Structure and function of the Structure and function of the respiratory systemrespiratory system

Functions of the respiratory systemFunctions of the respiratory system

The respiratory is the breathing mechanism The respiratory is the breathing mechanism of the body. It includes the mouth, nose, of the body. It includes the mouth, nose, larynx voice box), trachea (wind pipe), larynx voice box), trachea (wind pipe), lungs, diaphragm, intercostal muscles and lungs, diaphragm, intercostal muscles and the thoracic cage (rib cage).the thoracic cage (rib cage).

The respiratory system helps the body take The respiratory system helps the body take in oxygen and remove carbon dioxide and in oxygen and remove carbon dioxide and heat.heat.

Structure of the respiratory systemStructure of the respiratory system

Passage of oxygen through the bodyPassage of oxygen through the body

When we breathe in, oxygen comes in through the When we breathe in, oxygen comes in through the nose and mouth. Air comes down the nose and mouth. Air comes down the tracheatrachea and and enters the enters the bronchibronchi, the main tubes that branch off , the main tubes that branch off the windpipe into each lung. The bronchus goes the windpipe into each lung. The bronchus goes through all the lobes of the lung, and branches out through all the lobes of the lung, and branches out like an upside-down tree into smaller like an upside-down tree into smaller bronchiolesbronchioles which divide into tiny which divide into tiny alveolar sacsalveolar sacs and and alveolialveoli. . These air sacs allow oxygen and other nutrients to These air sacs allow oxygen and other nutrients to change places.change places.

Gaseous exchangeGaseous exchange The method by which oxygen and carbon The method by which oxygen and carbon

dioxide change places is called dioxide change places is called gaseous gaseous exchange. exchange. These gases can only change These gases can only change places through the process of diffusion. places through the process of diffusion. This is where a high concentration of gas This is where a high concentration of gas moves to a low concentration of gas. The moves to a low concentration of gas. The exchange of these gases occurs in the exchange of these gases occurs in the capillary network.capillary network.

Capillary networkCapillary network The high concentration of The high concentration of

oxygen found in the alveoli oxygen found in the alveoli during inspiration (breathing during inspiration (breathing in) moves to the smaller in) moves to the smaller vessels of the pulmonary vessels of the pulmonary vein. This is so that blood vein. This is so that blood can take oxygen to the heart can take oxygen to the heart for distribution. The high for distribution. The high concentration of carbon concentration of carbon dioxide in the smaller vesels dioxide in the smaller vesels of the pulmonary artery of the pulmonary artery moves to the alveoli, so that moves to the alveoli, so that it can be removed during it can be removed during expiration (breathing out)expiration (breathing out)

Mechanics of breathingMechanics of breathing InspirationInspiration During inspiration the During inspiration the

lungs need to expand lungs need to expand so they can hold more so they can hold more air. In order to make air. In order to make room for the lungs to room for the lungs to do this, the do this, the diaphragm contracts diaphragm contracts and the ribs move up and the ribs move up and out due to the and out due to the contraction of the contraction of the intercostal muscles.intercostal muscles.

ExpirationExpiration During expiration, the During expiration, the

lungs slightly deflate; lungs slightly deflate; when this happens do when this happens do not take up as much not take up as much room and so the ribs can room and so the ribs can move downwards and move downwards and inwards and the inwards and the diaphragm can relax. diaphragm can relax. This helps the lungs to This helps the lungs to expel some of the air expel some of the air inside them.inside them.

Key termsKey termsTERMTERM DESCRIPTIONDESCRIPTION

Breathing frequencyBreathing frequency The amount of breaths per The amount of breaths per minuteminute

Tidal volumeTidal volume The volume of air breathed in The volume of air breathed in or out per breathor out per breath

Minute ventilation Minute ventilation Minute ventilation the volume Minute ventilation the volume of air breathed per minuteof air breathed per minute

Vital capacityVital capacity Maximum amount of air that Maximum amount of air that can be forcibly inhaled and can be forcibly inhaled and exhaled In one breathexhaled In one breath

Total lung capacityTotal lung capacity All the air in the lungs after a All the air in the lungs after a maximum inhalationmaximum inhalation

Residual lung volumeResidual lung volume The amount of air left in the The amount of air left in the lungs after a forced breath outlungs after a forced breath out