Respiratory System

Respiratory System Main functions:

Provide oxygen to cells Eliminate carbon dioxide

Works closely with cardiovascular system to accomplish gas exchange

Gas exchange occurs in lungs

Upper Respiratory Passageways Air enters through nose, past sinus

cavities Air then passes through pharynx Pharynx divided into three regions:

Nasopharynx (upper) Oropharynx (middle) Laryngeal (lower)

Lower Respiratory Passageways and Lungs

Pharynx conducts air into trachea, through larynx and glottis

Epiglottis prevents food from entering respiratory tract

Larynx contains vocal cords (allows speech) Trachea divides into bronchus

Smallest tubes = bronchioles Alveoli = microscopic air sacs where gas exchange

occurs

Breathing Ventilation made up of:

Inspiration Phrenic nerve stimulates diaphragm to

contract and flatten Chest cavity enlarges Change in pressure causes air to be

pulled in Expiration

Breathing muscles relax Lungs return to original size Air forced out

Pulmonary Ventilation

Gas Transport Oxygen in blood

Attached to hemoglobin in red blood cells

Released to cells as needed

Carbon dioxide mostly as carbonic acid Amount formed regulates blood pH

Clinical Aspects of Respiration

Pulmonary function affected by conditions that: Cause resistance to air flow Limit proper expansion of chest

Conditions directly affecting respiratory system: Infection Injury Allergy Aspiration Cancer

Changes in Ventilation Changes in ventilation affect pH of blood

Alkalosis = too much carbon dioxide exhaled by hyperventilation (blood too alkaline)

Acidosis = too little carbon dioxide exhaled by hypoventilation (blood too acidic)

Infections Pneumonia

Caused by several different microorganisms Leading cause of death in debilitated

patients Tuberculosis

Caused by Mycobacterium tuberculosis Symptoms:

Fever Weight loss Weakness Cough Hemoptysis (sputum with blood)

Influenza Viral disease of respiratory tract

Emphysema Overexpansion and destruction of

alveoli Causes:

Exposure to cigarette smoke or pollution

Chronic infection Classified under chronic

obstructive pulmonary disease (COPD) heading

Asthma Narrowing of bronchial tubes Main factor may be irritation caused by

allergy Symptom of wheezing indicated by:

Constriction of bronchial tubes Edema of bronchial linings Accumulation of mucus

Extreme “attacks” may result in: Dyspnea Cyanosis

Disorders of Pleura

Pleurisy = inflammation of pleura, usually with infection Main symptom is pain which causes rapid, shallow

breathing Accumulation of substances between layers

of pleura lead to other conditions: Pneumothorax Empyema Hemothorax Hydrothorax

Fluids removed by thoracentesis

Lung Cancer

Leading cause of cancer-related deaths Usually cannot be detected early Metastasizes rapidly

Major risk factors: Cigarette smoking Other forms of cancer

Diagnosed by: Radiographic studies CT scans Sputum examination Bronchoscope

Respiratory Distress Syndrome

Occurs in premature infants Results from lack of surfactant in lungs Acute respiratory distress syndrome

May result from: Trauma Allergic reactions Infection Other causes

Involves edema that can cause respiratory failure

Diagnosis

Methods for diagnosing respiratory disorders: Radiographs CT scans MRI scans Lung scans Bronchoscopy Tests of pleural fluid removed with

thoracentesis

Methods for diagnosing respiratory disorders

Examination of arterial blood gasesEvaluating gas exchange, it measures: Carbon dioxide Oxygen Bicarbonate Blood pH

Pulse oximetry: Measure oxygen saturation of arterial blood

Pulmonary function tests: Spirometer measures volume of air moved with varying degrees of effort