topic 20 :The gross anatomy and histology of the lungs, the bronchopulmonary segments and pleura. The innervation of the pleura

Question 1

general structure of lungs

Answer 1

General Structure:

Right Lung: Comprises three lobes (superior, middle, and inferior) separated by the horizontal and oblique fissures.

Left Lung: Comprises two lobes (superior and inferior) separated by the oblique fissure. It has a cardiac notch on its medial side to accommodate the heart.

Surfaces:
-Costal Surface: Convex surface facing the ribs.
-Mediastinal Surface: Concave surface facing the mediastinum. Has a hilum-area where bronchi, blood,vessels, lymphatics, nerves enter and exit lung
-Diaphragmatic Surface (Base): Concave surface resting on the diaphragm.
-Apex: The superior, pointed portion that extends above the first rib.

Question 2

histology of lungs

Answer 2

layers:
-Mucosa-Respiratory Epithelium: Pseudostratified ciliated columnar epithelium with goblet cells.
-submucosa-loose ct & submucosal glands in trachea & bronchi to produce mucus
-cartilage layer: trachea & bronchi- hyaline cartilage which provides structural support / bronchiole & smaller airways: lack cartillage but has smmoth muscle
-adventitia: outermost layer w/ collagen fiber bundles & anchors airways

Alveolar Epithelium:
-Type I Alveolar Cells (Pneumocytes): Simple squamous cells that form the structure of the alveolar walls and facilitate gas exchange.
-Type II Alveolar Cells (Pneumocytes): Cuboidal cells that secrete surfactant, reducing surface tension within the alveoli.

Question 3

bronchopulmonary segements

Answer 3

divided into functional units called bronchopulmonary segments, each supplied by its own segmental bronchus and artery. There are 10 segments in the right lung and 8-10 segments in the left lung.
———————-
Right Lung:

-3 Superior Lobe/ ( Apical, posterior, anterior segments)
- 3 Middle Lobe: Lateral, medial segments.
- 5 Inferior Lobe (Superior, medial basal, anterior basal, lateral basal, posterior basal segments.)

Left Lung:
- 5 Superior Lobe (Apicoposterior anterior, superior lingular, inferior lingular segments.)

-5 Inferior Lobe (Superior, medial basal, anterior basal, lateral basal, posterior basal segments)

Question 4

PLEURA

Answer 4

The pleura is a serous membrane that envelops the lungs and lines the thoracic cavity.

Visceral Pleura: Adheres tightly to the surface of the lungs, including the fissures.

Parietal Pleura: Lines the thoracic cavity, diaphragm, and mediastinum.
-Subdivisions: Costal, diaphragmatic, mediastinal, and (cervical (cupula) pleura.)

Pleural Cavity: The potential space between the visceral and parietal pleura containing a thin layer of lubricating serous fluid.

Question 5

innervation of pleura

Answer 5

Visceral Pleura:
-Innervation: Autonomic nerves from the pulmonary plexus (sympathetic and parasympathetic).

-Function: Insensitive to pain but sensitive to stretch.

Parietal Pleura:
Innervation:
-Costal Pleura: Intercostal nerves.
-Diaphragmatic Pleura: Phrenic nerve (central part) and lower intercostal nerves (peripheral part).
-Mediastinal Pleura: Phrenic nerve.

Function: Sensitive to pain, temperature, pressure, and touch.