Shefali was tidying her bookshelf when she came across a flowchart. She took the flowchart to her mother. “Look Mom, I found a chart in my bookshelf. I made it when I was in Grade 3,” said Shefali. “Oh, how lovely!” exclaimed her mother, “Can you tell me what it shows?”
Cells Tissues Organs Organ systems Organisms
“The flowchart shows the levels of organisation in our body.”
Learning Outcomes
• Identify different organs that make up the human circulatory system
• Explain the functions of blood and blood vessels
• Differentiate between the arteries and veins
• Explain the structure and functioning of the heart
• Explain the process of circulation in the human body
• Discuss various ways to keep our heart healthy and strong
Our body is made up of tiny building blocks called cells. We have various types of cells. Cells group together to form a tissue. There are different types of tissues in our body. Tissues group together to make an organ. The brain, heart, kidneys, lungs and stomach are some of the important organs of our body.
A group of organs that work together to perform a specific function form an organ system. There are several organ systems in our body, for example, the digestive system and excretory system. All these organ systems should work properly for the proper functioning of the body.There are many organ systems in our body, such as the skeletal system, circulatory system, muscular system, respiratory system and nervous system. In this chapter, we will learn about the circulatory system.
What helps oxygen, water and nutrients flowing through the body?
We need substances such as nutrients, oxygen and water to survive. These substances are transported to the various parts of our body with the help of a transport system called the circulatory system. The circulation of substances is carried out with the help of a fluid known as blood. The circulatory system also removes waste from our body. For example, carbon dioxide is removed from the body through the blood.
What makes up the circulatory system?
The main parts of circulatory system are blood, blood vessels and heart.
BloodIt is a thick, red-coloured fluid that transports nutrients, oxygen, carbon dioxide and water in our body. It flows through a network of tubes. These tubes are called blood vessels. Blood contributes to nearly eight per cent of our body weight.
Functions of bloodSome important functions of the blood are mentioned below.
• Red blood cells (RBCs), present in the blood, transport oxygen from the lungs to the cells of the body. They also transport carbon dioxide from the body cells to the lungs.
• Blood carries nutrients generated from the digestive system to the body cells.
• Blood helps in transporting waste products to the kidneys.
• Blood helps in adjusting the body temperature.• Blood has the property of turning into a gel-like
substance by clotting, thus preventing excessive loss of blood during an injury.
• The white blood cells (WBCs), present in the blood, protect the body against diseases.
Blood vesselsBlood vessels are hollow muscular tubes through which the blood flows. They are connected to the main organ of the circulatory system called heart. They form a network to transport blood to all the parts of the body. There are three types of blood vessels in our circulatory system—arteries, veins and capillaries.
Structure and functions of blood vesselsLet us study about the structure and functions of blood vessels in our body.
ArteriesArteries carry oxygenated blood from the heart to different parts of the body. The pulmonary artery is an exception, as this artery carries deoxygenated blood from the heart to the lungs. Of the three blood vessels, arteries are the thickest ones. The smaller blood vessels that branch and extend out from the arteries are called arterioles. The largest artery in our body
is aorta. It is the main artery that emerges from the heart. Carotid artery is another important artery that carries blood from the heart to the brain. Arteries are deeply placed inside the skin and are reddish in colour.
VeinsVeins carry deoxygenated blood from different parts of the body to the heart. The pulmonary vein is an exception as it carries oxygenated blood from the lungs to the heart. The small blood vessels that branch and extend out from veins are called venules. The walls of the veins are thinner and less elastic than those of arteries. There are special structures present in veins called valves. The valves allow a one-way flow of the blood towards the heart and prevent it from flowing backward. The major veins in the human body are superior vena cava and inferior vena cava.The superior vena cava transports blood from the upper portion of the body to the heart. The inferior vena cava transports blood from the lower portion of the body to the heart. Veins are placed very close to the surface of the skin and are bluish in colour.
CapillariesCapillaries are extremely thin blood vessels, which connect arteries and veins. They have very thin walls. These are also responsible for the absorption of oxygen, digested soluble food and waste products produced in the body.
Differences between arteries and veins
Arteries Veins• Arteries carry blood to all parts of
the body from the heart.• Veins carry blood from different
parts of the body to the heart.
• Valves are absent. • Valves are present.
• Except the pulmonary artery, they carry oxygenated blood.
• Except the pulmonary vein, they carry deoxygenated blood.
• They are placed very close to the surface of the skin.
• Arteries are reddish in colour. • Veins are bluish in colour.
HeartThe heart is a muscular organ, which is roughly equal to the size of our closed fist. It is located between the lungs, slightly to the left and is well-protected by the ribcage. The main function of the heart is to pump blood into the blood vessels so that the blood keeps moving throughout the body.
Structure of the heartThe heart is shaped like a cone and is triangular. It is divided into four chambers—right auricle, left auricle, right ventricle and left ventricle. The two upper chambers are called auricles or atria and the two lower chambers are called ventricles. The auricles and ventricles of the heart are separated completely so that the blood flowing in them do not get mixed. The left auricle is connected to the left ventricle and the right auricle is connected to the right ventricle, through valves. Valves allow blood flow in one direction only, that is, from auricles to ventricles.
Functions of the heartThe main function of the heart is to pump oxygenated (rich in oxygen) blood through blood vessels and deliver nutrients and oxygen to all the parts of the body.The heart also contains deoxygenated (rich in carbon dioxide) blood, which is received from all parts of the body. The deoxygenated blood is transported to the lungs. In lungs, the blood gets rid of carbon dioxide and takes in oxygen from the air inhaled into the lungs. This oxygen-rich blood is received by the heart from lungs and is pumped to all parts of the body.
Heartbeat and pulseThe heart pumps blood due to its rhythmic movement at an average of 70–72 times per minute. This rhythmic movement of the heart is known as heartbeat. Doctors listen to the sound of the heartbeat using an instrument called the stethoscope. You must have felt a throbbing sensation in some parts of the body, such as the neck or wrist. This sensation of rhythmic pumping of blood through veins and arteries is called pulse. Pulse can be felt at these places in the artery with every heartbeat. The number of heartbeats per minute is called the pulse rate. The average pulse rate of a resting person is between 72 and 80.
Activity 1
Sit in pairs. Check your friend’s pulse rate and heartbeat. Place your middle and index finger on the side that has the thumb of your friend’s wrist. You will feel a pumping or throbbing movement. This is the pulse. Record it. Now stand up and sit down five times. Measure the pulse rate again. Compare the pulse rate before and after the exercise.
Sit in pairs. Check your friend’s pulse rate and heartbeat. Place your middle
Process of circulationThe continuous movement of blood inside the body is called blood circulation. The blood rich in oxygen enters the heart from the lungs. This blood is then pumped to different parts of the body through arteries. It distributes oxygen and collects carbon dioxide from different parts of the body. The gaseous exchange takes place in the capillaries. The blood rich
Stethoscope: steth-uh-skop
Enunciation
ExtraOrdinary MindsOrdinary MindsOrdinary Minds
Dr Christiaan Barnard was South African doctor, who performed the world’s first heart transplant at Groote Schuur Hospital, Cape Town.
in carbon dioxide from different parts of the body reaches the heart through the veins. The heart pumps the impure blood to the lungs. In the lungs, the gaseous exchange takes place through the capillaries, thus converting deoxygenated blood into oxygenated blood. This oxygen-rich blood is then pumped back to the heart and then from the heart, to the other parts of the body.
How can we keep our heart healthy and strong?
The heart is one of the most important organs of our body. It is important to keep it healthy so that our body can function properly. We should follow certain practices regularly to keep our heart healthy.Exercise regularly for at least 30 minutes to keep your body fit and healthy. Always eat a balanced diet containing all the essential nutrients. Avoid eating a lot of oily, fried and junk food. These food items contain fat and can make you obese. People who are obese are at a higher risk of suffering from heart diseases. Restrict your consumption of soft drinks or soda drinks. Avoid sitting for prolonged hours. Do physical exercises such as walking, running, jumping, jogging and cycling. Exercising daily increases the efficiency of the heart. Aerobic exercises increase pumping of the heart, thus supplying oxygenated blood to the muscles. Sleep for at least 7–8 hours daily to give proper rest to your body.Eat food which is good for the heart such as whole grains, oats, avocado, nuts, olive oil, berries, etc. Participate actively in outdoor sports such as cricket, hockey, football, etc.Try to stay away from polluted surroundings. Stay in a hygienic environment. Avoid being around people who smoke cigarettes or bidis. Stay happy and avoid stress.
Yoga—a boon to the heart and body
Yoga plays an important role in keeping our heart and body healthy. It is a system of physical exercises or postures known as asanas. These postures involve a combination of stretching, breathing and meditation. There are
Round-tableRound-table
Discuss how all the parts of the circulatory system are involved in the process of circulation.
many benefits of practicing yoga. Some of them are given below. It helps in maintaining the overall fitness of our body. It helps our body become strong and flexible. It improves our memory and increases concentration. It helps in reducing stress and gives a feeling of well-being. We can practise the following basic asanas to keep ourselves healthy. Swastikasana (auspicious pose), Vrikshasana (tree pose), Bhujangasana (cobra pose), Trikonasana (traingle pose), Dhanurasana (bow pose), Marjariasana (cat pose) and Tadasana (mountain pose) are some asanas that help keep our heart healthy.Yoga asanas should always be practised under the guidance of an expert or a trained teacher.
Yogasanas
Vrikshasana(Tree pose)
Trikonasana(Triangle pose)
Swastikasana(Auspicious pose)
Science in ActionHeart disease is one of the major threat to human health due to today’s lifestyle. A person diagnosed with cardiovascular disease suffers from emotional toll, mood swings and negative outlook. Weight control and regular exercise keep our heart in shape. Also, eating a heart-healthy diet may reduce risk of heart disease or stroke by 80%. This diet helps to lower cholesterol, prevent heart disease and high blood pressure. A heart-healthy diet includes apple, avocado, olive oil, fish, walnuts, green leafy vegetables, whole grains, soy and tomatoes.
WondermentWondermentWonderment
Healthy heart, decreased blood pressure and weight control are some of the benefits of aerobic exercises.
A Fill in the blanks.1. The circulation of substances in our body is carried out with the help of a
transport system called _____________.
2. Blood flows through a network of tubes called _______________.
3. Blood transports _____________ from the lungs to the cells of the body.
4. ______________ present in blood protect the body against diseases.
5. Blood helps in transporting waste products to the _______________.
Walk Through
BloodFunctions:• Transports oxygen
from the lungs to the cells of the body, and transport carbon dioxide from the body cells to the lungs
• Carries nutrients to the body cells and transports waste products to the kidneys
• Helps in adjusting the body temperature and protects the body against diseases
Blood vessels (arteries, veins and capillaries)Functions:• Arteries carry
oxygenated blood from the heart to different parts of the body.
• Veins carry deoxygenated blood from different parts of the body to the heart.
• Capillaries are extremely thin blood vessels, which connect arteries and veins.
Circulatory System
HeartFunctions:Pumps oxygenated blood through blood vessels and deliver nutrients and oxygen to all the parts of the bodyContains deoxygenated (rich in carbon dioxide) blood received from all parts of the body, which is then transported to the lungs
A pacemaker is a small electrically charged medical device that is implanted in the chest or abdomen to help control abnormal heartbeats. This device uses electrical pulses to prompt the heart to beat at a normal rate. A person needs a pacemaker if the heart is pumping too quickly or slowly. In either case, the body doesn’t get enough blood. This can cause fatigue, fainting or lightheadedness, shortness of breath, damage to vital organs and eventual death. A pacemaker can also track and record a person’s heartbeat. Such records can help our doctors better understand the condition of one’s heart.
1. Why does a person need a pacemaker?
2. How can a pacemaker help to control abnormal heartbeats?
3. What will happen if our body doesn’t get enough blood?
Exemplar Problems
1. The diets of Roopali and Jitesh are given below. Answer the questions that follow.
Roopali: Chapattis, fish, potato, vegetables and fruits
a. Which diet is superior in quality? Justify your answer.
b. Which diet will affect our body adversely? What will be its impact on the working of the heart? Record your findings and suggestions.
2. Why is the pulmonary artery an exception?
3. Our heart beats faster when we run as compared to when we are at rest. Give reason.
4. What would have happened in the absence of valves in veins?
Value-Add
• Have you heard about blood donation? There are different societies that work in this area to spread awareness about blood donation and organise blood
donation camps. Find out more about this. Spread awareness and encourage your family and friends to donate blood.
• Our blood group is the type of blood we have in our body. There are four blood groups defined by the ABO system: A, B, O and AB. Make a list of the blood groups of students in your class.
Subject Bridge
Social Studies
Find out the history of stethoscope, who invented it and the story behind its invention.
Investigate
• Sit on a chair. Place your hand on the centre of your chest with the fingers towards the left side. Count your heartbeats. Now run up and down 20 stairs at least three times. Again, count your heartbeats as before. Is there any difference? Why do you think this has happened?
• Cardiac arrest is a common phenomenon nowadays. When our heart stops pumping blood, cardiac arrest occurs. What precautions can be taken by a person to avoid chest pains and heart attacks? What first aid can be given to a person who has chest pain? Find out.
Shefali was flipping through some of the books on her bookshelf. She came across a picture as shown alongside in one of the books. Carefully observe the picture. What did you notice?
What helps us to stand upright and move?
The skeletal system is a framework of bones that holds our body together. It is also known as the skeleton. It is our skeleton that helps us to stand upright and move.
What is the skeleton made up of?
The bone is a hard and rigid structure that forms the skeletal system of our body. A newborn baby has more than 300 bones. As the baby grows older, some bones fuse. Thus, the skeleton of an adult has 206 bones. The bones are of different shapes and sizes. All of them, however, are attached to one another.
Structure of a boneBones are made of minerals such as calcium and phosphorus. Bones are very hard from outside. Inside, however, they are soft and spongy. They contain nerves, blood vessels and a soft tissue called bone marrow. New blood cells are produced in the bone marrow. Bones are connected to each other through joints. These joints allow movement of various parts of our body.
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The stirrup bone is the smallest bone in the human body. Its length is 2–3 mm. It is one of the three bones present in the middle ear.
X-rays are a type of radiation that help create pictures of the inside of our body. These pictures show the different types of bones present in our body. The X-rays help doctors detect any kind of fracture or bone displacement.
What are the different types of bones present in the human body?
The human skeleton consists of skull, jawbone, backbone, ribcage, limbs (forelimbs and hindlimbs) and girdles.
SkullA hollow, bony structure present in our head is known as the skull. It gives shape to our face and the head. It protects the brain, the most important organ in our body. It also has holes for the eyes, nose and ears. The skull is made up of 22 bones. Out of these, 14 bones form the face and jaw. The remaining 8 bones are present in the upper part of the head that protects the brain. All the bones of the skull are fixed and cannot move, except the lower jawbone.
Jawbone The jawbone is the only movable bone in the face. It is U-shaped and consists of a lower set of teeth and allows us to talk and chew food.
BackbonePlace your fingers at the back of the neck of one of your friends and then move your fingers straight in the downward direction. You can feel a long, hard and
uneven structure at the back. This is the backbone, which is made up of 33 small bones called vertebrae (singular: vertebra). The vertebrae are joined with one another to form a column. It is also called spine or vertebral column. Each vertebra has a hole in it. The spinal cord, which is a delicate organ, passes through these holes. The backbone protects the spinal cord and is flexible. It connects the base of the skull to the lower back of the human body and supports our skeleton.
RibcageTake a deep breath and hold it for a moment. Try to feel the bones present in your chest. Can you feel the shape of these bones? They are flat, thin and curved bones called ribs. These are 24 bones arranged in 12 pairs to form a cage-like structure known as ribcage. The ribcage has another long bone called the sternum (or chest bone), present at the centre of the chest. The ribcage is attached to the sternum in the front and to the backbone at the back. The last two pairs of ribs are attached only to the backbone and not to the sternum and are known as floating ribs. The ribcage protects the heart and the lungs.
LimbsThere are two pairs of limbs in our body—forelimbs and hindlimbs. The arms are called the forelimbs or the upper limbs. The legs are called the hindlimbs or the lower limbs.
Upper limbThe bone in the upper arm is called humerus. There are two bones in the lower arm called radius and ulna. The lower ends of radius and ulna are connected to the wrist. The hand and wrist have several small bones.
Backbone
Vertebra
Ribcage
Ribs
Sternum
Floating ribs
WondermentWondermentWonderment
The hands and the feet of our body contain about more than half of the total number of bones in our body.
Lower limbThe bone in the upper leg is called femur or thigh bone. It is the longest bone in the body. Femur bears the weight of the whole body. Tibia and fibula are the two bones in the lower leg.The lower ends of these two bones are connected to the ankle joint. The foot and ankle also have several small bones.
GirdlesA ring-like structure made of bones is known as a girdle. A pair of pectoral girdles forms the shoulder joint and a pair of pelvic girdles forms the hip joint. The pectoral girdle consists of a pair of shoulder blades and collar bones. It provides support and mobility to our arms. The humerus bone in the upper limb is attached to the pectoral girdle. The pelvic girdle consists of hip bones and a part of the backbone called sacrum. It provides support and mobility to our legs. The femur bone in the lower limbs is attached to the pelvic girdle.
Pelvic girdle Pectoral girdle
What are the functions of bones in the human body?
The main functions of the skeletal system are as follows:Shape and Rigidity: The skeletal system provides support to our body and gives it a shape.
Upper limb
HumerusRadius
Ulna
Lower limb
Fibula
Tibia
Femur
ExtraOrdinary MindsOrdinary MindsOrdinary Minds
Wilhelm Conrad Roentgen, a German physicist is credited with the accidental discovery of X-rays in 1895. He took the first X-ray photographs of the interiors of metal objects and of the bones in his wife’s hand.
Protection: It protects the vital internal organs of our body. For example, our brain is protected by the skull. Our heart and lungs are protected by the ribcage. The spinal cord is protected by the backbone.Movement: It helps us in moving different parts of our body and in moving from one place to another.Production: Blood cells are produced by the bone marrow present inside the bones.
How do you bend or rotate your body parts?
Think of the different activities that you perform by bending your arms and legs. Bones are hard structures that cannot be bent. The movement in different parts of the body occurs due to the presence of joints. A joint is a place where two bones are joined together. Joints allow us to bend or rotate our body parts. The bones are held in position at the joints with the help of tissues called ligaments. Ligaments are soft tissues that connect a bone to a bone. At the joint, the ends of the two bones are covered with a soft tissue called cartilage.Cartilage is a firm, elastic, yellow or white-coloured tissue present around the joints. Since cartilage can bend, it helps in producing movement around the joint. The cartilage acts like a cushion and avoids friction between the two bones when they move. Thus, it prevents the bones from getting damaged due to continuous motion. Cartilage is also present in the upper part of the ear and at the tip of our nose.
Activity 1 Aim: To show movement in different jointsProcedure: Move your knee joint in different directions. Now, move your neck in different directions. The neck can move in many directions, whereas the knee joint cannot move in multiple directions. This is because the movable joints in the neck and the knee are different.
There are two types of joints in our body—immovable and movable. The joints in the skull except the joint of lower jaw cannot move and are called immovable joints or fixed joints. All other joints including lower jaw are called movable joints. Movable joints allow movement in different directions.
Movable joints There are four types of movable joints in the human body.
Ball-and-socket jointIn this type of joint, one bone has a ball-shaped end whereas the other bone has a cup-shaped socket. The ball-shaped end of one bone fits into the cup-shaped socket of the other bone. This allows maximum movement in all directions forward and backward as well as side to side movements. This joint is somewhat like the joystick of a computer. The hip and shoulder joints are examples of ball-and-socket joints.
Hinge jointHave you ever observed the movement of a door? The door is attached to the frame by metal clips called hinges. These hinges allow the door to be opened or closed. The hinges or joints allow movement only in one plane—back and forth.Similarly, joints in our elbows, fingers and knees and toes allow movement only in one plane. Since these joints allow movement only in one direction, like the hinge of a door, they are called hinge joints.
Pivot jointIn which direction can you move your neck? You can bend your neck sideways as well as in upward and downward directions. In our body, the pivot joint is found between the skull and the backbone. This joint allows sideways as well as up and down movement. In
this joint, one end of a bone is cylindrical and the end of another bone is in the shape of a ring. The cylindrical bone fits into the ring in such a way that one bone can rotate over the other.
Gliding jointOur wrists and ankles have gliding joints. Gliding joints allow the bones to glide smoothly over one another. These joints are also present between the vertebrae, that is, bones of the vertebral column. They help the back to bend, twist and turn at each joint.
What supports the movement of our body part?
There are about 600 muscles in our body. Muscles are attached to our bones by tissues known as tendons. When the muscles contract or relax, they move the bones to which they are attached. This enables us to move our body parts. We use our muscles even for the small tasks.
Types of musclesOur muscular system consists of three types of muscles.
Voluntary musclesThe muscles that are under our control are called voluntary muscles. We can use them as per our will. The skeletal muscles in our arms, legs, hands and feet are examples of voluntary muscles. Since these muscles have stripes on them, they are also called striped or striated muscles.
Involuntary muscles
The muscles that are not under our control are called involuntary muscles. We cannot control the muscles responsible for the flow of blood, movement of food
or breathing. We cannot use or control involuntary muscles as per our wish. These muscles work on their own and are controlled by the brain and spinal cord. Involuntary muscles are also called smooth muscles, as they do not have any stripes.
Cardiac muscles
Cardiac muscles are present in our heart and are not attached to any bone. These muscles help our heart pump blood all over the body. The muscles of the heart keep working 24 hours a day, throughout our lifetime. Cardiac muscles are very strong and hence, they do not get tired. These are also involuntary in nature.
Smooth muscle Striated muscle Cardiac muscle
What is the importance of bones, joints and muscles?
We have studied that bones and joints form the skeletal system and the muscles form the muscular system in our body. Each of these parts have their own importance in our body.
Bones provide support to the body and give it a shape.
Bones are rigid and cannot bend. However, joints present in our body allow movement of different body parts, thus making our body flexible.
Muscles provide support to our bones. They produce movement in the limbs by moving bones at their joints.
Round-tableRound-tableRound-table
Discuss why it is important to wear helmet, elbow guards and knee guards while playing sports such as skating and cycling.
What should we do to take care of our bones and joints?
We must take care of our bones, joints and muscles for their proper functioning. A balanced diet, regular exercise, good posture and sufficient rest are important for the proper functioning of bones and muscles. We should follow the given measures to make the bones, joints and muscles strong.
Eat food rich in proteinsProteins help in growth and building of muscles. They also help in repairing the tissues of the body and in healing small cuts and wounds. They are also called body-building food. Milk, eggs, meat, curd, soya bean, fish and pulses are rich in proteins.
Eat food rich in vitamins and minerals Vitamins and minerals make our bones, joints and muscles strong. They also help protect our body from various diseases. Food rich in vitamins and minerals are called protective food. Vitamins keep our body fit and help it resist diseases. Vitamins A, B, C, D, E and K are the different types of the vitamins that our body needs. Fresh fruits and vegetables, eggs and fish are good sources of vitamins. Vitamin C helps in the repair of cartilage in the joint. Vitamin D helps in
Body-building food
Protective food
Vitamins: vahy-tuh-min-s
Enunciation
RememberRememberRemember
Muscles, bones and joints, all help us to move. If any one of them is missing, we won’t be able to move any part of our body.
the absorption of calcium in the bones. Food items rich in vitamin C are citrus fruits and green leafy vegetables. Some food items rich in vitamin D are egg yolks, fatty fish and cheese. Minerals help our body grow well and develop properly. Iron, iodine and calcium are some important minerals required by our body. Milk, green leafy vegetables and fruits are rich sources of minerals. Calcium makes our bones stronger. It is a very crucial mineral needed by our bones and joints. The food items rich in calcium are green leafy vegetables, broccoli, milk, yoghurt, cheese, dry fruits and seafood.
Good posture and exercisePosture is the position in which we hold our body while sitting or standing. Standing and sitting in the correct posture is very important for healthy bones and joints. An incorrect posture can place a burden on the bones and joints which may lead to joint and muscle pain later in life. We should always keep our back straight while sitting and standing. If something heavy is to be lifted, we should bend our knees rather than bending our back.Regular exercise keeps the bones, joints and muscles strong and healthy. Walking, running and playing outdoor games such as football, tennis, cricket and basketball are some of the physical activities which are good for bones and joints. Some yoga asanas which involve stretching and balancing also keep our body healthy and fit. In addition to exercising regularly, taking rest is also important to keep our body healthy and fit. We should sleep for at least 7–8 hours daily to give proper rest to our body. After complete rest, our body feels more refreshed and we are ready to perform our daily activities.
Skull: It is a hollow, bony structure present in our head that protects our brain and gives shape to our face and the head.
Jawbone: It is the only movable bone in the face that allows us to talk and chew food.
Backbone: It is a long, hard and uneven structure at the back made up of 33 small bones called vertebrae. It protects the spinal cord and forms central supporting rod of the skeleton.
Bones
Voluntary muscles are the muscles that are under our control, for example, skeletal muscles in our arms, legs, hands and feet.
Cardiac muscles present in our heart help it to pump blood all over the body.
Involuntary muscles are the muscles that are not under our control, for example, the muscles responsible for the flow of blood, movement of food or breathing. These are controlled by brain and spinal cord.
Movable joints are joints that allow movement in different directions. There are four types of movable joints—ball and socket, hinge, pivot and gliding.
Immovable joints are fixed joints present in the skull, except the joint of lower jaw.
Ribcage: It is a cage-like structure and protects the heart and the lungs.
Girdles: A ring-like structure made of bones is known as a girdle, such as pelvic and pectoral. It provides support and mobility to our arms and legs.
Upper limbs: It has a single bone called humerus in the upper part, two bones called radius and ulna in the lower part and several bones in the wrist.Lower limbs: It has a thin bone, femur in the upper leg, two bones tibia and fibula in the lower leg and several small bones in the foot and ankle. The femur is the longest bone in the body that bears the weight of the whole body.
A Fill in the blanks.1. The __________ is a framework of bones that hold our body together.2. __________ is the hard and rigid structure that forms the skeleton.3. The skeleton of an adult has __________ bones.4. The bones contain a soft tissue called __________.
5. Bones are made up of minerals such as __________ and __________.
B Choose the correct answer.1. The skull protects our ______________. a. lungs b. brain c. heart d. liver2. The backbone is made up of __________ small bones known as vertebrae. a. 31 b. 32 c. 33 d. 343. The ribcage is formed by __________ pairs of ribs. a. 10 b. 11 c. 12 d. 134. The bone in the upper arm is called ____________. a. radius b. ulna c. humerus d. tibia5. Which of the following is the longest bone in the human body?
a. Humerus b. Femur c. Tibia d. Fibula
C Answer in one word.1. A place where two bones are joined together ______________2. The ends of the two bones are covered with this soft tissue ______________3. Joints in the skull ______________4. The joints that allow movement in all directions ______________
5. Connective tissue that holds bones in position ______________
D Identify the error in each statement and write them correctly.1. Muscles hold the body upright.2. Joints are rigid and cannot bend.3. Eggs, cheese and milk are a few food items rich in vitamin D.4. Lemon is a good source of vitamin A.
5. Bone marrow is a hard tissue present inside the bone.
Answer these questions. 1. Name the major bones in the human body.
2. What is the vertebral column?
3. Write a short note on the structure of following:
a. a bone b. an upper limb c. the ribcage
4. What does a human skull consist of? Which bone of the human skull is responsible for chewing food?
5. Differentiate between the following:
a. Pectoral girdle and pelvic girdle b. Pivot joint and a hinge joint
c. Voluntary and involuntary muscles
6. List the functions of bones in the human body.
7. What is a joint? Name the different types of joints.
8. How does a cartilage help in producing movement around the joint?
9. How many types of movable joints are there in a human body? What is the function of a jawbone?
10. Why are bones, joints and muscles important to us?
Look-Observe-Interpret
Observe the images given below, identify them and write one functions for each.
Comprehension
Bone marrow is a soft tissue inside our bones. It is of two types: red and yellow. Red bone marrow is present in flat bones such as those in the shoulder and ribs. Blood
cells and platelets are made in the red bone marrow. Platelets help us stop bleeding when we get a cut. Yellow marrow is present in long bones, such as the thigh bones. It is made up of fat. a. How are platelets helpful to us? b. What is bone marrow made up of?
Exemplar Problems
1. Which joints are not working in the following situations?
a. A person is not able to walk. b. A person is not able to write.
2. Do you think it would be better if we had voluntary muscles in the stomach and involuntary muscles in the legs? Why or why not?
3. Radhika is fond of junk food. She loves to watch television and play indoor games. She does not like to eat green leafy vegetables or drink milk. Is Radhika living a healthy lifestyle? Why or why not?
Value-Add
Bones support our body. They also protect the important organs of our body. It is, therefore, important for us to have strong bones. Vitamins and minerals make our bones stronger. Find out the sources of the vitamins and minerals that we should include in our diet. Also, find out different types of health drinks rich in vitamins, minerals and protein that you can add to your diet. Draw different bones on a chart paper and label them.
Subject Bridge
EnglishThe words ‘voluntary’ and ‘involuntary’ are antonyms. Find out what antonyms are. Write down five pairs of antonyms.
Investigate
• Move your lower jaw. Now, try moving your upper jaw. Did you notice any difference? Why can’t you move your upper jaw?
• Find out what a fracture is. How does a fracture heal?
• Discuss various components of food required for a healthy living
• Explain the need for a balanced diet
• Explain the meaning of junk food and its adverse effects on the body
• Suggest a few ways to make our diet healthier
• Discuss different lifestyle diseases and measures to prevent them
• List some deficiency diseases, their cause and prevention
• Develop awareness about adulteration in food
Take Off
Deepak and Ravi are friends. Deepak prefers to eat burgers, pizzas and cold drinks, while Ravi prefers to eat vegetables and fruits. They both ride their cycles in the evening. While cycling, Deepak gets easily tired as compared to Ravi. Can you find out the reason behind this?
Deepak frequently catches a severe cough and cold. He often misses school and his grades suffer because of his illness. His mother takes him to a doctor. The doctor asks his mother about his food habits. She tells the doctor that Deepak does not eat properly. He often skips meals and likes to eat junk food all the time.
The doctor tells Deepak’s mother that he falls ill frequently due to improper dietary habits. He explains the importance of eating healthy food in detail.
Food is essential for our body due to the following reasons.
• It gives us energy to work and play.
• It helps us grow.
• It repairs damaged body cells.
• It makes our bones and muscles strong.
• It protects our body from diseases.
How does food provide nourishment to our body?
The food that we eat contains certain essential components that nourish our body. These essential components are also called nutrients. There are five main components of food—carbohydrates, fats, proteins, vitamins and minerals. All these are essential for the growth and development of our body.
Food items such as vegetables and fruits contain fibrous matter called roughage. Roughage is the part of the plant food that cannot be digested. It helps in removing waste materials from our body. Roughage does not have any nutritional value, but it is essential for the proper digestion of food.
Water helps in digestion and removal of wastes from our body in the form of sweat and urine. We should drink at least 8–10 glasses of water in a day.
Carbohydrates: The main sources of carbohydrates are cereals, bread, pulses, potato and sugar. They provide energy to our body for work.
Proteins: Milk and its products, eggs, meat and pulses are good sources of proteins. They help the body grow and repair the worn-out cells present in it.
Fats: Oil, ghee, butter, cream and nuts are rich sources of fats. They provide more energy, than carbohydrates to our body. However, they should be consumed in a less amount.
Vitamins and Minerals: Fresh fruits and vegetables, milk, fish, eggs and meat are good sources of vitamins and minerals. They are needed in small quantities, but are essential for the normal functioning of our body. They protect the body against diseases.
What should we eat?
Balanced dietOur parents always insist that we should eat chapatti, rice, pulses, vegetables, fruits, eggs, curd, butter and nuts every day. They also tell us to drink milk and an adequate quantity of water regularly. Do you know why they emphasise on eating all kinds of nutritious food? Do all food items contain all the essential nutrients?
ExtraOrdinary MindsOrdinary MindsOrdinary Minds
Casimir Funk, a Polish biochemist, was first to highlight the role of vitamins in maintaining good health. He called vitamins—‘vital amines’.
Different food items are rich in different types of nutrients. For example, rice, wheat, potato, banana and sugar are rich in carbohydrates, whereas ghee and oil contain fats. Therefore, we need to include various kinds of food items in our daily diet for proper nourishment and growth. A diet that contains the right proportions of carbohydrates, fats, proteins, vitamins and minerals, along with water and roughage, is called a balanced diet.The diet of a person depends on various factors such as the age and gender of the person, the type of work or physical activity that one does and the condition of the body—whether diseased or healthy.For example, growing children need more protein in their diet for proper growth and development of their bodies.People working as labourers need more carbohydrates because their work involves intense physical activity and so, they need more energy. People who have desk jobs and sit most of the time, need less fat and carbohydrate intake. This prevents them from gaining weight.Elderly people generally need low-fat and protein-rich diet for the proper functioning of their bodies.People who are sick are advised to consume less fatty food as they are difficult to digest.
Why should we have a balanced diet?
A balanced diet is essential for proper growth and good health. It makes us physically as well as mentally fit and strong. Following a balanced diet plan has the following benefits.Improves energy: A balanced diet provides adequate energy to all the body parts so that they can perform their functions properly.Growth and development: A balanced diet is important for children as it helps in the growth and development of their body.
Balanced diet
RememberRememberRemember
Keratin is a type of protein that our hair, nails and outer skin are made of.
Mentally strong: A balanced diet enhances memory and concentration and thus helps us to focus on our day-to-day activities.Controls weight: A balanced diet includes nutrient-rich food items such as fruits, vegetables, whole grains and so on. These food items help in maintaining an ideal body weight and reduce the risk of obesity or malnutrition.Reduced risk for illness: A balanced diet enhances the ability of our body to fight or resist diseases.
What should we avoid eating?
Junk foodThe food items that have very low nutritional value and contain large amounts of salt, sugar and fats are called junk food.Junk food items appear to be tastier and more appealing. But they do not contain the essential nutrients needed to maintain good health.Also, junk food contains an excess of fats, which cannot be used completely by the body. This excess fat gets stored in the body and results in weight gain and poor health over a period of time. Chips, pizzas, burgers, patties, candies, chocolates, ice creams and fizzy drinks are a few examples of junk food.
Why should we avoid eating junk food?
We should avoid eating junk food as it is not good for our health. There are many adverse effects of eating junk food on our health and well-being. Some of these effects are given below.• Inadequate growth and development of the body due to lack of essential
nutrients and weight gain due to excess intake of sugar and fats
Junk food
Round-tableRound-tableRound-table
Why can’t a person eat only chocolates to survive? Discuss in a class.
• Poor concentration levels due to the absence of necessary minerals and vitamins
• Cavities in the teeth due to excess consumption of sugar
• Poor functioning of the digestive system due to low roughage, causes susceptibility to many diseases, especially heart diseases, due to lack of various nutrients
How can we make our diet healthy?
We should always avoid junk food and prefer a balanced diet. The following are some of the ways by which we can make our diet healthier.• Never overcook or undercook the food. Overcooked food is devoid of
nutrients and undercooked food is difficult to digest.• Use the minimum required quantity of sugar, salt or oil while cooking food.• Always wash fruits and vegetables before chopping them. Most of the
vitamins get washed away if they are washed after chopping. Eat plenty of seasonal fruits and vegetables daily. Use whole grains instead of polished cereals.
• Sprouting of pulses is also a good way to make them healthier. Let us understand the process of sprouting with an activity.
Activity 1
Take a few gram seeds. Soak them in water overnight. Remove water the next day and wrap the seeds in a wet cloth. Keep the seeds in the wet cloth for another 24 hours. Unwrap them the next day. Do you find any change in them? You will observe tiny white slender outgrowths called radicles on the seeds. Such seeds are called sprouts and this process is called sprouting.
Process of sprouting
WondermentWondermentWonderment
Research shows that nearly 60% of our brain is made of fat. So, our brain will not be able to function properly if we do not consume fats at all! One must consume ‘good fats’ like the ones found in nuts.
• Use fermented food in your diet. The fermentation of food items helps in adding important bacteria that help in the process of digestion. Some commonly used fermented food items are dhokla, idli, vada and dosa.
Activity 2
Work in groups. Collect a few names of healthy and junk food items. Discuss a few ways of avoiding junk food. You can also prepare slogans that encourage people to avoid junk food and explain them in your class.
How does our lifestyle affect our health?
The diseases that are related to the way we lead our lives are called lifestyle diseases. These diseases are mainly caused due to unhealthy food habits (such as eating a lot of junk food), lack of physical exercise, inadequate sleep and smoking. Obesity, anaemia, diabetes and blood pressure are a few common lifestyle diseases.
ObesityObesity means to have excessive weight gain. It generally occurs due to the consumption of large amounts of fat-rich food and lack of physical exercise. It is common among both children and adults. The symptoms of obesity are excessive weight gain in different parts of body, tiredness, lack of energy and breathing problems such as shortness of breath.
AnaemiaAnaemia is caused due to unhealthy food habits. People who avoid eating food rich in iron suffer from anaemia. Spinach, lentils, beans and tofu are some good sources of iron. Iron helps in the formation of blood. The symptoms of anaemia are tiredness, lack of energy in the body, paleness of the skin, loss of appetite and shortness of breath.
Round-tableRound-tableRound-table
Discuss how obese or very fat people are at a risk of high blood pressure, diabetes and heart diseases.
DiabetesDiabetes is the most common lifestyle disease nowadays. It is caused when the level of sugar becomes too high in our blood. Improper diet, lack of exercise, obesity and stress are some of the major causes of diabetes.The symptoms of diabetes are excessive thirst and hunger, frequent urination, high blood pressure, extreme fatigue and heart diseases.
High blood pressureThe pressure exerted by the blood on the walls of blood vessels is called blood pressure. When the level of blood pressure becomes high, the person is said to have high blood pressure or hypertension. Stress, lack of physical exercise, improper diet and eating too much salty and fatty food are the main causes of high blood pressure. High blood pressure may lead to heart diseases. A person suffering from high blood pressure over a long period of time may experience frequent headaches, shortness of breath, dizziness, nosebleeds and chest pain.A healthy lifestyle is the best way to prevent lifestyle diseases. Following are the ways in which these diseases can be prevented.• Stick to a diet plan that contains important nutrients. Avoid eating junk food
and food rich in salt and sugar. Include various fruits and vegetables in your diet. Drink at least 8–10 glasses of water every day.
• Regular exercise and physical activities such as walking, running and cycling along with yoga asanas are ways to stay healthy.
• Always stand and sit in the correct posture. Also, avoid sitting for long periods of time; take breaks and move around at regular intervals.
• Adopt a healthy routine for day-to-day activities. Sleep for eight hours daily. Wake up early in the morning and go to bed early at night. Meditate to avoid stress.
What are deficiency diseases?
One may be eating enough food but not necessarily the right type of food. If our diet does not contain appropriate amounts of the essential nutrients, our body starts showing symptoms of deficiencies. These deficiencies, over a long period of time, lead to deficiency diseases. Deficiency diseases are the result of malfunctioning of the body due to lack of one or more nutrients in the diet.
We can prevent these diseases by consuming all the essential nutrients in the right quantities. The given table lists some of the common deficiency diseases along with their symptoms and the preventive measures.
Various deficiency diseases
Diseases Cause (Deficient nutrient)
Symptoms Preventive measures
Kwashiorkor Proteins • Inhibition of growth in children
• Swelling in the abdomen and other body parts due to accumulation of fluids
• Thinning of legs• Dry and flaky skin
Include eggs, milk, fish, meat, cereals and pulses in diet
Marasmus Proteins and carbohydrates
• Accumulation of fluids in different body parts
• Weight loss and weakness
• Thinning of body parts• Loose folds in the skin• Diarrhoea
Include milk, eggs and cereals in diet
Night blindness
Vitamin A Inability to see at night or in dim light
Include carrot, butter, papaya, milk, mango and green vegetables in diet
Anaemia Iron • Weakness and paleness• Loss of appetite• Reduced growth rate
Include green leafy vegetables such as spinach, broccoli and fruits such as apple, guava and banana, jaggery and meat in diet
Food adulterationMixing of unwanted and harmful substances in food items to enhance its quantity or appearance is called food adulteration. The unwanted substances that make food unfit for human consumption are called adulterants.Sellers generally add adulterants, such as colours and various chemicals, to make their food items more attractive, and thus earn more profit. These adulterants may affect the health of the buyers when they consume the adulterated food. Food adulteration is a punishable offence in India.
Some common examples of food adulterationOne of the most common examples of food adulteration is the addition of water, chalk powder or soap to milk. This is done by milk sellers to increase the quantity of milk, and thus earn more profit by selling adulterated milk. Black pepper, which is used as a spice and for seasoning, is adulterated by adding papaya seeds to it. Another example of food adulteration is the addition of marble chips and stone chips in cereals and pulses. Pulses are even coloured to make them look attractive and fresh.The commonly used desi ghee is adulterated by using vegetable oils and animal fats. Spices such as chilli powder and turmeric powder are generally adulterated by using brick powder and yellow dye. Food adulteration
Adulterant: uh-duhl-ter-uhnt
Enunciation
Science in Action
Eating too much fat-rich food can make us overweight and eventually lead to obesity. Consumption of excess fats can cause deposition of a chemical called cholesterol in our arteries and make them narrow. This makes the flow of blood in arteries difficult and may even lead to heart attack and other heart diseases.
A diet that contains the right proportions of carbohydrates, fats, proteins, vitamins and minerals, along with water and roughage, is called a balanced diet.
Carbohydrates (provide energy), eg. cereals, sugar, rice, etc.
Protein (enhances growth and repair of worn-out cells), eg. pulses, meat, etc.
Fat (provides energy), eg. butter, ghee, etc.
Vitamins and Minerals (protect from diseases), eg. fruits, vegetables, etc.
Lifestyle diseases: The diseases that are related to the way we lead our lives are called lifestyle diseases.
Obesity (excessive weight gain) Anaemia (weakness and loss of appetite) Diabetes (high sugar level in blood)High blood pressure (hypertension)
Deficiency diseases: The result of malfunctioning of the body due to lack of one or more nutrients in the diet.
Kwashiorkor: Protein deficiencyMarasmus: Protein and carbohydrate deficiencyNight blindness: Vitamin A deficiencyRickets: Vitamin D deficiencyScurvy: Vitamin C deficiencyBeriberi: Vitamin B1 deficiency
Match the food components of the balanced diet to their sources.
1. Proteins 2. Vitamins and minerals 3. Carbohydrates
a. b. c.
Comprehension
The food products that we buy from a grocery store have food labels printed on their packets or containers. These labels have basic information about the food item. This helps to compare different food products and choose more healthy options. This label shows number of calories (kcals) in one serving. The label will also list the percentage of daily values for various nutrients, vitamins and minerals. These values tell you what portion of the recommended amount one serving contains. So, if you eat everything in the container at one time, you will have to multiply the numbers on the label by the number of servings.
1. How many servings are there in the container?
2. How many calories are there in the whole container?
Nutrition FactsServing Size 5 oz. (144g)Servings Per Container 4
1. Fats are an important component of our balanced diet as they provide us with energy. So why are they considered to be a major reason of obesity?
2. Saarah gets tired very soon while playing. She also complains about shortness of breath and she does not feel like eating her meals. The doctor has asked her to eat food rich in iron. Which deficiency disease is Saarah suffering from? Why?
3. Nidhi noticed that the milk delivered by the milkman was thin. She complained and asked the milkman to deliver good quality of milk. Why did she say so?
Value-Add
Do you know that lakhs of children around the world, including India, die at a very young age due to lack of food? Many children fall ill and suffer from diseases such as Marasmus because they do not get a balanced diet. We should feel fortunate that we get sufficient and good quality food. Are there children in your class who do not finish their tiffin or sometimes waste food? Discuss in class why this act is considered wrong.
Subject Bridge
English
Visit your family doctor and discuss about healthy food habits, deficiency diseases and ways to prevent them. Speak about the importance of a balanced diet and healthy eating habits in your school assembly.
Investigate
• Observe the diet of each member of your family for about a week. Find out whether all of them (including you) are following a balanced diet plan. Also conduct a survey in neighbourhood for the same.
• Make a diet chart for the whole week for yourself. Include all the nutrients in your diet. You can take your parents’ help to prepare this chart.
