Note on Respiratory System Mechanism Of Sound

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mechanism of sound production

in resting condition the vocal cords lie at the anacute angle to one another enclosing the glottis between their edges the larynx is called abducted. no sound is produced but at the time of sound production the vocal cords are regulated by action of set laryngeal muscles attached to the cartilage of the larynx and become parallel to each other the vocal cords come closer and glottis size is decreased .this is called chink of glottis now the foul air is passed through them under pressure from the lungs the glottis being narrow the air concentrates and increase the pressure behind the vocal cords ,which start vibrating and sound is produced larynx condition called adducted, containing the vocal cords the larynx also enable vocalized by manipulating these cords to vibrate at a desired pitch when air is passed through the larynx the pitch of the voice is highly dependent upon the elasticity and tension in these true voice cords when the angle of the thorid cartilage decrease in male during puberty.

A trachea

it is the short tube about 10 to 11 cm in length thin-walled tubular structure which turns run downwards through the neck in font of oesophagus extend up to 5 to vertebra it is supported by 16 to 20 dorsally in complete C-shaped cartilage tracheal ring which prevents its collapsing. it is lined by pseudo stratified ciliated epithelium with mucus secreting goblets cell the mucous and debris upward into the pharynx.
where on its swallowed when the upper trachea or pharynx become blocked so as to cut off airways .as from swelling of the tissue a small incision is made in the throat and into the trachea in an opening called tracheotomy which allows air to pass into the windpipe.

fig trachea

Primary bronchi

trachea in the posterior bifuracte into two bronchi right branch is about 2.5 cm in length and left bronchus is about 5 cm in length looks small thin-walled tubular structure formed by the division of trachea at the level 5 the thoracic vertebra near the heart. these are also supported buy cartilage ting each primary bronchus enters the lungs of its won side through the hilus and from a bronchial intercome.

fig trachea


the diaphragm is a thin muscular wall lies in between thoracic cavity and abdominal cavity. the intercostal and abdominal muscles are responsible for contacting and expanding the thoracic cavity to effect respiration .the ribs serve a structure support for the whole thoracic arrangement and pleural membranes help provide lubrication for the respiratory organs so that they are not chafed during respiration.


lungs are of soft elastic and spongy organ present in air tight thoracic cavity one either side of the heart .It is surrounded thin transparent two-layered peritoneal sac it inner and outer layer is respectively called visceral pleural and parietal pleuron the pleura of the thorax are the serous membranes which enclose the upper chest cavity the parietal pleuron is the exterior layer of the pulmonary pleural sac ,which connects to the thorax wall the mediastinal membrane and the diaphragm muscles.

2 plural membrane are continuous over the primary bronchus .at the hilum between this layer there is narrow pleural cavity filled a watery pleural fluid which performs three functions:-

1 allows free frictionless movement of leather and the lungs expanded,
2 protect the lungs from mechanical shocks,
3 keeps the pleura tog,

each lung is conical shaped having an upper narrow apex and lower broader base. its outer convex posterior semi lunar shaped and inner concave surfaces are called costal diaphragmatic and mediastinal ,surface through which blood and primary bronchus and nerves enter the lung.

each lung is donated organs and is divided externally into lobes by transverse and oblique grooves called fissure .the left lung divided into 2 lobes superior and inferior lobes while the right lungs is divided into 3 lobes superior middle and inferior lobes the right and left lungs are each enclosed in pleural sac and are separated by mediastinum membrane which extends from the vertebral column in back to the sternum in front between, the lungs is space for the heart this cavity is more pronounced on the left lungs which are slightly concave and is called cardiac notch the pericardium of the heart is in direct contact with the pleural lining of the lungs and is attached to the centrally placed tendinous portion of the diaphragmatic muscles.

bronchial intercom

its network present inside the lungs formed by the division nad re-division of primary bronchus the bronchi are the tubes which carry air from the trachea to the inner recess of the lungs ,where it is can transfer oxygen to the blood in small air sac called alveoli. two main bronchi the right and left bronchus branch off the low end of the trachea in what is called tracheal bifurcation on the brounchus extends into each of the rights and left lungs right bronchus inside the lungs divides into three bronchi extends into each of the right and left lungs right bronchus inside the lungs divided into three smaller branches called secondary bronchi one bronchi to each lungs lobes.


bronchial intercom


Agrawal, sarita. principle of biology. 2nd edition . kathmandu: Asmita book Publication, 2068 ,2069

Mehta, Krishna Ram. Principle of biology. 2nd edition. kathmandu: Asmita, 2068,2069.

Jorden, S.L. principle of biology. 2nd edition . Kathmandu: Asmita book Publication, 2068.2069.

  1. trachea in the posterior bifuracte into two bronchii right brounch is about 2.5 cm in length
  2.  left bronchus is about 5 cm in length looks small thin walled tubular structure formed by the division of trachea
  3. diaphragm is a thin muscluar wall lies in between throcic cavity
  4. abodominal cavity the intercostal and abodominal muscles are responsible for contacting 
  5. lungs are of soft elastic and spongy ogan present in air tight throcic cavity one either side of heart It is surrounded thin transparent two layered peritoneal sac it inner
  6. outer layer are respitively called visceral pleural

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