2. LUNGS
• The lungs are the vital organs of respiration.
• Their main function is to oxygenate the blood by bringing inspired
air into close relation with the venous blood in the pulmonary
capillaries.
• The lungs provide an alveolar surface area of approximately 40 m2
for gaseous exchange.
3. • Although cadaveric lungs may be shrunken, firm or hard, and
discolored,
• Healthy lungs in living people are normally light, soft, and spongy,
and fully occupy the pulmonary cavities.
4. Each lung has:
• an apex which
reaches above
the sternal end
of the 1st rib.
• A base
overlying the
diaphragm.
5. • Two or three
lobes.
• Three borders
(anterior,
inferior, and
posterior).
7. The right lung has
• oblique and horizontal
fissures that divide it into
three lobes: superior,
middle, and inferior.
• Larger and heavier than
the left,
• Shorter and wider
because the right dome of
the diaphragm is higher.
• The anterior border of the
right lung is relatively
straight.
8. The left lung has
• a single left oblique
fissure dividing it into
two left lobes, superior
and inferior.
• The anterior border of
the left lung has a deep
cardiac notch.
• The notch indents the
antero-inferior aspect
of the superior lobe.
• The indentation shapes
into a thin, tongue-like
process, the lingula.
9. The costal
surface of the
lung is
• Large, smooth,
and convex.
• It is related to
the costal
pleura, which
separates it
from the ribs,
costal
cartilages, and
intercostal
muscles.
10. • The diaphragmatic
surface is concave,
forms the base of the
lung, which rests on
the dome of the
diaphragm.
11. • The concavity is deeper in the right lung because of the higher
position of the right dome, which overlies the liver.
13. • If embalmed, there is a groove for the esophagus and a cardiac
impression for the heart on the mediastinal surface of the right
lung.
14. • The left lung features much larger cardiac impression, groove for
the arch of the aorta and descending aorta
15. • The hilum of
the lung is a
wedge-shaped
area on the
mediastinal
surface of
each lung
through which
the structures
forming the
root of the
lung pass to
enter or exit
the lungs.
16. The roots:
• the bronchi,
• bronchial vessels,
• pulmonary arteries,
• superior and inferior
pulmonary veins,
• the pulmonary
plexuses of nerves,
• and lymphatic
vessels.
These structures are
ensheathed in a
loose pleural cuff
17. Bronchopulmonary segments.
• The largest subdivisionsof a lobe.
• Pyramidal-shaped segments of the
lung, with their apices facing the
lung rootand their bases at the
pleural surface.
• Separated fromadjacent segments
by connective tissue septa.
• Supplied independently by a
segmental bronchusand a tertiary
branch of the pulmonary artery.
• Named accordingto the segmental
bronchisupplying them.
• Drained by intersegmentalparts of
the pulmonary veins.
• Usually 18–20 in number (10 in the
rightlung; 8–10 in the left lung,
depending on the combiningof
segments).
• Surgically resectable.
18. Blood supply:
• Bronchi and the lungs are
supplied by bronchial
arteries; branches of the
descending thoracic aorta.
• Bronchial veins drain into
azygosand hemiazygos.
• Alveoli receive deoxygenated
blood from terminal
branches of pulmonary
arteryand oxygenated blood
returns via tributaries of
pulmonaryveins.
• Two pulmonaryveins return
blood from each lung to the
left atrium.
19. Lymphatic drainage
of the lungs: lymph
returns from the
periphery towards
the hilar
tracheobronchial
groups of nodes and
from here to
mediastinal lymph
trunks.
20. Nerve supply of the lungs:
• A pulmonary plexus is located at
the root of each lung.
• The plexus is composed of
sympathetic fibres (from the
sympathetic trunk) and
parasympathetic fibres (from
the vagus).
• Efferent fibres from the plexus
supply the bronchial
musculature and
• Afferents are received from the
mucous membranes of
bronchioles and from the
alveoli.
22. Each lung is invested
by and enclosed in a
serous pleural sac
that consists of two
continuous
membranes:
• the visceral pleura,
which invests all
surfaces of the lungs
forming their shiny
outer surface, and
• the parietal pleura,
which lines the
pulmonary cavities
23. • At the hilum of the lung the visceral
and parietal layers become
continuous.
• This cuff hangs loosely over the
hilum and is known as the
pulmonary ligament.
• It permits expansion of the
pulmonary veins and movement of
hilar structures during respiration
24. • The two (right and left)
pleural cavities do not
connect.
• The pleural cavity contains
a small amount of pleural
fluid which acts as a
lubricant decreasing
friction between the
pleurae.
• During maximal inspiration
the lungs expand fully into
the costodiaphragmatic
and costomediastinal
recesses of the pleural
cavity.
• In quiet inspiration the
lungs do not.
25. • The parietal pleura is sensitive to pain and touch (carried by the
intercostal and phrenic nerves).
• The visceral pleura is sensitive only to stretch (carried by
autonomic afferents from the pulmonary plexus).
26. • Pneumothorax: Air in the pleural cavity following a fractured rib or
a torn lung. This eliminates the normal negative pleural pressure,
causing the lung to collapse.
• Inflammation of the pleura (pleuritis) can results from infection of
the adjacent lung (pneumonia). A pleural rub can often be
auscultated over the affected region during inspiration and
expiration.
• Pus in the pleural cavity is termed an empyema.
