Bones?

Answer:

• Bones are attached to the other bones and muscles with the help of connective tissues.
• The ligaments join bones to bones.
• The tendons join muscle to bone.