Respiratory System Histology - Downing Flashcards by Whitney Bertram

What is respiratory epithelium (3 types of cells)?

Respiratory epithelium of mucosa =

Goblet cells (30%): mucus secretion
Ciliated columnar cells (30%): move mucus
Basal cells: (30%) mitotic, undifferentiated; replenish goblet, ciliated columnar, and brush cells

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Where is olfactory epithelium found? What is it composed of?

Where = limited region of posterior nasopharynx
What is it =
-Bipolar cells (neuronal cells)
-Sustentacular cells (supporting cells)
-Basal cells (mitotic cells)
-Lamina propria

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What are the differences between the functions of the conducting and respiratory division of the respiratory system?

Conducting - warms, moistens, & filters air. Delivers air to respiratory division. No gas exchange.
Respiratory - function = gas exchange

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What are the histological features of the anterior nasopharynx?

Anterior portion = vestibule

Lined with skin
Coarse hairs: vibrissae (stop from inhaling foreign bodies)
Dermis contains sebaceous and sweat glands

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What are the histological features of the oropharynx?

Stratified squamous epithelium

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What are the histological features of the laryngeal pharynx?

Stratified squamous epithelium

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What are the histological features of the larynx?

Short cylindrical tube (4 cm x 4 cm)

Cartilages reinforce laryngeal wall:

Hyaline cartilages = *thyroid, *cricoid
Elastic cartilages = *epiglottis
Cartilages connected by ligaments = movements controlled by intrinsic and extrinsic skeletal muscles

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What are the 3 histological layers of the trachea?

Mucosa
Submucosa
Adventitia

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What are the histological features of the Intrapulmonary bronchi?

C-shaped cartilage rings replaced by irregular *plates of hyaline cartilage
Smooth muscle at interface of lamina propria and submucosa in two distinct layers
Seromucous glands and lymphoid elements present in submucosa
Pseudostratified ciliated epithelium on mucosal surface
**Presence of alveoli

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What are the histological features of the Non-olfactory region of the posterior nasopharynx?

Non-olfactory regions:

Respiratory epithelium = pseudostratifed ciliated columnar epithelium
-Richly vascularized
-Seromucous glands (in underlying connective tissue)
-Many lymphoid elements = lymphoid nodules; mast cells; plasma cells (produce IgA, IgE, and IgG)
–Protects nasal mucosa from inhaled antigens and microbial invasion

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What are the histological features of the Olfactory region of the posterior nasopharynx?

Small region of roof of nasal cavity; superior aspect of nasal septum; superior concha

Olfactory epithelium:

Bipolar cells
Sustentacular cells
Basal cells
Lamina propria

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What are the histological features of the Epiglottis?

Supported by a core of *elastic cartilage
Superior surface = stratified squamous epithelium
Inferior surface = pseudostratified ciliated columnar epithelium

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What are the histological features of the Vestibular (ventricular) fold of the Larynx?

Superior location
Immovable
Pseudostratified ciliated columnar epithelium
Lamina propria

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What are the histological features of the Vocal fold of the Larynx?

Inferior position
Reinforced by the elastic vocal ligament
Vocalis muscle attaches to vocal ligament
Superior surface covered with stratified squamous epithelium

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What are the histological features of the Mucosa layer of the Trachea?

Pseudostratified ciliated columnar epithelium
Thick basement membrane
Lamina propria
-Loose fibroelastic tissue
-Lymphoid elements
-Mucous and seromucous glands
-Elastic lamina separates lamina propria from underlying submucosa (rings of fibers)

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What are the histological features of the Submucosa layer of the Trachea?

Dense irregular fibroelastic connective tissue
Mucous and seromucous glands
Lymphoid elements
Rich vascular and lymph supply

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What are the histological features of the Adventitious layer of the Trachea?

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Fibroelastic connective tissue
C-shaped hyaline cartilages
Anchors trachea to esophagus

What type of cartilage forms the C-shaped rings on the trachea?

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Hyaline cartilage

-Open ends face posteriorly; joined by smooth muscle (trachealis muscle)

Where is respiratory epithelium found?

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Trachea

What are histological trends as you descend down the bronchial tree?

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As you go down bronchial tree:

Decreasing amounts of cartilage, glands, goblet cells, and epithelial height
Increasing amounts of smooth muscle and elastic tissue

How do you differentiate a bronchus from a bronchiole?

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Bronchus: cartilage present (plates of cartilage)
Bronchiole: no cartilage

What are the histological features of the bronchioles?

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Epithelium:

Larger bronchioles = ciliated simple columnar with goblet cells
Smaller bronchioles = Simple cuboidal (some ciliated) with club (“Clara”) cells and no goblet cells

Lamina propria: smooth muscle; no glands and ***NO cartilage; abundant elastic fibers in connective tissue surrounding the smooth muscle

What are the function(s) of club (“Clara”) cells?

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Secretory granules in apical cytoplasm
Secretory product protects bronchiolar epithelium
Help degrade toxins via cytochrome P-450 enzymes in smoother (detoxifying)
Produce a surfactant-like material
Divide and help replenish epithelium

Where are club (“Clara”) cells found?

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smaller bronchioles

look like clubs
replace Goblet cells

What is the source of pulmonary surfactant?

Type II Pneumocytes Lamellar bodies -Contain pulmonary surfactant --Dipalmitoyl phosphatidylcholine (DPPC) and phosphatidylglycerol --4 unique proteins: surfactants A, B, C, & D Surfactant is released into the lumen --Decreases surface tension, thus preventing collapse of the alveolus --Produced & phagocytosed by the Type II’s and alveolar macrophages

What is the function(s) of Type I pneumocytes?

``` Squamous epithelial cell Covers ~95% of alveolar surface Slightly fewer in number than Type II’s Extremely thin Tight junctions formed between cells Sit on a basal lamina (except at pores) ```

What is the function(s) of Type II pneumocytes?

``` Cuboidal in shape Covers only 5% of alveolar surface Slightly more numerous than Type I’s Form tight junctions with Type I’s Rest on a basal lamina Membrane-bound lamellar bodies in cytoplasm Produce pulmonary surfactant => Decreases surface tension, thus preventing collapse of the alveolus Phagocytose excess surfactant ```

What are the components of the blood-gas barrier in the lungs?

Surfactant and Type I pneumocytes Fused basal laminae of Type I pneumocytes and endothelial cells of the capillaries Capillaries are of the continuous type

What type of blood vessel is often found in the same section of a small bronchiole?

Branch of pulmonary artery

How do you tell where the terminal bronchioles end?

Bronchiole gets smaller and smaller, then see tiny little pockets => ALVEOLI & Respiratory bronchioles

What structure do respiratory bronchioles terminate in to?

Alveolar sacs

What are the histological features of the terminal bronchioles?

Epithelium Club (“Clara”) cells and cuboidal cells Lamina propria Not much of it; fibroelastic tissue surrounded by one or two layers of smooth muscle

What are the histological features of the respiratory bronchioles?

Similar to terminal bronchioles with the following important exception: the walls are interrupted by occasional alveoli First place that gaseous exchange takes place!

What are the histological features of the alveolar ducts?

Do not really have walls Walls comprised of linearly arranged alveoli Interalveolar septa reinforce the alveolar ducts Opening of alveolus controlled by a single smooth muscle cell (form a ‘knob’) Terminate in alveolar sacs

What are the histological features of the alveolar sacs?

Clusters of alveoli at the ends of alveolar ducts

What are the histological features of the alveoli?

- Small outpocketings - Some alveoli connected by small pores (regulate pressure) - Interalveolar septum - -Between adjacent alveoli - -Lined on both sides by alveolar epithelium

What are the components of the thinnest areas of the Interalveolar septums?

- Capillary and its basal lamina | - Surfactant

What are the components of the thicker areas of the Interalveolar septums?

Type III collagen, elastic fibers, macrophages, fibroblasts, mast cells and lymphoid elements

What is the vascular supply of the lungs?

Pulmonary artery branches parallel bronchial tree Bring deoxygenated blood to lungs Break into extensive capillary network at level of respiratory bronchioles Venous drainage in septa between lobules (follow different path than the arteries) Bronchial arteries Branches of the thoracic aorta Bring nutrient and oxygen-rich blood to bronchial tree Bronchial veins drain into azygous system of veins

What is the lymphatic drainage of the lungs?

Superficial system in visceral pleura Drain into hilar lymph nodes at root of each lung Deep network in the pulmonary interstitium (3 groups) Follow pulmonary arteries Follow pulmonary veins Follow bronchial tree

Respiratory System Histology - Downing Flashcards

(40 cards)