Body Movements Class 6 Science Chapter 5 Notes

Body Movements Class 6 Science Chapter 5 Notes are available here. These notes are prepared by the subject experts of our website CBSE Wale.

Body Movements Class 6 Science Chapter 5 Notes

Locomotion

Locomotion refers to the movement of an organism from one place to another. It’s how living things, like animals (including humans!), change their position. Examples of locomotion are walking, running, jumping, flying, swimming, crawling, slithering etc.

Movement

Movements, can be any kind of motion, even if it doesn’t involve going anywhere. For instance, wiggling your toes or bending your arm at the elbow are movements, but they wouldn’t be considered locomotion because you’re not changing your overall position. Examples are breathing, heart beating, eye blinking, running, elbow bending, swimming etc.

Skeletal System

The skeletal system is your body’s internal framework, giving your body its shape and allowing for movement. It’s more than just bones, though! The skeletal system also includes cartilage, ligaments, and tendons that all work together to keep you supported and moving. The human skeleton has 206 bones in total. The number of bones can vary slightly from person to person, depending on how some bones have fused together. For example, the sacrum in the lower spine is actually several bones that have fused together in adults.

Here are the main functions of the skeletal system:

Support: The skeleton provides a strong and rigid framework that supports the body and keeps it upright.
Movement: Bones act as levers, working with muscles to produce movement. Ligaments and tendons connect bones to muscles, allowing them to pull on the bones and create movement at the joints.
Protection: The skeleton protects your vital organs from injury. For example, the skull protects the brain, and the rib cage protects the heart and lungs.
Storage: Bones store minerals, such as calcium and phosphorus, which are important for keeping bones strong and healthy.
Blood cell production: Bone marrow, the soft tissue found inside some bones, is responsible for producing red blood cells, white blood cells, and platelets.

Joints

Joints are the areas where two or more bones meet in your body. They allow for movement and flexibility. There are different types of joints, each allowing a different range of motion. Joints are essential for our ability to move around, but they also play a role in supporting our body weight and protecting our bones.

Here are the main parts of a joint:

Cartilage: A smooth, rubbery tissue that covers the ends of bones at a joint. Cartilage helps to reduce friction and absorb shock.
Ligaments: Tough bands of connective tissue that connect bones to other bones at a joint. Ligaments provide stability to the joint and limit its movement.
Synovial membrane: A thin membrane that lines the joint capsule and produces synovial fluid.
Synovial fluid: A thick, slippery fluid that lubricates the joint and nourishes the cartilage.
Joint capsule: A tough, fibrous membrane that surrounds the joint and holds the bones together.

Types of Joints

1. Hinge Joint

A hinge joint is a type of joint in your body that works just like a door hinge. Imagine how a door moves – it swings open and closed in one direction. That’s exactly how a hinge joint works, but inside your body!

Here are some key points about hinge joints:

Movement: Hinge joints allow movement in one direction, just like the hinge on a door. This movement is back and forth, or up and down.
Examples: The most common places you can find hinge joints in your body are your elbows and knees. When you bend your elbow to bring your hand to your shoulder or straighten your leg to stand up, you’re using hinge joints.
Function: These joints are super important because they help you do many daily activities, like walking, picking things up, and even chewing food.
Stability: Hinge joints are strong and stable, which helps them handle a lot of movement and weight.

So next time you bend your knee or elbow, remember you’re using a hinge joint, just like how a door swings on its hinge!

2. Ball and Socket Joint

A ball and socket joint is a type of joint in your body that allows for a lot of movement in many different directions. Imagine a ball fitting into a cup, and you can see how it can move around easily.

Here are some key points about ball and socket joints:

Movement: Ball and socket joints allow movement in almost all directions. This means you can move the joint in a circle, back and forth, and side to side.
Examples: The most common places you can find ball and socket joints in your body are your shoulders and hips. When you swing your arm in a circle or kick your leg out to the side, you’re using ball and socket joints.
Function: These joints are very flexible and give you a wide range of motion. This flexibility helps you do things like throw a ball, dance, or even reach up to grab something from a high shelf.
Stability and Strength: While they are very flexible, ball and socket joints are also strong and stable to support the movements and weight of your arms and legs.

So next time you move your shoulder or hip in a big circle, remember you’re using a ball and socket joint, which is like a ball fitting into a cup!

3. Pivot Joint

A pivot joint is a type of joint in your body that allows for rotation. Imagine a turning doorknob or a spinning top, and you’ll understand how a pivot joint works.

Here are some key points about pivot joints:

Movement: Pivot joints allow for rotational movement. This means the joint can turn around a central point, letting parts of your body twist or rotate.
Examples: The most common places you can find pivot joints in your body are your neck and the part of your arm near your elbow. When you shake your head “no” or twist your forearm to turn your palm up and down, you’re using pivot joints.
Function: These joints are crucial for activities that involve rotation. For example, turning your head to look around or twisting your arm to use a screwdriver involves pivot joints.
Stability and Flexibility: Pivot joints balance stability with the ability to turn, allowing for precise movements without compromising the joint’s integrity.

So next time you turn your head or twist your arm, remember you’re using a pivot joint, which acts like a rotating knob!

4. Gliding Joint

A gliding joint is a type of joint in your body that allows bones to slide over each other. Imagine a stack of playing cards sliding smoothly across a table, and you’ll get an idea of how gliding joints work.

Here are some key points about gliding joints:

Movement: Gliding joints allow bones to move past each other in any direction along the plane of the joint – up and down, left and right, and diagonally. This movement is usually small and smooth.
Examples: The most common places you can find gliding joints in your body are in your wrists, ankles, and between the small bones in your spine. When you bend your wrist or twist your ankle, you’re using gliding joints.
Function: These joints are important for small, precise movements. They help you do things like write, wave your hand, or walk smoothly.
Stability and Flexibility: Gliding joints provide a combination of stability and flexibility, allowing bones to move freely while keeping the joints aligned properly.

So next time you move your wrist or ankle, remember you’re using a gliding joint, which allows your bones to slide smoothly over each other!

5. Fixed Joint

A fixed joint, also known as an immovable joint, is a type of joint in your body where bones are tightly connected and don’t move at all. Think of it like bricks in a wall – they’re stuck together and don’t bend or twist.

Here are some key points about fixed joints:

Movement: Unlike other joints that allow movement, fixed joints don’t move. They’re stiff and rigid.
Examples: The most common places you can find fixed joints in your body are in your skull. The bones of your skull are fused together, forming a solid structure that protects your brain.
Function: Fixed joints play a crucial role in providing support and protection to vital organs, like your brain. They ensure that certain parts of your body stay strong and stable.
Stability: These joints are extremely stable because they don’t move. They provide a strong framework for your body and protect delicate organs.

So next time you touch your head, remember that your skull is made up of fixed joints, keeping your brain safe and secure!

Human Skeletal System

The human skeletal system is like the frame of a house, providing structure, support, and protection for the body. It’s made up of bones, cartilage, and ligaments, and it has several important functions:

Support: The skeletal system gives your body its shape and provides a framework for muscles and organs to attach to. Without it, you would be like a jellyfish!
Protection: Your bones protect vital organs like your brain, heart, and lungs. For example, your skull protects your brain, and your ribcage shields your heart and lungs.
Movement: Bones work together with muscles and joints to allow movement. When muscles contract, they pull on bones, causing them to move at joints.
Blood Cell Production: Inside some bones, there’s a soft, spongy tissue called bone marrow. This is where red blood cells, white blood cells, and platelets are made.
Mineral Storage: Bones act as a storage bank for minerals like calcium and phosphorus. When your body needs these minerals for things like muscle contraction or nerve signaling, it takes them from your bones.

The skeletal system is divided into two main parts:

Axial Skeleton: This includes the bones along the body’s central axis, such as the skull, spine, and ribcage.
Appendicular Skeleton: This includes the bones of the limbs (arms and legs) and the bones that connect them to the axial skeleton, like the shoulder girdle and pelvic girdle.

In total, the human body has 206 bones!

Bones

Bones are essential components of the human body’s skeletal system. Here’s a breakdown of their key aspects:

Structure: Bones are rigid organs that form the skeleton, providing support and protection for soft tissues and organs. They give the body its shape and framework, helping us stand upright and move.
Composition: Bones are made up of a combination of collagen, a tough protein, and minerals like calcium and phosphorus. This combination gives bones their strength and hardness while also allowing them to be somewhat flexible.
Types of Bones: There are two main types of bones in the body:
- Compact Bone: Dense and strong, compact bone forms the outer layer of most bones. It provides protection and support.
- Spongy Bone: Found inside the ends of long bones and in flat bones, spongy bone is less dense and contains small spaces filled with bone marrow. It helps reduce the weight of bones while providing structural support.
Bone Marrow: Bone marrow is a soft, spongy tissue found inside certain bones, such as the ends of long bones and the pelvic bones. It’s responsible for producing blood cells, including red blood cells, white blood cells, and platelets.
Function: Bones have several important functions:
- Support: Bones provide a framework for the body, supporting muscles, organs, and tissues.
- Protection: Bones protect vital organs such as the brain, heart, and lungs from injury.
- Movement: Bones, along with muscles and joints, enable movement and locomotion.
- Mineral Storage: Bones store minerals like calcium and phosphorus, releasing them into the bloodstream as needed for various bodily functions.
- Blood Cell Production: Bone marrow produces blood cells through a process called hematopoiesis.
Growth and Development: Bones grow and develop from infancy through adolescence in a process known as ossification. During childhood and adolescence, bones undergo growth and remodeling, guided by hormones and physical activity.
Number of Bones: The adult human skeleton typically consists of 206 bones. However, the number can vary slightly from person to person due to individual differences and the fusion of certain bones during development.

Bones are remarkable structures that play a vital role in supporting and protecting the body, facilitating movement, and maintaining overall health and well-being.

Cartilage

Cartilage is a flexible connective tissue found in various parts of the body. Here’s some key information about cartilage:

Composition: Cartilage is primarily composed of cells called chondrocytes and a gel-like substance called matrix. The matrix consists of collagen fibers, which provide strength and resilience, and proteoglycans, which help retain water and maintain the tissue’s flexibility.
Types of Cartilage: There are three main types of cartilage in the human body:
- Hyaline Cartilage: This is the most common type of cartilage and is found in areas such as the nose, trachea, and ends of long bones. It provides smooth surfaces for joint movement and supports structures like the respiratory passages.
- Elastic Cartilage: Elastic cartilage contains more elastic fibers and is found in the external ear, epiglottis, and parts of the larynx. It is highly flexible and helps maintain the shape of these structures.
- Fibrocartilage: Fibrocartilage is the toughest type of cartilage and contains dense collagen fibers. It is found in areas such as the intervertebral discs, pubic symphysis, and certain joint capsules. Fibrocartilage provides support and absorbs shock in areas subject to heavy pressure and movement.
Function: Cartilage serves several important functions in the body:
- Support: Cartilage provides structural support to various body parts, helping maintain their shape and integrity.
- Cushioning: In joints, cartilage acts as a shock absorber, reducing friction and preventing damage to bones during movement.
- Smooth Joint Movement: Hyaline cartilage covers the ends of bones in joints, providing smooth surfaces for frictionless movement and reducing wear and tear.
- Flexibility: Cartilage allows for flexibility and elasticity in tissues such as the ears and nose, enabling them to bend and return to their original shape.
Healing and Repair: Cartilage has limited ability to heal and repair itself compared to other tissues in the body. Injuries to cartilage, such as tears or damage to joint cartilage, can be challenging to treat and may require surgical intervention or specialized therapies.

Overall, cartilage is a versatile tissue that plays a crucial role in supporting the body’s structure, facilitating movement, and protecting vital organs and structures. Its unique properties make it essential for maintaining overall health and mobility.

Exoskeleton and Endoskeleton

Exoskeleton:

Location: An exoskeleton is located on the outside of the body.
Composition: It is typically made of a hard, protective outer layer composed of chitin or calcium carbonate.
Function: The exoskeleton provides support, protection, and structure to the organism’s body. It serves as a barrier against predators, physical damage, and desiccation (drying out).
Examples: Exoskeletons are commonly found in arthropods such as insects, crustaceans (like crabs and lobsters), and some mollusks (like snails and clams).

Endoskeleton:

Location: An endoskeleton is located inside the body, providing support and structure internally.
Composition: It is composed of bones or cartilage, which are living tissues that grow and develop throughout an organism’s life.
Function: The endoskeleton provides support for the body, protects internal organs, and facilitates movement by providing attachment points for muscles.
Examples: Endoskeletons are found in vertebrates, including mammals, birds, reptiles, amphibians, and fish.

Differences:

Position: The main difference between exoskeletons and endoskeletons is their position relative to the body. Exoskeletons are external structures, while endoskeletons are internal.
Composition: Exoskeletons are composed of rigid materials like chitin or calcium carbonate, while endoskeletons are made of bones or cartilage, which are living tissues capable of growth and repair.
Flexibility: Endoskeletons generally allow for more flexibility and freedom of movement compared to exoskeletons, which can be restrictive.
Growth: Endoskeletons can grow and adapt to changes in the body size of the organism, while exoskeletons must be periodically shed and replaced to accommodate growth.

Both exoskeletons and endoskeletons have evolved to suit the needs of different organisms and provide support, protection, and mobility in their respective environments.

Skull

What is a skull?

The skull is the bony case that forms your head.
It’s like a super strong helmet, protecting the important parts inside!

What does it do?

The skull has two main jobs:
- Protection: It shields your brain, eyes, ears, and nose from bumps and injuries.
- Support: It provides a framework for your face and gives your muscles something to attach to for chewing and making expressions.

Cool Skull Parts:

Cranium: This is the rounded top and back part of your skull. It’s made of several fused bones that create a smooth, protective surface.
Face Bones: These are 14 separate bones that form your eye sockets, nose, jaw, and cheekbones.
Suture Lines: These aren’t cracks! They’re the lines where the different skull bones fit together. They allow a little bit of movement as you grow.
Mandible: This is your lower jawbone, the only moving bone in your skull! It lets you open and close your mouth for talking, eating, and yawning.

Fun fact: Even though your skull is strong, it’s not invincible! Always wear a helmet when biking, skateboarding, or doing anything that could cause a head injury.

Backbone or Spine

Backbone and spine are two terms for the same structure in your body. It’s a long, flexible column of bones that runs down the middle of your back, from your neck all the way down to your tailbone.

The backbone, or spine, is an important part of your body because it:

Supports your body: Your spine helps you stand upright, bend, and twist.
Protects your spinal cord: The bones of your spine form a hollow canal that runs down the center. This canal shelters your spinal cord, a bundle of nerves that carries messages between your brain and the rest of your body.
Allows you to move: The muscles and ligaments attached to your spine allow you to move your back and bend over.

Ribcage

The ribcage, also known as the thoracic cage, is a bony cage-like structure in your chest that protects your vital organs.

Parts of the Ribcage:

Ribs: There are 24 ribs in total, 12 on each side of your body. They are thin, curved bones that connect to the spine in the back and the sternum (breastbone) in the front.
Sternum: This is the flat bone in the front of your chest, also known as your breastbone.
Vertebrae: These are the bones of your spine that connect to the ribs in the back.
Cartilage: These are flexible pieces of connective tissue that connect some of the ribs to the sternum.

Functions of the Ribcage:

Protection: The ribcage’s main function is to protect your vital organs, including your heart, lungs, and major blood vessels. The bones of the ribcage absorb the impact of blows to the chest and help prevent them from injuring these organs.
Breathing: The ribcage plays an important role in breathing. When you inhale, the muscles between your ribs contract, pulling your ribs upward and outward. This increases the volume of your chest cavity, which allows your lungs to expand and take in more air. When you exhale, the muscles relax, and your ribs and chest cavity return to their resting position, forcing air out of your lungs.

Pelvic Girdle

The pelvic girdle, also sometimes called the bony pelvis, is a ring-shaped structure made of bone and cartilage in the lower part of your torso. It connects your axial skeleton (your spine) to your lower limbs (legs).

Parts of the Pelvic Girdle:

Hip Bones (Innominate Bones): The main bone of the pelvic girdle. Each hip bone is actually three bones that fuse together in early adulthood: the ilium, the ischium, and the pubis.
- The ilium is the uppermost, flaring part of the hip bone. It attaches to the sacrum in the back and forms the sides of your hips.
- The ischium is the lower and back part of the hip bone. It’s the part you sit on!
- The pubis is the front part of the hip bone. The two pubis bones meet at the pubic symphysis in the front of the pelvis.
Sacrum: This is a triangular bone at the base of your spine that connects to the ilium of each hip bone.
Coccyx: This is the small, tail-like bone at the very end of your spinal column. It attaches to the sacrum.

Functions of the Pelvic Girdle:

Support: The pelvic girdle provides support for your upper body weight, transferring it from your spine to your legs.
Stability: It helps to keep your body stable when you stand, walk, run, and jump.
Protection: The pelvic girdle helps to protect your internal organs in your lower abdomen and pelvis, including your bladder, bowels, and reproductive organs.
Movement: The pelvic girdle allows for a wide range of motion at the hip joint, which is essential for walking, running, and other activities.

Shoulder Girdle

The shoulder girdle, also known as the pectoral girdle, is a group of bones and cartilage that connects your upper limbs (arms) to your torso. Unlike the pelvic girdle, which is a complete bony ring, the shoulder girdle is an incomplete ring of bones. This structure allows for the wide range of motion in the shoulder joint.

Bones of the Shoulder Girdle:

Clavicle (collarbone): This is the only bone that connects the upper limb directly to the axial skeleton (your sternum). It’s a slender, S-shaped bone that lies across the upper front of your chest.
Scapula (shoulder blade): This is a flat, triangular bone that lies on your upper back. It doesn’t directly connect to the sternum but instead connects to the clavicle via the acromion process. The scapula provides attachment points for many of the muscles that move your arm.

Joints of the Shoulder Girdle:

Sternoclavicular joint: This joint connects the medial end of the clavicle to the manubrium of the sternum (breastbone). It allows for a slight gliding movement of the clavicle.
Acromioclavicular joint: This joint connects the acromion process of the scapula to the lateral end of the clavicle. It also allows for a gliding movement.
Glenohumeral joint (shoulder joint): This is the joint between the head of the humerus (upper arm bone) and the glenoid cavity of the scapula. It’s a ball-and-socket joint that allows for a wide range of motion in your arm, including flexion, extension, abduction, adduction, and rotation.
Scapulothoracic joint: This is not a true joint but rather a gliding movement between the scapula and the rib cage. It allows the scapula to move on the back of the thorax during arm movement.

Functions of the Shoulder Girdle:

Support: The shoulder girdle provides support for the weight of your arm.
Movement: It allows for a wide range of motion in your shoulder joint, which is essential for many everyday activities.
Protection: The muscles attached to the shoulder girdle help to protect the glenohumeral joint from injury.

Tendon

A tendon is a tough, flexible tissue that acts like a rope to connect muscle to bone. Tendons are made mostly of collagen, a protein that gives them strength and flexibility. They transmit the force generated by muscle contractions to bones, allowing us to move our limbs.

Tendon injuries are common, especially in people who participate in repetitive activities that put stress on the tendons. These injuries can cause pain, swelling, and difficulty moving the affected joint.

Here are some of the important functions of tendons:

Transferring Force: They transmit the pulling force of muscles to bones, allowing for movement.
Stabilizing Joints: Tendons help to stabilize joints by holding bones together.
Shock Absorption: They act as shock absorbers, reducing the impact of forces on muscles and bones.

Ligament

Ligaments are another type of connective tissue in your body, but unlike tendons, they connect bone to bone, rather than muscle to bone. They are also made mostly of collagen, but the arrangement of the fibers is different, making ligaments even tougher and less stretchy than tendons.

Ligaments are like strong, flexible bands that wrap around joints and hold the bones together. They provide stability to your joints and limit the range of motion, preventing bones from moving out of their proper position.

Here are some of the key functions of ligaments:

Joint Stability: Ligaments provide stability to joints by preventing excessive movement and dislocation of bones.
Joint Support: They offer support to joints, especially those that bear a lot of weight, like the knees and ankles.
Proprioception: Ligaments contain nerves that help you sense the position and movement of your joints, which is important for coordination and balance.

While ligaments are very strong, they can be sprained or torn if a joint is forced beyond its normal range of motion. This can happen during a sudden twist or fall. A sprained ligament is a stretch or tear of the ligament fibers, while a torn ligament is a complete rupture of the ligament.

Movement in Earthworm

Muscles: Earthworms use two sets of muscles for movement:
- Circular muscles: Contract to elongate the body.
- Longitudinal muscles: Contract to shorten the body.
Setae: Tiny bristles that help anchor the worm in the soil.
Movement sequence:
1. Front part extends, anchoring back with setae.
2. Longitudinal muscles contract, shortening the body and pulling the back end forward.
3. Back part anchors with setae, front part relaxes and extends.
4. Circular muscles contract, lengthening the front part.
Mucus: Slimy substance secreted to aid movement through soil.

This wave-like motion of contracting and relaxing muscles, along with setae for grip, allows earthworms to burrow and inch forward in the soil.

Movement in Snail

Muscular foot: A thick, muscular underside that propels the snail.

Mucus: Secreted by the foot, it lubricates the surface and reduces friction.

Waves of contraction: Muscular contractions travel down the foot, creating a rippling motion.

Land snails: Waves move in the same direction as travel (prograde locomotion).
Water snails: Waves move in a reverse pattern (retrograde locomotion).

Slow and steady: This method allows snails to move slowly but efficiently on various surfaces, even climbing!

Movement in Cockroach

Multi-talented mover: Cockroaches can walk, run, climb, and even achieve short bursts of flight.
Legs: Three pairs of legs enable walking and running.
Wings: Two pairs of win gs (though not for graceful gliding) aid in short-distance flight.
Segmented exoskeleton: Hard outer shell with flexible joints allows for leg and wing movement.
Muscles: Dedicated sets of muscles power legs for walking and wings for flight.

Movement in Birds

Flight: The defining feature! Wings, modified forelimbs with feathers, are key.

Flapping: Downward wing strokes create lift, while upstrokes help maintain position.
Feathers: Adjustable for steering, gliding, and takeoff/landing.

Beyond Flight: Birds are versatile movers on land and water.

Walking/Running: Strong legs with clawed feet adapted for various surfaces.
Hopping: Efficient for small birds, using powerful legs.
Swimming: Webbed feet (ducks, geese) or paddling wings (penguins) propel them in water.

Specialized Adaptations: Beaks are used for climbing (parrots) or swimming (puffins).

Movement in Fish

Fish utilize a variety of methods for movement in water, depending on their body shape, fin configuration, and desired speed. Here’s a quick breakdown:

Body shape: Most fish have a streamlined body for efficient movement, reducing drag in the water.
Fins: Play a crucial role in propulsion, steering, and stability.
- Tail fin (caudal fin): The primary source of thrust, it propels the fish forward with side-to-side flicks.
- Other fins: Pectoral, pelvic, dorsal, and anal fins provide stability, maneuvering, and braking.
Main movement types:
- Lateral flexion: The most common method. The body bends in wave-like motions, pushing water and propelling the fish forward. There are variations in how the wave travels along the body for different levels of efficiency and speed.
- Fin propulsion: Some fish, like angelfish, rely more on pectoral fins for swimming, with a stiffer body.
- Undulatory locomotion: Elongated fish like eels use a snake-like sinuous motion to move through the water.
Additional movements: Certain fish can:
- “Walk” on the seabed using pectoral and pelvic fins (e.g., mudskipper).
- Burrow in mud with their bodies.
- Leap out of water for short distances.
- Glide for brief periods using specialized body shapes.

Movement in Snake

Snakes, lacking limbs, have evolved a unique and effective way to move on land and even in water. Here’s how they get around:

Serpentine Movement (Lateral Undulation): This is the classic “slithering” motion most associated with snakes. The snake throws its body into S-shaped curves and pushes against the ground with these loops to inch forward.
Role of Spine and Ribs: Their flexible spine and numerous ribs provide the foundation for these undulations. Muscles attached to the ribs contract and relax, creating the wave-like movement.
Grip and Terrain: Rough surfaces or objects in the environment (rocks, plants) provide grip for the snake’s body to push against for efficient movement. On smooth surfaces like sand, slithering can be less effective.
Alternative Techniques: Snakes have additional movement tricks in their repertoire:
- Rectilinear Locomotion (Concertina): The snake pushes its body forward by expanding and contracting its entire body length like an accordion, useful in tight spaces.
- Sidewinding: Primarily used by vipers on loose sand, the snake throws its body into sideways waves for locomotion.

These various techniques allow snakes to navigate diverse environments, climb, and even swim