Human Respiratory System

Breathing is the physiological mechanism through which terrestrial vertebrates transport air in and out of their lungs. Breathing is generally referred to as respiration. But it is also known as cellular respiration, which is the primary cause of breathing.

Cells require oxygen from the air to extract energy from glucose via respiration, which results in the production of carbon dioxide and water as waste. As a result, oxygen is required for every aspect of normal cellular activity, and oxygen shortage can result in serious health problems.

Breathing is easier with the respiratory system. Passive transport carries oxygen and carbon dioxide molecules from the air to the bloodstream in the alveoli tissue of the lungs, allowing oxygen to be absorbed. In contrast, carbon dioxide and water are removed.

Organs of the Respiratory Tract

Humans have the following parts in their respiratory system:

• Air is inhaled through the external nostrils.
• The nasal chamber is a hair and mucus-lined chamber that filters dust and dirt from the air.
• The pharynx is a tract located behind the nasal chamber that acts as an air and food conduit.
• The vocal cords, which are crucial in sound creation, are housed in the larynx, also known as the soundbox.
• The epiglottis, a flap-like structure covering the glottis, prevents food from entering the windpipe.
• The trachea is a long tube that runs through the middle of the thoracic cavity. It is divided into two bronchi: left and right.
• Each bronchus is further divided into bronchioles, which are smaller channels.
• The bronchioles end in alveoli, which are balloon-like structures.
• Humans have two lungs, sac-like organs covered by the pleura, a double-layered membrane.

Functions of the Respiratory System

• Inhalation and exhalation: The respiratory system, or pulmonary ventilation, helps in breathing. Air is inhaled through the nasal and oral passages. It enters the lungs via the pharynx, larynx, and trachea. The air is then exhaled through the same path. Pulmonary ventilation is triggered by changes in volume and air pressure in the lungs. The diaphragm and external intercostal muscles contract and the ribcage rises during regular inhalation. Air pressure drops when the volume of the lungs expands, and air rushes in. Muscles relax during regular exhalation. Air is ejected as the lungs contract, the air pressure rises, and the lungs contract.
• Exchange of gases from the lungs to the bloodstream: External respiration is a process that involves exchanging oxygen for carbon dioxide waste inside the lungs. Hundreds of millions of tiny sacs called alveoli carry out the breathing process. The oxygen inhaled by the alveoli diffuses into the pulmonary capillaries surrounding them. It attaches to haemoglobin molecules in red blood cells and circulates the body. In the meantime, carbon dioxide from deoxygenated blood diffuses into the alveoli and is exhaled.
• Exchange of gases from blood to body tissues: When the blood reaches the capillaries, it releases the oxygen carried around the body from the lungs. The oxygen diffuses into the body tissues through the capillary walls. Carbon dioxide diffuses into the bloodstream and is transported back to the lungs for exhalation.
• Smell or olfaction: When air enters the nasal cavities during inhalation, some molecules in the air trigger nervous system receptors on the cilia. The brain sends the signals to the olfactory bulbs.
• Sound generation: Sound created by structures in the upper respiratory tract of the respiratory system is known as phonation. During exhalation, air flows from the lungs to the larynx or voice box. The arytenoid cartilages are moved by muscles in the larynx when we talk. The vocal cords, also known as vocal folds, are pushed together by the arytenoid cartilages. When the cords are pressed together, air passing through causes them to vibrate, producing sound. Increased tension in the vocal cords leads to faster vibrations and higher-pitched sounds. When the tension is low, the vibrations are slower, and the pitch is low too.

Respiratory System Disorders

• Asthma is a breathing problem that causes wheezing due to bronchi and bronchioles inflammation.
• Emphysema is a chronic disease in which the alveolar walls are compromised, reducing the respiratory surface. A leading cause of emphysema is cigarette smoking.
• Occupational respiratory disorders are caused in certain industries, mainly grinding or stone-breaking. These industries produce so much dust that the body’s defence mechanisms are overwhelmed. Long-term exposure can cause inflammation and fibrosis (the development of fibrous structures), resulting in substantial lung damage. Workers should wear protective masks in such environments.

Conclusion

The respiratory system, which consists of air passageways, pulmonary veins, the lungs, and breathing muscles, assists the body in exchanging gases between the air, blood and the cells that make up the body. A majority of the respiratory system’s organs assist in air distribution, but only the tiny grape-like alveoli and alveolar ducts are responsible for actual gas exchange.