32 - Respiratory System Flashcards Preview

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Flashcards in 32 - Respiratory System Deck (117):

What are the three primary functions of the respiratory system?

1 - Air conduction
2 - Air filtration
3 - Gas exchange


What does "air conditioning" consist of?

Air conditioning = air conduction + air filtration (the first two primary functions of the respiratory system)


What are some things that happen to air as it moves through the respiratory system?

The air is...
- Refined
- mucus and cilia remove fine particular matter
- humidified
- increased in temperature


What is the extrapulmonary system?

Everything outside of the lung tissue
- Beginning with the nasal vestibule
- Nasal cavities
- Oropharynx, nasopharynx, larynx
- Trachea
- Two main bronchi


What is the intrapulmonary system?

Everything within the lung tissue
- Secondary and tertiary bronchi
- All other 20 divisions within the lungs
- Up until the terminal bronchioles


What does the conducting portion of the respiratory system consist of?

Extrapulmonary + Intrapulmonary = Conducting portion


What does the respiratory portion of the respiratory system consist of?

Structures associated with alveoli
- Alveolar ducts and sacs
- Alveoli themselves (gas exchange)


Why do the alveoli have a tremendous amount of surface area?

For gas exchange to occur


The most distal components of the airways are part of the ___________ portion of the respiratory system

Respiratory portion


Each respiratory bronchiole of the more distal respiratory portion supplies a __________.

Respiratory bronchiolar unit (AKA primary pulmonary lobule).


What happens at the primary pulmonary lobule?

This is where the gas exchange is going to take place - It is the functional level


What supplies the primary pulmonary lobule?

Each primary pulmonary lobule is supplied by a single respiratory bronchiole and its alveolar branches


What is anthracosis?

Carbon pigment that outlines secondary pulmonary lobules


What supplies these secondary pulmonary lobules?

Lobular bronchioles


What accounts for the pigment?

Carbon pigment has been consumed by macrophages and is flowing through the lymph vessels


Where do lymphatics travel in the lungs?

Lymphatics travel within the septa between secondary lobules - that is why carbon is seen surrounding secondary pulmonary lobules


What are the septa of the lungs?

Septa separate one secondary pulmonary lobule from another - provides a space for lymphatics and pulmonary veins to run between the secondary pulmonary lobules


Where is the olfactory region?

Located along the superior nasal concha and includes...
- Roof of nasal cavity
- Superior aspect of nasal septum (both sides)


What type of epithelium is found in the olfactory region?

Specialized pseudostratified columnar epithelium on a basal lamina


What is located deep to the epithelium?

A connective tissue component called the lamina propria


So what all does the mucosa layer of the olfactory region include?

Mucosa = epithelium + basal lamina + connective tissue


What are the four types of cells that are present in the olfactory region?

1. Olfactory receptor cells
2. Sustentacular cells
3. Brush cells
4. Basal cells


What type of neurons are found in the olfactory receptor cells?

BIPOLAR neurons


Where do dendritic projections attach to? What do they form there?

Dendritic projections attach to the surface of the epithelium. They dilate and form olfactory vesicles on the surface of the epithelium.


Describe the olfactory vesicles

Olfactory vesicles give rise to 6-8 nonmotile cilia that emanate from the vesicle. They lay flat on the surface of the epithelium and look like starfish


Describe the axon by which the sensory information (smell) travels)

The axon perforates the BL and the lamina propria
It is NOT myelinated, but it is instead wrapped by a specialized glial cell for insulation


So overall, what is the main function of the olfactory receptor cells?



What is the main role of sustentacular cells?

Supporting cells
- Think "sustentacular" = "sustaining cells" - they help to sustain the quality and nourishment of the olfactory neurons


What cell type are sustenacular cells?

Columnar cells with microvilli on the apical surface... This forms the "brush border"


We know that sustentacular cells are "sustaining cells," but what specific functions do they have?

- Support and nourish olfactory neurons
- Insulate olfactory neurons so their signals do not disrupt each other


What do sustenacular cells contain that aids in their function?


Finely granular yellow-brown pigment granules composed of lipid-containing residues of lysosomal digestion. It is considered to be one of the aging or "wear-and-tear" pigments.


What are brush cells?

Sensory cells that make contact with the terminal endings of the trigeminal nerve


Where is this contact made?

The basal domain of the brush cells makes contact with the trigeminal nerve on the basal lamina


Describe the characteristics of brush cells

Brush cells have a well developed striated border with abundant microvilli on the apical surface


What is the function of the basal cells?

Basal cells are STEM CELLS that replenish any of the other cell types that may be lost over time


What are Bowman's glands?

AKA olfactory glands - they are serous glands in the lamina propria (deep to basal lamina) that have ducts which go all the way to the surface of the olfactory epithelium


What are three things that are found in the lamina propria?

1. Olfactory (Bowman's) glands
2. Unmyelinated nerve fibers and bundles
3. Swell bodies


What are swell bodies?

Erectile venous bodies found within the lamina propria of the mucosa and function in "rehydration" of the lamina propria


How do swell bodies rehydrate the lamina propria?

Swell bodies accumulate and engorge themselves with blood on one side of the nasal cavity


How do swell bodies make sure one side gets all the blood at a time during the process of rehydration?

- The lamina propria expands on the side that is being reconditioned so that blood is occluded
- 20 minutes later the other side's swell bodies will swell to allow them to rehydrate


What is a distinctive quality of the lamina propria?

There is much more of a "psuedostratified" appearance to the lamina propria than the typical pseudostratified epithelium and the nuclei will be at many different levels


Are cilia associated with any of the epithelial cells of the lamina propria?

Yes, some of them


Do olfactory axons all remain separate or do they coalesce into bundles?

Coalesce into bundles


What are the three layers of the larynx?

1. Epithelium
2. Lamina propria
3. Reinke's space


Describe the epithelium of the larynx

Contains two different types of epithelium in different areas:
1. Respiratory epithelium (pseudostratified ciliated columnar with goblet cells)
2. Stratified squamous, nonkeritinized epithelium


Where is respiratory epithelium found in the larynx?

It is in most places - respiratory epithelium is the most common - there are only two exceptions... (next card)


Where is the stratified squamous, nonkeritinized epithelium found in the larynx?

Where there are more intense forces (from chewing/voice vibrations)
- Epiglottis (tongue/lingual surface)
- Level of true vocal cords


What structures are found in the lamina propria of the larynx?

1. Seromucous glands
2. Vocal ligament


Where are the seromucous glands found?

Seromucous glands are found in the laryngeal ventricle (saccule) of the larynx - this ventricle extends above and behind the false vocal cords


What is the function of the seromucous gland?

Form and secrete mucous that flows over the surface of the true vocal cords to keep them moist


What is Reinke's space?

A space that lies just deep to the lamina propria of the larynx


As we progress from larger airways to smaller airways, does the cell population get more or less diverse in the epithelium?

Larger airways are more diverse ("large diversity")
Small airways are less diverse ("small diversity")


What cells exist in the epithelium of the largest parts of the airway?

1. Ciliated columnar cells
2. Goblet cells
3. Basal cells
4. Neuroendocrine cells
5. Brush cells
6. Nonepithelial cells: Intraepithelial lymphocytes and mast cells


What is the function of ciliated columnar cells?

The action of the cilia beat the mucus up to the pharynx where we are able to swallow it - mucus is thick and rich in glycoproteins so we have some in our diet this way


What types of things would lead to an accumulation of mucus in distal airways?

Anything that irritates or plugs up the mucociliary cells - smoking would be a major irritant


What is the function of basal cells?

Progenitor stem cells


What are neuroendocrine cells?

AKA "cells of kulchinsky"
- THese cells can form tumors that leads to hypersecretion of hormones


What is the function of brush cells?

Brush cells are the sensory cells of the airway - they have a well developed striated border of microvilli


What are the two types of nonepithelial cells in the larger airways?

Intraepithelial lymphocytes and mast cells


What type of cells are intraepithlial lymphocytes? What is their function?

T cells with an intense immune surveillance function - this makes sense because this region is directly exposed to the external environment and need to fight off everything they are exposed to


What are the functions of mast cells?

When activated, mast cells will constrict the smooth muscles of the airway, making it harder to breath


At the level of the primary or lobular bronchiole, the cell population becomes less diverse... What cells exist in this region?

1. Ciliated columnar cells
2. Ciliated cuboidal cells
3. Goblet cells
4. Basal cells
5. Brush cells (very few)


What is important about the goblet cells in the region of primary bronchioles?

This is the most distal region you will find goblet cells... They are not found any further "downstream" than this


What cells exist in the region of terminal bronchioles?

1. Ciliated cuboidal cells
2. Non-ciliated cuboidal cells
3. Club cells
4. Brush cells (sensory)


What cells exist in the region of respiratory bronchioles?

1. Ciliated cuboidal cells
2. Non-ciliated cuboidal cells
3. Club cells
4. Type I pneumocytes


Compare and contrast the region of terminal bronchioles and the region of respiratory bronchioles...

The two regions have similar cell types, but since alveoli form in the region of the respiratory bronchioles, they also have type I pneumocytes


What cells exist in the region of alveoli?

Type I pneumocytes and type II pneumocytes


What is important about the region of alveoli?

LEAST diverse cell population


What are the wall layers of the trachea and primary bronchus

There are four:
1. Mucosa
2. Submucosa (with glands)
3. Cartilage (and trachealis)
4. Adventitia


What are the wall layers of the intrapulmonary bronchi?

(i.e. bronchi within the lungs) - there are five:
1. Mucosa
2. Muscularis
3. Subucosa (with glands)
4. Cartilage
5. Adventitia


What are the wall layers of the bronchioles?

Least complex - only three layers:
1. Mucosa
2. Muscularis
3. Adventitia


Where is the submucosa found? What is the hallmark feature?

- Found in trachea, primary bronchus and intrapulmonary bronchi
- Signature feature is the presence of mucus glands


In the intrapulmonary bronchi, what will you find?

Submucosa with mucus glands that secrete mucins containing....
- Lactoferrin
- Lysozyme
- IgA
- Alpha-antitrypsin (and other protease inhibitors)


What is the function of lactoferrin?

It is an iron-binding protein that binds to and eliminates iron from the type of bacteria that feed on iron - lactoferrin are protective and bacteriocidal


What is the function of lysozyme?

An enzyme that destroys bacteria - also a protective function


Where is IgA found? Where is it synthesized? How does it get to its destination?

- Found: surface of the mucosa
- Synthesized: by the plasma cells in the connective tissue of the submucosa
- Transport: IgA is endocytosed on the basal lamina, moves through the GLANDULAR CELLS, and is secreted into the duct system before arriving at the surface of the mucosa


What is the function of alpha-antitrypsin and other protease inhibitors?

Keep proteases in check that are released when there is a state of inflammation


What five modifications do you see in the wall of the respiratory system during asthma

1. Increase in mucus
2. Increased thickness of basal lamina
3. Increased thickness of lamina propria (due to edema and emigration of inflammatory cells)
4. Increase in thickness of muscularis
5. Increase in the glands of the submucosa


Where along the respiratory tract will these asthma modifications occur?

The entire airway down to the level of the bronchiole - the five modifications are due to the inflammatory component of asthma


What causes the increased thickness of the muscularis?

Smooth muscle hypertrophy and hyperplasia
- increased cell size
- increased cell number
The muscle is also more active/constrictive when it is triggered by the inflammatory state


What modifications will you see in patients with chronic bronchitis?

Similar to asthma


In bronchitis, what happens to the epithelium?

It changes (metaplasia)... Instead of respiratory type epithelium you will see stratified squamous instead


In bronchitis, what happens to the basement membrane?

You will see swelling, edema and dark staining basophilic cells due to the inflammation


Other changes in bronchitis...

- Hypertrophied muscularis (and hyperplasia)
- More submucosa glands secreting mucus


What are the three types of bronchioles?

1. Lobular bronchiole
2. Terminal bronchiole
3. Respiratory bronchioles


Lobular bronchiole

- Largest type of bronchiole
- Gives rise to the terminal bronchiole


Terminal bronchiole

- Each terminal bronchiole gives rise to several branches of respiratory bronchioles


Respiratory bronchioles

- Smallest type of bronchiole


Epithelium of the bronchioles

The epithelium becomes shorter and smaller as you go further along the branching pattern
- First, respiratory epithelium
- Then, pseudostratified epithelium
- Then, simple columnar
- Finally, simple cuboidal


What types of cells will you find in bronchioles?

1. Goblet cells (in larger bronchioles)
2. Brush cells
3. Ciliated cells
4. Non-ciliated cells
5. Neuroendocrine
6. Club (AKA Clara) cells (found in smaller bronchioles)


What layers will you find in a terminal bronchiole?

1. Mucosa
2. Muscularis
3. Fibroelastic layer


Describe the mucosa of a terminal bronchiole

- Simple columnar, short cuboidal cell types
- Ciliated and clara cells will be present, but you can't discern these
- Has a thin lamina propria


Is the muscularis of the terminal bronchiole thin or prominent?

Very prominent


Describe the function of the fibroelastic layer

It is a connective tissue layer that functions to keep the lumen of the bronchiole open and prevent it from collapsing
*** Note that cartilage is NOT present and is NOT necessary to keep the lumen open


Do bronchioles have a submucosa?

NO - no submucosa, no submucosal glands
Why? Because if there was mucus where gas exchange was trying to take place it would be prevent the respiratory process


Where are club cells located?

In the terminal and respiratory bronchioles


What do club cells look like?

They are dome shaped and the apical domain is club-like with secretory components included


What do club cells secrete? What is the function?

CC 16 (club cell 16) protein, a surfactant-like substance
- Anti-inflammatory
- Anti-oxidation
- Protective against cytokines


When would you find CC 16 in the blood?

When there has been damage done to the epithelium of the bronchioles


What is the function of stem cells in club cell function?

Stem cells may have some involvement in the transport of chloride ions


Describe respiratory bronchioles

- First segment of the respiratory portion of the airway
- Alveoli extend from the respiratory bronchioles
- Lined by cuboidal epithelium


What types of cells will you find in alveoli

1. Epithelial cells
- Type I pneumocytes
- Type II pneumocytes
- Brush cells
2. Macrophages


What are type I pneumocytes?

- Flattened squamous cells
- These cells occupy a large surface area of the alveolus (90%)


What is the function of type I pneumocytes?

- Decrease blood-air barrier
- Facilitate the movement CO2


What are type II pneumocytes?

- More cuboidal cells that have microvilli
- Type II is more numerous than type I, but they cover way less surface area


Where are macrophages found in alveoli?

- alveolar lumen
- the connective tissue space in the septa that divide alveoli


What is the role of macrophages in alveoli?

The macrophages are capable of migrating into the alveolus lumen in order to remove debris


What is the function of type II alveolar cells?

Lung surfactant synthesis


When does lung surfactant synthesis begin?

20-22 weeks gestation


What stimulates the synthesis of surfactant?



What inhibits corticosteroids?



What does this mean for diabetic mothers?

Hyperinsulinemia in fetuses of diabetic mothers leads to a higher incidence of respiratory distress syndrome because the high levels of insulin decrease the corticosteroid content and there is therefore no stimulus for lung surfactant production


What is the signature feature of type II alveolar cells?

Lamellar bodies - these contain surfactant material which produce and secrete surfactant


What happens to the lungs in heart failure?

Alveolar macrophages are "heart failure cells" when blood dams up into the heart tissue and fluid/RBCs get into the lumen of the alveoli


Describe heart failure cells

The macrophages of the alveoli degrade RBCs and they accumulate hemosiderin


What forms the blood-air barrier?

- Surfactant
- Type I alveolar cells
- Basal laminae of cells above and below
- Endothelial cells


Case study: What would lead to voice problems and choking due to smoking and dehydration?

Enlarged vocal folds due to an accumulation of fluid in Reinke's space, leading to massive swelling of Reinke's space