Lungs: Anatomy

Development

Development of the tracheobronchial tree and lungs occurs in 5 stages. The tracheobronchial tree originates from the foregut Foregut Development of the Abdominal Organs of the embryonic gut tube, beginning at week 4 of gestation and ending in childhood.

Gross Anatomy

General characteristics

• The lungs are paired viscera composed of spongy tissue. 
• Asymmetrical, with each lung having a slightly different morphology and weight:
  • Left lung is slightly smaller than the right lung.
  • On average, lungs are heavier in men than in women.
• Location and spatial relations:
  • Located in the thoracic cavity on either side of the mediastinum Mediastinum The mediastinum is the thoracic area between the 2 pleural cavities. The mediastinum contains vital structures of the circulatory, respiratory, digestive, and nervous systems including the heart and esophagus, and major thoracic vessels. Mediastinum and Great Vessels: Anatomy
  • Surround the bronchial tree Bronchial tree The collective term “bronchial tree” refers to the bronchi and all of their subsequent branches. The bronchi are the airways of the lower respiratory tract. At the level of the 3rd or 4th thoracic vertebra, the trachea bifurcates into the left and right main bronchi. Both of these bronchi continue to divide into secondary or lobar bronchi that bifurcate further and further. Bronchial Tree: Anatomy
  • Enclosed within the visceral pleura Visceral pleura Pleura: Anatomy
  • Attached to the trachea Trachea The trachea is a tubular structure that forms part of the lower respiratory tract. The trachea is continuous superiorly with the larynx and inferiorly becomes the bronchial tree within the lungs. The trachea consists of a support frame of semicircular, or C-shaped, rings made out of hyaline cartilage and reinforced by collagenous connective tissue. Trachea: Anatomy via the main bronchi Bronchi The larger air passages of the lungs arising from the terminal bifurcation of the trachea. They include the largest two primary bronchi which branch out into secondary bronchi, and tertiary bronchi which extend into bronchioles and pulmonary alveoli. Bronchial Tree: Anatomy of the tracheobronchial tree
  • Attached to the heart via pulmonary vessels
• Basic structure: 
  • Each lung has a base, apex, 2 surfaces, and 3 borders:
    • The base sits on the diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm: Anatomy.
    • The apex projects above the 1st rib.
    • 1 surface faces the ribs Ribs A set of twelve curved bones which connect to the vertebral column posteriorly, and terminate anteriorly as costal cartilage. Together, they form a protective cage around the internal thoracic organs. Chest Wall: Anatomy (costal); the other faces medially (mediastinal) and contains the hilum
    • 3 borders: inferior, posterior, and anterior
• Hilum:
  • Located between T5 and T7
  • Constitutes the roots of the lungs, a pleura-encased passageway for the pulmonary neurovasculature
  • The following structures pass through the hilum of each lung:
    • Principal bronchus
    • Pulmonary artery
    • 2 pulmonary veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology
    • Bronchial vessels
    • Pulmonary autonomic plexus
    • Lymph nodes Lymph Nodes They are oval or bean shaped bodies (1 – 30 mm in diameter) located along the lymphatic system. Lymphatic Drainage System: Anatomy and vessels
    • Connective tissue Connective tissue Connective tissues originate from embryonic mesenchyme and are present throughout the body except inside the brain and spinal cord. The main function of connective tissues is to provide structural support to organs. Connective tissues consist of cells and an extracellular matrix. Connective Tissue: Histology

Right versus left lung

The 2 lungs are not symmetrical Symmetrical Dermatologic Examination and vary both in weight and morphology. This difference is due to the size and location of the heart in the left hemithorax. 

Right lung:

• 3 lobes: superior, middle, and inferior 
• 2 fissures: oblique and horizontal 
• Its medial or mediastinal surface is adjacent to:
  • Heart
  • Inferior vena cava Inferior vena cava The venous trunk which receives blood from the lower extremities and from the pelvic and abdominal organs. Mediastinum and Great Vessels: Anatomy
  • Superior vena cava Superior vena cava The venous trunk which returns blood from the head, neck, upper extremities and chest. Mediastinum and Great Vessels: Anatomy
  • Azygos vein 
  • Esophagus Esophagus The esophagus is a muscular tube-shaped organ of around 25 centimeters in length that connects the pharynx to the stomach. The organ extends from approximately the 6th cervical vertebra to the 11th thoracic vertebra and can be divided grossly into 3 parts: the cervical part, the thoracic part, and the abdominal part. Esophagus: Anatomy

Left lung:

• 2 lobes: superior and inferior
• 1 fissure Fissure A crack or split that extends into the dermis Generalized and Localized Rashes: oblique
• Its medial or mediastinal surface is adjacent to:
  • Heart
  • Aortic arch Aortic arch Mediastinum and Great Vessels: Anatomy
  • Thoracic aorta Aorta The main trunk of the systemic arteries. Mediastinum and Great Vessels: Anatomy
  • Esophagus Esophagus The esophagus is a muscular tube-shaped organ of around 25 centimeters in length that connects the pharynx to the stomach. The organ extends from approximately the 6th cervical vertebra to the 11th thoracic vertebra and can be divided grossly into 3 parts: the cervical part, the thoracic part, and the abdominal part. Esophagus: Anatomy 
• The cardiac notch is located on the anteroinferior aspect of the superior lobe of the left lung on the anterior border to make room for the heart.

Bronchopulmonary segments

Beyond the lobes and following the branching of the bronchial tree Bronchial tree The collective term “bronchial tree” refers to the bronchi and all of their subsequent branches. The bronchi are the airways of the lower respiratory tract. At the level of the 3rd or 4th thoracic vertebra, the trachea bifurcates into the left and right main bronchi. Both of these bronchi continue to divide into secondary or lobar bronchi that bifurcate further and further. Bronchial Tree: Anatomy, the lungs are divided into bronchopulmonary segments, which are the largest functional divisions of the pulmonary lobes.

• Each segment has its own air and blood supplies.
  • Air supply: tertiary or segmental bronchi Bronchi The larger air passages of the lungs arising from the terminal bifurcation of the trachea. They include the largest two primary bronchi which branch out into secondary bronchi, and tertiary bronchi which extend into bronchioles and pulmonary alveoli. Bronchial Tree: Anatomy
  • Blood supply: branch of the bronchial arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology
• Asymmetrical distribution of segments between the right and left lungs:
  • Right lung: 10 segments
  • Left lung: 8–10 segments (some may fuse)

Microscopic Anatomy

The microscopic anatomy of the bronchial tree Bronchial tree The collective term “bronchial tree” refers to the bronchi and all of their subsequent branches. The bronchi are the airways of the lower respiratory tract. At the level of the 3rd or 4th thoracic vertebra, the trachea bifurcates into the left and right main bronchi. Both of these bronchi continue to divide into secondary or lobar bronchi that bifurcate further and further. Bronchial Tree: Anatomy varies as the airways ramify. In general, the respiratory tract becomes smaller in diameter and has thinner walls with every ramification.

Alveoli Alveoli Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place. Acute Respiratory Distress Syndrome (ARDS)

• Hollow sacs that serve as the site of gas exchange Gas exchange Human cells are primarily reliant on aerobic metabolism. The respiratory system is involved in pulmonary ventilation and external respiration, while the circulatory system is responsible for transport and internal respiration. Pulmonary ventilation (breathing) represents movement of air into and out of the lungs. External respiration, or gas exchange, is represented by the O2 and CO2 exchange between the lungs and the blood. Gas Exchange
• Found in respiratory bronchioles Bronchioles The small airways branching off the tertiary bronchi. Terminal bronchioles lead into several orders of respiratory bronchioles which in turn lead into alveolar ducts and then into pulmonary alveoli. Bronchial Tree: Anatomy along the walls ducts, and in the alveolar sacs
• Separated by interalveolar septa, which is made of elastic Elastic Connective Tissue: Histology fibers and capillaries Capillaries Capillaries are the primary structures in the circulatory system that allow the exchange of gas, nutrients, and other materials between the blood and the extracellular fluid (ECF). Capillaries are the smallest of the blood vessels. Because a capillary diameter is so small, only 1 RBC may pass through at a time. Capillaries: Histology
• Lined by type I and II pneumocytes:
  • Type I: comprise 95% of the total alveolar area and form the blood–air barrier
  • Type II: comprise 5% of the total alveolar area and secrete surfactant Surfactant Substances and drugs that lower the surface tension of the mucoid layer lining the pulmonary alveoli. Acute Respiratory Distress Syndrome (ARDS)

Neurovasculature

Blood supply

• The vessels enter the lungs at the hilum.
• The lung has a dual circulatory system:
  • Pulmonary arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology:
    • Originate as the pulmonary trunk Pulmonary Trunk Truncus Arteriosus
    • Branch into left and right pulmonary arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology and then into lobar and segmental branches according to the branching of the bronchial tree Bronchial tree The collective term “bronchial tree” refers to the bronchi and all of their subsequent branches. The bronchi are the airways of the lower respiratory tract. At the level of the 3rd or 4th thoracic vertebra, the trachea bifurcates into the left and right main bronchi. Both of these bronchi continue to divide into secondary or lobar bronchi that bifurcate further and further. Bronchial Tree: Anatomy
    • Carry oxygen-poor blood from the right ventricle to be oxygenated in the lungs
  • Pulmonary veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology:
    • Originate from the millions of alveoli Alveoli Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place. Acute Respiratory Distress Syndrome (ARDS) in the lungs
    • The tributaries merge following the branching of the bronchial tree Bronchial tree The collective term “bronchial tree” refers to the bronchi and all of their subsequent branches. The bronchi are the airways of the lower respiratory tract. At the level of the 3rd or 4th thoracic vertebra, the trachea bifurcates into the left and right main bronchi. Both of these bronchi continue to divide into secondary or lobar bronchi that bifurcate further and further. Bronchial Tree: Anatomy.
    • Become the right and left, and superior and inferior pulmonary veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology
    • Drain into the left atrium as 4 veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology 
    • Carry oxygen-rich blood from the lungs to the left atrium to be distributed throughout the body

Innervation

The lung receives mixed innervation from the pulmonary plexus containing the parasympathetic, sympathetic, and visceral afferent Afferent Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology fibers.

• Parasympathetic fibers:
  • Presynaptic fibers from the vagus nerve Vagus nerve The 10th cranial nerve. The vagus is a mixed nerve which contains somatic afferents (from skin in back of the ear and the external auditory meatus), visceral afferents (from the pharynx, larynx, thorax, and abdomen), parasympathetic efferents (to the thorax and abdomen), and efferents to striated muscle (of the larynx and pharynx). Pharynx: Anatomy
  • These fibers synapse Synapse The junction between 2 neurons is called a synapse. The synapse allows a neuron to pass an electrical or chemical signal to another neuron or target effector cell. Synapses and Neurotransmission with parasympathetic ganglion cells Ganglion Cells The Visual Pathway and Related Disorders.
  • Motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology innervation to the smooth muscle of the bronchial tree Bronchial tree The collective term “bronchial tree” refers to the bronchi and all of their subsequent branches. The bronchi are the airways of the lower respiratory tract. At the level of the 3rd or 4th thoracic vertebra, the trachea bifurcates into the left and right main bronchi. Both of these bronchi continue to divide into secondary or lobar bronchi that bifurcate further and further. Bronchial Tree: Anatomy (constrictor), pulmonary vessels (dilator), and glands of the bronchial tree Bronchial tree The collective term “bronchial tree” refers to the bronchi and all of their subsequent branches. The bronchi are the airways of the lower respiratory tract. At the level of the 3rd or 4th thoracic vertebra, the trachea bifurcates into the left and right main bronchi. Both of these bronchi continue to divide into secondary or lobar bronchi that bifurcate further and further. Bronchial Tree: Anatomy (secretory-motor)
• Sympathetic fibers:
  • Postsynaptic fibers with cell bodies in the paravertebral sympathetic ganglia (sympathetic trunks)
  • Innervation to the smooth muscle of the bronchial tree Bronchial tree The collective term “bronchial tree” refers to the bronchi and all of their subsequent branches. The bronchi are the airways of the lower respiratory tract. At the level of the 3rd or 4th thoracic vertebra, the trachea bifurcates into the left and right main bronchi. Both of these bronchi continue to divide into secondary or lobar bronchi that bifurcate further and further. Bronchial Tree: Anatomy (dilator), pulmonary vessels (constrictor), and type II secretory cells of alveoli Alveoli Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place. Acute Respiratory Distress Syndrome (ARDS) (inhibitor)
• Visceral fibers:
  • Reflexive: conduct subconscious sensations connected to the regulation and control of reflexes (accompany parasympathetic fibers)
  • Nociceptive: pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways as a response to injury (accompany sympathetic fibers)

Functions

The main role of the lungs is to oxygenate the body and rid it of CO₂. 

Ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing:

• Movement of air between the environment and the lungs via inhalation and exhalation
• Requires assistance of the intercostal muscles Intercostal Muscles Respiratory muscles that arise from the lower border of one rib and insert into the upper border of the adjoining rib, and contract during inspiration or respiration. Chest Wall: Anatomy, diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm: Anatomy, and accessory muscles of respiration Respiration The act of breathing with the lungs, consisting of inhalation, or the taking into the lungs of the ambient air, and of exhalation, or the expelling of the modified air which contains more carbon dioxide than the air taken in. Nose Anatomy (External & Internal)

Respiration Respiration The act of breathing with the lungs, consisting of inhalation, or the taking into the lungs of the ambient air, and of exhalation, or the expelling of the modified air which contains more carbon dioxide than the air taken in. Nose Anatomy (External & Internal) or gas exchange Gas exchange Human cells are primarily reliant on aerobic metabolism. The respiratory system is involved in pulmonary ventilation and external respiration, while the circulatory system is responsible for transport and internal respiration. Pulmonary ventilation (breathing) represents movement of air into and out of the lungs. External respiration, or gas exchange, is represented by the O2 and CO2 exchange between the lungs and the blood. Gas Exchange:

• Removal of CO₂ from the blood into the air, and absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption of oxygen from environmental air into the blood
• Relies on the concentration and structural integrity of hemoglobin

Respiratory regulation Respiratory regulation Human cells are reliant on aerobic metabolism. Chemoreceptors in the lungs and tissues sense changes in the concentration of respiratory gasses and send messages to the CNS, which, in turn, modifies breathing parameters such as the respiratory rate or tidal volume to compensate for any imbalance. Disruption of this control mechanism can be caused by severe disease and also result in severe disease. Respiratory Regulation:

• By the chemoreceptors in the lungs and tissues that sense changes in the concentration of oxygen and CO₂
• By the respiratory center of the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification, with constant feedback from the central and peripheral chemoreceptors Peripheral chemoreceptors Respiratory Regulation

Clinical Relevance

The following conditions of various origins can affect the lungs:

• Infectious:
  • Pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia: acute or chronic inflammation Chronic Inflammation Inflammation of the lung tissue commonly known as pulmonary inflammation Pulmonary inflammation Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia. Causes of pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia include bacterial, viral, or fungal infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease. In rare cases, pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia can also be caused by toxic triggers via inhalation, in immunological processes, or during the course of radiotherapy.
  • Tuberculosis Tuberculosis Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis complex bacteria. The bacteria usually attack the lungs but can also damage other parts of the body. Approximately 30% of people around the world are infected with this pathogen, with the majority harboring a latent infection. Tuberculosis spreads through the air when a person with active pulmonary infection coughs or sneezes. Tuberculosis: an infectious disease caused by bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology of the Mycobacterium tuberculosis Mycobacterium tuberculosis Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis complex bacteria. The bacteria usually attack the lungs but can also damage other parts of the body. Approximately 30% of people around the world are infected with this pathogen, with the majority harboring a latent infection. Tuberculosis spreads through the air when a person with active pulmonary infection coughs or sneezes. Tuberculosis complex, which usually attack the lungs, but can also affect other parts of the body. Tuberculosis Tuberculosis Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis complex bacteria. The bacteria usually attack the lungs but can also damage other parts of the body. Approximately 30% of people around the world are infected with this pathogen, with the majority harboring a latent infection. Tuberculosis spreads through the air when a person with active pulmonary infection coughs or sneezes. Tuberculosis spreads through air when an individual with an active pulmonary infection coughs or sneezes. Diagnosis is established using the tuberculin Tuberculin A protein extracted from boiled culture of tubercle bacilli (Mycobacterium tuberculosis). It is used in the tuberculin skin test (tuberculin test) for the diagnosis of tuberculosis infection in asymptomatic persons. Type IV Hypersensitivity Reaction skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions test, sputum culture, and lung imaging. Management is with antimycobacterial drugs.
  • COVID-19 COVID-19 Coronavirus disease 2019 (COVID-19) is an infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that mainly affects the respiratory system but can also cause damage to other body systems (cardiovascular, gastrointestinal, renal, and central nervous systems). : an infectious disease caused by SARS-CoV-2 that mainly affects the respiratory system, but can also damage other organs. Coronavirus disease 2019 Coronavirus disease 2019 Coronavirus disease 2019 (COVID-19) is an infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that mainly affects the respiratory system but can also cause damage to other body systems (cardiovascular, gastrointestinal, renal, and central nervous systems). may present asymptomatically as a mild “flu-like” illness, or severely, with shortness of breath Shortness of breath Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea and life-threatening complications. Management is based on supportive care.
• Malignant:
  • Lung cancer Lung cancer Lung cancer is the malignant transformation of lung tissue and the leading cause of cancer-related deaths. The majority of cases are associated with long-term smoking. The disease is generally classified histologically as either small cell lung cancer or non-small cell lung cancer. Symptoms include cough, dyspnea, weight loss, and chest discomfort. Lung Cancer: a condition associated with a relatively high risk of mortality Mortality All deaths reported in a given population. Measures of Health Status. Lung cancer Lung cancer Lung cancer is the malignant transformation of lung tissue and the leading cause of cancer-related deaths. The majority of cases are associated with long-term smoking. The disease is generally classified histologically as either small cell lung cancer or non-small cell lung cancer. Symptoms include cough, dyspnea, weight loss, and chest discomfort. Lung Cancer has become the leading cause of death among men worldwide. This malignant tumor Tumor Inflammation originates from the respiratory epithelium Epithelium The epithelium is a complex of specialized cellular organizations arranged into sheets and lining cavities and covering the surfaces of the body. The cells exhibit polarity, having an apical and a basal pole. Structures important for the epithelial integrity and function involve the basement membrane, the semipermeable sheet on which the cells rest, and interdigitations, as well as cellular junctions. Surface Epithelium: Histology of the bronchi Bronchi The larger air passages of the lungs arising from the terminal bifurcation of the trachea. They include the largest two primary bronchi which branch out into secondary bronchi, and tertiary bronchi which extend into bronchioles and pulmonary alveoli. Bronchial Tree: Anatomy, bronchioles Bronchioles The small airways branching off the tertiary bronchi. Terminal bronchioles lead into several orders of respiratory bronchioles which in turn lead into alveolar ducts and then into pulmonary alveoli. Bronchial Tree: Anatomy, and alveoli Alveoli Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place. Acute Respiratory Distress Syndrome (ARDS). In 90% of men and 80% of women, bronchial carcinoma appears to be associated with the inhalation of tobacco smoke.
• Obstructive:
  • Asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma: a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. Asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma presents with wheezing Wheezing Wheezing is an abnormal breath sound characterized by a whistling noise that can be relatively high-pitched and shrill (more common) or coarse. Wheezing is produced by the movement of air through narrowed or compressed small (intrathoracic) airways. Wheezing, cough, and dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea. The diagnosis is confirmed with pulmonary function tests, which show a reversible obstructive pattern. Treatment of asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma is with bronchodilators Bronchodilators Asthma Drugs and inhaled corticosteroids Corticosteroids Chorioretinitis. 
  • Chronic obstructive pulmonary disease Pulmonary disease Diseases involving the respiratory system. Blastomyces/Blastomycosis ( COPD COPD Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Signs and symptoms include prolonged expiration, wheezing, diminished breath sounds, progressive dyspnea, and chronic cough. Chronic Obstructive Pulmonary Disease (COPD)): a lung disease characterized by progressive, irreversible airflow obstruction. Chronic obstructive pulmonary disease Pulmonary disease Diseases involving the respiratory system. Blastomyces/Blastomycosis presents with progressive dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea, chronic cough, prolonged expiration Expiration Ventilation: Mechanics of Breathing, and wheezing Wheezing Wheezing is an abnormal breath sound characterized by a whistling noise that can be relatively high-pitched and shrill (more common) or coarse. Wheezing is produced by the movement of air through narrowed or compressed small (intrathoracic) airways. Wheezing. The diagnosis is based on pulmonary function tests. Management includes smoking Smoking Willful or deliberate act of inhaling and exhaling smoke from burning substances or agents held by hand. Interstitial Lung Diseases cessation, pulmonary rehabilitation, and pharmacotherapy.
  • Emphysema Emphysema Enlargement of air spaces distal to the terminal bronchioles where gas-exchange normally takes place. This is usually due to destruction of the alveolar wall. Pulmonary emphysema can be classified by the location and distribution of the lesions. Chronic Obstructive Pulmonary Disease (COPD): a condition characterized by dilation of the airways, with decreased elasticity Elasticity Resistance and recovery from distortion of shape. Skeletal Muscle Contraction and increased compliance Compliance Distensibility measure of a chamber such as the lungs (lung compliance) or bladder. Compliance is expressed as a change in volume per unit change in pressure. Veins: Histology, due to destruction of the alveolar walls. The most common cause of emphysema Emphysema Enlargement of air spaces distal to the terminal bronchioles where gas-exchange normally takes place. This is usually due to destruction of the alveolar wall. Pulmonary emphysema can be classified by the location and distribution of the lesions. Chronic Obstructive Pulmonary Disease (COPD) is smoking Smoking Willful or deliberate act of inhaling and exhaling smoke from burning substances or agents held by hand. Interstitial Lung Diseases. Alpha-1-antitrypsin deficiency may also result in the development of emphysema Emphysema Enlargement of air spaces distal to the terminal bronchioles where gas-exchange normally takes place. This is usually due to destruction of the alveolar wall. Pulmonary emphysema can be classified by the location and distribution of the lesions. Chronic Obstructive Pulmonary Disease (COPD).
  • Atelectasis Atelectasis Atelectasis is the partial or complete collapse of a part of the lung. Atelectasis is almost always a secondary phenomenon from conditions causing bronchial obstruction, external compression, surfactant deficiency, or scarring. Atelectasis: a partial or complete collapse of a part of the lung, usually as a secondary phenomenon from conditions causing bronchial obstruction, external compression External Compression Blunt Chest Trauma, surfactant Surfactant Substances and drugs that lower the surface tension of the mucoid layer lining the pulmonary alveoli. Acute Respiratory Distress Syndrome (ARDS) deficiency, or scarring Scarring Inflammation. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship are often asymptomatic and the diagnosis is made by imaging. The management of atelectasis Atelectasis Atelectasis is the partial or complete collapse of a part of the lung. Atelectasis is almost always a secondary phenomenon from conditions causing bronchial obstruction, external compression, surfactant deficiency, or scarring. Atelectasis includes treatment of the underlying etiology, lung-expansion exercises, and chest physiotherapy Physiotherapy Spinal Stenosis.
• Vascular:
  • Pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism: a potentially fatal intraluminal obstruction of the main pulmonary artery or its branches by an embolus. The most common presenting symptom is dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea. The diagnosis of pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism is by radiographic imaging. The initial management is supportive and focuses on restoring oxygenation and hemodynamic stability.
  • Pulmonary hypertension Pulmonary Hypertension Pulmonary hypertension (PH) or pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary arterial pressure, which can lead to chronic progressive right heart failure. Pulmonary hypertension is grouped into 5 categories based on etiology, which include primary PAH, and PH due to cardiac disease, lung or hypoxic disease, chronic thromboembolic disease, and multifactorial or unclear etiologies. Pulmonary Hypertension: a condition associated with elevated pulmonary arterial pressure Pulmonary Arterial Pressure Pulmonary Hypertension Drugs, which can lead to chronic progressive right heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR). Pulmonary hypertension Pulmonary Hypertension Pulmonary hypertension (PH) or pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary arterial pressure, which can lead to chronic progressive right heart failure. Pulmonary hypertension is grouped into 5 categories based on etiology, which include primary PAH, and PH due to cardiac disease, lung or hypoxic disease, chronic thromboembolic disease, and multifactorial or unclear etiologies. Pulmonary Hypertension presents as progressive dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea, and is either primary or occurs due to other medical conditions. Diagnosis is based on echocardiography Echocardiography Ultrasonic recording of the size, motion, and composition of the heart and surrounding tissues. The standard approach is transthoracic. Tricuspid Valve Atresia (TVA), ECG ECG An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Electrocardiogram (ECG), chest X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests, and pulmonary function tests. Management is aimed at treating the underlying etiology. 
  • Cor pulmonale Cor Pulmonale Cor pulmonale is right ventricular (RV) dysfunction caused by lung disease that results in pulmonary artery hypertension. The most common cause of cor pulmonale is chronic obstructive pulmonary disease. Dyspnea is the usual presenting symptom. Cor Pulmonale: right ventricular dysfunction caused by lung disease, which results in pulmonary hypertension Pulmonary Hypertension Pulmonary hypertension (PH) or pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary arterial pressure, which can lead to chronic progressive right heart failure. Pulmonary hypertension is grouped into 5 categories based on etiology, which include primary PAH, and PH due to cardiac disease, lung or hypoxic disease, chronic thromboembolic disease, and multifactorial or unclear etiologies. Pulmonary Hypertension. Cor pulmonale Cor Pulmonale Cor pulmonale is right ventricular (RV) dysfunction caused by lung disease that results in pulmonary artery hypertension. The most common cause of cor pulmonale is chronic obstructive pulmonary disease. Dyspnea is the usual presenting symptom. Cor Pulmonale is caused by COPD COPD Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Signs and symptoms include prolonged expiration, wheezing, diminished breath sounds, progressive dyspnea, and chronic cough. Chronic Obstructive Pulmonary Disease (COPD). Dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea is the usual presenting symptom, and signs of right-sided heart failure Right-Sided Heart Failure Ebstein’s Anomaly and hypoxemia Hypoxemia Neonatal Respiratory Distress Syndrome may be observed. Most patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship are diagnosed clinically. Initial treatment is by using oxygen therapy and is targeted at identifying the underlying disease.
• Interstitial:
  • Idiopathic Idiopathic Dermatomyositis pulmonary fibrosis Fibrosis Any pathological condition where fibrous connective tissue invades any organ, usually as a consequence of inflammation or other injury. Bronchiolitis Obliterans: a specific entity of the major idiopathic Idiopathic Dermatomyositis interstitial pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia classification within interstitial lung diseases Interstitial Lung Diseases Interstitial lung diseases are a heterogeneous group of disorders characterized by the inflammation and fibrosis of lung parenchyma, especially the pulmonary connective tissue in the alveolar walls. It may be idiopathic (e.g., idiopathic pulmonary fibrosis) or secondary to connective tissue diseases, medications, malignancies, occupational exposure, or allergens. Interstitial Lung Diseases. Idiopathic Idiopathic Dermatomyositis pulmonary fibrosis Fibrosis Any pathological condition where fibrous connective tissue invades any organ, usually as a consequence of inflammation or other injury. Bronchiolitis Obliterans is often characterized by its rapid progression. The average life expectancy Life expectancy Based on known statistical data, the number of years which any person of a given age may reasonably expected to live. Population Pyramids is 3–4 years from diagnosis. Lung transplantation Lung transplantation The transference of either one or both of the lungs from one human or animal to another. Organ Transplantation is the only curative intervention. 
  • Hypersensitivity pneumonitis Pneumonitis Human Herpesvirus 6 and 7: an immunologically induced inflammatory disease caused by repeated inhalation of an inciting agent that triggers a type III and IV hypersensitivity reaction. Hypersensitivity pneumonitis Pneumonitis Human Herpesvirus 6 and 7 presents as cough, fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, and malaise Malaise Tick-borne Encephalitis Virus. Diagnosis is aided by high-resolution CT High-resolution CT Imaging of the Lungs and Pleura scans and analysis of the bronchoalveolar lavage Bronchoalveolar lavage Washing out of the lungs with saline or mucolytic agents for diagnostic or therapeutic purposes. It is very useful in the diagnosis of diffuse pulmonary infiltrates in immunosuppressed patients. Pulmonary Fibrosis fluid. Management is with steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors and by avoiding exposure to the inciting agent.