Term
| Describe the basic asymmetric structure of the lungs. |
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Definition
1) LEFT (heart)
- smaller trachea leads into left lung divided into upper (LUL) and lower lobes (LLL).
- LUL consists of Upper Division (apical-posterior, anterior) and Lingula (superior, inferior)
- LLL consists of superior, antero-medial basal, lateral basal and posterior basal divisions.
2) RIGHT
- larger trachea leads into right lung, which is divided into RUL (apical, posterior, anterior), RML (medial, lateral) and RLL (superior, anterior basal, medial basal, lateral basal, posterior basal). |
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Term
| Why do aspirated foreign bodies wind up in the right lung in a patient with Kartagener's syndrome? |
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Definition
"Primary ciliary dyskinesia"
1) Mirror image of normal chest with dextrocardia and reversal of normal branching pattern of lungs
2) Left mainstem bronchus is longer than right and more acutely angled (this angle leads to more apirates). |
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Term
| What is the basic structuring of the conducting airways (conducting zone), transitional zone and respiratory zone? |
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Definition
Conducting zone (16 generations by 16 weeks gestation) is airways without alveoli directly attached (BR, BL and TBL)
1) Bronchi (BR) give way to bronchioles (BL), which are distinguished by having no cartilage in their walls
2) Terminal BL (TBL) give way to respiratory bronchioles (RBL), which have alveoli budding off their walls (transitional zone)
3) Respiratory zone generations (3) are made up of alveolar ducts (AD), which are alveoli with bands of smooth muscle in their walls
4) Gas exchange occurs in alveolar sacs (AS).
** an ACINUS is a respiratory BL with all of its branches and alveoli. |
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Term
| How does the microanatomy of the epithelium change over the course of an airway? |
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Definition
** non-ciliated Goblet cells are found throughout**
1) Pseudostratified columnar in Trachea and Bronchi
- have sub-mucosal glands to secrete water , electrolytes and mucins into the airway lumen
2) Cuboidal in Bronchioles
- Mostly ciliated except Clara cells (secretes "clara" protein)
- Mucociliary escalator located between Trachea and BL
3) Squamous in alveoli (flat and non-ciliated)
- 93% area taken up by Type 1 (squamous)
- 7% area taken up by Type 2 (granular)- more numerous, but less SA
- Type 2 makes surfactant and can differentiate into Type 1 in injury |
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Term
| Why do patients with primary ciliary dyskinesia and CF tend to get lower airway infections and bronchiectasis? |
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Definition
| Impaired mucus clearance because of damaged mucociliary escalator between trachea and BL. |
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Term
| What are the major differences between alveolar epithelial cells? |
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Definition
1) 93% of surface area taken up by terminally-differentiated, flat, Type 1 cells (fewer in number than type 2)
2) 7% of surface area taken up by found, surfunctant-producing, granular type 2 cells.
- Surfactant lipoprotein reduces surface tension (SP A and C are involved in host defenses and SP B is required for life) |
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Term
| What types of non-ciliated cells are found in the airway? |
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Definition
1) Goblet cells (mucin-producing) throughout
2) Clara cells (produce "clara protein) in BL
3) sub-mucosal Serous cells that secrete a) mucins and b) bicarb-ric serious fluid dense with CFTR) |
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Term
| What are the important functionalities of the principal site of liquid and solute filtration in the airway? |
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Definition
This is the capillary endothelium
1) Converts ang-1 to ang-2
2) Produces factor 8 (platelet activating)
3) Inactivates PGE2 and PGF2a, leukotrienes and 5-HT
fluid is drained by pulmonary lymphatics |
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Term
| How does oxygen travel at the alveolar-capillary interface? |
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Definition
0.5 microns thick
1) Surfactant (mainly phosphatidyl choline)
2) Type I epith. Cell
3) Fused basement membrane
4) Endothelial cell
5) RBC |
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Term
| What is the basic structure of pulmonary circulation? |
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Definition
2 supplies (systemic via bronchial arteries and directly from right heart through pulmonary arteries)
1) Pulmonary arteries leaves right ventricle and follows pulmonary anatomy before returning to the left heart
2) Bronchial arteries arise from aorta and return to left heart contributing to a venous shunt.
**remember, interstitial fluid is returned via lymphatics** |
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Term
| True or False: Transplanted lungs have no bronchial circulation. |
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Definition
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Term
| How is the pleural space lubricated? |
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Definition
Remember the NEGATIVE pressure in pleural space.
Visceral pleura of lungs and parietal pleura of thoracic wall are continuously in contact.
Fluid enters through parietal pleura and is drained by lymphatics after traversing the visceral pleura |
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Term
| What are the primary inspiratory and expiratory muscles? |
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Definition
1) Inspiration
- Primarily diaphragm (C3-5 phrenic nerve)
- Accessory muscles include SCM, EXT. intercostals (raise bucket handle of sternum)
2) Expiratory (passive except for cough or increased respiratory work)
- rectus abdominus, obliques, and transverse abdominal muscles and the internal intercostals |
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Term
| What is the basic motor/autonomic innervation of the respiratory system? |
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Definition
1) Motor
- Diaphragm: Phrenic (C3-C5)
- Intercostals: Intercostal nerves (thoracic segmental)
2) Autonomic
- Sympathetic (upper thoracic ganglia) stimulates bronchodilation (beta 2), constriction of pulmonary blood vessels (alpha), inhibition of glandular secretion
- Parasympathetic (vagus) results in airway constriction, dilation of pulmonary circulation and increased glandular secretion
- Non-arenergic, non-cholinergic (NANC) mediated by NO |
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Term
| What sensory receptor types are found in the respiratory system? |
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Definition
1) Stretch receptors (slowly adapting) in airway smooth muscle react to inflation and increase transpulmonary pressure
2) Irritant (rapidly adapting) receptors in epithelium, larynx and intrapulmonary react to mechanical stress
3) C-fiber receptors are responsible for sensation of dyspnea.
- Pulmonary (in alveolar wall to sense interstitial congestion, chemical injury and microembolism)
- Bronchial (bronchoconstriction in response to bradykinin) |
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Term
| What is the role of J receptors in the respiratory system? |
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Definition
Juxtapulmonary-capillary receptor found in interstitium between alveoli and capillary.
- Mediate the hyperpnea associated with increases in left atrial pressure as in vascular congestion and pulmonary edema of other causes |
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Term
| Why do patients with weak respiratory muscles tend to get pneumonia? |
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Definition
| Weak/ineffective cough due to weak accessory expiratory muscles (rectus abdominus, transverse abdominals, obliques) cannot clear secretions from chest |
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Term
| What are the 4 structural layers of the trachea and bronchi of the conducting respiratory system? |
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Definition
From trachea to respiratory BL
1) Respiratory Mucosa
-pseudostratified columnar, goblet, basal and Kulchitsky cells
2) Submucosa
- Loose connective tissue around lamina propria with mucous and serous secreting glands and blood vessels
3) Muscularis and cartilage
- C-shaped rings of hyaline cartilage
- smooth muscle between epithelium and cartilage at posterior gap (keeps trachea open)
4) Adventitia
- Dense connective tissue containing large nerves, lymphatics and fats (blend with central mediastinum) |
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Term
| What 4 principle cell types are found in the respiratory mucosa of the trachea and bronchi? |
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Definition
Mucociliary escalator
1) Psuedostratified columnar epithelium
2) Mucous-secreting Goblet cells
- Oval, ER-rich cytoplasm with vescicles
3) Basal/germinal cells
- Progenitor cells
4) Kulchitsky cells at base with endocrine function
- small, pale-staining cells with dendritic processes that release factors into blood stream via basal lamina
Underneath are Basement membrane (open-network) and Lamina Propria (mast cells) |
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Term
| What types of metaplastic changes take place in the respiratory mucosa? |
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Definition
1) Squamous (chronic irritation)
2) Goblet cell (lesser irritation)
3) Type II cell/bronchiolar (scarring below terminal bronchiole)
4) Smooth muscle cell (almost all scars) |
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Term
| What happens to Bronchioles as they become smaller (ultimately becoming respiratory bronchioles)? |
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Definition
Each terminal bronchiole supplies a unit of lung called a "Lobule" and each respiratory bronchiole and its surrounding structures is an "Acinus"
1) Lose goblet cells, cilia and seromucous glands
**Goblet cells replaced by dome-shaped Clara cells containing osmiophillic surfunctant)
2) Epithelium is simple columnar (bronchioles) and then becomes simple cuboidal (terminal) and finally low cuboidal (respiratory)
3) Smooth muscle increases and hyaline cartilage decreases |
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Term
What are the basic characteristics of
1) Bronchioles
2) Terminal bronchioles
3) Respiratory bronchioles |
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Definition
1) Bronchioles
- Simple columnar epithelium with few goblet cells and cilia
- No cartilage
- Full circle of smooth muscle
2) Terminal BL
- Within lung lobules
- Simple cuboidal epithelium
- No goblet cells or cilia, but 80% Clara cells
- Patches of smooth muscle but no cartilage or submucosal glands
3) Respiratory
- Within lung acini
- low cuboidal epithelium
- Interrupted by outpockets of alveoli
- First gas exchange leading into alveolar duct |
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Term
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Definition
Replace Goblet cells as bronchioles get progressively smaller.
1) Non-ciliated peg-shaped cells with numerous small microvilli that secrete surfactant proteins, IG and lysozyme
2) Serve as main progenitor cells after bronchiolar injury |
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Term
| What is the basic structure of a lung Acinus? |
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Definition
basic functional unit of lung consisting of respiratory bronchiole (low cuboidal epithelium), alveolar ducts and alveolar sacs.
1) Gas exchange occurs through alveolar walls between epithelium, shared basement membrane and capillary endothelium
2) Alveolar epithelium consists of Type 1 and Type 2 (osmiophillic lamellar bodies) pneumoncytes |
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Term
| How does bronchiolar and pulmonary arterial circulation differ? |
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Definition
1) Bronchiolar is high-pressure system arising from aorta accompany airways only until terminal bronchioles
2) Pulmonary is low-pressure system arising from heart and runs along bronchi and bronchioles |
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Term
| What happens to air as it moves distally into the lung through the conduction and respiratory systems? |
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Definition
Conduction: Nasal-pharyx-larynx-trachea-bronchi-bronchioles-terminal bronchiole
Respiration: Respiratory bronchiole-avleolar duct-alveolar sac-alveoli.
1) Cross-sectional area increases
2) Air flow velocity decreases
3) Air turbulence increases
4) Humidity and warmth increase |
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Term
| What are Kulchitsky cells and why are they important? |
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Definition
"APUD cells" (Amine precursor Uptake and Decarboxylase)
1) Specialized secretory cells found in the base of the epithelium in the tracheal mucosa.
2) Secrete 5-HT, ADH, cacitonin and somatostatin into basal lamina and carried into the blood stream
**small, pale-staining cells with dendritic processes in base of epithelium** |
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Term
| What are the major differences between bronchi and bronchioles in terms of general tissue features? |
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Definition
Bronchiole-transition
1) Loss of submucosal glands
2) No cartilage
3) No goblet cells (a few in largest)
4) Cilia decrease and disappear
5) Clara cells appear |
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Term
| What are the 3 major components and functions of the respiratory zone? |
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Definition
1) ACINUS: Respiratory bronchioles, Alveolar ducts/sacs, Alveoli
2) Gas exchange, immune and ACE |
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Term
| How can alveolar epithelial cells initiate cellular waste removal? |
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Definition
| Surfactant protein A produced by Type II epithelial cells (numerous but take up little room) will activate Alveolar macrophages for debris removal. |
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