Human Respiratory System
Habish Ribin Haneef
The network of organs and tissues that help you breathe is called the respiratory system. The respiratory system’s primary function is to introduce oxygen into the body and expel carbon dioxide from the body. The respiratory system consists of lungs, blood vessels, and airways. The respiratory system also includes the muscles that power your lungs. Working together, these parts transport oxygen throughout the body and remove waste gases like carbon dioxide. In this blog let’s discuss the respiratory system in brief.
The important features of the human respiratory system are listed below,
- The energy is generated by the breakdown of glucose molecules in all living cells of the human body
- The inhaled oxygen travels to various parts of the body, where it is used in chemical reactions to burn food particles (to break down glucose molecules) at the cellular level
- To carry out essential life processes, the human body uses glucose molecules to discharge energy in the form of ATP- adenosine triphosphate molecules.
Parts of the Human Respiratory System:
The respiratory system consists of many parts that work together to help you breathe. Let’s see the different parts of the human respiratory system and their functions.
Nose: Nose is the part of the respiratory system that allows air to enter your body, then filters debris and warms and moistens the air. It gives you a sense of smell and helps shape your appearance. The exterior nostrils are divided by a framework of cartilaginous structure known as the septum. The septum separates the right nostril from the left nostril. The interior lining of the nostrils is covered by tiny hair follicles and they serve as the body’s first line of defence against foreign pathogens. They also provide extra humidity for inhaled air.
Larynx: Larynx is a hollow tube that allows air to pass from your throat to your trachea on the way to your lungs. The larynx is located in front of the neck. It consists of your vocal cords essential for human speech and hence the larynx is also called the “voice box.” In adults, the larynx is about two inches long. The main functions of the larynx include breathing, creating vocal sounds, and preventing food and other particles from getting into the trachea, lungs, and remaining parts of the respiratory system.
Pharynx: Pharynx is a muscular funnel-shaped passageway inside the body. The pharynx connects the mouth and nose to the oesophagus(leading to the stomach) and larynx(leading to the trachea and lungs). The pharynx is about 4.5 inches long and is located in the middle of the neck. The main functions of the pharynx include carrying air to the respiratory system, delivering food and liquid to the digestive system, pushing food into the oesophagus so that it’s not breathed in, equalizing pressure in the ears and draining fluid from the eyes. The pharynx consists of the nasopharynx, oropharynx, and hypopharynx.
The oropharynx is the middle part of the pharynx behind the mouth. The oropharynx allows air, food, and fluid to pass through.
The nasopharynx is the upper part of the throat behind the nose. It let’s air pass through.
The hypopharynx is the bottom part of the pharynx and is located near the larynx. The hypopharynx regulates the passage of air to the lungs and food and fluid to the oesophagus.
Trachea: The trachea is a long U-shaped tube that connects the larynx to the lungs. It is also called windpipe. The main function of the trachea is to carry air in and out of the lungs. The trachea provides a reliable pathway for oxygen to enter the body as it is a stiff flexible tube. In most people, the trachea is about 4 inches long. The trachea is located in the lower neck and upper chest, below the larynx. The trachea consists of two parts- cervical trachea and thoracic trachea. The trachea is made up of 16 to 20 cartilage rings. Mucosa, a moist tissue lines each ring of the tracheal cartilage. The mucosa consists of goblet cells and these cells produce a sticky substance called mucus. When you inhale, the mucus traps dust or other small particles and blocks them from reaching your lungs. The inner layer of the trachea consists of small, hair-like structures called cilia. The cilia help to push the mucus out of the trachea and as a result of this process you either expel the mucus or swallow it.
Bronchi: The bronchi are two large tubes that carry air from the windpipe to the lungs. The left bronchus carries air to your left lung and the right bronchus carries air to your right lung. Your bronchi distribute air within your lungs as you breathe and expand your lungs. The bronchi divide into secondary and tertiary bronchioles and it further divides into small air-sacs known as alveoli. Alveoli are tiny, balloon-shaped air sacs in the lungs. The function of the alveoli is to move oxygen and carbon dioxide molecules into and out of your bloodstream. A fluid called surfactant lines the alveoli and it is this fluid that maintains the shape of the air sac and helps keep it open so that oxygen and carbondioxide can pass.
Lungs: The lungs are known as the “center of the respiratory system.” These spongy, air-filled organs are located on either side of the chest (thorax). Our body require oxygen to stay healthy and at the same time needs to eliminate carbon dioxide. The lungs are designed to exchange these gases every time you breathe in and out. A thin tissue, called pleura covers the lungs. A thin layer of fluid acts as a lubricant allowing the lungs to slip smoothly as they expand and contract with each breath.
Epiglottis: The epiglottis is a small movable “lid” that prevents food and drink from entering the windpipe. It is located just above the larynx.
Diaphragm: The diaphragm is the major muscle of respiration. It is located below the lungs. A large, dome-shaped muscle, the diaphragm contracts rhythmically and continually. When you inhale, your diaphragm flattens and contracts and your chest cavity enlarges. When you exhale, your diaphragm relaxes and gets back to it’s dome shape and the air goes out of the lungs.
Ribs: The ribs are curved flat bones which form the majority of the thoracic cage. The main function of the ribs is to aid respiration. The ribs also surround and protect your lungs and heart.
Conditions affecting the Respiratory System
There are some factors affecting the respiratory system. This may be due to the entry of some foreign particles or organisms like bacteria, viruses, etc. or may be due to ageing. Let’s see some of these conditions that can create a bad impact on your respiratory system.
Allergies: Allergies are caused by inhaling proteins like dust, mold, and pollen. There are different types of allergies such as food allergies, skin allergies, and seasonal allergies. These allergies affect the upper respiratory tract. Some allergies cause mild symptoms like congestion, runny nose, and itchy throat. But some other allergies can be very serious leading to complications like anaphylaxis and closing of the airways.
Asthma: Asthma is a chronic disorder where your airways narrow and swell and may produce extra mucus. This will make breathing difficult and can cause strong coughing. When you breathe out, a whistling sound will also be produced. The signs and symptoms of asthma include shortness of breath, chest tightness or pain, and trouble in sleeping due to shortness of breath, coughing, or whistling.
Common cold: Common cold is a viral infection that affects your nose and throat. It is usually harmless. Many types of viruses can cause common cold. Most people recover from this sickness within a week or 10 days. The symptoms of common cold include runny or stuffy nose, sore throat, cough, congestion, sneezing, low-grade fever, and mild headache.
Laryngitis: Laryngitis is an inflammation that affects your voice box, the larynx. This condition occurs due to overuse, irritation, or infection to the larynx. The vocal cords are situated inside the larynx and in usual case, the vocal cords open and close smoothly, thereby forming sounds through their movement and vibration. But in the case of laryngitis, the vocal cords become irritated or inflamed and as a result of this, the vocal cords swell which distorts the sounds produced by air passing over them. Due to this situation, your voice may sound too rough and harsh and in some occasions, your voice cannot be even detected. The symptoms of laryngitis include hoarseness, loss of voice or weak voice, sore throat, dry throat, dry cough, and tickling sensation and rawness in the throat. Laryngitis may be acute or chronic.
Pharyngitis: Pharyngitis is commonly called “sore throat”. It is an inflammation that affects the pharynx that results in a sore throat. Pharyngitis is usually caused by bacterial (infection caused by streptococcus bacterium) or viral infections (common cold, flu). Fungus also causes pharyngitis. The symptoms of pharyngitis include sore throat, pain when speaking, pain when swallowing, and dry, scratchy throat.
Sinusitis: Sinusitis or sinus infection is an inflammation or swelling of the tissue lining the sinuses. The hollow spaces within the bones between your eyes, behind your cheek bones, and in your forehead are called sinuses. The sinuses produce mucus that keeps the inner part of your nose moist. This provides protection fro dust, allergens, and pollutants. Usually, sinuses are filled with air. But, when they becomes block or filled with fluid, germs can grow and this may cause infection. The common cold, allergic rhinitis (swelling of the lining of the nose caused by allergens), nasal polyps (small growth in the lining of the nose), and a deviated septum (shift in the nasal cavity). Sinusitis may be acute or chronic. The symptoms of acute sinusitis include facial pain or pressure, runny nose, stuffed-up nose, cough or congestion, loss of smell, fever, bad breath, fatigue, and dental pain. The symptoms of chronic sinusitis include nasal blockage, pus in the nasal cavity, a feeling of congestion or fullness in your face, and runny nose.
Bronchitis: The bronchial tubes carry air to and from your lungs. Bronchitis is the inflammation of the lining of bronchial tubes. Bronchitis may be acute or chronic. People with bronchitis usually cough up thickened mucus, which can be discoloured. The symptoms of bronchitis include cough, production of mucus (may be clear, white, yellowish-grey, green, or in some rare occasions strained with blood), fatigue, shortness of breath, chest discomfort, and slight fever and chills.
Chronic Obstructive Pulmonary Disease(COPD): COPD is a chronic lung disease that causes obstructed airflow from the lungs. This disorder is caused due to long-term exposure to harmful gases or irritating matter. Smoking is one of the main reasons for COPD. People with COPD have a high chance of developing serious health issues like heart disease and lung cancer. The symptoms of COPD include shortness of breath (especially during physical activities), chest tightness, wheezing, frequent respiratory infections, unintended weight loss, lack of energy, a chronic cough that produce mucus with clear, white, yellow or greenish colour, and swelling in ankles, feet or legs.
Pneumonia: Pneumonia is an infection that inflames the air sacs in one or both lungs. Bacteria, viruses, and fungi can cause pneumonia. The symptoms of pneumonia include chest pain during breathing and coughing, confusion or changes in mental awareness, fatigue, cough that produce phlegm, fever, nausea, vomiting or diarhhea, shortness of breath, sweating and shaking chills, and lower than normal body temperature. Pneumonia is more common in infants, children, people older than 65 years, and people with health problems or weak immune systems.
Lung cancer: Lung cancer is a type of cancer that badly affect your lungs. It is estimated that lung cancer is the leading cause of cancer deaths worldwide. Lung cancer commonly occurs in people who are addicted to smoking. Cigarette contains dangerous chemical compounds and toxic chemicals like tar, carbon monoxide, DDT, arsenic, formaldehyde, etc. that can damage your lungs. Hence, quitting smoking is one of the important ways to get rid of the threat of lung cancer. The symptoms of lung cancer include a cough that does not disappear, coughing up blood, chest pain, shortness of breath, unintended weight loss, hoarseness, headache, and bone pain.
Emphysema: Emphysema is a disorder that affects your lungs. In the case of emphysema, the air sacs in the lungs (alveoli) are damaged. Emphysema causes the interior parts of the air sacs to rupture and as a result of this, large air spaces are formed instead of small ones. This decreases the surface area of your lungs and also decreases the amount of oxygen reaching your bloodstream. When you exhale, the weak alveoli will not function properly and because of this, the old air gets trapped. This will not allow fresh, oxygen-rich air to enter your lungs. The main symptom of emphysema is shortness of breath. Emphysema may also lead to Chronic Obstructive Pulmonary Disease (COPD).
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Answer. Pleura
Answers. Asthma, Bronchitis, and Chronic Obstructive Pulmonary Disease (COPD)