1.anatomy of the pleura

8/13/2019 1.Anatomy of the Pleura

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1.ANATOMYOFTHE PLEURA

PLEURAL DISEASES SERIES 08

BY WIDIRAHARDJO


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1. ANATOMY OF THE PLEURA The pleura is the serous membrane that

covers the lung parenchyma, the

mediastinum the diaphragm and the rib cage.

This structure is divided into the visceralpleura and the parietal pleura.

Parietal pleura divided into costal,mediastinal and diaphragmatic parietalpleura.

Posterior to the lung root, the pleura iscarried downward as a thin double fold as thepulmonary ligament.

Pleural fluid as a film of fluid is normally

present between the two pleuras.


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1. ANATOMY OF THE PLEURA

The (potential) space between the two

pleuras called pleural space.


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EMBRYOLOGY OF THE PLEURA

= In the embryo, pericardium communicatewith pleural canals bilaterally, which in turn

communicate with theperitoneal canals.= Three sets of partitions: septum

transversum, pleuropericardial membranes

and pleuroperitoneal membranes.

= The newly formed pleural cavity is fully lined

by mesothelial membrane: the pleura.

= No communication between two pleural

cavities.


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BODY CAVITIES: many vital organs are suspended in either thedorsal or the ventral body cavity where the diaphragm separatethe body cavity into superior thoracic cavity enclosed by theChest wall and an inferior abdominopelvic cavity.


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HISTOLOGY OF THE PLEURA

= Parietal pleura: loose, irregularconnective tissue (composed mainlyof collagen and elastic fiber) covered

by single layer of mesothelial cells.Within the pleura are blood vessels,mainly capillaries, and lymphatic

lacunas. The lacunas are initiallymphatic shaped, located over theintercostals spaces.


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= Visceral pleura: differs markedly from

parietal pleura (there are no lymphaticlacuna), and varies among species,

primarily on its thickness, whereas

human have a thick visceral pleural,that predominant source of blood

supply come from systemic circulation.

Thick visceral pleura composed by twolayer: mesothelial cells and connective

tissue.


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Two important function of theconnective tissue in the visceral

pleura that contain collagen and

elastic fibers:1. Contributes to the elastic recoil of

the lung

2. To restricts the volume to whichthe lung can be hyperinflated


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= Microvilli are present diffusely overall

the pleural surface, most numerous inthe inferior parts of the visceral pleura,

and the anterior and inferior

mediastinum on the parietal pleura.More microvilli are present in the

parietal pleura.

The function of microvilli may beenmesh glycoproteins that are rich in

hyaluronic acid, to lessen the friction

between the lung and the chest wall.


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1. ANATOMY OF THE PLEURA MESOTHELIAL CELLS

These are active cells, sensitive andresponsive to various stimuli, thecytoplasm always contains a moderateto abundant amount of organelles,

suggestive an active metabolicallycells. Any important functions are:

= Regeneration: come from migration

mesothelial cells= Converts to myofibroblast by TGF-

(transforming growth factor)


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1. ANATOMY OF THE PLEURA= Produced type I, II and IV collagens

elastin, fibronectine and laminin.= Also produced nitric oxide and

TGF-1 (transforming growth factor).

PLEURAL FLUID= Volume

Normally: small amount; 8,4 4,3 ml

= CellsWBC 1.716 cells/mm3, 75%macrophage

RBC 700 cells/mm3


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= Physicochemical factors

Protein electrophoresis pattern similar

to serum.

Ionic concentration differ significantly

from serum: bicarbonate increased by

20-25% from serum, but K, Na & Cl

slight lowered.


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BLOOD SUPPLY TO THE PLEURA

The parietal and visceral pleura receives fromsystemic capillaries.

PLEURAL LYMPHATIC

The lymphatic plexuses in the costal pleura aremainly in the intercostal spaces and are absentor minimal over the ribs.The lymphatic vessels in the parietal pleura are

in communication with pleural space by stoma.The stomas are found mostly on the mediastinaland on the intercostal surface, especially in thedepressed areas just inferior to the ribs in thelower thorax.


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The lymphatic vessels in the parietal

pleura have many branches, some of itsubmesothelialy have dilated, called

lacunas.

The visceral pleura dont have stoma.The lymphatic vessels form a plexus

that run over the surface of the lung

toward the hilum and also penetratethe lung to joint the bronchial lymph

vessels.


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INNERVATION OF THE PLEURASensory nerve endings are present

in the costal and diaphragmatic

(peripheral portion) parietal pleura.The central portion of the diaphragm

is innervated by the phrenic nerve.

The visceral pleura contains no painfibers.

1.anatomy of the pleura

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