Respiratory System

Lecture 1 Overview

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Anatomy

• The respiratory system consists of upper and lower respiratory tracts

• Upper respiratory tract: filter and warm air • Lower respiratory tract: gas exchange• The upper and lower respiratory tract work

together to facilitate ventilation • Ventilation : is movement of air in and out of

the airways

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Upper respiratory tract

• The upper respiratory tract consists of : Nose, sinuses, nasal passages, pharynx, tonsils and adenoids, larynx, and trachea

• Nose: act as a passage for air ways. The nose is lined with highly ciliated mucus membrane called the nasal mucosa

• Nasal mucosa secrete mucous• The nose filter and humidify air

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Cont--Upper respiratory tract

• Paranasal sinus : four pairs of bony cavities that are lined with nasal mucosa

• Main function for sinus is to serve as a resonating chamber for speech

• Sinus is a common site for infection: sinusitis• Turbinate bone( conchae): bone with curve

increases the mucos membrane surface of nasal pasage

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Cont--Upper respiratory tract • Pharynx: connect nasal and oral cavities to the larynx• Tonsils : lymphoid tissue that has a role in immunity• The adenoid(pharyngeal tonsils): located in the roof

of nasopharynx• Larynx: the voice organ. Connect the pharynx and

trachea.• Epiglottis : cover the opening of larynx during

swallowing • Trachea : passage between larynx and bronchi

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Lower respiratory tract

• Lungs : left lung has 2 lobes . The right lung has 3 lobes

• Pleura : the lungs and the wall of thorax are lined with serous membrane called the pleura. The visceral pleura cover the lung and the parietal pleura line the thorax.

• Mediastinum: the middle of the chest

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• Pulmonary circulation: blood pumped by the right ventricle . The pulmonary artery pressure is 20-30 systole/ 5-15 diastole mmHg.

• Ventilation-perfusion: ventilation is the flow of gas while perfusion is the filling of pulmonary capilary with blood.

• Under normal condition 4L of air enter respiratory tract while 5 L blood go through pulmonary circulation : ventilation perfusion match

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• The normal ventilation/perfusion ratio is 4/5 which is 0.8

• Low ventilation perfusion ratio ( shunt) : perfusion exceed ventilation such as in most lung disease

• High ventilation perfusion ratio ( dead space): no enough blood reach the lung such as pulmonary embolism

• Silent unite : no ventilation and no perfusion such as pneumothorax

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Assessment of respiratory system• Dyspnea: difficult or labored breathing• Orthopnea: inability to breath easily except in

upright position• Cough : dry cough indicate viral infection, cough with

sputum especially at morning indicate bronchitis.• Sputum production: usually sputum that is thick

yellow, green or rust indicate bacterial infection.• Sputum: smoking is contraindicated in sever sputum

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• Chest pain• Wheezing : heared during expiration indicate

narrowing of the air way.• Clubbing of finger: spoon like nail• Hemoptysis : expectoration of blood from

respiratory tract indicate infection, cancer or abnormal blood vessles

• Cyanosis: very late indicator of hypoxia

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Respiratory system diagnostic evaluation

• Pulmonary function test: usually for patient with chronic respiratory disorder .

• Non invasive• Give many measures that include : tidal

volume, forced expiratory volume in 1 second, and vital capacity.

• Arterial blood gas samples : give PO2, PCO2, HCO3, pH

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Arterial blood gas sample (ABG )

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• Pulse oximetry: non invasive monitor for oxygen saturation. Should be above 95%. Value below 85% indicates that the tissue is not getting enough oxygen

• sputum culture: to identify microorganisms that cause an infection

• Sterile procedure• Patient is instructed to rinse the mouth, take few

deep breath then cough ( not spit) and expectorate into sterile container

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• Chest x ray: non invasive. Preferably taken during inhalation

• Computed tomography ( CT scan): multiple layers in the lung is scanned using narrow beam x ray. Give cross-sectional views for the lung

• Magnetic reasonance imaging (MRI): Similar to CT scan except that magnetic filed and radiofrequency is used.

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Bronchoscopy: • dierct visualization of the respiratory tract• Used to diagnose and treat respiratory disease.

also can be used to obtain specimen • Can be sued to remove secretion or foreign

bodies• Invasive ( need informed consent).• Patient should be NPO 6 hrs before the

procedure• Patient should remove denture

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Cont---Bronchoscopy:

• Minor sedation is given ( midazolam)• After the procedure NPO till patient resume

cough reflex

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Bronchoscopy

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• Thoracentesis: aspiration of pleural fluid for diagnostic or therapeutic purpose .

• Local anesthetic agent is needed• Needle is inserted in the pleural space while

patient is concious to aspirate either excess pleural fluid as in pleural effusion or blood

• Usually pain is minimal

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Position for Thoracentesis

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Thoracentesis

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• Pleural biopsy: excision of small amount of the pleura

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