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Histology / Embryology Unit 3 > Respiratory System > Flashcards

Flashcards in Respiratory System Deck (58)
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What are the two divisions of the respiratory system and their components?

1. Conducting (upper) - nasal cavity, nasopharynx, oropharynx, laryngopharynx, larnyx, trachea, bronchi, and bronchioles through the level of terminal bronchioles

2. Respiratory (lower) division - respiratory bronchioles, alveolar sacs, alveolar ducts, and alveoli


What is the function of the conducting (upper) division of the respiratory system?

transmit / conduct air to lower division while warming, moistening, and removing particulate matter


What is the function of the respiratory (lower) division of the respiratory system?

Serves as site of gas exchange between air and blood


What is the vestibule of the nasal cavity and what are the epithelia / CT?

The inside of the nostrils
Epithelium - stratified squamous, slightly keratinized. Has some sebaceous glands, sweat glands, and hair follicles
Connective tissue - blends with perichondrium of nasal cartilage


What are the five main types of cells in respiratory epithelium? What type of epithelium is it?

Pseudostratified columnar
1. Ciliated cells - beat synchronously in a posterior direction
2. Goblet cells - produce mucus to trap particulate matter
3. Basal cells - precursors of other cell types
4. Neuroendocrine cells - resemble basal cells but have secretory granules. Part of amine precursor uptake and decarboxylation system
5. Brush cells - general name for cells that bear short blunt microvilli


What is the significance of the lamina propria underneath the respiratory epithelium of the nasal cavity?

1. Contains both mucus and serous glands for entrapment of particulate matter
2. Contains capillary loops - thin-walled venules to warm the air
3. Connective tissue blends with periosteum / perichondrium


What are capillary loops of the lamina propria for? What can they cause?

They are thin-walled venules which near the surface warm the air. However, they can rupture and let fluid out during upper respiratory infection


How does the respiratory epithelial lining in the paranasal air sinuses differ?

It is slightly thinner


Where is the olfactory mucosa of the nasal cavity found?

In spheno-ethmoidal recess, also extends a short distance over superior choncha and adjacent nasal septum


What is the structure of the olfactory epithelium? What does it lack, in comparison to respiratory epithelium.

Exceptionally tall pseudostratified columnar epithelium which LACKS goblet cells


What are the four cell types of the olfactory epithelium + their general functions / structures?

1. Supporting (sustentacular) - support olfactory cells physically and metabollically. Have apical microvilli, narrow at base, broad at apex
2. Basal cells -Mitotically active cells regenerate olfactory function in a few weeks. Small, conical cells at base
3. Brush cells - cells with apical microvilli which function in general sensation. They are presynaptic to afferent fibers
4. Sensory cells - bipolar neurons with cell bodies in middle layers of epithelium, between the supporting cells


What is the shape of olfactory sensory cells on the apical surface? Basal surface?

They are spindle shaped cells which an apical process / dendrite which is bulb-like, known as the olfactory vesicle or knob.

There are 10-20 modified cilia on it

Basal surface: extends into lamina propria as an axon, which continues to the olfactory bulb of the brain. Schwann cells will organize them but not ensheath them (unmyelinated)


How are olfactory neurons unusual?

They are continuously replaced, and have a 30-60 day lifespan (by basal cells)


How do the cilia of the olfactory vesicle / knob work?

They contain 350 types of odorant receptors, which have different affinities for different chemicals. All cells can detect the full range of odorants, but have varying sensitivities. Signal is transduced by G-protein-linked receptors that use second messengers


What are olfactory / Bowman glands? What else do they secrete?

Branched tubuloalveolar glands which produce a watery secretion to trap odorants and moisten / cleanse the surface (much like serous gland of von Ebner for taste buds) (via ducts)

Also secrete: Lysozyme, sIgA


Where are the olfactory / Bowman glands?

The lamina propria of the olfactory epithelium, along with the unmyelinated axons of bipolar olfactory neurons before going through cribriform plate


Where does the respiratory epithelium of the nasopharynx propel material?

Towards the oropharynx. This epithelium may be stratified in areas of abrasion


What is contained in the lamina propria of the nasopharynx?

Contains mostly mucous glands, with abundant lymphatic tissue including adenoids


What is squamous metaplasia and how does it relate to the larynx?

A change of the respiratory epithelium from pseudostratified columnar to stratified squamous epithelium. It is generally reversible but persists in areas of altered air flow (i.e. chronic bronchitis)

Larynx: areas of mechanical stress will have stratified squamous


How do the vocal folds differ from the vestibular folds with respect to mucosa?

Vocal folds are under much more mechanical stress, moving all the time for phonation, so they will be covered with stratified squamous nonkeratinized epithelium.

Vestibular folds are typically covered with pseudostratified columnar respiratory epithelium


What are the components in the larynx submucosa?

1. Few serous and many mucous glands
2. True vocal folds contain fibroelastic connective tissue and skeletal muscle of vocalis muscle


What makes up the wall of the larynx?

Supported by hyaline + elastic cartilages, as well as connective tissue and skeletal muscle.


What is special about the respiratory epithelium in the trachea?

Has a distinct basement membrane under the epithelium


What can happen if the ciliated epithelium of the trachea becomes damaged / loses cilia?

Mucus accumulation in the lungs, since it functions to move mucus to the pharynx.


What is the cycle of chronic bronchitis?

1. Irritation causes loss of cilia.
2. Loss of cilia forces mucus to be ejected via coughing
3. Coughing further irritates epithelium, causing squamous metaplasia
4. Decreased number of ciliary cells from loss of ciliary epithelium leads to further coughing and worsening of condition


What is the function of neuroendocrine cells (also found in trachea)?

They are small granule cells with granules that are released into underlying connective tissue and provide local regulatory control via a wide range of neuropeptides.

Cells can be part of the APUD system and release biogenic amines like serotonin, and are visualized via silver or dichromate stains

Function is based on control of smooth muscle contraction in blood vessel walls or bronchial tree


What defines the mucosa of the trachea? What makes its border with the submucosa?

Respiratory epithelium + lamina propria - separated by submucosa by band of elastic tissue


What are the other three layers of the trachea besides the mucosa?

1. Submucosa - contains mixed serous + mucous glands + lymphatics
2. Cartilaginous layer - 20 C-shaped hyaline cartilages which open posteriorly to a bundle of smooth muscle called the trachealis
3. Adventitia - connective tissue, blood vessel, and nerves outside the cartilages


What connects the adjacent cartilaginous rings of the trachea?

Fibroelastic connective tissue which blends with their perichondrium


What are the extrapulmonary bronchi?

The right and left primary bronchi - they split outside the lung and vary from the trachea only by diameter