Lung Anatomy, Histology, and Development Flashcards
vertebrosternal ribs
ribs 1-7
vertebrocostal ribs
ribs 8-10
vertebral (floating) ribs
ribs 11-12
costodiaphragmatic recess
a region of parietal plerua that extends two ribs below the lung margins and is a site where fluid/blood can accumulate and be sampled
extends to the 12th rib posteriorly and 9th rib anterolaterally
structure of the right lung
three lobes - superior (upper), middle, and inferior (lower)
horizontal fissure separtes superior and middle lobes
oblique fissure separates middle and lower lobes
structure of the left lung
two lobes, superior and inferior separated by an oblique fissure
upper lobe has a “tongue-shaped” lingula that lies against the heart
components of the mediastinum
primary bronchus
pulmonary artery
pulonary veins
bronchial arteries off the descending aorta
autonomic plexus
lymphatic vessels and nodules
bronchial vs. pulmonary artery circulation
bronchial arteries come off of the descending aorta and supplies blood to the bronchi - drains into the pulmonary veins and some into the azygous system
pulmonary artery circulation is for alveoli and gas exchange
components of the autonomic plexus on the bronchi and pulmonary arteries
parasympathetics from the vagus nerve
postsynaptic sympthetics from the upper thoracic (T1-5) cardiopulmonary splanchnic nerves
reflex afferents in vagus (pain fibers in splanchnics)
Which side of the lung is aspirated material likely to go into?
right - right primary bronchus is shorter and more in line with the trachea than the left
carina
the internal crest at the bifurcation of the trachea
eparterial bronchus
secondary (lobar) bronchi - right upper lobar artery
tertiary (segmental) bronchi
supply bronchopulmonary segments that are defined by the tertiary bronchi and the arteries that run with them
smallest lung units that can be surgically resected
Kerley B lines
radiologic descriptions of dilated lymphatics in interlobular septa at the periphery of the lung lower lobes
muscles used for inspiration
diaphragm
external oblique
accessory - scalenes, pectoralis minor, pectoralis major
serratous anterior
muscles used for expiration
internal oblique
abdominal muscles (rectus abdominus)
How many generations of branching of the airway are there?
23 generations
conducting portion of the airway
moves air into and out of the respiratory part
first 16 generations of branches away from the trachea
respiratory part of the airway
7 distal generation os branching that contains alveoli for gas exchange
branching sequence of the airway
trachea -> bronchi -> bronchioles -> respiratory bronchioles -> alveolar ducts -> alveolar sacs -> alveoli
cells of the conducting part of the airway from trachea through bronchi
pseudostratified columnar (respiratory) epithelium with cilia and mucous-secreting globlet cells
silhouette sign
the similar densities of pneumonia and the heart obscure the heart borders
C-shaped rings
strcutres that make up the trachea
entirely made up of hyaline cartilage
surrounds the lamina propria of loose connective tissue and submucosa of denser CT with mucous glands
no continuous muscle layer
elastic membrane between mucosa and submucosa
ends of the rings are united by a fibroelastic membrane and trachealis muscle
structure of the bronchi
cartilage plates rather than rings
continuous layer of smooth muscle under the cartilage plates
epithelium is the same, and goblet cells are present
structure of the bronchioles
lack of cartilage plates and glands (some cartilage may be present at branch points)
smooth muscle layer that is relatively thick
What happens to the epithelium during the transition from the largest bronchioles to the terminal bronchioles?
epithelium goes from ciliated, pseudostratified columnar in the largest bronchioles to simple cuboidal in the terminal bronchiole
acinus
the functional unit of the lung that contains all of the components of the alveoli
Clara cells
simple cuboidal cells that replace goblet cells and secrete a surfce active lipoprotein that keeps the wall sfrom sticking to each other
CC16
an airway fluid marker of pulmonary disease (Clara cell injury)
respiratory bronchioles
the first part of the airway where gas exchange occurs
alveoli start to line the walls
also ciliated and Clara cells (mostly Clara cells)
Describe gas molecule movement through the lungs.
velocity goes down corresponding to drastic opening of airways
air velocity increases a little with the first few generations of branching
in the lungs, the secondary and tertiary bronchi cross-sectional area is smaller
helps facilitate a cough, moves air faster through the big airways
type I alveolar cells (pneumocytes)
make up 40% of alveolar cells but 95% of the alveolar surface area because of their thin shape
lined by surfactant that prevents their collapse by reducing surface tension
alveolar septum (pulmonary membrane or air-blood barrier)
gas exchange happens here
consists of thin type I cell with its coating of usrfactant, the blood capillary endothelium, and a basal lamina shared by the two walls
very thin, 0.15-0.50 microns between air and blood
type II alveolar cells
comprise 60% of alveolar cells, but only 5% of the surface area
comprise the thick wall of the alveolar septum along with collagen fibrils, elastic fibers, fibroblasts, and macrophages
secrete phospholipid DPPC for reducing surface tension
secrete surfactant proteins that regulate the synthesis, secretion, and spreading of surfactant and modulate immune and allergic responses
alveolar ducts
the progression of respiratory bronchioles that consists of only rows of alveoli
alveolar sacs
the end of alveolar ducts with a cluster of alveoli opening into a central space
alveolar sacs may occur along the walls of alveolar ducts as well
elastic fibers
important for pulmonary stroma, oriented in all directions and help the lungs dilate
atelectasis
the obstruction of a bronchus
Where does the larnx, trachea, and lungs develop from?
laryngotracheal (lung bud) diverticulum of splanchnopleure that grows ventrally off the foregut
What gives rise to the carilage, smooth muscle, connective tissue, and visceral pleura?
splanchnic mesoderm
embryonic period of lung development
branching of the bronchi
the epithelim is undifferentiated simple cuboidal epithelium
pseudoglandular period
6 to 16 weeks
the airway resembles and exocrine gland
branching vessels to the level of terminal bronchioles, but no air exchange segments
epithelium begins to differentiate
blood vessels elaborate but are not closely applied to the airway
canalicular stage
16 to 26 weeks
branching down to primordial alveolar ducts surrounded by a rich vascular network
epithelium is thinning at the location of alveoli
breathing is possible, but surfactant is not yet produced
type I cells differentiate
saccular (terminal sac) stage
26 weeks to birth
elaboration of primordial alveoli with the differentation of Type I and Type II alveolar cells
surfactant is being produced, and preterm viability is possible
alveolar stage
32 weeks to 8 years
alveoli and acini continue to develop, and more generations of airway branching continue after birth
only about half the number of adult alveoli are present at birth
