Respiratory System: Anatomy, Physiology, and Common Diseases

Respiratory System Functions

Provide oxygen to body tissues (for cellular respiration), remove carbon dioxide (a waste product), and maintain acid-base balance in blood.

Olfaction

The sense of smell, which is one of the roles of the respiratory system.

Speech Production

A function of the respiratory system that involves the use of air from the lungs to create sound.

Nasal Septum

Structure that divides the left and right nasal cavities, composed of cartilage and bone.

Conchae (Turbinates)

Structures that increase surface area in the nasal cavity, warming, humidifying, and filtering air.

Paranasal Sinuses

Frontal, Maxillary, Sphenoidal, and Ethmoidal sinuses that warm and moisten air, lighten the skull, and provide resonance for voice.

Olfactory Epithelium

Tissue in the nasal cavity that detects smell.

Pseudostratified Ciliated Columnar Epithelium

Type of epithelium that moves mucus and debris toward the throat.

Pharynx

Throat region divided into three regions: nasopharynx, oropharynx, and laryngopharynx.

Nasopharynx

Upper region of the pharynx that connects to Eustachian tubes and contains pharyngeal tonsil.

Oropharynx

Middle region of the pharynx that connects to the mouth and contains palatine and lingual tonsils.

Laryngopharynx

Lower region of the pharynx that connects to the larynx and esophagus.

Thyroid Cartilage

The largest cartilage of the larynx, commonly known as the 'Adam's apple.'

Cricoid Cartilage

Cartilage that forms a full ring at the base of the larynx.

Epiglottis

Flap that closes the airway during swallowing to prevent choking.

True Vocal Cords

Structures in the larynx that vibrate to produce sound.

Trachea

Windpipe supported by 16-20 C-shaped rings of hyaline cartilage to prevent collapse.

Bronchial Tree

Structure that includes primary bronchi, secondary bronchi, tertiary bronchi, bronchioles, and terminal bronchioles.

Terminal Bronchioles

End of the conducting zone that leads to the respiratory zone.

Alveoli

Tiny air sacs (200 µm wide) where O₂ and CO₂ exchange occurs.

Lungs

Organs of respiration; the right lung has 3 lobes and the left lung has 2 lobes plus a cardiac notch.

Apex

Top of the lung.

Base

Bottom of the lung that rests on the diaphragm.

Hilum

Entry/exit for bronchi, blood vessels, and nerves.

Lobules

Small divisions of the lung separated by connective tissue.

Visceral pleura

Covers the lung surface.

Parietal pleura

Lines the thoracic wall, mediastinum, and diaphragm.

Pleural cavity

Space between the pleurae filled with pleural fluid that reduces friction and creates surface tension.

Pulmonary Ventilation

Air movement in and out of lungs (breathing) driven by pressure gradients.

Inspiration

Diaphragm contracts and rib cage expands, increasing thoracic volume and decreasing pressure, causing air to move in.

Expiration

Diaphragm and intercostals relax, decreasing thoracic volume and increasing pressure, causing air to move out.

Quiet (Eupnea)

Normal rest breathing involving diaphragm and intercostals.

Diaphragmatic breathing

Deep breathing using the diaphragm only.

Costal breathing

Shallow breathing using intercostals only.

Forced (Hyperpnea)

Breathing during exercise or singing using diaphragm, intercostals, and accessory muscles.

Respiratory Rate

Number of breaths per minute, varying by age: <1 year: 30-60, ~10 years: 18-30, Adults: 12-18.

Pulmonary arteries

Bring deoxygenated blood to the lungs.

Pulmonary capillary network

Surrounds alveoli for gas exchange.

Respiratory membrane

Thin barrier between alveolus and capillary for gas diffusion.

Pulmonary veins

Return oxygenated blood to the heart.

Nervous Innervation

Controlled by the autonomic nervous system, with parasympathetic causing bronchoconstriction and sympathetic causing bronchodilation.

Asthma

Chronic inflammation and bronchospasms causing wheezing, shortness of breath, coughing, and chest tightness.

COPD (Chronic Obstructive Pulmonary Disease)

Chronic lung disease including bronchitis and emphysema, characterized by chronic cough, shortness of breath, and sputum.

Lung Cancer

Uncontrolled growth of lung cells, with symptoms including wheezing, coughing blood, and weight loss.

Sleep Apnea

Condition where breathing stops during sleep, leading to snoring, fatigue, and headaches.

Effects of Second-Hand Smoke

Health risks from passive smoke inhalation, including ear infections, asthma, SIDS, and increased cancer risk.

O₂

Oxygen.

CO₂

Carbon dioxide.

CPAP

Continuous Positive Airway Pressure.

SIDS

Sudden Infant Death Syndrome.

NSCLC

Non-Small Cell Lung Cancer.

SCLC

Small Cell Lung Cancer.