lungs Flashcards
function of lungs
oxygenate the blood by bringing inspired air close to venous blood in pulmonary capillaries
inspired air flows along the following conducting ariways to reach the lungs: nasal cavity, pharynx (nasal and oral parts), larynz, trachea and bronchi
right lung
has 3 lobes (upper, middle, and lower); horizontal fissure separates the upper and middle lobes; oblique fissure separates the lower lobe from upper and middle lobes; is larger than the left lung, but shorter and wider because the right dome of the diaphragm is higher and the heart bulges to the left
left lung
has 2 lobes (upper and lower); oblique fissure separates the upper and lower lobes; its anterior border has the cardiac notch indenting its upper lobe and the lingula (tongue-like part of the upper lobe) extends below the cardiac notch
location of lower lobes of both lungs
located mainly posteriorly
oblique fissure of both lungs
from T2 spine posteriorly to 6th rib anteriorly; follows the medial border of the abducted scapula; horizontal fissure of right lung – from the oblique fissure, parallels the 4th rib anteriorly
apex
ascends into the root of the neck
3 surfaces of the lung
costal
mediastinal
diaphragmatic
costal surfaceof the lung
adjacent to sternum, costal cartilage and ribs
mediastinal surface of the lung
adjacent to the mediastinum
diaphragmatic surface of the lung
adjacent to the diaphragm
anterior border of the lung
where costal and mediastinal surfaces meet anteriorly
inferior border of the lung
separates diaphragmatic lung surface from costal and mediastinal suraces
posterior border of the lung
where costal and mediastinal lung surfaces meet posteriorly
root of the lung
is formed by structures connecting the lungs with the heart and trachea
each lung contains
pulmonary artery
pulmonary veins
main bronchus
autonomic nerves, sensory nerves, lymphocytes
pulmonary artery
located superiorly on the left; upper lobar bronchus
pulmonary veins
located anteriorly and inferiorly
main bronchus
located posteriorly; has bronchial vessels surrounding it
what encircles root structures
pleural sleeve with the pulmonary ligament hanging inferiorly
hilum of the lung
region on the lung’s mediastinal surface where parietal pleura of the pleural sleeve and pulmonary ligament is continuous with visceral pleura covering the lung and root structures enter and exit the lung
root structures entering the lung
bronchi, arteries, and nerves
root structures leaving the lung
veins and lymphatics
anterior of the hilum of the right lung
heart (forms cardiac impression) and superior vena cava
superior of the hilum of the right lung
arch of azygos vein
posterior of the hilum of the right lung
esophagus and azygos vein
anterior of the hilum of the left lung
anterior - heart (forms cardiac impression
superior of the hilum of the left lung
aortic arch
posterior of the hilum of the left lung
esophagus and thoracic (descending) aorta
main bronchi
arise from the bifurcation of the trachea at the level of the sternal angle; walls of trachea and bronchi are supported by cartilage; trachea contains the carina, a ridge that internally marks its bifurcation
bronchoscopy
during bronchoscopy, the carina marks the openings to the main bronchi; a deviation in carina position may indicate metastasis (spreading) oflung cancer to lymph nodes near the tracheal bifurcaton
aspiration of foreign objects
an aspirated foreign object usually enters the right main bronchus because it is shorter, wider, and more vertical than the left main bronchus; “inhale a bite, goes down to the right”
bronchial tree
each main (primary) bronchus branches into lobar bronchi (3 on the right; 2 on the left); right main bronchus gives off its upper lobar bronchus early, before entering the hilum; all other branching occurs within the lungs
each lobar (secondary) bronchus
branches into segmental (tertiary) bronchi (10 on the right; 8-10 on the left)
main bronchus and pulmonary artery
supply a lung
lobar branches
supply a lung lobe
segmental branches
supply a bronchopulmonary segment; each bronchopulmonary segment is a wedge-shaped area of lung tissue within a lung lobe; the segmental bronchus and artery run centrally within the bronchopulmonary segment
branching pattern for each segmental bronchus
segmental bronchus –> bronchioles –> terminal bronchioles –> respiratory bronchioles –> alveolar ducts –> alveolar sacs –> alveoli
where does gas exchange begin
respiratory bronchioles
intersegmental veins
drain oxygenated blood from adjacent segments and are tributaries of the pulmonary veins
surgical removal of lung segments
bronchopulmonary segments are independent functional and surgical units of the lung; intersegmental veins, lying in connective tissue septa between adjacent segments are surgical landmarks so a bronchopulmonary segment can be removed (segmentectoromy) without disrupting surrounding lung tissue
pulmonary arteries and veins
for gas exchange; deal with circulation of blood between the heart and lungs
bronchial arteries and veins
for nutrition; are the vascular supply to the lungs
pulmonary arteries
arise from the pulmonary trunk, which receives
deliver deoxygenated blood to the lungs for oxygenation
right pulmonary artery runs under the aortic arch and posterior to the ascending aorta and superior vena cava
left pulmonary artery is shorter and arches over the left main bronchus
pulmonary veins
transport oxygenated blood from the lungs to the left atrium of the heart
bronchial arteries
supply oxygenated blood to lung tissue, lung root, and visceral pleura
left bronchia arteries
arise from the thoracic aorta
right bronchial artery
variable origin (origin as a common trunk with the 3rd posterior intercostal artery is shown)
bronchial veins
only drain blood from the lung root near the hilum; most is drained by pulmonary veins (does not significantly reduce oxygen concentration of blood carried by pulmonary veins)
right bronchial veins
drain into azygos vein
left bronchial veins
drain into accessory hemiazygos vein
lymphatic drainage of the lungs
extensive and occurs via 2 lymphatic plexuses
superficialy plexus
lies deep to the visceral pleura and drains toward the hilum
deep plexus
follows the bronchial tree toward the hilum and includes pulmonary nodes within the lung
drainage routes
lymph from both plexuses drains to bronchipulmonary nodes, tracheobronchial nodes, paratrachealnodes, and then to a bronchomediastinal trunk
right and left bronchomediastinal trunks each drain to a venous angle (junctionof internal jugular and subclavian veins), either directly or through the right lymphatic duct and the thoracic duct, respectively
all drainage eventually reaches the brachiocephalicveins (tributaries of the superior vena cava)
metastasis of lung cancer
lung cancer cells may metastasize through the lymphatics (cancer cells enter lymphatic vessels and seed nearby lymph nodes), veins (cancer cells enter bronchial veins and pass to the azygos system), and arteries (cancer cells enter pulmonary veins and are returned to the left side of the heart)
innervation of the lungs
is via the anterior and posterior pulmonary plexuses located anterior and posterior to the roots of the lungs
both plexuses receive fibers from the sympathetic trunks (on each side of vertebral column) and vagus nerves (run posterior to roots of the lungs)
components of the pulmonary plexuses
sympathetic postganglionic fibers from upper thoracic ganglia of the sympathetic trunks
parasympathetic pregangiolinic fibers from the vagus nerves, parasympathetic ganglia, and postganglionic parasympathic fibers
visceral sensory fibers
sympathetic postganglionic fibers from upper thoracic ganglia of the sympathetic trunks
bronchiodilators, vasocontstrictors, and inhibit mucus secretion
parasympathetic preganglionic fibers
bronchoconstrictors, vasodilators, and stimulate mucus secretion
visceral sensory fibers
these fibers run in the vagus nerves; carry information involved in reflexes for coughing and for preventing over-inflation of the lungs
diaphragm
a dome-shaped skeletal muscle partition between the thoracic and abdominal cavities
superior relation of diaphragm
diaphragmatic parietal pleura are fibrous pericardium (attached to the central tendon of the diaphragm)
inferior relation of diaphragm
liver, stomach, spleen,suprarenal glands, and kidneys
functions of the diaphragm
drops on contraction, increasing the vertical dimension of the thoracic cavity and increasing intra-abdominal pressure
forcible contraction with anterior abdominal wall muscles assists in voiding responses such as micturtion (urination), childbirth, and defecation
diaphragm attachments
consists of peripheral muscle fibers that converge to insert on a central tendon (has no bony attachments)
muscle fibers are arranged in 3 parts by their origins
sternal muscle fibers
arises from the xiphoid process
costal muscle fibers
arises from the lower 6 ribs and costal cartilages
lumbar muscle fibers
arises from arcuate ligaments and crura of the diaphragm
acruate ligaments
medial and lateral acruate ligaments are tendinous arches of the psoas major and quadratus lumborum muscles, respsectively
crura of the diaphragm
arise from upper lumbar region of vertebral column; right crus is longer than the left; crura are united by the median acruate ligament
apetures of the diaphragm
openings that allow structures to pass between the thorax and abdomen
caval opening
an opening in the central tendon at T8 vertebral level; transmits the inferiore vena cava (IVC)
esophageal hiatus
an opening in the muscle of the right crus at T10 vertebral level; transmits the esophagus and the anterior and posterior vagal trunks
aortic hiatus
an opening posterior to the median acruate ligament at T12 vertebral level; transmits the aorta and the thoracic duct
thoracic surface arterial supply
supplied mostly by superior phrenic arteries from the thoracic aorta
abdominal surface arteral supply
supplied mostly by inferior phrenic arteries from the abdominal aorta
venous drainage of the diaphragm
most veins accompany arteries and all drainage eventually reaches the IVC
motor innervation of the diaphragm
all motor supply is from the right and left phrenic nerves (ventral rami C3-C5 of cervical plexus)
each nerve runs anterior to the root of the lung, between the fibrous pericardium and mediastinal pleura and supplies the hemidiaphragm on its respective side
sensory innervation
most sensory nerve supply from the diaphragm runs in the phrenic nerves
phrenic nerve lesion
a destructive lesion to a phrenic nerves results in paralysis and paradoxical movement of the affected hemidiaphragm; the paralyzed hemidaphragm fails to drop on inspiration and is forced upward by an increase in intra-abdominal pressure
