The primary function of the respiratory system is to supply the blood with oxygen in order for the blood to deliver oxygen to all parts of the body. The respiratory system does this through breathing. When we breathe, we inhale oxygen and exhale carbon dioxide. This exchange of gases is the respiratory system's means of getting oxygen to the blood.
Respiration is achieved through the mouth, nose, trachea, lungs, and diaphragm. Oxygen enters the respiratory system through the mouth and the nose. The oxygen then passes through the larynx (where speech sounds are produced) and the trachea which is a tube that enters the chest cavity. In the chest cavity, the trachea splits into two smaller tubes called the bronchi. Each bronchus then divides again forming the bronchial tubes. The bronchial tubes lead directly into the lungs where they divide into many smaller tubes which connect to tiny sacs called alveoli. The average adult's lungs contain about 600 million of these spongy, air-filled sacs that are surrounded by capillaries. The inhaled oxygen passes into the alveoli and then diffuses through the capillaries into the arterial blood. Meanwhile, the waste-rich blood from the veins releases its carbon dioxide into the alveoli. The carbon dioxide follows the same path out of the lungs when you exhale.
The diaphragm's job is to help pump the carbon dioxide out of the lungs and pull the oxygen into the lungs. The diaphragm is a sheet of muscles that lies across the bottom of the chest cavity. As the diaphragm contracts and relaxes, breathing takes place. When the diaphragm contracts, oxygen is pulled into the lungs. When the diaphragm relaxes, carbon dioxide is pumped out of the lungs.
Six basic parts of respiratory system are:
Nose
Pharynx
Larynx
Trachea
Bronchi
Lungs
Lets us now see the diagram of the respiratory system
Parts and Functions of Respiratory System -i
Nose
Structure: Nose has a basic framework of bone and cartilage attached to muscle and the outer skin lined with mucous membrane. The internal structure of the nose is connected to the pharynx by two openings called internal nares.
Function: Air breathed in through the nose is warmed, moistened and filtered as it passes through the conchae, three bony projections which are lined with mucous membrane composed of cells which can trap particles of dust and germs. The filtered air flows through the internal nare into the pharynx.
Pharynx:
Structure: Pharynx is shaped like a funnel. First portion of pharynx is known as nasopharynx. Middle portion as oropharynx. Lowest portion as laryngopharynx.
Function: Pharynx has three major functions; the passage of air and foo, forms a chamber for vocal sounds produced by larynx. Nasopharynx transports air and mucus downwards. It has an opening known as Eustachian tubes which equalizes air pressure between ears, nose and throat. Oropharynx receives air, food and fluid from the mouth. Laryngopharynx acts as a passageway for food, fluids and air.
Larynx:
Structure: The structure of ligaments, muscles and cartilage in the larynx control the tension in the cords. Epiglottis is a piece of elastic cartilage which is situated at the base of the tongue and is joined, while a flap of the cartilage can move freely.
Function: Larynx produces vocal sounds when air is expelled over the vocal cords, two membranes vibrate to produce sound. When food is swallowed the larynx rises and this triggers the free flap of the epiglottis to move downwards, thereby creating a lid over the larynx and channelling the food into the esophagus and not into the respiratory tract.
Parts and Functions of Respiratory System -ii
Trachea:
Structure: Trachea or wind pipe is approximately 10 cm long and its walls are supported by incomplete cartilage rings which provide support but also flexibility. Inner walls of trachea are covered with mucosal lining. The trachea then divides into the left and right bronchus.
Function: Trachea forms a passage for air to travel from larynx to lungs. The inner wall of trachea traps particles of dust and microorganisms which are moved upwardss and expelled from the respiratory tract.
Bronchi:
Structure: Trachea divides into left and right bronchus which are similar in structure to trachea and lead into left and right lung respectively. The bronchi then branch into secondary bronchi, then tertiary bronchi and the process of branching continues. Bronchioles branch into respiratory bronchioles then into alevolar ducts and finally into the alveolar sacs and the alveoli.
Function: Bronchi help in gaseous exchange within lungs.
Lungs:
Structure: Lungs are cone-shaped and extend from the collar bone to the surface of the diaphragm. The mid-line of each lung contains a region known as the hilus, the area through which blood and lymphatic vessels, nerves and primary bronchi enter and leave. Each lung is divided into lobes, three in the right lung and two in the left, within which there are smaller divisions known as lobules.
Function: Once the air reaches the alveoli, exchange of gases occur. Diffusion of gases takes place across the thin capillary and alveolar walls. Oxygen is passed into the capillaries for supply to body tissues and carbon dioxide is passed from the capillaries to the alveoli to be expelled from the body during exhalation.
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