Welcome to GattPrep!
Breathe in… breathe out. You’ve just used your respiratory system without even thinking about it! Amazing, isn’t it?
Every living cell in your body needs oxygen to release energy from food. The respiratory system is like your body’s air delivery service—it brings in oxygen and removes carbon dioxide, a waste gas. Without it, your cells would stop working, and you wouldn’t survive.
In this lesson, you’ll learn the structure and function of the human respiratory system, the process of breathing, and how this vital system works with others to keep you alive.
The respiratory system is a group of organs that work together to help you breathe. Its main functions are:
Taking in oxygen from the air.
Removing carbon dioxide, a waste product.
Enabling gas exchange in the lungs.
Here’s a simplified view of the major parts and their functions:
| Part | Function |
|---|---|
| Nose/Nasal Cavity | Warms, moistens, and filters air |
| Pharynx (Throat) | Pathway for air and food |
| Larynx (Voice Box) | Produces sound; blocks food from airways |
| Trachea (Windpipe) | Main airway that carries air to lungs |
| Bronchi | Two tubes that lead into the lungs |
| Bronchioles | Smaller branches inside the lungs |
| Alveoli | Tiny air sacs for gas exchange |
| Diaphragm | Muscle that helps with breathing |
Breathing involves two phases:
Inhalation (breathing in):
Diaphragm contracts and moves downward.
Chest cavity expands.
Air is drawn into the lungs.
Exhalation (breathing out):
Diaphragm relaxes and moves upward.
Chest cavity shrinks.
Air is pushed out of the lungs.
This movement of air is controlled automatically by your brainstem.
This happens in the alveoli, which are tiny balloon-like air sacs.
| Gas | Movement |
|---|---|
| Oxygen (O₂) | From alveoli → into blood |
| Carbon dioxide (CO₂) | From blood → into alveoli (then exhaled) |
This process is called diffusion.
| Type | Uses Oxygen? | Products | Example |
|---|---|---|---|
| Aerobic | ✅ Yes | Energy + CO₂ + Water | Normal breathing |
| Anaerobic | ❌ No | Less energy + Lactic acid | During heavy exercise |
| Condition | Description | Prevention |
|---|---|---|
| Asthma | Airways swell and narrow | Avoid triggers, use inhaler |
| Pneumonia | Infection of the lungs | Rest, antibiotics, vaccines |
| Tuberculosis (TB) | Bacterial lung infection | Early diagnosis, medication |
| Lung Cancer | Uncontrolled cell growth | Avoid smoking, air pollution |
🧠 Problem: You are running laps around your school field. After a while, you start breathing heavily and feel out of breath. What changes are happening in your respiratory system and why?
✅ Step-by-Step Solution:
During exercise, your body needs more oxygen and produces more carbon dioxide.
Your diaphragm contracts faster to increase breathing rate.
More air flows in and out of the lungs to keep up with oxygen demand and remove extra CO₂.
✔️ Answer: Your respiratory system increases breathing rate to deliver more oxygen to muscles and remove excess carbon dioxide during exercise.
(a) The tiny air sacs in the lungs where gas exchange happens are called _________.
(b) The muscle that helps you breathe by moving up and down is the __________.
Answers:
(a) alveoli
(b) diaphragm
| Part | Function |
|---|---|
| (i) Trachea | A. Produces sound |
| (ii) Larynx | B. Carries air to lungs |
| (iii) Alveoli | C. Site of gas exchange |
Answers:
(i) → B
(ii) → A
(iii) → C
Q: Why is it important that the alveoli are surrounded by blood capillaries?
A: Because this allows oxygen to diffuse into the blood and carbon dioxide to diffuse out quickly and efficiently.
Let’s review what we covered:
The respiratory system helps us take in oxygen and release carbon dioxide.
Key parts include the trachea, bronchi, lungs, alveoli, and diaphragm.
Breathing is controlled by the diaphragm and involves inhalation and exhalation.
Gas exchange occurs in the alveoli by diffusion.
Disorders like asthma and pneumonia affect respiratory health.
Think about what happens when you’re climbing stairs or running. Why do you breathe faster? Can you explain how your respiratory system responds to physical activity?
Write your answer in your science journal or share it in class!
English