Respiratory System Flashcards

Question

Bronchial Tree

Answer 1

1. Trachea divides into **2 Primary brochi** * series of aurway branches of progressively decreasing size: * Mucosa (Respiratory epithelium, lamina propia), Smooth muscle layer, Submucosa (loose CT), Cartilage layers (hyaline cartilage that fully encircle the lumen), Adventitia (loose to dense CT) 2. Primary bronchi give rise to: * **3 Secondary Lobar bronchi** (*Right lung*) * each supplies a pulmonary lobe * **2 Secondary Lobar bronchi** (*Left lung*) * each supplies a pulmonary lobe * to make space for the heart 3. Lobar bronchi form **Tertiary Segmental bronchi** * _bronchopulmonary segment_ * 10-12% of each lung with its _own CT capsule & blood supply_ that help facilitate surgical resection of diseased lung without affecting nearby healthy tissues * small _mucus & serous glands are abundant_ with ducts opening into the bronchial lumen * spirally arranged _smooth mucle & elastic fiber_ * numerous _lymph_ (lamina propia & epithelial cells) * abundant _MALT_ (mucosa-associated lymphoid tissue) 4. Tertiary bronchi give rise to **Bronchioles** * Series of smalller branches from bronchi * Lacks mucosal glands & cartilage * Smooth muscle helps the bronchioles open * Ciliated pseudostratified columnar epithlelium (large bronchioles) decreases in height & complexitiy in smallest terminal bronchioles & becomes ***Ciliated simple columnar epithelium*** or ***Simple cuboidal epithelium*** * consists of _club cells_ (bronchioles exocrine glands or clara cells) * _nonciliated dome-shaped apical ends_ containing secretory granules * _functions_: * secretion of surfactant * detoxification of inhaled xenobiotic compounds by SER enzymes * secretion of antimicrobial peptides & cytokines for immune defense * also contains chemosensory _brush cells_ & _DNES_ small granule cells * ciliary epithelial lining of bronchioles begins the _mucociliary apparatus or escalator_ which is important in clearing debris & mucus by moving it upward along the bronchial tree & trachea * smooth muscle layer, adventitia 5. Bronchioles enter a pulmonary lobule and branch to form **5-7 Terminal Bronchioles** * _Pulmonary lobule_ * pyramid-shaped * apex aimed at the pulmonary hilum * delineated with thin layer of CT (frequently incomplete in adults) * _Last part of air conducting system_ * _Simple cuboidal epithelium, club cells, smooth muscle layer, adventitia_ 6. Terminal ducts subdivides into 2 or more **Respiratory Bronchioles** * _1st part_ of the system's r_espiratory region_ * _smooth muscle & elastic CT_ comprise the lamina propia * epithelium consists of _club cells_ & _Ciliated simple cuboidal cells with apical domelike projections_ at the alveolar openings & extending into the alveolus 7. Distal ends of respiratory bronchioles branch into **Alveolar Ducts** * completely lined by openings of alveoli * cuboidal epithelium * _smooth muscle cells_ surround each alveolus opening * network of _elastic_ & _collagen fibers_ support duct & alveoli 8. **Alveolar Sac** * _clusters of alveoli_ * form _ends of alveolar ducts_ * _extremely thin lamina propia_ with _elastic_ & _reticular fibers_ * network of _capillaries_ surrounds each alveolus 9. **Alveoli** * saclike evaginations from respiratory bronchioles, alveolar ducts, & alveolar sacs * lined with _extremely attenuated squamous cells- type I pneumocytes_ * _has underlying CT & lamina propia_ * responsible for the spongy structure of the lungs * air in these structures _exchange O2 & CO2_ with blood in surrounding capillaries through thin walls for diffusion * ***Interalveolar septa*** lie between neigboring alveoli * O2 from alveloar air diffuse through BAB into capillary blood to bind hgb * CO2 diffuses to alveolar air from pulmonary blood (H2CO3)

Answer 2

(a) The epithelial lining (E) of bronchi is mainly pseudostratified ciliated columnar cells with a few goblet cells. The lamina propria (LP) contains the distinct layer of smooth muscle (SM) surrounding the entire bronchus. The submucosa is the site of the supporting cartilage (C) and the adventitia includes blood vessels (V) and nerves (N). Lung tissue (LT) directly surrounds the adventitia of bronchi. (b) In the smaller bronchi the epithelium is primarily of columnar cells with cilia (arrows), with fewer goblet cells. The lamina propria has both smooth muscle (SM) and small serous glands (G) near cartilage (C).

Answer 3

**Bronchiolitis**- inflammation of bronchioles d/t measles or adenovirus **Obliterative bronchiolitis**- complete & partial closure of the airway lumen d/t fibrosis in the wall **Asthma** * chronic inflammation within the _bronchial tree_ * _bronchospasm_- sudden constriction of smooth muscles in bronchioles d/t mast cell degranulation tiggered by specific antigen * _Epinephrine_ relaxes muscle & increase bronchiole diameter by stimulating sympathetic nervous system * _bronchiolar muscle\>bronchial walls_ **Squamous cell CA**- most type involve epithelial cells lining the larger segments of **_bronchi_**, NOT bronchioles **Small cell CA**- develops from small granule Kulchitsky cells in bronchial respiratory epithelium **Adenocarcinoma**- lung cancer that arises from epithelial cells in bronchioles and alveoli

Answer 4

The smallest branches of the bronchial tree are the bronchioles, which lack supporting cartilage and glands. (a) A large bronchiole has the characteristically folded respiratory epithelium (E) and prominent smooth muscle (arrows), but it is supported only by fibrous connective tissue (CT). (b) Staining for elastic fibers reveals the high elastic content of the smooth muscle (arrowhead) associated with the muscle of a smaller bronchiole in which the epithelium is simple columnar but still ciliated. Darkly stained elastic fibers are also present in the tunica media of a large arteriole (A) nearby and to a lesser extent in the accompanying venule (V). The connective tissue includes many lymphocytes (L) of diffuse MALT and lymphoid nodules. (c) In very small bronchioles the epithelium (E) is reduced to simple cuboidal cells with cilia. Several layers of smooth muscle cells (arrows) comprise a high proportion of the wall.

Answer 5

The last parts of the air conducting system before the sites of gas exchange appear are called the terminal bronchioles. (a) A terminal bronchiole has a mucosa with nonciliated cuboidal or low columnar epithelium (E), surrounded by only one or two layers of smooth muscle (SM) embedded in connective tissue (CT). Alveoli (A) are seen in the surrounding lung tissue. (b) Most of the epithelium consists of exocrine club cells (C) with bulging domes of apical cytoplasm contain granules, as shown here in a plastic section. * These cells have several important functions. They secrete components of surfactant which reduces surface tension and helps prevent collapse of the bronchioles. * The P450 enzyme system of their smooth ER detoxifies potentially harmful compounds in air. * In other defensive functions the cells also produce the secretory component for the transfer of IgA into the bronchiolar lumen; lysozyme and other enzymes active against bacteria and viruses; and several cytokines that regulate local inflammatory responses. * Also included among the cuboidal cells are stem cells that give rise to all of the cells within the bronchiolar epithelium.

Answer 6

Terminal bronchioles branch into respiratory bronchioles, which then branch further into alveolar ducts and individual alveoli. Respiratory bronchioles are similar in most respects to terminal bronchioles except for the presence of scattered alveoli along their length. (b) The micrograph shows the branching nature of the air passages in two dimensions: respiratory bronchiole (RB), alveolar ducts (AD), alveolar sacs (AS), and individual alveoli (A). (c) SEM shows in three dimensions the relationship of a terminal bronchiole (TB), respiratory bronchiole (RB), alveolar duct (AD), alveolar sacs (AS), and individual alveoli (A).

Answer 7

Lung tissue has a spongy structure because of the abundant air passages and pockets called alveoli. (a) Typical section of lung tissue includes many bronchioles, some of which are respiratory bronchioles (RB) cut lengthwise, and shows the branching continuity with alveolar ducts (AD) and sacs (AS). Respiratory bronchioles still have a layer of smooth muscle and some regions of cuboidal epithelium, but alveolar ducts consist of a linear series of alveoli, each with smooth muscle fibers around the opening. Individual alveoli (A) all open to the sacs or ducts. The respiratory bronchiole runs along a thin-walled branch of the pulmonary artery (PA), while branches of the pulmonary vein (V) course elsewhere in the parenchyma. (b) Higher magnification shows the relationship of the many rounded, thin-walled alveoli (A) to alveolar ducts (AD). Alveolar ducts end in two or more clusters of alveoli called alveolar sacs (AS). Smooth muscle around the alveolar openings appears as eosinophilic “knobs” between adjacent alveoli. The alveoli here that do not show openings to the ducts or the sacs have their connections in planes of adjacent sections.

Answer 8

Gas exchange between air and blood occurs at a membranous barrier between each alveolus and the capillaries surrounding it. (a) This diagram shows the relationship between capillaries in the interalveolar septa and the saclike alveoli. The alveolar pores (of Kohn) allow air pressure to equilibrate and air to circulate between alveoli on different ducts or sacs if the local airway becomes blocked.

Answer 9

(b) The air-blood barrier consists of an alveolar type I cell, a capillary endothelial cell, and their fused basement membranes. Oxygen diffuses from alveolar air into capillary blood and carbon dioxide moves in the opposite direction. The inner lining of alveoli is covered by a layer of surfactant (not shown) which lowers fluid surface tension and helps prevent collapse of alveoli.

Answer 10

The septa between alveoli (A) contain several cell types. As seen here, the capillaries (C) include erythrocytes and leukocytes. The alveoli are lined mainly by squamous type I alveolar cells (I), which line almost the entire alveolus surface and across which gas exchange occurs. Type II alveolar cells line a bit of each alveolus and are large rounded cells, often bulging into the alveolus (II). These type II cells have many functions of club cells, including production of surfactant. Also present are alveolar macrophages (M), sometimes called dust cells, which may be in the alveoli or in the interalveolar septa.

Answer 11

TEM of a capillary (C) in an interalveolar septum shows areas for gas exchange between blood and air in three alveoli (A). The endothelium is continuous but extremely thin, and its basal lamina (B) fuses with that of the type I alveolar cells (I) and type II cells. A fibroblast (F) can be seen in the septum, and the thickened nuclear regions of two endothelial cells (E) are also included. The nucleus at the bottom belongs to an endothelial cell or a circulating leukocyte.

Answer 12

TEM of a type II alveolar cell protruding into the alveolar lumen shows unusual lamellar bodies (L) that contain newly synthesized pulmonary surfactant after processing of its components in rough ER (RER) and the Golgi apparatus (G). Smaller multivesicular bodies (MVB) with intralumenal vesicles are also present. Short microvilli (M) cover the apical cell surface at the alveolus (A) lumen. The type II cell is attached via junctional complexes (JC) to the neighboring type I cell (I). Reticular fibers (RF) are prominent in the ECM.

Answer 13

The pleura are serous membranes (serosa) associated with each lung and thoracic cavity. (b) Both layers are similar histogically and consist of a simple squamous mesothelium (M) on a thin layer of connective tissue, as shown here for visceral pleura covering alveoli (A). The connective tissue is rich in both collagen and elastic fibers and contains both blood vessels (V) and lymphatics (L).

Answer 14

**Atelectasis** * _collapse of pulmonary lobules_ d/t obstruction of air supply in bronchi d/t excess mucus or to apsirated material * _reversible_ when blockage is removed * persistence can lead to _fibrosis_ or _loss of respiratory function_

Answer 15

**Diffuse Alveolar damage** * aka _Adult Respiratory Distress syndrome_ * d/t: * respiratory tract infection * inhalation of toxic gas * air with excessive O2 * ***fat embolism syndrome*** (adipocytes enter blood during surgery which later block capillaries)

Answer 16

**Interalveolar septa** * lie between neighboring alveoli * 2 neighboring type I pneumocytes & underlying CT of each cell * consist of ***scattered fibroblasts*** & ***sparse ECM*** * notable elastic & reticular fibers * ***elastic fibers***- enable alveoli to expand with inspiration & contract with expiration * ***reticular fibers***- prevent collapse & excessive distention of alveoli * vascularized with _richest capillary network in the body_ * macrophages & other leukocytes can be found here

Answer 17

Alveolar **Blood Air Barrier** (BAB) * _2 or 3 highly attenuated thin cells_ lining the alveoli * _fused basal lamina_ & _endothelial cells_ of capillaries * thin ***continuous capillary*** edothelial cells

Answer 18

**Alveolar pores (of Kohn)** * penetrate the interalveolar septa & connect neighboring alveoli that open to different bronchioles * equalize air pressure in alveoli & permit collateral circulation of air if a bronchiole becomes obstructed

Answer 19

**Type I Alveolar cells** * _Type I pneumocytes_ * _extremely attenuated cells_ that line the alveolar surface * constitute the alveolar side of BAB * make up _95% of alveolar lining_ * _desmosomes & tight junction_ help prevent leakage of tissue fluid into alveolar air space * involve in gas exchange **Type II Alveolar cells** * _Type II pneumocytes_ * _Septal cells_ * _cuboidal cells_ that bulge into air space intersperesed among the type I alveolar cells bound with tight junctions & desmosomes * often occur in _groups of 2 or 3_ * _nuclei are rounded_ & may have _nucleoli_ * lightly-stained sytoplasm with many vesicles (lamellar bodies) * ***lamellar bodies*** secrete lipids, phospholipids, & proteins that act as pulmonary surfactant _to lower surface tension_ at the air-epithelium surface to prevent alveolar collapse * _DPPC_, _cholesterol_, & _Surfactant Protein-A_ (hydrophilic glycoprotein), _SP-B_ (innate immune protection), _SP-P_ & _SP-C_ (hydrophobic membrane proteins required for proper orientation of DPPC)

Answer 20

**Infant Respiratory Distress Syndrome** * incomplete differentiation of type II alveolar cells resulting to deficit of surfactant & difficulty in expanding alveoli in breathing * Treatment: CPAP & exogenous surfactant

Answer 21

**Alveolar macrophages** * ***Dust cells*** * found in _alveoli & interalveolar septum_ * _slightly dark_ d/t hemosiderin from RBC * 3 life path :) * to the bronchioles mucuciliary apparatus for _removal into esophagus_ * exit lungs in _lymphatic drainage_ * _remain in interalveolar septa_ CT for years

Answer 22

**Bronchoalveolar fluid** * _bronchial mucus_ & _alveolar lining fluid_ * remove particulate components form inspired air * bacteriostatic which contain _lysozome_, _club cells_, t_ype II alveolar cells_, & _alveolar macrophages_

Answer 23

**Congestive Heart Failure (CHF)** * lungs become congested with blood * ***heart failure cells***- erythrocytes pass into alveoli and get phagocytized by alveolar macrophages

Answer 24

Inhalation of toxic gas-\> kills type I and type II cells lining pulmonary alveoli-\> stimulates mitotic activity in remaining type II cells (1%/day)-\> During increased toxic stress-\> stem cells are stimulated to divide

Answer 25

**Pulmonary circulation**- carrying _O2-depleted blood_ **Bronchial circulation**- carrying _O2-rich blood_

Answer 26

**Emphysema** * _dilation & permanent enlargement of bronchioles_ leading to pulmonary acini * _irreversible_ loss of respiratory function (alveoli & airway walls) * ***penumonia***- inflammatory condition d/t infection in the respiratory region

Answer 27

**Pleura** * _serous membrane_ that covers the lung's outer surface & internal walls of the thoracic cavity * composed of _simple squamous mesothelial cells_ on a thin CT layer containing _collagen_ & _elastic fibers_ * ***visceral pleura***- membrane attached to lung tissue- lymphatics and blood will be found here * ***parietal peura***- membrane lining the thoracic walls * ***pleural cavity***- entirely lined with _mesothelial cells_ that produces a thin film of serous fluid as lubricant

Answer 28

**Pleural effusion**- blood plasma accumulates in pleural cavity during inflammation & other abnormal condition **Pneumothorax**- partially or completely collapsed lung caused by air trapped in pleural cavity leading to hypoxia **Pleuritis** or **Pleurisy**- inflammation of the pleura caused by acute viral infection or pneumonia

Answer 29

Inhalation-\> contraction of internal intercostal muscles-\> elevation of ribs & contraction of diaphragm-\> lowers bottom of thoracic cavity increasing its diameter-\> pulmonary expansion-\> bronchi & bronchioles increase in length & diameter-\> expansion of alveolar duct-\> respiratory portion enlarges: * alveoli enlarges only slightly * elastic fibers of of the pulmonary parenchyma are stretched

Answer 30

**Anthracosis** * Coal workers' pneumoconiosis (CWP), also known as black lung disease or black lung, is caused by long-term exposure to [coal dust](https://en.wikipedia.org/wiki/Coal). * Inhaled coal dust progressively builds up in the lungs and leads to inflammation, fibrosis, and in worse cases, necrosis.

Answer 31

1. **Systemic circulati**on- supplies blood to all peripheral tissues, including the lungs: Pulmonary veins- Left Atrium- Mitral valve- Left ventricle- Aortic semilunar valve- Aorta- BronchioArteries- Arterioles- Capillaries 2. **Pulmonary circulatio**n- supplies blood to lungs for gas exchange: Venules- Veins- Inferior and Superior vena cava- Right atrium- Tricuspid valve- Right ventricle- Pulmonary semilunar valve- Pulmonary arteries- bigger vasculature to smaller branches- capillary bed to get rid of CO2 and take O2

Respiratory System Flashcards

(57 cards)