Breathing Mechanics: Build a Model Lung

Breathing Mechanics: Build a Model Lung

Year 8 Biology Understanding respiratory system function Hands-on investigation

What Do You Already Know?

How do you think your lungs work? What makes you breathe in and out? Why do we need to breathe?

Why Do We Need to Breathe?

Oxygen is essential for cellular respiration Cells need oxygen to produce energy (ATP) Carbon dioxide is a waste product that must be removed Without breathing, cells would die within minutes

The Human Respiratory System

Key Structures of the Respiratory System

Nose/Mouth: Air enters and is filtered, warmed, humidified Trachea: Main airway tube to the lungs Bronchi: Branching tubes that divide into smaller airways Alveoli: Tiny air sacs where gas exchange occurs Diaphragm: Main muscle that controls breathing

The Amazing Diaphragm

The diaphragm is a dome-shaped muscle that sits below your lungs. When it contracts and flattens, it creates more space in your chest cavity, causing air to rush into your lungs.

How Breathing Works: The Mechanics

Inspiration (breathing in): Diaphragm contracts and moves down This increases chest cavity volume Lower pressure inside lungs draws air in Expiration (breathing out): Diaphragm relaxes and moves up Chest cavity volume decreases, pushing air out

Feel Your Diaphragm Working

Place one hand on your chest, one on your stomach Take a deep breath in - which hand moves more? The hand on your stomach should move out as your diaphragm pushes down Try breathing only with your chest - notice the difference

Building Our Model Lung: Materials Needed

Large plastic bottle (1-2 liters) 2 balloons (different colors if possible) Rubber band or tape Scissors Drinking straw Modeling clay or playdough

Model Lung Construction Steps

Cut the bottom off the plastic bottle Insert one balloon into the bottle through the neck Stretch the balloon opening over the bottle neck and secure Cut the second balloon and stretch it over the cut bottom of the bottle Attach the straw to represent the trachea

How Our Model Represents Real Lungs

Plastic bottle = Chest cavity (rib cage) Balloon inside bottle = One lung Bottom balloon = Diaphragm muscle Straw = Trachea (windpipe) When you pull the bottom balloon down, the lung balloon inflates

Testing Our Model

Gently pull the bottom balloon (diaphragm) down Watch the lung balloon inflate as air rushes in Push the diaphragm balloon up Observe the lung balloon deflate as air is pushed out Try different speeds - fast vs slow breathing