Lungs.pptx

The lungs are a pair of spongy, air-filled organs located on either side of the chest (thorax). The trachea (windpipe) conducts inhaled air into the lungs through its tubular branches, called bronchi. The bronchi then divide into smaller and smaller branches (bronchioles), finally becoming microscopic.

The bronchioles eventually end in clusters of microscopic air sacs called alveoli. In the alveoli, oxygen from the air is absorbed into the blood. Carbon dioxide, a waste product of metabolism, travels from the blood to the alveoli, where it can be exhaled. Between the alveoli is a thin layer of cells called the interstitium, which contains blood vessels and cells that help support the alveoli.

1. ANATOMY & DEVELOPMENT OF LUNGS Dr Mathew Joseph MBBS, MD(AIIMS), BCC(Palliative Medicine) Assistant Professor Department of Anatomy Amala Institute of Medical Sciences, Thrissur

2. C ONTEN T S GROSS ANATOMY OF LUNGS SURFACES AND BORDERS OF LUNGS HILUM AND ROOT OF LUNGS FISSURES AND LOBES OF LUNGS BRONCHOPULMONARY SEGMENTS BLOOD SUPPLY OF LUNGS NERVE SUPPLY OF LUNGS LYMPHATICS OF LUNGS PLEURA DEVELOPMENT OF LUNGS

3. GROSS ORGANIZATION OF LUNGS Lungs are pair of respiratory organ s situated in thoracic cavity. Texture: S pongy Color: Y oung- Pinkish brown Adult-mottled black due to deposition of carbon particle s Lungs weigh 650 to 800 g ,of which 40 to 50% is blood.

4. Each lung has an apex , three surfaces ( costal, medial, and diaphragmatic ), and three borders ( anterior, inferior, and posterior ). The right lung is divided into upper, middle, and lower lobes by oblique and horizontal fissures. The left lung has usually only upper and lower lobes, separated by an oblique fissure .

5. APEX OF LUNG BLUNT Lie above level of anterior end of 1 st rib Reaches 1-2 cm above medial 1/3 rd of clavicle Coverings-cervical pleura ,suprapleural membrane Grooved by subclavian artery and vein

6. BORDERS OF LUNGS ANTERIOR BORDER Corresponds to the anterior (Costomediastinal) line of pleural reflection. It is deeply notched in the left lung posterior to 5 th costal cartilage by the pericardium and extends vertically downwards to form Lingula . This is called ca r diac no t c h (pe r cussion in th i s a r ea gi v es a du l l no t e as compared to dull note obtained over lung).

7. INFERIOR BORDER Thin and sharp It seperates the base of lung from the costal surface.

8. POSTERIOR BORDER Thick and ill defined Fits into deep paravertebral gutter. Extends from C7 to T10.

9. SURFACES OF THE LUNG Costal Surface It is in contact with costal pleura and overlying thoracic wall. Posterior / Vertebral Part Medial Surface Anterior or mediastinal part

10. Relations of Posterior Part Vertebral Part Intervertebral Discs Posterior Intercostal Vessels Splanchnic Nerves

11. RELATIONS OF ANTERIOR PART RIGHT SIDE Right atrium Small part of RV SVC Right brachiocephalic vein(lower part) Azygos vein Esophagus IVC Trachea Right vagus nerve Right phrenic nerve LEFT SIDE Left ventricle Pulmonary trunk Arch of Aorta Descending thoracic aorta Left Subclavian Artery Thoracic duct Left Brachiocephalic Vein Left vagus nerve Left phrenic nerve L e f t r ecur r e n t la r y n g eal nerve

12. RIGHT LUNG MEDIAL VIEW

13. LEFT LUNG MEDIAL VIEW

14. ROOT AND HILUM OF LUNGS The bronchi and pulmonary vessels, which extend from the trachea and heart, respectively, collectively form the root of the lung. The part of the medial surface where these structures enter the lung is known as the hilum of lung.

15. ROOT OF RIGHT LUNG Eparterial and H y par t er i al b r onchus One pulmonary artery . Two pulmonary veins - Bronchial arteries (one)

16. ROOT OF LEFT LUNG Principal Bronchus Pulmonary artery Pumonary vein Bronchial artery •

17. The right lung is divided into upper, middle, and lower lobes by oblique and horizontal fissures. Azygous lobes occur in 0.25 % cases on Right side.Azygous vein seprate medial part of right upper lobe from rest of lung produce linear mark on radiograph The left lung has usually only upper and lower lobes, separated by an oblique fissure.

18. FISSURES AND LOBES OF LUNGS

19. OBLIQUE FISSURE • The oblique fissure start at 3 rd thoracic spine, descend downward laterally and anteriorly cutting midaxillary line in 5 th rib, ending at 6 costal cartilage 3 inches from midline

20. HORIZONTAL FISSURE The horizontal fissure begins at the oblique fissure near the midaxillary line (of the right side), at about the level of rib 6 to 4 th costal cartilage. Important for localization of particular lobe during chest injury.

21. TR A CH E A Extend from larynx to bifurcation at the level of 5 th thoracic vertebra. Rigid fibroelastic structure. Incomplete rings of hyaline cartilage maintain patency of lumen. Average length of trachea 10-12 cm in adult and diametre is 2-2.5 cm in diametre. Lower end divides into right and left main bronchus. The trachea has 15 to 20 C-shaped bars of hyaline cartilage that prevent it from collapsing. Bridged posteriorly by Trachealis muscle.

22. Trachea is supplied by cervical portion of Inferior Thyroid artery and thoracic portion of bronchial artery Venous Inferior thyroid venous plexus Nerve supply general secretion by vagus and recurrent laryngeal nerves Autonomic secretion sympathetic T1 ,T2 Parasympathtic -vagus

23. CARINA The carina is the upward-directed ridge seen internally at the bifurcation and is a landmark during bronchoscopy. T rachea is supplied mainly by the inferior thyroid arteries. Its smooth muscle is supplied by parasympathetic and sympathetic fibers, and pain fibers are carried by the vagi.

24. Right bronchus Right direct continuation 1-2.5 cm long Shorter Wider More in line with trachea Clinical Anatomy Foreign body traversing the trachea are more likely to enter the right main bronchus. Left bronchus Left run more oblique About 5 cm long Longer narrower

25. Bronchopulmonary segment A bronchopulmonary segment is the area of lung supplied by a segmental bronchus and its accompanying pulmonary artery branch. Bronchopulmonary segment is the smallest, functionally independent region of a lung The smallest area of lung that can be isolated and removed without affecting adjacent regions.

26. CLINICAL SIGNIFICANCE Se g me n t al r esection with m i ni m al de s truct i on to the surrounding lung tissue. To visualize the interior of a bronchi through a bronchoscope when diseases process is limited in a segment.

27. BLOOD SUPPLY OF LUNGS Two types 1. Bronchial circulation 2. Pulmonary circulation

28. Bronchial circulation • The trachea (and esophagus), main-stem bronchi, and pulmonary vessels into the lung , as well as the visceral pleura in humans are supplied by the bronchial (systemic) circulation. • The bronchial circulation has enormous growth potential. In longstanding inflammatory and proliferative diseases, such as bronchiectasis or carcinoma, bronchial blood flow may be greatly increased.

29. Pulmonary circulation In humans the pulmonary artery enters each lung at the hilum in a loose connective tissue sheath adjacent to the main bronchus. Anatomically, the pulmonary blood vessels can be divided into two groups in Extra-alveolar Alveolar.

30. Sequestered lung is an embryonic Lung tissue which separate from tracheobronchial tree. This is seen in lower lobe of left lung. It may be supplied by abnormal branch of abdominal aorta.

31. NERVE SUPPLY OF LUNGS Anterior and posterior pulmonary plexus Parasympathetc fibres-Right and Left vagus Sympathetic fibre 4 or 5 thoracic ganglion

32. LYMPHATICS OF LUNGS Right upper lobe: Upper 2/3rd -Right tracheobronchial nodes Lower l/3rd -Dorsolateral hilar nodes Right middle lobe: Hilar nodes around middle lobe bronchus Right lower lobe: Porsolateral part-Dorsolateral hilar nodes Ventromedial part- Ventromedial hilar and carinal nodes

33. Left upper lobe: Apex-para-aortic node Other than apex-Anterior and posterior hilar nodes Left lower lobe Dorsolateral part-Dorsolateral hilar nodes Ventromedial paraVentromedial hilar and carinal nodes

34. PLEURA The pleura is a thin, glistening, slippery serous membrane, inflammation of which is called pleurisy. The pleura lines the thoracic wall and diaphragm, where it is known as the parietal pleura. It is reflected onto the lung, where it is called the visceral pleura. Both are derivatives of mesoderm germ layer

35. The parietal pleura has costal, mediastinal, diaphragmatic parts and a cupola. the cupola of the pleura and the apex of the lung project upward into the neck, hence may be injured in wounds of the neck. Their highest point is 2 to 3 cm above the level of the medial third of the clavicle.

36. The inferior limit of the lung crosses rib 6 in the midclavicular line and rib 8 in the midaxillary line and then proceeds toward the 10th thoracic vertebra. • Inferior limit of pleura is rib 8 in MCL, rib 10 in MAL and 12th thoracic vertebra along paravertebral line.

37. The pleural cavity, which is the potential space between the two layers, contains only a thin film of fluid. Air in the pleural cavity (pneumothorax) results in collapse of the lung. Irritation of the parietal pleura causes pain referred to the thoraco-abdominal wall to the shoulder (phrenic nerve). Visceral pleura is pain insensitive.

38. Lung Development

39. Initial Changes The respiratory system is derived from the primitive gut tube . E ndodermal - L ateral folding At week 4 -R espiratory D iverticulum. R espiratory diverticulum is continuous with the foregut - not functionally suitable. L ongitudinal ridge - T racheoesophageal septum The diverticulum bifurcates into two buds - L eft and right primary bronchi. The primary bronchi then proliferate to give rise to secondary and tertiary bronchi

40. STAGES OF DEVELOPMENT OF LUNGS Lung bud Initiation : 21-28 Days Embryonic : 9-12 Weeks Pseudoglandular : 6-16 weeks Canalicular : 16-26 weeks Saccular : 26 weeks till Birth Alveolar : Birth - 8 years

41. EMBRYONIC 21-28 DAYS Lungs appear as epithelial bud at the caudal end of laryngotracheal tube on 26 th day of ovulation Developing lung bud divides into 2 halves an elongates grows caudally on either sides of esophagus. By day 33 Trachea become separated from the foregut. ABNORMAL partition results in esophgeal atresia ,Tracheoesophgeal fistula.

42. PSEUDOGLANDULAR STAGE 6 -1 6 WEEKS Dichotomous and lateral branching takes place forming pulmonary tree comprise 22 to 23 generation. Stage of conducting airway formation Lungs have characteristic tubuloacinus gland Type 2 pneumocyte appear Respiration not possible

43. CANALICULAR STAGE (16-26WEEKS) Patterning of bronchial tree is completed at beginning of canalicular stage and cell constituting the proximal epithelium continue to diferentiate as ciliated nonciliated and secretory cells. Vascularization Acini formed in this phase (respiratory bronchiole,alveolar duct,alveolar sacculi) Fetus may survive in case of Intensive support

44. SACCULAR STAGE (24-38WEEKS) T erminal acinar tubule continue branching and air space increases Capillary multiply around acini Viable fetus ALVEOLAR STAGE 36 WEEKS TO 18 M postnatal alveoli generated from terminal saccules. Surfactant production increases

45. MOLECULAR REGULATION OF LUNG DEVELOPMENT DIFUSIBLE MEDIATORS TRANSCRIPTIONAL Fibroblast growth factors and receptors Retinoic acid Platelet derived growth factors Vascular endothelial growth factors Thyroid transcriptional factor 1

46. Tracheoesophagal Fistula D irect connection between the trachea and the oesophagus. C omplication of surgical procedures or C ongenital. Congenital - T racheoesophageal septum fails or forms abnormally – and leaves the trachea in continuity with the oesophagus. Oesophagus empties into the trachea . Oesophagus is blind ended proximally and arises from the carina distally The infant may become cyanosed during feeding or may vomit/regurgitate food. Management - surgical resection of the fistula -- anastomosis of any discontinuous segments

47. Case Scenerio A mother brought her new born baby to the pediatrician with a complaint of feeding difficulty as the baby is not swallowing the milk and when tried to feed there wewe episods of choking. The pediatrician tried to introduce a nasogastric tube but failed. He ordered for an x-ray chest which showed absence of stomach bubble. When enquired about antenatal history it was found to be a case of polyhydramniosis.

48. Esophagal Atresia -Tracheoesophagal Fistula Polyhydramniosis Absence of stomach bubble Impossible to introduce nasogastric tube Chocking

49. Respiratory Distress Syndrome If a baby is born prior to the development of type II pneumocytes, they will be unable to produce surfactant. As a result, they will have difficulty expanding their lungs to take their first breath. If a pre-term delivery is unavoidable or inevitable, the mother can be given glucocorticoids to stimulate surfactant production in the fetus.

50. R e f e r ence Crofton and Douglas’s Respiratory diseases 5 th edition Murray and Nadel’s Textbook of Respiratory Medicine 6 Th edition Fishman’s Pulmonary diseases and disorders 5 th edition

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