Ch: 2 Skeletal System

The human body is made up of bones, muscles, and organs that work together to keep us alive and moving. The skeletal system is the framework of bones that provides support and shape to our body, protects vital organs, and helps us move.

Functions of the Skeletal System

1. Support: The skeleton provides a strong framework that supports the body’s shape and structure.

2. Protection: It protects vital organs. For example, the skull protects the brain, and the ribcage protects the heart and lungs.

3. Movement: The bones work with muscles to allow movement.

4. Production of Blood Cells: Bone marrow inside bones produces red and white blood cells.

5. Storage of Minerals: Bones store important minerals like calcium and phosphorus, which keep them strong.

Parts of the Skeletal System

The skeletal system consists of 206 bones in the adult human body. These bones can be grouped into two main parts:

1. Axial Skeleton: Includes the skull, backbone (spine), and ribcage.

2. Appendicular Skeleton: Includes the girdles, limbs, legs, and arms.

1. The Skull

Structure: The skull is made up of 22 bones. It consists of the cranium, which protects the brain, and the facial bones.

Function: It protects the brain and supports the structures of the face.

2. The Backbone (Spine)

Structure: The spine consists of 33 small bones called vertebrae. These bones are stacked on top of each other.

Function: It supports the body, protects the spinal cord, and allows flexible movement.

3. The Ribcage

Structure: The ribcage is made up of 12 pairs of ribs connected to the spine at the back and to the sternum (breastbone) at the front.

Function: It protects the heart and lungs.

4. The Diaphragm

Structure: The diaphragm is a large, dome-shaped muscle located below the lungs.

Function: It helps in breathing by contracting and expanding, allowing air to flow in and out of the lungs.

5. The Girdles

Shoulder Girdle: Connects the arms to the body.

Pelvic Girdle: Connects the legs to the body.

Function: They provide attachment points for the limbs and support the weight of the body.

6. The Limbs

Upper Limbs (Arms): Help in holding, lifting, and performing various activities.

Lower Limbs (Legs): Support body weight and help in walking, running, and jumping.

Structure of Bones

Bones: Are hard and strong. They consist of:

Bone Marrow: A soft, spongy tissue inside bones where blood cells are produced.

Cartilage: A soft, flexible tissue found at the ends of bones. It prevents bones from rubbing against each other.

Types of Joints and Their Functions

Joints are places where two or more bones meet. They help in movement and flexibility. There are four main types of joints:

1. Pivot Joint:

Location: Found in the neck.

Function: Allows the head to rotate from side to side.

2. Hinge Joint:

Location: Found in the elbows, knees, fingers, and toes.

Function: Allows movement in one direction, like opening and closing a door.

3. Ball and Socket Joint:

Location: Found in the shoulders and hips.

Function: Allows movement in all directions, including rotation.

4. Gliding Joint:

Location: Found in the wrists and ankles.

Function: Allows bones to slide over each other, providing flexibility.

The Muscular System

Muscles are tissues that help the body move. There are three types of muscles:

1. Cardiac Muscles:

Location: Found only in the heart.

Function: They help the heart pump blood throughout the body.

2. Smooth Muscles:

Location: Found in the walls of internal organs like the stomach and intestines.

Function: They help in involuntary actions like digestion.

3. Skeletal Muscles:

Location: Attached to the bones.

Function: They help in voluntary movements like walking, running, and lifting objects.

How the Arm Folds and Stretches

When you bend your arm, the biceps (the muscle on the front of your arm) contracts and the triceps (the muscle on the back of your arm) relaxes.

When you straighten your arm, the triceps contract and the biceps relax.

Taking Care of Bones and Muscles

1.Eating a Balanced Diet:

Eat foods rich in calcium (milk, cheese, yogurt) and vitamin D to keep bones strong.

Protein-rich foods (eggs, meat, beans) help maintain strong muscles.

2. Exercise:

Regular exercise strengthens bones and muscles.

Practicing yoga improves flexibility and strength.

3. Maintaining Good Posture:

Sitting and standing straight prevents strain on bones and muscles.

4. Avoiding Injuries:

Wear protective gear during sports to prevent bone and muscle injuries.

5. Staying Hydrated:

Drinking enough water keeps muscles healthy and prevents cramps.

Summary

The skeletal system provides support, protection, and helps in movement.

Bones are strong and contain bone marrow that produces blood cells.

Joints connect bones and allow movement.

The muscular system works with bones to enable body movements.

Taking care of our bones and muscles includes eating a balanced diet, exercising, and practicing yoga.

By understanding and taking care of our skeletal and muscular systems, we can ensure our bodies remain strong, healthy, and active!