The nose is the organ of smell and the main entrance for air into the respiratory system. It:
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Detects odors (smell),
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Filters, moistens, and warms the air we breathe,
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Plays a role in speech resonance.
🧩 Structure of the Nose
The human nose consists of external and internal parts:
🔹 External Nose
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Nostrils (nares): Openings that allow air in.
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Nasal bridge and tip: Made of cartilage and bone; gives the nose its shape.
🔹 Internal Nose (Nasal Cavity)
| Part | Function |
|---|---|
| Nasal septum | Wall dividing the nasal cavity into left and right sides |
| Turbinates (conchae) | Curved bones that increase surface area and warm/humidify air |
| Olfactory epithelium | Contains smell receptors; located at the top of the nasal cavity |
| Sinuses | Air-filled spaces that lighten the skull and affect voice |
| Mucous membrane | Produces mucus to trap dust, allergens, and microbes |
| Cilia | Tiny hairs that move mucus and debris out of the nose |
🧠 Main Functions of the Nose
| Function | Description |
|---|---|
| Breathing | Draws air in and passes it to the lungs |
| Filtering | Traps dust, microbes, and allergens with mucus and hairs |
| Humidifying & warming | Conditions the air before it reaches the lungs |
| Smelling (olfaction) | Detects odors and sends signals to the brain's smell center |
| Resonance in speech | Helps amplify and shape the sound of your voice |
⚙️ How Smell Works
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Airborne molecules enter the nose and reach the olfactory epithelium.
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Olfactory receptors detect the scent and send electrical signals.
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These signals go through the olfactory nerve to the olfactory bulb.
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The brain interprets the signals as specific smells (like flowers, smoke, or food).
🧠 Fun fact: Humans can detect over 10,000 different smells!
🩺 Common Nose-Related Problems
| Condition | Description |
|---|---|
| Rhinitis | Inflammation of the nasal lining (due to allergy or virus) |
| Sinusitis | Infection or inflammation of the sinuses |
| Nasal congestion | Blockage of nasal passages due to swelling or mucus |
| Nosebleeds (epistaxis) | Bleeding from nasal blood vessels (often due to dryness or trauma) |
| Anosmia | Loss of the sense of smell (can be caused by colds, injury, or COVID-19) |
| Deviated septum | Crooked nasal septum that may affect breathing |
| Nasal polyps | Noncancerous growths in the nasal passage |
🧪 Tests & Diagnostics
| Test Name | Purpose |
|---|---|
| Nasal endoscopy | Visual inspection of the nasal cavity with a tiny camera |
| Smell test | Evaluates ability to identify different odors |
| CT scan or MRI | Used for diagnosing sinus or structural problems |
| Allergy tests | Identify triggers of allergic rhinitis |
✅ Summary Table
| Part | Function |
|---|---|
| Nostrils & septum | Let air in and divide the nasal cavity |
| Turbinates | Warm, filter, and humidify the air |
| Olfactory area | Detect and process smell |
| Sinuses | Reduce skull weight and affect voice |
| Mucus & cilia | Trap and remove dust and microbes |
🧠 Extra Fun Facts
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The olfactory system is directly linked to memory and emotions.
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Dogs have 40 times more smell receptors than humans.
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Your nose warms the air to body temperature before it reaches the lungs.