Breathe In: The Respiratory System
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Breathe In: The Respiratory System
Year 8 Biology Understanding How We Breathe Essential for Life
What Do You Already Know?
How many times do you breathe per minute? What happens when you hold your breath? 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 oxygen, cells die within minutes
The Complete Respiratory System
The Nose: First Line of Defense
Filters dust and particles from incoming air Warms cold air to body temperature Adds moisture to dry air Contains smell receptors
The Trachea: The Windpipe
Tube connecting throat to lungs Supported by C-shaped cartilage rings Lined with cilia and mucus About 12cm long in adults
Feel Your Breathing Structures
Place your hand on your throat and swallow Feel for the hard cartilage of your trachea Put your hands on your ribs and take a deep breath Notice how your chest expands
Bronchi and Bronchioles
Trachea branches into two main bronchi Bronchi divide into smaller bronchioles Like an upside-down tree structure Bronchioles end in tiny air sacs called alveoli
Alveoli: Where Gas Exchange Happens
Tiny air sacs at the end of bronchioles Surrounded by capillaries (tiny blood vessels) Oxygen passes into blood, carbon dioxide passes out About 300 million alveoli in each lung
Quick Check: Can You Match?
Which structure filters and warms air? What keeps the trachea open? Where does gas exchange occur? What carries oxygen in the blood?
The Diaphragm: Our Breathing Muscle
Large dome-shaped muscle below the lungs Contracts and flattens when breathing in Relaxes and rises when breathing out Works with rib muscles to change chest volume
Breathing In vs Breathing Out
{"left":"Diaphragm contracts and moves down\nRib muscles contract, ribs move up and out\nChest cavity gets larger\nAir pressure decreases\nAir rushes into lungs","right":"Diaphragm relaxes and moves up\nRib muscles relax, ribs move down and in\nChest cavity gets smaller\nAir pressure increases\nAir is pushed out of lungs"}