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Histology > Histology of Respiratory System > Flashcards

Histology of Respiratory System Flashcards

1
Q

What are the 2 portions of the respiratory system?

A

2 Portions:

Conducting Portion

Respiratory Portion

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2
Q

What are the components of the conducting portion?

A

Consists of all the components that condition air and bring it into the lungs: trachea, main bronchus, lobar bronchi, segmental bronchi, terminal bronchiole

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3
Q

What are the components of the respiratory portion?

A

Responsible for gas exchange: respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli

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4
Q

What are the histological features of the respiratory epithelium?

A

Pseudostratified ciliated columnar epithelium

  • rests on very thick BM
  • most abundant with long cilia on bulging apical ends
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5
Q

Identify the 3 types of cells of the respiratory epithelium.

A

3 Main Cell Types of Respiratory Epithelium:

  • ciliated epithelial cells
  • goblet cells
  • basal cells
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6
Q

Role of Ciliated Epithelial Cells

A

Features: extend to the surface, possess cilia

Role: move the mucus toward lymphatics

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7
Q

Role of Goblet Cells

A

Features: mucinogen granules

Role: produce mucus

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8
Q

Where are stem cells in the respiratory epithelium located?

A

Located in the basement membrane

Most of the small rounded cells at the basement membrane are stem cells

Makeup ~30% of the epithelium

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9
Q

Identify the immune cells found in the respiratory epithelium.

A

Types of Immune Cells:

  • mucus-secreting goblet cells
  • intraepithelial lymphocytes
  • dendritic cells: antigen-presenting cells; stimulate T cells
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10
Q

Give the functional significance of Cilia in respiratory epithelium

A
  • film of mucus traps most airborne dust particles and microorganisms
  • ciliary movements continuously propel the sheet of mucus toward the pharynx for elimination
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11
Q

What are brush cells and their characteristics?

A

Brush cells are another form of columnar cells

Characteristics:

  • small apical surfaces
  • short, blunt microvilli
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12
Q

What is the main role of olfactory epithelium?

A

-Olfactory epithelium contains olfactory chemoreceptors of the sense of smell

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13
Q

Where do olfactory receptor cells axons project?

A

-sends axons to the brain via small openings in the cribriform plate of the ethmoid bone

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14
Q

Give the histological features and cell types of the olfactory epithelium

A

Histology: pseudostratified epithelium

Cell types: basal stem cells, columnar support cells, bipolar olfactory neurons

-dendrites of these neurons have cilia specialized with many membrane receptors for odor molecules

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15
Q

How is the sense of odor detected and relayed to the brain?

A

Odor molecules bind to olfactory receptor cells - depolarization occurs, passing along basal axons to the olfactory bulb of the brain

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16
Q

Where is larynx located?

A

Between pharynx and trachea

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17
Q

What is the function of the Larynx?

A

Sound production: its wall contains skeletal muscles and pieces of cartilage for sound production (phonation)

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18
Q

Give the histological features of the larynx

A
  • laryngeal vestibule is surrounded by seromucous glands

- lateral walls of this region bulge as a pair of vestibular folds

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19
Q

Identify the histological features of vestibular folds

A
  • contain seromucous glands
  • is areolar tissue with lymphoid nodules
  • are largely covered by respiratory epithelium (regions near the epiglottis have stratified squamous epithelium)
  • ventricles (narrow spaces) located below each large vestibular fold
  • below each ventricle is another pair of lateral folds or cords
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20
Q

Identify the histological features of vocal cords

A
  • covered by stratified squamous epithelium

- contains a large striated vocalis muscle and nearer the surface a small ligament

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21
Q

How is sound produced through vocal cords

A

Muscles cause variable tension of these ligaments that produces different sounds as air is expelled across the vocal cords

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22
Q

Give the major histological features of the trachea

A
  • lines by typical respiratory epithelium
  • connective tissue of the lamina propria lies below the RE
  • seromucous glands are present in the lamina propria and submucosa
  • submucosa also contains C-shaped rings of hyaline cartilage covered by perichondrium
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23
Q

Where do the primary bronchi enter the lungs?

A
  • trachea bifurcates as right and left primary bronchi
  • primary bronchi enter the hilum on the posterior side of each lung along with the pulmonary vessels, lymphatics, and nerves
  • within each lung, bronchi subdivide further to form the bronchial tree
  • bronchial tree is the last component of the air conducting system
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24
Q

Identify the branching features of a bronchial tree

A

bronchi –> bronchioles –> terminal bronchioles –> respiratory bronchioles –> alveolar ducts/sacs –> alveoli

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25
Q

Vestibules of nasal cavities

A
  • epithelium: stratified squamous, keratinized to nonkeritinized
  • musculoskeletal support: hyaline cartilage
  • functions: filter and humidify air; has vibrissae (stiff hairs)
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26
Q

Most areas of the nasal cavities

A
  • epithelium: respiratory
  • musculoskeletal support: bone and hyaline cartilage
  • functions: humidify and clean air; have glands and rich vasculature
27
Q

Superior areas of nasal cavities

A
  • epithelium: olfactory, with bipolar neurons
  • musculoskeletal support: bone (ethmoid)
  • functions: solubilize and detect odorant molecules in air
28
Q

Nasopharynx and posterior oropharynx

A
  • epithelium: respiratory and stratified squamous
  • musculoskeletal support: bone and skeletal muscle
  • functions: conduct air to larynx, pharyngeal, and palatine tonsils
29
Q

Larynx

A
  • epithelium: respiratory and stratified squamous
  • musculoskeletal support: elastic and hyaline cartilage, ligaments, skeletal muscle
  • functions: site for phonation, epiglottis closes while swallowing
30
Q

Trachea

A
  • epithelium: respiratory
  • musculoskeletal support: C-shaped rings of hyaline cartilage with smooth (trachealis) muscle in posterior opening of each
  • functions: conduct air to primary bronchi entering lungs; some MALT
31
Q

Epithelium and Function of Bronchi

A
  • epithelium: respiratory

- function: repeated branching;; conduct air deeper into lungs

32
Q

Epithelium and Function of Bronchioles

A
  • epithelium: simple ciliated cuboidal to columnar, with Clara cells
  • function: conduct air; important in bronchoconstriction and vbronchodilation
33
Q

Epithelium and Function of Alveolar Sacs

A
  • epithelium: simple cuboidal between any alveoli

- function: conduct air; gas exchange

34
Q

Give the major histological features of a tertiary bronchus

A
  • the lining of respiratory epithelium and the mucosa are folded due to contraction of its smooth muscle; the wall is also surrounded by many pieces of hyaline cartilage
  • contains many seromucous glands in the submucosa; these glands drain into the lumen
  • arteries and veins are seen in the connective tissue surrounding the bronchi; these vessels branch as smaller vessels as they approach the respiratory bronchioles
  • all bronchi are surrounded by distinctive lung tissue; lung tissue is characterized by many empty spaces of pulmonary alveoli
35
Q

Give the histological features of the bronchial wall

A
  • epithelial lining of bronchi; pseudostratified ciliated columnar cells with a few goblet cells
  • lamina propria contains the distinct layer of smooth muscle surrounding the entire bronchus
  • submucosa - site of supporting cartilage
  • adventitia - blood vessels and nerves; surrounded by lung tissue
36
Q

What are the prominent histological features of a large bronchiole?

A
  • folded respiratory epithelium
  • prominent smooth muscle
  • supported only by fibrous connective tissue
37
Q

What are the characteristics of the smooth muscle of bronchioles?

A

-smooth muscle has elastic fibers with high elastic content

38
Q

Where are the elastic fibers present?

A

-elastic fibers present in the tunica media of large arteriola and to lesser extent in accompanying venule

39
Q

What is the nature of epithelium in small bronchioles and terminal bronchiole?

A

Small Bronchioles: epithelium is columnar and ciliated

Terminal Bronchiole: epithelium is ciliated cuboidal cells and many low columnar nonciliated cells

40
Q

Where are Clara cells present?

A

Terminal bronchioles*****, respiratory bronchioles, bronchioles

41
Q

What are the histological characteristics of Clara cells?

A

nonciliated; have bulging domes of apical cytoplasm containing granules

42
Q

What are the functions of Clara cells?

A
  • secrete components of surfactant which reduces surface tension and helps prevent the collapse of the bronchioles
  • also produce the secretory component for the transfer of: IgA into the bronchiolar lumen; lysozyme and other enzymes active against bacteria and viruses; several cytokines that regulate local inflammatory responses
43
Q

Where are stem cells located in bronchiolar epithelium?

A
  • give rise to all the cells within the bronchiolar epithelium
  • also included among Clara cells
44
Q

What are the components of the respiratory portion?

A
  • respiratory bronchioles
  • alveolar ducts
  • alveolar sacs
  • alveoli
45
Q

What gives rise to respiratory bronchiole?

A
  • similar to terminal bronchioles except for the presence of scattered alveoli along their length
  • pulmonary blood vessels travel with the bronchioles
46
Q

What structures surround each alveoli?

A

a dense layer of branching capillaries travel with the bronchioles

47
Q

What are the histological features of respiratory bronchioles

A
  • lung tissue has a spongy structure (due to alveoli)
  • branching continuity with alveolar ducts and sacs
  • have a layer of smooth muscle and some regions of cuboidal epithelium
  • runs along a thin-walled branch of the pulmonary artery
  • branches of the pulmonary vein course elsewhere in the parenchyma
  • alveolar ducts and alveoli
48
Q

What is the histology of alveoli?

A

Alveolar ducts consist of a linear series of alveoli

  • each with smooth muscle fibers around the opening
  • end in two or more clusters of alveoli called alveolar sacs
  • individual alveoli all open to the sacs or ducts
49
Q

What are the components of the air-blood barrier?

A

Air-blood barrier: gas exchange between air and blood occurs at a membranous barrier between each alveolus and the capillaries surrounding it

Components: alveolar type I cell, endothelial cell, their fused basement membranes

50
Q

Where does gas exchange take place at the air-blood barrier?

A

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 which lowers fluid surface tension and prevents the collapse of alveoli

51
Q

Compare the features and functions of alveolar Type I and Type II cells

A

Type I alveolar cells: Squamous; line almost entire alveolus surface; gas exchange occurs across these cells

Type II alveolar cells: line a bit of each alveolus; are large rounded cells; often bulge into the alveolus; have many functions of Clara cells, including the production of surfactant

52
Q

Where are alveolar macrophages present?

A

Present in alveoli or in interalveolar septa

53
Q

What is the role of alveolar macrophages?

A

Clean debris to avoid hindrance of gas exchange

54
Q

Outline the steps involved in surfactant production by type II cells

A
  • protein-lipid complexes are synthesized initially in the ER and Golgi apparatus
  • further processing and storage in large organelles: lamellar bodies
  • smaller multivesicular bodies form initially
  • the vesicles in multivesicular bodies are added to lamellar bodies
  • surfactant is secreted continuously by exocytosis (forms an oily film containing phospholipids and surfactant protein)
55
Q

What is asthma?

A

A chronic inflammatory disease of the airways characterized by episodes of acute bronchoconstriction

Symptoms: shortness of breath, cough, chest tightness, wheezing, rapid respiration

56
Q

What are the histological changes occurring in asthma?

A

Airflow obstruction in asthma is due to bronchoconstriction that results from:

Contraction of bronchial smooth muscle

Inflammation of the bronchial wall

Increased secretion of mucus

57
Q

What is COPD?

A

A chronic, irreversible obstruction of airflow that is usually progressive and characterized by persistent symptoms

Symptoms: cough, excess mucus production, chest tightness, breathlessness, difficulty sleeping, fatigue

58
Q

What is the greatest risk factor for COPD?

A

smoking

59
Q

What are the histological changes in COPD?

A

there is small airway fibrosis

Obstruction and/or destruction of alveoli and of elastin fibers in the lung parenchyma

60
Q

What is pleura?

A

A serous membrane (serosa) associated with each lung and thoracic cavity

61
Q

Parietal pleura

A

lines the inner surface of the thoracic cavity

62
Q

Visceral pleura

A

Covers the outer surface of the lung

63
Q

Pleural cavity

A

narrow space between the pleuras

64
Q

What are the histological features of pleura?

A

Simple squamous mesothelium on a thin layer of connective tissue

Histology (3 decks)

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