Introduction to the Respiratory System

The Respiratory system is a system of structures that revolves around intaking air and and removing harmful gaseous waste from the body.

Fun Fact: The Lungs are the only human organ that can float on water!

• Lungs (The organ that drives the whole respiratory system)

• Nose

• Larynx (Voice Box)

• Pharynx (Throat)

• Trachea (Windpipe)

• Bronchi

• Diaphragm

Your body needs oxygen for cellular respiration. During cellular respiration, cells break down glucose, which releases energy that our body can use.

You use this energy in your everyday activities but you also use this energy to maintain homeostasis and perform actions like removing wastes, growing, and regulating body temperature.

However, cellular respiration doesn't just require oxygen from the respiratory system. No it requires multiple systems working together which we will come to understand in due time.

When you breathe in, air and particles such as pollen and dirt move through a series of structures and then to the lungs.

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One of these structures is the nose, which pictured to the right.

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The Nose is responsible for filter trapping larger particles before reaching the lungs. There are also cells in the nose that line the nasal cavity and produce mucus to moisten the air and trap more particles.

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The air that enters the nose then travels to pharynx or throat.

From the nose the air we breathe then enters into the pharynx. Here in the picture the pharynx is separated into the

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1. Nasopharynx: allows breathing through the nose.

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2. Oropharynx: vital to both respiratory and digestive systems, many swallowing muscles are located here as well as passing food from the mouth to other parts of the hypopharynx.

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3. Hypopharynx: Also called the laryngopharynx, this is a critical point that separates the esophagus from the Larynx and Windpipe.

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To recall the different parts of the Pharynx just think NOH; Naso, Oro, and Hypopharynx!

Next in the whole process of breathing is the Trachea or Windpipe.

But have you ever wondered why how our throats ensure food does not go down our windpipe? Well the Epiglottis pictured has a role to play in that. It is a flap that actually closes to cover the trachea so that food does not get into your windpipe.

Have you ever wondered why we cough or what causes the coughing? Well wonder no more because you can look at the diagram shown to get a better idea.

Basically the cells that line the trachea have specialized "hairs" called cilia (singular: cilium). These cilia sweep mucus made by the cells in the trachea up to the pharynx. If particles irritate these cilia "hairs" then you cough, which sends the particles back into the air.

• Air is going to travel down the trachea into either the left or right bronchus.

• These two bronchus then split into multiple pathways called secondary bronchi.

• You then have further splits into tertiary bronchi and then finally we have the bronchioles.

• Bronchioles are the smallest division of the main bronchus and are where we can find alveoli in the lungs.

• Alveoli (singular: alveolus) are tiny thin walled sacs of lung tissue where gases are able to move between the air and blood.

At the ends of the Bronchioles are these small balloon like sacs. There are around 700 million alveoli in each lung. The Alveoli are also covered in capillaries beds.​

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These alveoli facilitate gaseous exchange of oxygen and carbon dioxide between inhaled air and the bloodstream.

When a breath is taken during inhalation, the concentration of the incoming oxygen is higher in the alveolus than in the red blood cells. For this reason, oxygen will leave the alveolus and enter the red blood cells.

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During exhalation, the opposite occurs. The concentration of carbon dioxide is lower in the alveolus than in the red blood cells, thus, carbon dioxide leaves the red blood cell, enters the alveolus, and is exhaled.

The same air that moves in and out of our lungs also helps us speak, sing, shout, and whisper. This is due to the previously mentioned Larynx or "Voice Box" located that the top of the trachea.

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If you check out the picture to the right you will see the "Voice Box" contains vocal cords or vocal folds that can open and close.

We have muscles in our throat that can control the vocal cords in our larynx; the combination of air rushing into and out of voice box and muscular contractions lead to a sound being produced, that sound being your voice.

• Both the respiratory system and the circulatory system go hand in hand with one another.

• For the circulatory system to re-oxygenate the blood the lungs and alveoli are crucial to perform the gas exchange needed to expel CO2 and receive O2.

• For the respiratory system to perform any of its duties their must be blood pumping through each of the tissues in the system, this blood is where gas exchange can occur.

• Both systems work together to circulate blood throughout the body as shown in the picture to the right.