🔸 Components of the Human Respiratory Syste

🔹 Structure of the Respiratory Tract

The respiratory tract is like a road for air — a pathway that allows air to go in and out.

🔹 Two Major Divisions

1. Upper Respiratory Tract
2. Lower Respiratory Tract

Let’s start with the Upper Respiratory Tract:

🔸 Upper Respiratory Tract

1. Nasal Cavity 👃

• Air enters the body through nostrils.
• The nasal cavity is a large, open space behind your nose.
• It is divided by a nasal septum (a wall made of bone and cartilage).

✅ Functions:

• Warming and moistening air
  ➤ Blood vessels in the nose warm the air.
• Filtering air
  ➤ Hairs and sticky mucus trap dust and germs.
• Smelling
  ➤ Special sensors (chemoreceptors) help us smell.
• Helping in taste
  ➤ Smell contributes to how we experience flavors.

🔍 Example:
When you have a blocked nose, food tastes bland — because the sense of smell is reduced.

2. Pharynx (The Throat)

• The pharynx is a common passage for air and food.
• It connects:
  • Nose ➝ Larynx (for air)
  • Mouth ➝ Esophagus (for food)

📌 Important Point:
Since air and food share the same passage, the body has to control which one goes where — this is done using a flap called the epiglottis (explained shortly).

3. Larynx (Voice Box)

• The larynx is the part where your voice is produced.
• It connects the pharynx to the trachea (windpipe).
• Made of cartilage and muscles.
• Contains vocal cords — two bands of muscle.

💬 How Voice is Produced:
When air flows over these cords, they vibrate, just like strings of a guitar — and produce sound.

🎵 Example:
Tight cords = high pitch.
Loose cords = low pitch.

🔸 Epiglottis – The Gatekeeper

The epiglottis is a soft flap made of cartilage. It works like a lid to protect your lungs.

🛑 Its job:

• When you breathe, it stays open to let air go in.
• When you swallow food, it closes the airway to stop food from going into the lungs.

🚫 If food enters the airway, it causes choking — that’s why we sometimes cough when food “goes the wrong way.”

🔚 Recap of Upper Respiratory Tract

Part	Function
Nasal Cavity	Warms, moistens, and filters air; detects smell
Pharynx	Common passage for food and air
Larynx	Produces sound using vocal cords; connects to trachea
Epiglottis	Closes the windpipe when swallowing to protect the lungs from food