Respiratory System – Structure, Functions, and Common Disorders

Respiratory System – The respiratory system is one of the most vital systems in the human body. It is responsible for taking in oxygen—essential for cell metabolism—and removing carbon dioxide, a waste product. Understanding how this system works helps learners appreciate how breathing keeps the body alive and balanced.

Overview of the Respiratory System

The respiratory system includes both the upper and lower airways. These structures ensure that oxygen reaches the lungs and that carbon dioxide is efficiently removed.

Main components include:

Nose and mouth: Entry points for air.

Pharynx (throat): Passageway for air to reach the larynx.

Larynx (voice box): Contains vocal cords and connects the throat to the trachea.

Trachea (windpipe): A tube that directs air to the lungs.

Bronchi and bronchioles: Branching airways that distribute air throughout the lungs.

Lungs: The main organs where gas exchange occurs.

Alveoli: Tiny air sacs surrounded by capillaries where oxygen enters the blood and carbon dioxide exits.

Function of the Respiratory System

The primary function is gas exchange — the transfer of oxygen from inhaled air into the blood and the removal of carbon dioxide from the blood into exhaled air.

Key functions include:

1. Ventilation: The process of moving air in and out of the lungs.

2. External respiration: The exchange of gases between alveoli and blood.

3. Internal respiration: Exchange of gases between blood and body tissues.

4. Oxygen transport: Oxygen binds to hemoglobin in red blood cells for distribution.

5. Carbon dioxide elimination: Carbon dioxide, produced by metabolism, is exhaled.

6. Speech production: The larynx enables vocal sounds during exhalation.

7. Smell (Olfaction): The nasal cavity contains receptors for detecting odors.

Medical Terms Related to the Respiratory System

Let’s explore important terms and their meanings from the image provided:

Anoxia

A severe condition characterized by a lack of oxygen in arterial blood and body tissues. It can lead to tissue damage if prolonged.

Antitussives

These are cough-suppressant drugs that reduce the urge to cough, often used in dry cough conditions.

Apnea

Refers to the absence of breathing for a temporary period. Sleep apnea is a common disorder where breathing repeatedly stops during sleep.

Bradypnea

Means slow breathing — often seen in drug overdose or brain injury affecting respiratory centers.

Bronchoconstriction

Narrowing of the airways due to muscle contraction in the bronchial walls, commonly observed in asthma or allergic reactions.

Bronchodilator

A medication that widens airways, improving airflow. These are vital in treating asthma and chronic obstructive pulmonary disease (COPD).

Cyanosis

A bluish-gray discoloration of the skin and mucous membranes due to low oxygen levels in the blood.

Dyspnea

Refers to difficulty in breathing or shortness of breath, often a symptom of heart or lung diseases.

Expectorant

Drugs that thin and loosen mucus, making it easier to expel sputum during coughing.

Hypoxemia

Indicates a low oxygen level in the arterial blood — an early sign of respiratory failure or hypoxia.

Orthopnea

Describes shortness of breath when lying flat, typically associated with heart failure or pulmonary congestion.

Tachypnea

Refers to rapid breathing, often seen in fever, anxiety, or lung infections.

Common Respiratory Disorders

1. Asthma:
A chronic inflammatory condition leading to airway constriction, wheezing, and breathlessness.

2. Chronic Obstructive Pulmonary Disease (COPD):
Includes chronic bronchitis and emphysema — both restrict airflow and cause difficulty in exhaling.

3. Pneumonia:
Infection that inflames air sacs (alveoli), filling them with fluid or pus.

4. Tuberculosis (TB):
A bacterial infection caused by Mycobacterium tuberculosis affecting the lungs.

5. Bronchitis:
Inflammation of the bronchial tubes, often causing persistent cough and mucus production.

6. Emphysema:
Damage to alveoli resulting in reduced surface area for gas exchange.

7. Sleep Apnea:
Repeated interruptions in breathing during sleep, leading to daytime fatigue and cardiovascular risks.

8. Lung Cancer:
Uncontrolled growth of abnormal cells in lung tissue; smoking is a major cause.

9. Pulmonary Edema:
Fluid accumulation in lungs, usually due to heart problems.

10. Pleural Effusion:
Accumulation of fluid in the pleural space, causing chest pain and breathing difficulty.

Regulation of Breathing

Breathing is an involuntary process controlled by the brainstem (medulla oblongata and pons).

Medulla: Detects carbon dioxide levels and adjusts breathing rate.

Pons: Smoothens the transition between inhalation and exhalation.

Chemoreceptors: Found in arteries, they sense oxygen, carbon dioxide, and pH levels.

Diagnostic Tests for Respiratory Health

Spirometry: Measures lung capacity and airflow.

Pulse Oximetry: Monitors blood oxygen levels.

Chest X-ray: Reveals infections, tumors, or fluid buildup.

Arterial Blood Gas (ABG) Test: Determines oxygen and carbon dioxide levels in blood.

CT Scan: Provides detailed lung imaging for complex conditions.

Maintaining a Healthy Respiratory System

1. Avoid smoking and pollutants.
2. Exercise regularly to strengthen lung capacity.
3. Maintain good posture to improve chest expansion.
4. Eat antioxidant-rich foods (fruits, vegetables) to support lung health.
5. Stay hydrated — helps keep mucous membranes moist.
6. Practice deep-breathing exercises like diaphragmatic breathing.
7. Get vaccinations against influenza and pneumonia.

FAQs About the Respiratory System

Q1. What is the main function of the respiratory system?

The main function is to supply oxygen to the blood and remove carbon dioxide from the body.

Q2. What are the two main parts of the respiratory system?

The upper respiratory tract (nose, pharynx, larynx) and the lower respiratory tract (trachea, bronchi, lungs).

Q3. What is the difference between hypoxia and hypoxemia?

Hypoxia refers to low oxygen in tissues, while hypoxemia means low oxygen in arterial blood.

Q4. What causes shortness of breath (dyspnea)?

Dyspnea can be caused by asthma, heart failure, pneumonia, or anxiety.

Q5. How do bronchodilators help asthma patients?

Bronchodilators relax the muscles of the airways, making breathing easier.