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Human Body_TP > Respiratory System Histology > Flashcards

Respiratory System Histology Flashcards

1
Q

what are the two respiratory segments?

A

types of bronchioles and alveolus

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2
Q

cellular components of respiratory system

A

-type I pneumocyte
-type II pneumocyte
-surfactant
-alveolar macrophages

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3
Q

what are the two alveolar structures?

A

interalveolar septa and blood-brain barrier

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4
Q

bronchioles

A

-first structure in respiratory portion —> directs air movement into alveoli
-clara cells
-smooth muscle cells and elastic fibers- contract and dilate to control airflow
-no cartilage and glands present

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5
Q

what shape are clara cells?

A

ciliated and non-ciliated columnar and cuboidal

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6
Q

what do clara cells do?

A

-block and clear debris
-secrete proteins to protect epithelium
-degrade airborne toxins
-regenerate the epithelium

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7
Q

what are the types of bronchioles?

A

terminal, respiratory, and branching

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8
Q

terminal bronchioles

A

-most distal conducting airways
-each branches giving rise to two to five respiratory bronchioles

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9
Q

respiratory bronchioles

A

-initial airways into where gas exchange happens
-presence of alveoli

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10
Q

branching function

A

-gas exchange
-air velocity

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11
Q

alveoli

A

-thin-walled sac with type I and type II pneumocytes
-site of gas exchange
-contains elastic and reticular fibers, which provide structural support and allow for expansion/contraction
-opening is sphincter of smooth muscle
-pores of kohn promote collateral circulation and are a route for alveolar macrophages

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12
Q

type I pneumocyte

A

-facilitates gas exchange between alveoli and capillaries
-thin, squamous cell shape
-covers 97% of lung surfaces, yet only encompasses 10% of total lung cells

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13
Q

type I pneumocyte structural relevance

A

-type I basal laminae are fused with the laminae of pulmonary capillaries in interalveolar septa
-type I cells join with other cells via tight junctions
-these tight junctions prevent leakage of fluid into alveolar space

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14
Q

type II pneumocyte

A

-secretes surfactant, a mixture of proteins, phospholipids, and glycosaminoglycans
-also functions as stem cell that differentiates into both type I and II pneumocytes

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15
Q

type II pneumocyte structural relevance

A

-features numerous membrane-bound multi-lamellar bodies in cytoplasm (responsible making for surfactant)
-found at sites where alveoli walls join
-joined to type I cells by tight junctions and desmosomes

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16
Q

surfactant

A

-covers the alveolar epithelium
-reduces surface tension in alveoli
-facilitates alveoli expansion during inspiration
-prevents alveolar collapse during expiration

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17
Q

alveolar macrophages

A

-derived from monocytes of blood
-most numerous cells in lung
-“patrol” air spaces to phagocytose debris and bacteria
-found in the interalveolar septa and on the surface of alveolar lumen

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18
Q

interalveolar septum

A

-alveolar wall shared by adjacent alveoli
-contains a dense capillary network (pulmonary capillaries)
-perforated by pores of Kohn

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19
Q

what are the 3 components of the interalveolar septum?

A

epithelium (of adjacent alveoli), interstitium (collagen and elastic fibers), and capillary endothelium

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20
Q

what does the interalveolar septum do?

A

provides structural basis for gas exchange in the lung

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21
Q

blood-air barrier

A

-barrier between capillary blood and alveolar air
-specialized region of alveolar wall across which gas exchange occurs —> O2 enters the blood and CO2 enters the alveoli

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22
Q

what is the structure of the blood-air barrier?

A

trilayered structure:
1. alveolar epithelium (type I pneumocytes) which is a thin layer of surfactant that cover these cells
2. capillary endothelium (endothelial cells)
3. fused basal laminae of these two cells

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23
Q

what do type I pneumocytes do for the blood-air barrier?

A

form a simple squamous epithelium lining the majority surface area of the alveoli

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24
Q

what do the capillaries provide for the blood-air barrier?

A

single-layer endothelium

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25
Q

makeup of the blood-air barrier

A

-cytoplasms of both the type I pneumocytes and endothelial cells are highly attenuated
-the two cell types share a fused basement membrane
-minimize the barrier to increase gas exchange efficiency

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26
Q

air flow in the blood-air barrier

A

O2 into the alveoli —> cytoplasm of type I pneumocyte —> basement membrane —> cytoplasm of endothelial cells —> reach the blood
CO2 goes the opposite way

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27
Q

functions of the respiratory system

A

-gas exchange
-regulates blood pH
-sense of smell
-phonation
-air filtration
-excretes water and heat

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28
Q

respiratory and cardiovascular systems

A

respiratory is involved in gas exchange and cardiovascular is distribution

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29
Q

structural division of the respiratory system

A

-upper respiratory: nasal cavity, oral cavity, pharynx, epiglottis
-lower respiratory: larynx, esophagus, trachea, primary bronchi, right and left lung

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30
Q

functional division of the respiratory system

A

-conducting zone: the upper and lower respiratory systems
-respiratory zone: alevolar ducts, alveolar sacs, respiratory bronchiole, atrium, capillary beds, alveoli

31
Q

visceral pleura

A

-layer intimately covers the lungs, wrapping every nook and cranny of the lung space
-layers include:
1. mesothelial
2. sub mesothelial
3. external elastic
4. interstitial
5. internal elastic
-secretes pleural fluid

32
Q

parietal pleura

A

-layer lines the chest wall and covers the diaphragm and mediastinum
-layers include:
1. mesothelial
2. sub mesothelial
3. fibroadipose
4. interstitial
5. internal elastic
-protective and very fibrous —> provides structure to the lung structure

33
Q

lung lobule

A

-fundamental respiratory unit of the lungs
-made up of 10 to 30 acini
-composed of:
1. alveolar ducts
2. alveolar sacs
3. alveoli
-gas exchange

34
Q

relationship between lung lobule and pleura

A

-each lobule lies beneath the visceral pleura
-the pleural fluid in the cavity between the visceral and parietal pleura ensures that as each lobule expands and contracts without friction or resistance

35
Q

layers of trachea and bronchi

A

-mucosa: innermost layer lined with epithelia cells and contains goblet and basal cells
-submucosa: connective tissue supporting the mucosa
-cartilaginous layer: cartilaginous rings and intervening smooth muscle for structural support
-adventitia: most external fibroelastic layer of connective tissue

36
Q

what composes the mucosa?

A

respiratory epithelium and contains goblet cells which produce mucus to keep the airway moist and trap impurities

37
Q

what does the bronchi have that the trachea does not?

A

-within the mucosa, the bronchi have the muscularis mucosae that the trachea does not have
-the muscularis mucosae is made up of muscle cells that help expel mucus secretions and facilitates the movement of the mucosa
-helps the bronchi contract and dilate when breathing whereas the trachea needs structural integrity

38
Q

what does the submucosa do?

A

-provides hydration
-facilitates nutrient exchange
-allows for elasticity and expansion during breathing

39
Q

what does the cartilaginous layer do?

A

made of cartilage rings that provide structural support, ensuring the airways remain open during breathing

40
Q

what does the adventitia do?

A

made of connective tissue that anchors the trachea to surrounding structures

41
Q

epithelia of the trachea

A

-lined with ciliated pseudostratified epithelial cells
-cilia move in unison to help support mucosal transport towards the pharynx where it can be swallowed and expelled —> necessary mechanism to trap and get rid of dust, microbes, and other particles inhaled with the air
-epithelium also contain goblet and basal cells

42
Q

what is the primary function of goblet cells?

A

secrete mucin which form a protective mucus layer lining the epithelium but they are also thought to be involved with immunoregulation

43
Q

what do basal cells do?

A

-smaller cells below the layer of pseudostratified epithelial cells —> stem cells that can divide and differentiate into specialized cells
-anchor the basement membrane and replenish the epithelial tissue

44
Q

epithelia of the bronchi

A

composed of ciliated pseudostratified epithelial cells, goblet, and basal cells

45
Q

submucosal glands and ducts (SMG)

A

-secretory structures found in the submucosa that line cartilaginous airways
-located in the larynx, trachea, and primary bronchi
-tubuloacinar secretory regions joined by ducts
-defend against inhaled and exhaled pathogens

46
Q

what does the SMG secrete?

A

a mixture of water, ions, mucus, and antimicrobial proteins that make up the airway surface liquid —> defends against infections and pathogens by physically moving these pathogens out of the lung

47
Q

what do abnormal SMGS cause?

A

cystic fibrosis

48
Q

how do secretions move through the submucosal glands and ducts?

A

secretions are produced in the secretory region —> move through mucous tubules and accumulate in the non-ciliated collecting ducts —> ciliated ducts connect the SMG to the airway lumen and expel the secretions onto the epithelial surface

49
Q

cartilage rings

A

-C shaped rings composed of hyaline cartilage
-located in the trachea
-16-20 C shaped rings that line the entire length of the trachea
-support the trachea and allow it to move and flex without collapsing while breathing

50
Q

what is at the posterior end of the cartilage rings?

A

posterior ends of the cartilage rings are connected by smooth muscles —> this is where the esophagus connects

51
Q

what does the smooth muscle allow the esophagus and trachea to do?

A

the trachea needs to not collapse and the esophagus need to contract to transport food down —> smooth muscle ensures that both the trachea and esophagus can do their jobs

52
Q

cartilage plates

A

-hyaline cartilage structures that are within bronchial walls
-located in the bronchi
-crescent shaped plates or islands
-keep the airway open and the bronchi from collapsing during inhalation and exhalation

53
Q

segments of bronchi and their cartilage rings

A

-main primary bronchi is enclosed by cartilage rings
-secondary and segmental bronchi have irregularly arranged crescent-shaped cartilage plates —> numbers will also decrease as e move towards the bronchioles, which lack cartilages and are enclosed by smooth muscles

54
Q

adventitia

A

-most superficial layer of the trachea and bronchi
-composed of loose connective tissue
-anchors the trachea and bronchi to adjacent tissues
-provide elasticity, strength, and support

55
Q

mesothelioma

A

-simple epithelial cells derived from the mesoderm:
1. serous membranes aka serosa
2. pericardium (heart)
3. pleura (lungs)
4. peritoneum (GI systems)
5. tunica vaginalis (testicles)

56
Q

malignant mesothelioma

A

cancerous growth of the mesothelium and 80% of cases is due to asbestos exposure

57
Q

symptoms and prevalence of malignant mesothelioma

A

-~4,000 cases/year in the US
-majority of cases are men in their 50-70s
-aggressive cancer, almost always fatal
-even with treatment, the survival is less than 10%
-symptoms are difficulty breathing, painful cough, unintended weight loss

58
Q

how do the asbestos fibers reach the pleura?

A

-dominant path is unknown
-inflammation with negative pressure gradient
-macrophage mediated

59
Q

why does malignant mesothelioma target the parietal pleura?

A

-pleural fluid is predominantly drained via the lymphatic ducts called stroma on the parietal surface
-stroma are a few microns to 10 microns in diameter
-fibers can become trapped in the stroma
-macrophages can become frustrated and cannot effectively degrade the fibers

60
Q

overview of malignant mesothelioma

A

-asbestos fibers are trafficked to pleura (through inflammation + negative pressure gradient or macrophage-mediated)
-asbestos fibers cause frustrated phagocytosis
-mutagenic environment on the parietal mesothelium results in cancerous transformation

61
Q

chronic bronchitis

A

-severe, long-term inflammation of the bronchi
-chronic cough for at least three month for two years
-form of COPD
-caused by cigarette smoking or noxious pollutants

62
Q

symptoms of chronic bronchitis

A

-coughing and wheezing
-cyanosis (blue color)
-shortness of breath
-lungs appear hyperinflated

63
Q

how is CB diagnosed?

A

-in obstructive lung diseases, airflow is limited —> FEV1 falls proportionately faster than FVC so the FEV1/FVC ratio is reduced (less air will get out of your lungs)
-in restrictive lung diseases, FEV1 and FVC are reduced proportionately —> ratio remains normal (less air will get into your lungs)

64
Q

how do COPD lungs usually appear?

A

-hyperinflated compared to healthy lungs —> lung tissue is expanded and the lungs appear larger than normal
-this is due to air trapping because the narrowed airways and difficulty exhaling fully

65
Q

CB pathophysiology

A

-goblet cell hyperplasia —> excess mucus production —> luminal occlusion
-squamous metaplasia
-cilia are damaged, so the mucus is able to accumulate
-immunosuppression of alveolar macrophages by tobacco smoke (predisposition to lower respiratory tract infection)

66
Q

squamous metaplasia

A

-change from pseudostratified ciliated columnar epithelium —> stratified squamous epithelium
-limited window where if the irritants are addressed, the process can be reversed but the cells would go to an intermediate shape and not fully back to the columnar shape
-if not addressed, could lead to a larger neoplastic transformation

67
Q

goblet cell hyperplasia

A

-proliferation of goblet cells
-leads to increased production of mucus, which can narrow the airways

68
Q

treatment for CB

A

-damage is irreversible —> treatment goals are to stop progression and manage symptoms
-stop smoking
-bronchodilators to relax the muscles in the airways and allow air to flow
-inhaled steriods that can be taken with bronchodilators to reduce inflammation
-supplemental O2 if the O2 levels are consistently low

69
Q

respiratory distress syndrome (RDS)

A

-caused by lack of surfactant in premature infant lungs —> leads to alveoli collapse
-also called hyaline membrane disease since the cell debris accumulates in the airways
-60-80% of infants born before 28 weeks have this but 90% survive and the prevalence decreases with gestational age

70
Q

RDS symptoms

A

-difficulty breathing
-cyanosis
-rib muscles pulling inwards on inhale
-CO2 —> acidosis —> organ disfunction

71
Q

RDS physiology

A

-type II pneumocytes secrete surfactant starting around 28 weeks
-premature infants born before type II pneumocytes are fully develops lack surfactant and have difficulty breathing
-surfactants are amphiphilic so they have both hydrophilic and hydrophobic parts —> when they come into contact with a liquid, the hydrophilic part attaches to the water molecules while the hydrophobic part attaches to the air or oil

72
Q

RDS treatment

A

-continuous positive airway pressure (CPAP), which pushes air into the lungs to inflate the alveoli
-surfactant replacement through an endotracheal tube
-mechanical ventilation but only in severe cases and can cause airway/lung injury
-glucocortcoids can be given to women before premature delivery to speed up the development of the lungs and surfactant production

73
Q

acute respiratory distress syndrome (ARDS)

A

-inflammation in the lungs due to COVID-19, sepsis, flu
-pneumocytes are the inflammatory cytokines and neutrophils are the proteases, reactive oxygen species
-injury to alveolar-capillary membrane, which makes it more permeable —> leading to pulmonary edema which washes away surfactant and leads to alveoli collapse

Human Body_TP (16 decks)

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