LEC 21: Lungs - 08.29.14 Flashcards
Gross Anatomy of the Lungs (Right, Left)
RIGHT:
- 3 lobes
- Right Upper [horizontal fissure], Right Middle [oblique fissure], Right Lower
LEFT:
- 2 lobes
- Left Upper [oblique fissure], Left Lower
NB: oblique fissure = major fissure
Front View of Lungs
(what is palpated with stethoscope)
RIGHT:
- Right Upper and Right Middle equally apparent
- Right Lower very small
LEFT:
- Majority is Left Upper
- Very small portion of Left Lower
Right Lateral View of Lungs
(what can you palpate)
RIGHT:
- Right Upper (~1/3)
- small portion of Right Middle
- Significant portion of Right Lower
Left Lateral View of Lungs
(what can you palpate)
LEFT:
- Left Upper
- Left Lower
Back View of Lungs
RIGHT:
- mostly Right Lower
- small portion of Right Upper
LEFT:
- mostly Left Lower
- small portion of Left Upper
Describe this image from the lung
Lung lymphatics
- white lines under shiny visceral surface
- channel lymph toward hilum and to mediastinal lymph nodes
- carbon (turns black) within visceral pleural lymphatic channels
What layer of pleura covers the lung
Visceral pleura
What is the layer of pleura against chest wall
Parietal pleura
What is the cellular composition of the pleura
- single layer of mesothelial cells
- mesothelial cells are a form of simple squamous epithelium
pleural cavity
Space between parietal and visceral layers of lungs = pleural cavity;
should not have anything between these layers except for a small amount of lubricating fluid
hemothorax
collection of blood in the space between the chest wall and the lung (the pleural cavity)
pneumothorax
collection of air in the space between the chest wall and the lung (the pleural cavity)
What is the result if there is a tear/puncture in the parietal pleura
AFFERENT NERVE: intercostal and phrenic
RESULT: GSA pain
What is the result if there is a tear/puncture in the visceral pleura
AFFERENT NERVE: vagus and sympathetics
RESULT: little/no pain
Gray’s: visceral pleura is innervated by visceral afferent nerves that accompany bronchial vessels, pain is generally not elicited from this tissue
What nerve senses everything but tear/puncture in the lung
the vagus nerve (CN X - cranial nerve 10)
Location of vagus nerve in the lung
vagus nerve runs posterior to hilum of lung
Location and function of phrenic nerve in the lung
Phrenic nerve (C3-C5) runs anterior to hilum of lung;
Phrenic nerves carry motor (GSE) fibers to diaphragm
hilum
also known as the root of the lung;
formed by bronchus, pulmonary artery, pulmonary vein, bronchial artiers/veins, pulmonary plexus of nerves, lymphatic vessels, bronchial lymph glands, and areolar tissue
hilum is also where the viseral and parietal pleura meet
Order of arteries/bronchus/veins in hilum of lung (Left/Right)
LEFT: (Are Brides Vain)
- Artery, Bronchus, Vein
RIGHT: (Bride Are Vain)
- Bronchus, Artery, Vein
Where do the visceral and parietal pleura meet (reflection of the pleura)
root of the lung (hilum)
Pulmonary arteries
Carry deoxygenated blood away from the heart to the lungs (where blood gets oxygenated)
NB: these arteries do not “supply” the lungs – the material they carry is not beneficial; lungs are supplied by bronchial arteries/intercostal arteries (aorta) or subclavian arteries
Pulmonary veins
carry oxygenated blood from the lungs back to the heart; blood enters at left atrium, flows to left ventricle where it will be circulated (aorta)
Impressions on the Left Lung
LEFT:
- Left Subclavian Artery
- Arch of Aorta
- Brachiocephalic Vein
- Left Ventricle
“LABL”
Impressions on the Right Lung
RIGHT:
- Superior Vena Cava
- Inferior Vena Cava
- Azygos Vein
- Brachiocephalic Trunk (Artery)
- Esophagus
- Right Atrium
“BRAISE”
What blood vessels supply the lungs
- bronchial arteries (from aorta)
- intercostal arteries (from aorta)
- subclavian arteries
NB: These are nutrient arteries that supply oxygenated blood to lung tissue; they enter at the hilum
How are capillaries formed
Pulmonary arteries follow bronchial trees to form capillaries around alveoli; pulmonary arteries carry deoxygenated blood
Bronchopulmonary segments
- lung sub-units corresponding to bronchial tree
- no visible lines demarcating individual segments
Trace the tracheobronchial tree
- Trachea
- Intrapulmonary bronchus
- Main (1)
- Lobar (2)
- Segmental (3)
- Bronchiole
- Terminal Bronchiole
- Respiratory Bronchiole
- Alveolar Duct
- Alveolar Sac
- Alveolus
Carina
- cartilaginous ridge within trachea at site of tracheal bifurcation
- bifurcation usually at T5 vertebrae, with the angle of Louis
- lies more toward left side (foreign bodies most often aspirated into right side)
Histology of Trachea
C = cartilage
M = mucosa
T = trachealis muscle (smooth)
L = longitudinal muscle (smooth)
Adventitia
connective tissue on outside of trachea
C-shaped rings
Trachea made up of C-shaped rings (hyaline cartilage, incomplete dorsally)
What are the smooth muscles of the trachea
- trachealis
- longitudinal
What are the mucosal layers of the trachea
-
submucosa
- mucous and serous glands
-
muscosa
- epithelium - pseudostratified ciliated columnar cells, goblet cells
- lamina propria - connective tissue, elastic fibers
Label the parts of the slide
A. Mucosa - epithelium
B. Mucosa - lamina propria
C. Submucosa - serous glands
D. Submucosa - mucous glands
E. Perichondrium
F. Hyaline cartilage
What type of epithelium is found in the respiratory tract
ciliated, pseudostratified columnar; nuclei are at different heights, but all cells are anchored to the basement membrane
Label this epithelium
ciliated, pseudostratified columnar
A. Goblet cell
B. Cilia
What other types of cells are present in respiratory epithelium
-
Endocrine (Kulchisky) cells
- secrete serotonin, etc.
- regulate airway reflexes (smooth muscle contraction)
-
Basal cells (not columnar)
- undifferentiated precursors
Differences between angles of mainstem bronchi
Right mainstem bronchus is more vertical than left; inhaled objects tend to lodge in the right mainstem bronchus so often
Intrapulmonary Bronchus
- usually next to branch of pulmonary artery
- irregular cartilage plates
- smooth muscle
- goblet cells
- ciliated, pseudostratified columnar epithelium
- transitions to ciliated simple columnar as bronchi get smaller
Broncho-pulmonary segment
secondary/tertiary bronchi travel alongside, branch in parallel, with pulmonary arteries/arterioles
Bronchiole
- no cartilage
- smooth muscle
- very few goblet cells
- epithelium transitions from ciliated simple columnar to ciliated simple cuboidal
pattern of epithelium as you move down bronchiole tree
TRACHEA (RESPIRATORY EPITHELIUM): ciciliated, pseudostratified columnar
INTRAPULMONARY BRONCHUS: transitions to ciliated, simple columnar
BRONCHIOLE: transitions to ciliated simple cuboidal
Sympathetic Nervous System
4 Fs:
Fight
Flight
Fright
Fuck
Autonomic Innervation of Bronchial Glands
Sympathetic = inhibitory (need air passageway high and dry to run away)
Parasympathetic (Vagus nerve) = secretomotor
Autonomic Innervation of Bronchial Smooth Muscle
Sympathetic = bronchodilation
Parasympathetic (Vagus nerve) = bronchoconstriction
Autonomic Innervation of Bronchial Vasculature
Sympathetic = vasoconstriction
Parasympathetic = vasodilation (? - may have conflicting experimental evidence)
NB: No gas exchange in bronchi or bronchioles, thus want large diameter lumen!
Autonomic Innervation of Alveolar Vasculature
Sympathetic = no effect
Parasympathetic (Vagus never) = no effect
Sympathetic Nervous System in Respiratory Tract
- secretory inhibition
- bronchodilation
- vasoconstriction
Parasympathetic Nervous System in Respiratory Tract
- secretomotor
- bronchoconstriction
- vasodilation (?)
COPD / Asthma
may involve abnormally high parasympathetic discharge as well as inflammation
pulmonary plexus
- sympathetic axons
- parasympathetic axons and ganglia
Name the divisions of the bronchiole
- terminal bronchiole
- respiratory bronchiole
- alveolar duct
- alveolar sac
- alveolus
Histology of the Terminal Bronchiole
- surrounded by layer of smooth muscle
- no goblet cells
- ciliated simple cuboidal epithelium
- Clara cells
What do the green and purple arrows label (hint: terminal bronchiole)
GREEN: ciliated cuboidal cells
PURPLE: Clara cells
Clara cell
- precursors of bronchiolar epithelial cells
- detoxifies carcinogens
- synthesizes a surfactant-like protein
- secretes alpha-1-antitrypsin that inhibits digestion of elastin
emphysema = elastic tissue breakdown
Alveolar Wall (what do arrows point to)
Alveolar Wall contains elastic tissue
Acinus
(plural = Acini)
- functional subunit of the lung supplied by a single respiratory bronchiole
What are the divisions after the terminal bronchiole
- Terminal Bronchiole
- Respiratory Bronchiole
- Alveolar Duct
- Alveolar Sac
- Alveolus
Histology of the Respiratory Bronchiole
- simple cuboidal epithelium
- wall punctuated by alveoli and smooth muscle
- encircled by smooth muscle, interrupted by alveoli
What are A and B in this respiratory bronchiole
Respiratory bronchiole is encircled by smooth muscle, interrupted by alveoli
A. Alveolus
B. Smooth muscle
Histology of the Alveolar Duct
- wall punctuated by alveolar sacs and alveoli
Histology of the Alveolar Sac
terminal part of alveolar duct, alveolar clusters
Histology of the Alveolar Capillaries
end of tracheobronchial tree
What are the features of alveolar capillaries
- capillary walls protrude into lumen
- provide more surface area
- simple squamous epithelium
What are the (3) types of cells found in alveolar walls
- Endothelial cells
* thin, flat; gas exchange - Type I pneumocytes
- thin, flat; gas exchange
- only 40% of alveolar cells
- cover 90% surface of alveoli
- Type II pneumocytes
- thick, protruding, “foamy”
- 60% of alveolar cells
- Replace damaged Type I cells
- Secrete surfactant
What are the (3) types of alveolar cells (lining the alveoli)
Endothelial
- thin, flat cells for gas exchange
Type 1 pneumocytes
- flat cells
Type 2 pneumocytes
- round, “foamy” cells
Lamellar bodies
- Type II pneumocytes store surfactant in lamellar bodies
- gives foamy appearance on light microscopy
- product surfactant in form of tubular myelin weaves
Surfactant
- found on alveolar surface
- mix of phospholipids, cholesterol, carbohydrates, proteins
- acts as detergent to decrease alveolar surface tension
- keeps cell surface water layer thin, increasing gas exchange
- increases compliance (stretchability)
- prevents alveolar collapses
clinical sign of low surfactant levels
respiratory distress syndrome
Alveolar Pore (of Kohn)
Allow equalization of pressure between alveoli, facilitate flow between acini when bronchioles are blocked
Alveolar Pores (of Kohn) are sometimes partially obstructed by an accumulation of surfactant; how is extra surfactant removed
- Alveolar macrophages phagocytose extra surfactant
- also called “dust cells” because they ingest inhaled particulate matter
Alveolar macrophages
- also called “dust cells”
- phagocytose extra surfactant
- ingest inhaled particulate matter
What might lots of alveolar macrophages signify
- infection/irritation
- lungs can recruit ~1mm macrophages per hour
Smoker’s Lungs
- excess carbon particles (trapped in macrophages)
- chronic bronchitis (excess mucus from goblet cells)
- increased risk of pneumonia
- loss of elasticity (emphysema, fibrosis)
- cancer
- metaplasia (bronchi epithelium changes to stratified squamous)
- interstitial disease (thickened alveolar walls)
