Respiratory System Vocabulary

Introduction

• The cardiovascular and respiratory systems work together to supply O2 and eliminate CO2.
• Respiration involves ventilation, external respiration, and internal respiration.

Overview of the Respiratory System

• Consists of the nose, pharynx, larynx, trachea, bronchi, and lungs.
• Upper respiratory system: nose, pharynx.
• Lower respiratory system: larynx, trachea, bronchi, and lungs.
• Conducting system: nose, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles.
• Respiratory portion: respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.

Nose

• Warms, moistens, and filters incoming air; receives olfactory stimuli; modifies speech sounds.
• Nasal cavity is divided by the nasal septum.

Pharynx

• Regions: nasopharynx, oropharynx, and laryngopharynx.
• Nasopharynx: respiration.
• Oropharynx and laryngopharynx: digestion and respiration.

Larynx

• Connects the pharynx with the trachea.
• Contains the thyroid cartilage, epiglottis, cricoid cartilage, and arytenoid, corniculate, and cuneiform cartilages.

Structures of Voice Production

• Vocal folds produce sound; taunt folds produce high pitches, relaxed folds produce low pitches.
• Other structures are necessary for converting the sound into recognizable speech.

Trachea

• Anterior to the esophagus.
• Composed of smooth muscle and C-shaped rings of cartilage.
• Lined with pseudostratified ciliated columnar epithelium.
• Cartilage rings keep the airway open.
• Cilia sweep debris away from the lungs.

Bronchi

• The trachea divides into the right and left primary bronchi.
• The bronchial tree consists of the trachea, primary bronchi, secondary bronchi, tertiary bronchi, bronchioles, and terminal bronchioles.

Lungs

• Paired organs in the thoracic cavity, enclosed and protected by the pleural membrane.
• Right lung: three lobes.
• Left lung: two lobes and a cardiac notch.
• Alveolar walls consist of type I and type II alveolar cells and alveolar macrophages.
• Type II alveolar cells secrete surfactant.
• Gas exchange occurs across the alveolar-capillary membrane.

Respiration

• Three steps: pulmonary ventilation, external respiration, and internal respiration.
• Inhalation: air into the lungs.
• Boyle’s law: the volume of a gas varies inversely with pressure.

Factors Affecting Pulmonary Ventilation

• Surface tension causes alveoli to assume the smallest diameter.
• Surfactant alters the surface tension of the alveoli and prevents their collapse.

Compliance

• Compliance is the ease with which the lungs and thoracic wall can be expanded.

Breathing Patterns

• Eupnea: normal variation in breathing rate and depth.
• Apnea: holding breath.
• Dyspnea: painful or difficult breathing.
• Tachypnea: rapid breathing rate.

Lung Volumes and Capacities

• Measured with a spirometer.
• Tidal volume, inspiratory reserve volume, expiratory reserve volume, residual volume, and minimal volumes.

Exchange of Oxygen and Carbon Dioxide

• Dalton’s law: each gas in a mixture exerts its own pressure.
• Henry’s law: the quantity of a gas that will dissolve in a liquid is proportional to the partial pressure of the gas and its solubility coefficient.

Transport of Oxygen and Carbon Dioxide in the Blood

• Oxygen is transported via dissolved O2 in plasma and oxyhemoglobin (HbO2).
• Carbon dioxide is transported via dissolved CO_2, carbaminohemoglobin, and bicarbonate ions.

Control of Respiration

• Respiratory center in the brain stem.
• Medullary rhythmicity area controls the basic rhythm.
• Pneumotaxic area helps coordinate the transition between inspiration and expiration.
• Apneustic area prolongs inspiration.

Regulation of the Respiratory Center

• Cortical influences allow conscious control.
• Chemoreceptors monitor levels of CO2 and O2.
• Hypercapnia: increase in PCO_2.
• Hypocapnia: decrease in PCO_2.
• Hypoxia: oxygen deficiency.

Exercise and the Respiratory System

• Respiratory system works with the cardiovascular system to adjust for exercise.
• Increased ventilation and oxygen diffusion capacity.

Aging and the Respiratory System

• Decreased vital capacity, decreased blood oxygen level, diminished alveolar macrophage activity, and decreased ciliary action.

Disorders: Homeostatic Imbalances

• Asthma: spasms of smooth muscle, inflammation, inflated alveoli, and excess mucus.
• COPD: chronic obstruction of air flow.
• Bronchitis: inflammation of the bronchial tubes.
• Lung cancer: bronchial epithelial cells are replaced by cancer cells.
• Pneumonia: acute infection of the alveoli.
• Tuberculosis: inflammation produced by Mycobacterium tuberculosis.