Respiratory System in Humans (Pulmonary Respiration) : Respiratory Organs of Human Body (For CBSE, ICSE, IAS, NET, NRA 2022)

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The Human respiratory system consists of external nares or nostrils, nasal cavity, pharynx, larynx, trachea, bronchi, bronchiole and lungs. Air enters into the nasal cavity through the nostrils. The nasal cavity opens into the posterior part of pharynx. The pharynx leads into trachea or windpipe through a slit called glottis. While swallowing food, glottis gets covered by a small cartilaginous flap of skin called Epiglottis. The lungs lie in the thoracic cavity, which is separated from the abdominal cavity, by a muscular partition called Diaphragm. Within lungs, bronchi branch into many bronchioles. Each bronchiole terminates in a sac called alveolus or alveolar sac, giving the appearance of a bunch of grapes. Walls of alveoli are extremely thin and covered by blood capillaries. The lungs are covered by two thin membranes called Pleura.

Image Showing Human Respiratory System

Respiratory Organs of Human Body

Table Showing Respiratory Organs of Human Body
NostrilOpening of NoseFiltration of unwanted particles
Nasal cavityCovered with mucous membrane and ciliaTraps dust, bacteria, warms and moistens the air in the pharynx
Pharynx (Throat)Muscular TubeThe common passage for both respiratory gases and food moving into digestive passage, separated by epiglottis (Epiglottis is a flap like structure that closes the tracheal opening (opening of the windpipe) called glottis when food is swallowed) .
Larynx (Voice Box)A small cartilaginous organ with vocal cords: lined by ciliated epitheliumConnects pharynx to the trachea; helps in sound production
Trachea (Windpipe)Supported by C-shaped cartilaginous rings to prevent it from collapsing. Trachea divides into two bronchi and enters the two lungsPassages of air up to bronchi
Bronchus (Plural: Bronchi)Elastic, ciliated and covered with mucous epitheliumEnters the lungs and divides to form secondary bronchi, tertiary bronchioles and ultimately terminal bronchioles. Together they form the bronchial tree
BronchioleSmall terminal branch of bronchus leading to alveoliConvey air into alveoli
Alveoli (air sacs0Supplied with blood capillaries, thin moistExchange of Gases.
Image Showing Human Lungs
Mage Showing Branching of Bronchi upto Terminal Alveoli

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