Lungs and Pleurae Anatomy Quiz

Lungs and Pleurae

• The lungs and pleurae are vital for respiration.
• Learning objectives include the anatomy of the lungs, respiratory zone, lobes and bronchopulmonary segments, innervation, pleura structure and function, and pleural pathologies.
• Lung anatomy includes the trachea, carina, bronchi (primary, secondary, tertiary), bronchioles, and the respiratory zone (bronchioles, alveolar ducts, alveoli).
• The respiratory zone is deep within the lungs, and houses respiratory bronchioles, alveolar ducts, and alveoli.
• The conducting zone includes the nose, pharynx, larynx, trachea, bronchi and bronchioles. It forms a continuous passageway for air into and out of the lungs.
• The trachea is a fibrocartilaginous tube connecting the larynx and thorax. It divides at the carina into the primary bronchi.
• The primary bronchi further branch into secondary bronchi (lobar bronchi), then into tertiary bronchi (segmental bronchi), until reaching the bronchioles. Bronchioles are too small to be supported by cartilage.
• Alveoli are the site of gas exchange, increasing surface area via a single layer of type 1 and 2 pneumocytes for gas exchange.
• Type 2 pneumocytes produce surfactant which reduces surface tension and increases lung compliance, preventing alveolar collapse and facilitating alveolar recruitment.
• Alveoli have thin walls and are close to the capillaries, decreasing the distance for gas diffusion.
• Alveoli have high numbers and collateral channels for ventilation that help gas exchange work during respiration.

Lobes of the Lung

• The right lung has three lobes (superior, middle, inferior).
• The left lung has two lobes (superior, inferior).
• The right and left lung structure is similar but asymmetrical.

Bronchopulmonary Segments

• The lungs are divided into bronchopulmonary segments.
• Each segment is supplied by its own segmental bronchus.
• This branching pattern supports the bronchopulmonary segments.

Surface Mapping

• Surface mapping aids in understanding the lung's division into lobes, helping in both the diagnosis and treatment.

Hilum (Root)

• The hilum is the point where various structures enter and exit the lung.
• Bronchi, pulmonary vasculature, phrenic nerve, lymphatics, bronchial vessels, and pulmonary arteries and veins are found at the hilum.
• Key components include Bronchi, pulmonary vasculature, phrenic nerve, lymphatics, and bronchial vessels, pulmonary arteries, pulmonary veins (right and left).

Mediastinum

• The mediastinum is a central compartment in the thoracic cavity, located between the pleural sacs of the lungs.
• It's divided into superior and inferior portions with the inferior portion further subdivided into middle and posterior portions.

Pulmonary Circulation

• Pulmonary circulation receives the entirety of cardiac output from the right heart.
• It's a low-pressure, low-resistance system with an arterial and venous circuit, lymphatics, and bronchial circulation.

Innervation of the Lungs

• The lungs receive innervation from two main sources: pulmonary plexus (a combination of parasympathetic and sympathetic nerves), and phrenic nerve.
• Parasympathetic innervation constricts bronchi, dilates pulmonary vessels, and increases gland secretions. Conversely, sympathetic innervation dilates bronchi and constricts pulmonary vessels.

Pulmonary Lymphatic System

• The lymphatic system within the lungs maintains fluid homeostasis and fights infections.

The Pleura

• The pleura is formed by two layers: parietal pleura and visceral pleura.
• There is no anatomical connection between the right and left pleural cavities.

Pleural Cavity

• The pleural cavity is the space between the visceral and parietal pleura.
• It contains serous fluid which aids in reducing friction and generates surface tension.
• Pleural recesses are located where the pleural cavity isn't filled with lung.

Surface Tension

• Surface tension is created by water molecules at the air-liquid interface within the alveoli.
• Surfactant secreted by type 2 alveolar cells reduces surface tension, increasing lung compliance and preventing alveolar collapse.
• Pleural role in surface tension includes promoting lung expansion, preventing alveolar collapse, and improving lung compliance, along with facilitating pressure changes,

Pleural Pathologies

• This section discusses pleural pathologies, primarily pleural effusion, empyema, and pneumothorax

Pleural Effusion

• Pleural effusion is the accumulation of fluid in the pleural space.
• It can be caused by conditions such as congestive heart failure , cancer , bacterial pneumonia and pulmonary embolism.
• Symptoms include shortness of breath, chest pain, and a dry cough.

Empyema

• Empyema is the collection of pus in the pleural cavity.
• Common causes include post-surgical complications, pneumonia and alcohol abuse.
• Symptoms include pain, cough with increased sputum production, dullness in chest wall percussion, and palpable fremitus. 

Pneumothorax

• Pneumothorax is the collection of air outside the lung but within the pleural cavity, often causing lung collapse.
• It can be caused spontaneously or due to injury / trauma.
• Two types are tension and spontaneous.
• Tension pneumothorax : Mediastinum pushed AWAY, increasing pleural space pressure.
• Spontaneous pneumothorax : Mediastinum pulled TOWARDS, 
• Treatment can involve a drain.

Imaging

• Imaging techniques are used to visualize the lungs and diagnose conditions.

Key Points

• Lungs consist of lobes, divided into conducting and respiratory zones for gas exchange.
• Alveoli have features that promote gas diffusion. The pleura lines the chest, reducing friction and generating surface tension.
• Pleural pathologies affect lung function. Tension pneumothorax displaces the mediastinum, while spontaneous pneumothorax pulls it towards the affected side.

Test your knowledge on the anatomy and function of the lungs and pleurae. This quiz covers key concepts such as respiratory zones, lobes, bronchi, and pleural structures. Ideal for students studying human anatomy and physiology.