Respiratory System Anatomy Quiz

Respiratory System Anatomy

• The trachea is a flexible, slightly rigid tubular organ, often called the windpipe.
• It extends through the mediastinum, anterior to the esophagus and inferior to the larynx, superior to the primary bronchi of the lungs.
• The trachea is supported by 15-20 C-shaped cartilages, which provide rigidity to ensure it remains open.
• Cartilage rings are connected by elastic sheets called anular ligaments.

Trachea

• At the level of the sternal angle, the trachea bifurcates into two smaller tubes called the right and left primary bronchi.
• Each primary bronchus projects laterally toward its corresponding lung.
• The most inferior tracheal cartilage separates the primary bronchi at their origin and forms an internal ridge called the carina.
• The carina is highly sensitive to irritation, triggering the cough reflex.

Bronchi

• Tubes that branch off the trachea and enter the lungs are called bronchi.
• Branches in the bronchi tree are: primary bronchi, secondary bronchi (lobar bronchi), tertiary bronchi (segmental bronchi), bronchioles, terminal bronchioles, respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.
• Primary bronchus: Incomplete rings of hyaline cartilage ensure that they stay open. The right primary bronchus is shorter, wider, and more vertically oriented than the left, increasing the likelihood of foreign particles lodging in the right.

Lungs

• The lungs are cone-shaped, with a wide concave base resting on the diaphragm and a relatively blunt superior region (apex).
• They are bordered by the thoracic wall anteriorly, laterally, and posteriorly, and supported by the rib cage.
• They are separated from one another in the midline by the mediastinum.
• Each lung is divided into lobes by fissures.
• The left lung has two lobes, separated by an oblique fissure.
• The right lung has three lobes divided by oblique and horizontal fissures.
• Lungs have structures like cardiac notches and lingula.

Bronchial Tree

• A highly branched system of air-conducting passages originating from the right and left primary bronchi.
• The bronchi progressively branch into narrower tubes, diverging throughout the lungs before terminating in terminal bronchioles.

Respiratory Bronchioles, Alveolar Ducts, and Alveoli

• Contain small saccular outpocketings called alveoli.
• An average alveolus is about 0.25 to 0.5 millimeters in diameter.
• Alveoli have thin walls for efficient gas exchange between the alveolus and the blood in the pulmonary capillaries.
• The lungs contain approximately 300-400 million alveoli contributing to its spongy texture due to their packing.

Bronchopulmonary Segments

• The anatomical divisions of each lung are called bronchopulmonary segments.
• Each segment is served by a tertiary bronchus. The left lung has 8-10 segments, and the right lung has 10 segments.

Pleura and Pleural Cavities

• The outer surface of each lung and adjacent internal thoracic wall is lined by a serous membrane called pleura, formed from simple squamous epithelium.
• The surface of each lung is covered by visceral pleura, while the internal thoracic walls are lined by parietal pleura.
• The parietal and visceral layers connect at the hilum of each lung. There is a potential space between these layers, the pleural cavity, containing serous fluid for reduced friction during breathing.

Breathing Mechanism

• During inhalation, muscles like the diaphragm and external intercostals contract increasing the size of the thoracic cavity and lowering internal pressure.
• Oppositely, during exhalation, muscles like the internal intercostals and abdominal muscles relax, decreasing the size of the thoracic cavity and raising internal pressure.
• The pleura and the pleural cavities play an important role in the breathing mechanics of the lungs.

Arteries and Veins

• Bronchial arteries supply blood to lung tissue.
• Pulmonary arteries carry deoxygenated blood from the heart to the lungs for oxygenation.
• Pulmonary veins return oxygenated blood from the lungs to the heart.
• Specific bronchial veins and lymphatic drainage systems are found surrounding the lungs.

Auscultation of the lungs

• Listening to the sounds of air movement in the lungs. These sounds are used as diagnostics.

Thoracic Wall Dimensional Changes

• The thoracic wall expands and contracts during breathing. This is driven by muscle contractions in the ribs, diaphragm, and additional accessory muscles to expand the thoracic cage laterally, vertically and anterior-posteriorly.

Test your knowledge of the anatomy of the respiratory system, focusing specifically on the trachea and bronchi. This quiz covers key features such as structure, function, and anatomical relationships. Ideal for students studying biology or related fields.