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RS Histology 3
Respiratory System Histology- Bronchioles
Question | Answer |
---|---|
Bronchioles are: | Intralobular airways with diameters of 5 mm or less |
What are bronchioles missing compared to the rest of the respiratory system? | Cartilage, glands, and lymphocytes Few goblet cells |
In the larger bronchioles what is the epithelium? | Pseudostratified columnar |
As you go down the airways the epithelium becomes: | Ciliated simple columnar or cuboidal epithelium in the smaller terminal bronchioles |
The epithelium of terminal bronchioles also contain which type of cells: | Clara cells |
Clara cells are: | 1) Devoid of cilia, have secretory granules in their apex 2) Secrete proteins that protect the bronchiolar lining against oxidative pollutants and inflammation. 3) Produce one of the components of the surfactants and also act as reserve cells |
Bronchioles also exhibit specialized regions called | Neuroepithelial bodies |
Neuroepithelial bodies are: | Groups of cells (80-100) that contain secretory granules and receive cholinergic nerve endings |
What is the function of the neuropethlial bodies? | 1) Chemoreceptors that react to changes in gas composition within the airway 2) They also seem involved in the reparative process of airway epithelial cell renewal after injury |
Lamina propria of bronchioles is composed of: | Smooth muscle and elastic fibers |
Musculature of both the bronchi and the bronchioles is under the control of the: | Vagus nerve and the sympathetic nervous system |
At the alveolar openings the bronchiolar epithelium becomes continuous with which cells? | Squamous alveolar lining cells |
Between alveoli, the bronchiolar epithelium consists of | Ciliated cuboidal epithelium |
Alveolar ducts open into atria that communicate with | Alveolar sacs |
What is the function of the elastic fibers and reticular fibers in the alveoli? | Enable the alveoli to expand with inspiration and to contract passively with expiration The reticular fibers serve as a support that prevents overdistention and damage to the delicate capillaries and thin alveolar septa |
What are the alveoli? | Saclike evaginations (about 200 um in diameter) responsible for the spongy structure of the lungs |
Blood-air barrier: | 1) The surface lining and cytoplasm of the alveolar cells 2) The fused basal laminae of the closely apposed alveolar and endothelial cells 3) Cytoplasm of the endothelial cells The total thickness: from 0.1 to 1.5 um |
Describe the structures within the interalveolar septum: | 1) Anastomosing pulmonary capillaries supported by a meshwork of reticular and elastic fibers 2) Fibers arranged to permit expansion and contraction of the interalveolar septum 3) Basement membrane, leukocytes,macrophages, and fibroblasts |
Cells in the interstitium: | Endothelial cells (capillaries) 30 % Fibroblasts and mast cells 36% Macrophages 10 % Type I cells 8 % Type II cells 16% Leukocytes |
Liberation of CO2 from H2CO3 is catalyzed by the enzyme: | Carbonic anhydrase |
Which two cells can be confused? | Endothelial cells and type 1 alveolar cells |
Endothelial lining of the capillaries is: | Continuous, not fenestrated |
The most prominent feature of the cytoplasm in the flattened portions of the cell is: | Numerous pinocytic vesicles |
Type 1 cells are: | 1)Squamous alveolar cells 2) Extremely attenuated cells 3) Make up 97% of the alveolar surfaces 4) Thin (sometimes only 25 nm) |
Why are organelles such as the Golgi complex, endoplasmic reticulum, and mitochondria grouped around the nucleus? | To reduce the thickness of the blood-air barrier |
Type II cells (great alveolar cells) or septal | These vesicles are caused by the presence of lamellar bodies |
What are lamellar bodies? | Contain phospholipids, glycosaminoglycans, and proteins, are continuously synthesized and released at the apical surface of the cells (12 microns) |
The lamellar bodies give rise to the | Pulmonary surfactant |
The surfactant layer consists of: | proteinaceous hypophase covered with a phospholipid film that i primarily composed of dipalmitoyl phosphatidylcholine and phosphatidylglycerol. |
Without surfactant, alveoli would: | Tend to collapse during expiration |
The lipoproteins are gradually removed from the surface by | The pinocytotic vesicles of the squamous epithelial cells, by macrophages, and by type II alveolar cells |
As the secretions pass up through the airways, they combine with bronchial mucus, forming: | Bronchoalveolar fluid which contains several lytic enzymes |
Pulmonary Lymphatic Vessels all drain into: | Lymph nodes in the region of the hilum |
Superficial network includes the | lymphatic vessels in the visceral pleura |
Lungs are innervated by: | Both parasympathetic and sympathetic efferent fibers General visceral afferent fibers, carrying poorly localized pain sensations |
The two layers of pleura are composed of: | Mesothelial cells resting on a fine connective tissue layer that contains collagen and elastic fibers |
Pleural cavity contains only a: | Fillm of liquid that acts as a lubricant, facilitating the smooth sliding of one surface over the other during respiratory movements |
This fluid is derived from the blood plasma by | Exudation |