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

Respiratory System

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 Carbon dioxide mostly as carbonic acid 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 Tuberculosis Influenza 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 Major risk factors: 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 gases Evaluating 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