Human Anatomy, Physiology, and Health Sciences

The Skeletal System

Your body has many parts that work together. One important part is the skeletal system.

The skeletal system is all the bones in your body. Bones make a strong frame inside you. This frame helps your body stand up, move, and stay in shape.

Think of bones like the strong sticks inside a tent. The tent needs the sticks to hold it up. Your body needs bones to hold it up too.

What bones do

• Hold up your body so you can stand, sit, and walk.
• Protect important body parts inside you.
• Help you move when they work with muscles.

Bones hold up your body

Your bones give your body its shape. Without bones, your body would be soft and floppy. Bones help you stand tall.

Your legs have big bones that help you stand and walk. Your back has many small bones that help you sit up and bend.

Bones protect body parts

Some bones act like hard covers. They help keep important body parts safe.

• Your skull protects your brain.
• Your rib cage helps protect your heart and lungs.

If you gently touch your head, you can feel the hard bone of your skull. If you touch your chest, you may feel your ribs. These bones are helping protect parts inside your body.

Bones help you move

Bones do not move by themselves. They work with muscles.

Muscles pull on bones. This helps your body move. When you run, jump, wave, or bend your arm, your bones and muscles are working together.

For example, your arm has bones inside it. Your muscles pull on those bones so you can lift a toy, draw a picture, or throw a ball.

Important bones to know

• Skull - the bone in your head
• Ribs - the bones in your chest
• Back bones - the bones in your back
• Arm bones - bones that help you lift and carry
• Leg bones - bones that help you stand, walk, and run

You have many bones in your body. They all work together as one skeletal system.

How the skeletal system and muscles work together

Your skeletal system does not work alone. It works with your muscles. Bones give your body a strong frame, and muscles help pull the bones to make movement.

When you kick a ball, your leg bones and leg muscles work together. When you nod your head, your neck muscles and bones work together. When you climb, many bones and muscles work together at the same time.

Keeping bones healthy

Your bones are strong, and it is important to take care of them.

• Eat healthy foods.
• Play and exercise safely.
• Wear a helmet when needed to help protect your skull.
• Be careful when running and climbing.

Taking care of your body helps keep your bones safe and strong.

Worked Examples

Example 1: Which body part protects the brain?

Question: What bone helps protect your brain?

Think: The brain is in your head. The hard bone around your head is the skull.

Answer: The skull protects the brain.

Example 2: Which bones help protect the heart?

Question: What bones help protect your heart?

Think: Your heart is in your chest. The bones in your chest are the ribs.

Answer: The rib cage helps protect the heart.

Example 3: How do you move your arm?

Question: Do bones move your arm all by themselves?

Think: Bones need help to move. Muscles pull on bones.

Answer: No. Bones and muscles work together to move your arm.

Example 4: Why does your body need bones?

Question: What are two jobs bones do?

Think: Bones hold up the body, protect body parts, and help with movement.

Answer: Bones hold up your body and protect important body parts.

Let’s Remember

1. The skeletal system is all the bones in your body.
2. Bones hold up your body and give it shape.
3. Bones protect important parts like the brain and heart.
4. Bones work with muscles to help you move.

Summary

The skeletal system is the framework of bones inside your body. Bones help your body stay strong and stand up.

Bones also protect important body parts. The skull protects the brain, and the rib cage helps protect the heart and lungs.

Bones and muscles work together so you can move. Your skeletal system is an important part of your body every day.

The Nervous System and Sensory Processing

Your body has a very special helper called the nervous system. The nervous system helps you feel, think, and move.

The nervous system has three big parts:

• The brain in your head
• The spinal cord in your back
• Nerves all through your body

You can think of the brain like the body's boss or a computer. It gets messages, figures them out, and tells your body what to do next.

The spinal cord is like a big road for messages. It carries messages between your brain and your body.

Nerves are like tiny message paths. They bring messages from your eyes, ears, nose, tongue, and skin to your brain. They also carry messages from your brain to your muscles.

What are senses?

Your senses help you learn about the world around you. You have five senses:

• Seeing with your eyes
• Hearing with your ears
• Smelling with your nose
• Tasting with your tongue
• Touching with your skin

When you use your senses, your body collects information. This is called sensory input. That means your body is taking in clues from the world.

For example, your eyes see a red ball. Your ears hear a bell. Your skin feels something warm. These are all kinds of sensory input.

How sensory processing works

Sensory processing means your body takes in information and your brain makes sense of it.

It happens in steps:

1. Your sense organ finds something. For example, your eyes see a dog.
2. Nerves carry the message.
3. The message travels to the brain, often through the spinal cord.
4. Your brain understands the message.
5. Your brain sends back a new message to your muscles.
6. Your body responds. Maybe you smile and wave.

This can happen very fast. Your body is very good at sending messages quickly.

The brain helps you stay safe

Your nervous system helps protect you. If you touch something too hot, your skin feels it right away. Nerves send a message. Your brain and body work together to pull your hand away.

This helps keep you safe from harm.

Muscles listen to messages too

Your muscles help you move. But muscles need directions from the brain.

If your brain says, "Kick the ball," nerves carry that message to your leg muscles. Then your leg moves.

So, the nervous system and muscles work as a team.

All the parts work together

Your brain, spinal cord, nerves, sense organs, and muscles all help one another. They are interdependent, which means they work together.

If you hear your name, your ears gather the sound, nerves carry the message, your brain knows it is your name, and your muscles help you turn your head.

Worked Example 1: Hearing your teacher

Question: What happens when your teacher says, "Line up"?

Step 1: Your ears hear the words.

Step 2: Nerves carry the message.

Step 3: Your brain understands the words.

Step 4: Your brain sends a message to your muscles.

Step 5: You stand up and walk to line up.

Answer: Your nervous system helps you hear, understand, and move.

Worked Example 2: Touching something cold

Question: What happens when you hold an ice cube?

Step 1: Your skin feels something cold.

Step 2: Nerves send the message.

Step 3: Your brain knows, "This feels cold!"

Step 4: Your brain may tell your hand muscles to drop it or hold it carefully.

Answer: Your skin, nerves, brain, and muscles work together.

Worked Example 3: Seeing a ball and catching it

Question: How do you catch a ball?

Step 1: Your eyes see the ball coming.

Step 2: Nerves send that message to your brain.

Step 3: Your brain decides, "Put your hands up!"

Step 4: Your brain sends a message through nerves to your arm and hand muscles.

Step 5: Your hands move to catch the ball.

Answer: Your nervous system helps you see and react fast.

Worked Example 4: Smelling cookies

Question: What happens when you smell cookies baking?

Step 1: Your nose smells the cookies.

Step 2: Nerves carry the message to your brain.

Step 3: Your brain says, "That smells good!"

Step 4: Your brain may tell your body to walk to the kitchen.

Answer: Smell is a sense, and your nervous system helps you notice it and respond.

Things to remember

• The brain is the body's boss or computer.
• The spinal cord carries messages between the brain and body.
• Nerves carry messages all around the body.
• Your five senses help you get information.
• Sensory processing means the brain understands information from the senses.
• The brain sends messages to muscles so your body can move.
• All parts of the nervous system work together to help you stay safe and do everyday things.

Brief Summary

The nervous system helps your body feel, think, and move. Your senses collect information, nerves carry messages, the brain understands them, and then the brain tells your muscles what to do. This is how you react when you see, hear, smell, taste, or touch something.