Chapter: 02. The Human Body
Answer the following.
I like the touch of soft blankets. I love the sight of a clear night sky with stars. I do not like to hear loud, screeching noises. I like the taste of sweet fruit. I love the smell of freshly baked cookies. Describe three activities that you perform using your senses at school.
Seeing (Eyes): Reading a book, watching the teacher write on the board, or drawing pictures. Hearing (Ears): Listening to the teacher’s instructions, hearing friends talk during recess, or listening to music in class. Touching/Feeling (Skin): Feeling the texture of different art supplies, touching a rough tree bark outside, or feeling the smooth surface of a desk. Smelling (Nose): Smelling the lunch from the cafeteria, sniffing markers for art projects, or noticing the scent of new books. Tasting (Tongue): Tasting snacks during break time, trying different fruits in a school activity, or sipping water from a bottle. Think!
A newborn baby has about 305 bones. Then how does an adult have 206 bones? Think!
A newborn baby has more bones than an adult because some of their bones are separate at birth. As the baby grows, some of these smaller bones fuse (join together) to form larger, stronger bones. This fusing process is complete by adulthood, resulting in fewer total bones. Quick check 1
Stomach : Food :: Kidneys : Urine Blood Vessels :: Lungs : Air Bones : Hard :: Muscles : Soft 206 : Bones :: 600 : Muscles Brain : Think :: Stomach : Digest Quick Check 2
Lungs are located on the left side of the chest cavity. False (Lungs are sponge-like, cone-shaped structures that fill most of the chest cavity, meaning both sides, not just the left.) Carbon dioxide is inhaled during breathing. False (Oxygen is inhaled; carbon dioxide is exhaled.) The diaphragm contracts during deep breathing. Fumes from car exhausts cause air pollution. Ozone layer is present in water. False (The ozone layer is present in the atmosphere.) Run-Through
I. Very Short Answer Questions
A. Tick the correct answer.
Many similar ________ join together to form tissues. ‘Megha can see a rocket in the sky.’ Which sense organ does Megha use here? The brain is protected by the ________. Which of the following is the smallest building block in the human body? The process of breathing out is called ________. B. Match the following.
Exhaled air - f. Carbon dioxide Ribs - a. Protect the heart and lungs Lungs - c. Two; For breathing Diaphragm - b. Muscle below lungs C. Label the diagram given below.
D. Complete the concept map.
Windpipe: Carries air to lungs Lungs: Provide oxygen from inhaled air to bloodstream and exhale carbon dioxide. II. Short Answer Questions
Name the five sense organs. The five sense organs are eyes, ears, nose, tongue, and skin. A cell is the smallest unit or building block of our body. How do kidneys help in removing waste from our body? Kidneys help in removing waste from our body by filtering waste products from the blood and producing urine. The urine is then carried by ureters to the bladder and passed out. Unjumble the given letters and define the terms: STOMACH: A J-shaped bag where food is churned and mixed with digestive juices. URETER: A tube that carries urine from the kidneys to the bladder. DIAPHRAGM: A muscle located below the lungs that helps in breathing by contracting downwards during inhalation and moving upwards during exhalation. SKELETON: The framework of bones that gives shape and support to our body. DEEP BREATHING: A breathing exercise that helps in complete exchange of gases, done by contracting the diaphragm. DIGESTION: The process by which food is broken down into substances that can be absorbed by the body for energy. III. Long Answer Questions
Draw a well-labelled diagram of the human respiratory system. A well-labelled diagram of the human respiratory system should include: Nose, Windpipe (Trachea), Lungs (left and right), and Diaphragm. Arrows indicating airflow (inhalation and exhalation) would also be helpful. With the help of an activity, explain how we inhale and exhale air. The chapter describes an activity using a plastic bottle, straw, and balloons. Model Setup: A plastic bottle with the bottom cut off, a balloon tied over the cut bottom (representing the diaphragm), and another balloon inside the bottle attached to a straw that goes through the bottle’s neck and is sealed with play dough (representing lungs and windpipe). Inhalation: When the balloon at the bottom (diaphragm) is pulled downwards, it creates more space inside the bottle (chest cavity). This causes air from outside to rush in through the straw (windpipe) and inflate the balloon inside (lungs). Exhalation: When the balloon at the bottom is released and moves upwards, the space inside the bottle decreases. This pushes the air out of the balloon (lungs) through the straw (windpipe), causing it to deflate. This demonstrates how the diaphragm’s movement changes the chest cavity size, causing air to move in and out of the lungs. What are the roles of the stomach and intestines in digestion? Stomach: The stomach is a J-shaped muscular organ. Its role is to churn the food received from the food pipe and mix it thoroughly with digestive juices. This process further breaks down the food. Small Intestine: After the stomach, food moves to the small intestine. Here, it is further digested by intestinal juices, and most importantly, the nutrients from the digested food are absorbed by the blood. Large Intestine: The undigested food then goes to the large intestine. Its role is to absorb any extra water present in the undigested food before it is eliminated from the body as faeces. Bones: Bones are hard parts of the body. They form the skeleton, providing shape, support, and protection to internal organs. An adult human has 206 bones. Muscles: Muscles are soft parts of the body that cover the bones. They help the bones to move. There are more than 600 muscles in the human body. Stomach: The stomach is part of the digestive system. It is a J-shaped organ located in the chest cavity, responsible for churning food and mixing it with digestive juices to break it down. Kidneys: Kidneys are part of the excretory system. We have two kidneys that filter waste from the blood and produce urine. c. Inhalation and exhalation Inhalation: Inhalation is the process of breathing in. During inhalation, oxygen-rich air is taken into the lungs, and the diaphragm contracts and moves downwards. Exhalation: Exhalation is the process of breathing out. During exhalation, carbon dioxide-rich air is released from the lungs, and the diaphragm moves upwards. Heart: The heart is a hollow muscular organ located in the chest cavity. Its primary function is to pump blood throughout the body via blood vessels. Brain: The brain is an organ located inside the skull. It is the control center of the body, responsible for thinking, processing information, and sending instructions to different body parts. List any two causes and effects of air pollution. Factories and industries releasing smoke and harmful gases. Burning garbage and bursting crackers. Fumes from car exhausts containing dangerous gases. Effects of Air Pollution: Makes people sick, causing breathing difficulties and leading to lung cancer, respiratory diseases, and heart diseases. Can trigger asthmatic attacks. Can damage the ozone layer in the atmosphere. IV. Challenge
Puneet often complains of pain in legs and arms. His mother keeps telling him to play and exercise daily. Why do you think she asks him to do physical activities daily? Discuss. Puneet’s mother likely asks him to play and exercise daily to strengthen his bones and muscles. Regular physical activity helps build strong bones, improves muscle flexibility and strength, and enhances blood circulation. This can reduce pain in his legs and arms, improve his overall physical health, and make his body more resilient. Lack of activity can lead to stiff joints and weak muscles, contributing to discomfort. Hema has a habit of burning old newspapers. The neighbours suggested her not to do so. Instead, she should sell it to the scrap dealer. Is the suggestion correct? Discuss. Yes, the suggestion is correct. Burning old newspapers releases smoke and harmful gases into the atmosphere, contributing to air pollution. This polluted air is harmful to humans, animals, and plants, causing respiratory problems and other health issues. Selling old newspapers to a scrap dealer, on the other hand, allows them to be recycled. Recycling reduces waste, conserves natural resources (like trees), and prevents harmful emissions, thus being much better for the environment and public health. V. Enrichment
A. Slogan Writing: Van Mahotsav
Task: Write a slogan for the theme ‘Van Mahotsav’ on a chart paper. “Plant a tree, plant a hope!” “Trees: The air we breathe, the life we need.” “Go Green, Live Clean: Celebrate Van Mahotsav!” B. Project: Model Making
Task: Make a model of a skeleton. Prepare cutouts of various bones and arrange them as shown in the picture. Description: This activity involves creating a visual representation of the human skeleton. Students would need to cut out shapes resembling bones (e.g., skull, ribs, limb bones, pelvis) from paper, cardboard, or other materials and then assemble them in the correct anatomical arrangement to form a complete skeleton. Science Quest
Which is the largest bone in the human body? The largest bone in the human body is the Femur (thigh bone). What do we call a doctor who treats conditions related to bones and muscles? A doctor who treats conditions related to bones and muscles is called an Orthopedist (or Orthopaedic Surgeon). Can we move our elbow in all directions? Why/Why not? No, we cannot move our elbow in all directions. The elbow is a hinge joint, which primarily allows movement in one plane, like a door hinge (bending and straightening). It allows us to flex (bend) and extend (straighten) our arm, but it does not allow for full rotational movement like a ball-and-socket joint (e.g., shoulder). Riddle Time!
ALVEOLI are tiny air sacs in our lungs. The human heart has the same size as our FIST. Windpipe is also called TRACHEA. Tiny hair that keep mucus and dirt out of our lungs are called CILIA. As we breathe in, the DIAPHRAGM contracts and flattens to give the lungs room to fill up with air. SMOG is formed from smoke and fog. Picture Survey
1. What does the picture show?
The picture shows an industrial area or city with many factories and buildings, emitting smoke from chimneys and with what appears to be polluted water or waste in the foreground.
2. Do you think people living in such a place will be healthy? Why/Why not?
No, people living in such a place are unlikely to be healthy.
Why not?
The heavy industrial activity and visible pollution suggest poor air quality due to smoke and emissions, which can lead to respiratory problems and other health issues. The presence of what appears to be waste or polluted water also indicates potential contamination of water sources and the environment, posing further health risks. 
Answers to textbook exercises
