Chapter 22: The Respiratory System

Importance of the Respiratory System

• Facilitates gas exchange (O2 and CO2) between atmosphere, lungs, blood, and tissues.
• Maintains homeostasis by regulating O2 and CO2 levels.
• Factors affecting respiratory rate: elevation changes (e.g., high altitudes).

Functions of the Respiratory System

• Extensive surface area for gas exchange.
• Moves air through respiratory passageways.
• Protects respiratory surfaces from dehydration, temperature changes, and pathogen invasion.
• Produces sounds for communication (speaking, singing).
• Detects olfactory stimuli via receptors in the nasal cavity.

Respiratory System Structure

Upper Respiratory Tract

• Components: Nose, nasal cavity, paranasal sinuses, pharynx.
• Nose: Primary air passageway; structures include nasal septum, cartilages, external nares.
• Paranasal Sinuses: Maxilla, frontal, ethmoid, sphenoid bones.
• Pharynx: Divided into nasopharynx, oropharynx, laryngopharynx.

Lower Respiratory Tract

• Larynx (Voice Box): Includes glottis, epiglottis, thyroid and cricoid cartilages.
• Trachea (Windpipe): Tough tube, composed of mucosa, submucosa, adventitia.
• Bronchial Tree: Divides into primary, secondary, tertiary bronchi; leads to bronchioles.
• Lungs: Right lung (3 lobes), left lung (2 lobes, cardiac notch).

Respiratory Membranes and Pleura

• Alveoli: Gas exchange sites.
• Pleura: Parietal (lines thoracic cavity), visceral (covers lungs).

Disorders and Conditions

• Asthma: Constricted airways, inflammation.
• COPD: Progressive airflow restriction.
• Emphysema: Alveolar surface destruction.
• Cystic Fibrosis: Excessive mucus production.
• Pneumothorax: Air in pleural space, lung collapse.
• Lung Cancer: Often linked to smoking.

Breathing Process and Mechanics

• Pulmonary Ventilation: Moving air in and out of lungs.
• Pressures: Atmospheric, alveolar, intrapleural.
• Boyle’s Law: Volume-pressure relationship.
• Muscles Involved: Diaphragm and intercostal muscles.

Gas Exchange and Transport

• External Respiration: Lung-blood gas exchange.
• Internal Respiration: Blood-tissue gas exchange.
• Oxygen Transport: Bound to hemoglobin in red blood cells.
• Carbon Dioxide Transport: Converted to bicarbonate, some as carbaminohemoglobin.

Control of Respiration

• Respiratory Centers: Located in brainstem (medulla, pons).
• Chemoreceptors and Baroreceptors: Monitor gas levels.
• Higher Brain Centers: Can influence respiratory rate.

Development and Lifecycle

• Fetal Development of Respiratory System: Early formation of lung structures.
• Aging and Respiratory Performance: Decreased efficiency and adaptability.

This concludes the overview of the respiratory system, covering its structure, function, mechanics of breathing, and common disorders.