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SORIANO, SHIELA MARIE P.
MEDICINE – E2
CLINICAL CASE #4 RESPIRATORY
APRIL 24, 2017
1. GIVE THE ORGANS THAT COMPRISE THE:
A. CONDUCTING PORTION OF RESPIRATORY SYSTEM
The conducting zone of the respiratory system is made up of the nose, pharynx, larynx, trachea, bronchi, bronchioles,
and terminal bronchioles; their function is to filter, warm, and moisten air and conduct it into the lungs. It consists of a
series of interconnecting cavities and tubes both outside and within the lungs. It is composed of the 1st through the 16th
division of the respiratory tract (airway).
The conducting zone is thus most of the respiratory tract (airway); it is the portion of the airway that conducts gases, but
excludes the portion that exchanges gases (which is the respiratory zone). Thus,conducting zone + respiratory
zone = respiratory tract (airway). Conducting zone is zone of gas exchange.
B. RESPIRATORY PORTION OF THE RESPIRATORY SYSTEM
The respiratory zone is the site of O2 and CO2 exchange with the blood. The respiratory bronchioles and the alveolar
ducts are responsible for 10% of the gas exchange.The alveoli are responsible for the other 90%. The respiratory zone
represents the 16th through the 23rd division of the respiratory tract.
2. DESCRIBE THE LAYERS OF THE ORGANS THAT COMPRISE THE CONDUCTING PORTION OF THE
RESPIRATORY SYSTEM.
1.
Pseudostratified ciliated columnar epithelium with goblet cells.
Extrapulmonary bronchi
2. Prominent basement membrane.
3. Relatively thin lamina propria (elastic layer at base)
4. Submucosa with seromucous glands
5.
"C" shaped hyaline cartilage rings w/ smooth muscle between ends of cartilage
1.
Pseudostratified ciliated columnar changing to ciliated simple columnar in smaller
Intrapulmonary bronchi
branches. Goblet cells at all levels.
2. Below lamina propria are interlacing spirals ofsmooth muscle
3. Seromucous glands decrease as bronchi get smaller.
4. Plates of cartilage gradually disappear
1.
Bronchioles (1 mm or less)
Ciliated columnar to ciliated cuboidal
2. Goblet cells decrease and Clara cells appear
3. Spirals of smooth muscle relatively heavier than elsewhere (gradually decrease in
amount)
4. No seromucous glands
5.
No cartilage
3. DESCRIBE THE LAYERS OF THE ORGANS THAT COMPRISE THE RESPIRATORY PORTION OF THE
RESPIRATORY SYSTEM.
1.
Cuboidal epithelium with some cilia. Clara cells and no goblet cells.
Respiratory broncioles
2. Thin supporting wall of C.T. and an incomplete layer of smooth muscle.
3. Outpocketings of alveoli, numbers inc. at lower levels.
1.
Thin tubes with an almost continuousoutpocketing of alveolar sacs and alveoli.
Alveolar ducts
2. The small areas of wall contain C.T. and smooth muscle covered by simple squamous
epithelium.
1.
Rotunda-like spaces with alveoli opening off of the center space
Alveolar sacs
2. Little connective tissue and no smooth muscle
4. GIVE THE CLINICAL SIGNIFICANCE OF THE FOLLOWING:
A. NASOPHARYNGEAL TONSIL
The adenoid, also known as a pharyngeal tonsil or nasopharyngeal tonsil, is the superior-most of the tonsils. It is a mass
of lymphatic tissue situated posterior to the nasal cavity, in the roof of the nasopharynx, where the nose blends into
the throat. Normally, in children, it forms a soft mound in the roof and posterior wall of the nasopharynx, just above and
behind the uvula.
Often adenoids A mass of lymphoid tissue located at the back of the nose in the upper partof the throat, normally present
only in children, that when infected and swollen can obstructbreathing.
B. GOBLET CELLS
A goblet cell is a glandular, modified simple columnar epithelial cell whose function is to secrete gel-forming mucins, the
major components of mucus. The goblet cells mainly use the merocrine method of secretion, secreting vesicles into a duct,
but may use apocrine methods, budding off their secretions, when under stress.
C. CLARA CELLS
Club cells, also known as bronchiolar exocrine cells, and originally known as Clara cells , are dome-shaped cells with
short microvilli, found in the small airways (bronchioles) of the lungs.
Club cells are found in the ciliated simple epithelium. These cells may secrete glycosaminoglycans to protect the
bronchiole lining. Bronchiolar cells gradually increase in number as the number of goblet cells decrease.
One of the main functions of club cells is to protect the bronchiolar epithelium. They do this by secreting a small variety of
products, including club cell secretory protein uteroglobin, and a solution similar in composition to pulmonary surfactant.
They are also responsible for detoxifying harmful substances inhaled into the lungs. Club cells accomplish this
with cytochrome P450 enzymes found in their smooth endoplasmic reticulum. Club cells also act as a stem cell,
multiplying and differentiating into ciliated cells to regenerate the bronchiolar epithelium.
D. PNEUMOCYTE II
Type 2 pneumocyte: The cell responsible for the production and secretion of surfactant (the molecule that reduces the
surface tension of pulmonary fluids and contributes to the elastic properties of the lungs). The type 2 pneumocyte is a
smaller cell that can replicate in the alveoli and will replicate to replace damaged type 1 pneumocytes.
E. LANGERHAN’S GIANT CELL
Giant cell, also called Langhans giant cell, large cell characterized by an arc of nuclei toward the outer membrane. The cell
is formed by the fusion of epithelioid cells, which are derived from immune cells called macrophages. Once fused, these
cells share the same cytoplasm, and their nuclei become arranged in an arc near the outer edge of the cell. Langhans giant
cells typically form at the centre of granulomas (aggregates of macrophages) and are found in the tubercle, or primary
focus of infection, in tuberculosis, in lesions of syphilis, leprosy, and sarcoidosis, and in fungal infections.
5. DESCRIBE THE AUTONOMIC SUPPLY OF THE ORGAN OF THE RESPIRATORY SYSTEM
The pulmonary nerve plexus lies behind each hilum, receiving fibres from both vagi and the second to 4th thoracic ganglia
of the sympathetic trunk. Each vagus contains sensory afferents from lungs and airways and bronchoconstrictor and
secretomotor efferents. Sympathetic fibres are bronchodilator.
Innervation of the lungs is via the pulmonary plexuses located anterior and posterior to the lung roots, innervating
the smooth muscle of the airways and blood vessels, and glands of the bronchial tree. Postganglionic sympathetic fibres
from the sympathetic trunks are bronchodilators, vasoconstrictors, and inhibit glandular secretion. Preganglionic
parasympathetic fibers from the vagus nerve (CN X), small parasympathetic ganglia, and postganglionic parasympathetic
nerves are bronchoconstrictors, vasodilators, and secretomotor to the glands. Visceral afferent fibers carry information
involved in cough reflexes, stretch reception, blood pressure, chemoreception, and nociception(detecting noxious stimuli).
The human airways are innervated via efferent and afferent autonomic nerves, which regulate many aspects of airway
function. The parasympathetic nervous system is the dominant neuronal pathway in the control of airway smooth muscle
tone. Stimulation of cholinergic nerves causes bronchoconstriction, mucus secretion, and bronchial vasodilation.
Although abnormalities of the cholinergic innervation have been suggested in asthma, thus far the evidence for cholinergic
dysfunction in asthmatic subjects is not convincing. Sympathetic nerves may control tracheobronchial blood vessels, but
no innervation of human airway smooth muscle has been demonstrated. beta-Adrenergic receptors, however, are
abundantly expressed on human airway smooth muscle and activation of these receptors causes bronchodilation.
Inhibitory nonadrenergic noncholinergic (NANC) nerves, containing vasoactive intestinal peptide and nitric oxide, may be
the only neural bronchodilator pathways in human airways. Although a dysfunction of inhibitory NANC nerves has been
proposed in asthma, thus far no differences in inhibitory NANC responses have been found between asthmatics and
healthy subjects
6. WHAT COMPRISES THE BLOOD AIR BARRIER?
The blood–air barrier (alveolar–capillary barrier or membrane) exists in the gas exchanging region of the lungs. It exists
to prevent air bubbles from forming in the blood, and from blood entering the alveoli. It is formed by the type
1 pneumocytes of the alveolar wall, the endothelial cells of the capillaries and the basement membrane between the two
cells. The barrier is permeable to molecular oxygen, carbon dioxide, carbon monoxide and many other gases.