Anatomy Respiratory Tract

RESPIRATORY SYSTEM I. FUNCTION •

To supply the body with oxygen and dispose carbon dioxide

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It involves at least 3 distinct process: 1. Pulmonary Ventilation 

Inflow and outflow of air between the atmosphere and alveoli of the lungs

2. External Respiration 

Diffusion of oxygen and carbon dioxide between the alveoli and pulmonary capillaries

3. Internal Respiration 

Transport of oxygen and carbon dioxide via the blood to and from the tissue

II. FUNCTIONAL ANATOMY OF THE RESPIRATORY SYSTEM A. Conducting Zone •

Also called as “dead space” because there is no gas exchange in these zones

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Respiratory passages extending from nose to the terminal bronchioles

B. Respiratory Zone •

Actual site of gas exchange

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Composed of the respiratory bronchioles, alveolar ducts, and alveoli

i.

Conducting Zone Structures a. b. c. d. e.

Nose Pharynx Larynx Trachea Bronchi

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Right bronchus Wider Shorter More vertical

Diameter Length Direction ii.

Respiratory Zone Structures a. b. c. d.

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Left bronchus Narrower Longer Oblique

Respiratory Bronchioles Alveolar ducts Alveolar sac Alveoli  actual site of gas exchange

The respiratory membrane is composed of several cell types A. Type I pneumocytes •

Walls of the alveoli composed of simple squamous epithelium

B. Type II pneumocytes •

Cuboidal secretory cells

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Secrete a fluid containing surfactant that coats the gas exposed alveolar surfaces

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Surfactant decreases the surface tension on the alveolar walls

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L:S ratio

C. Alveolar macrophages •

Dust cells

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Provide primary line of defense against inhaled dust, bacteria, and other foreign particles

III. LUNGS AND PLEURAL CAVITIES

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A. Lungs • • • •

Lobes Fissures Cardiac notch Lingula

Right Lung 3 1 horizontal

Left Lung 2 1 oblique

1 oblique (- ) (- )

(+) (+)

B. Pleura IV. MUSCULAR CONTROL OF BREATHING A. Inspiration •

Diaphragm contracts  moves inferiorly and flattens out  increase height of the thoracic cavity

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Contraction of the external intercostals muscles  elevates the rib cage and thrust the sternum forward  expand the diameter of the thorax

B. Expiration •

Inspiratory muscles relax  rib cage descends and lungs recoil

V. AIRWAY RESISTANCE AND COMPLIANCE A. Airway resistance •

Determined chiefly by radium or size of the airway

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Changes in bronchial diameter  alters the rate of air flow for a given pressure gradient during respiration

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↑ resistance – greater than normal respiratory effort is required

B. Compliance •

A measure of the elasticity, expandability, and distensibility of the lungs and thoracic structures

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Normal compliance  lungs and thorax easily stretch and distend when pressure is applied

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High or ↑ compliance  lungs have lost elasticity and the thorax is overdistended  ? (example)

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Low or ↓compliance  lungs and thorax are stiff  ? (example)

VI. GAS EXCHANGE IN THE BODY VII. CONTROL OF RESPIRATION A. Medullary Respiratory Centers a. Dorsal respiratory group or inspiratory center b. Ventral respiratory group or expiratory center B. Pons Respiratory Centers a. . Pneumotaxic Center  rhythm and prevents over inflation of the lungs b. Apneustic Center  inspiratory drive C. Chemical Control of Respiration a. Central chemoreceptor i. Located bilaterally in the medulla ii. Sensitive to small changes in blood CO2 and pH iii. Hypercapnia / ↑ CO2  the most powerful respiratory stimulant iv. Release of H ions in the CSF  reflexive increase in the rate and depth of breathing b. Peripheral chemoreceptor i. Found within vessels of the neck (carotid and aortic bodies) ii. Sensitive to arterial oxygen levels iii. ↓ arterial pressure of oxygen (below 60 mmHg)  becomes the major stimulus for respiration  ↑ ventilation ASSESSMENT Major Signs and Symptoms of Respiratory Diseases

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a. Dyspnea  How much exertion triggers SOB?  Is there an associated cough?  Is dyspnea related to the symptoms?  At what time of day or night does the dyspnea occur?  Is the SOB worse when the patient is flat in bed?  Does the SOB occur at rest? With exercise? Running? Climbing stairs?  Is the SOB worse while walking?  Management: Identify and correcting its cause, rest, positioning, oxygen administration b. Sputum production  Purulent with change in color – bacterial infection  Profuse, frothy, pink material – pulmonary edema  Foul smelling associated with bad breath – lung abscess, bronchiectasis  Management: ↑ OFI, inhalation of aerosolized solutions, chest physiotherapy c. Chest Pain  Sharp, stabbing, and intermittent – pulmonary problem  Dull, aching, and persistent  Management: Analgesics d. Wheezing  Bronchoconstriction or airway narrowing  Management: Bronchodilators e. Hemoptysis  Most common causes: pulmonary infection, lung Ca, heart or blood vessel abnormalities, pulmonary artery or vein abnormalities, pulmonary emboli and infarction

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 Determine the source and treat the underlying cause of bleeding f. Cyanosis  A very late indicator of hypoxia  Nor a reliable sign of hypoxia g. Clubbing of the Fingers  Found in patients with chronic hypoxic conditions, chronic lung infections, lung Ca

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