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...
- mucus and cilia remove fine particular matter
- increased in temperature
What is the extrapulmonary system?
Everything outside of the lung tissue
- Beginning with the nasal vestibule
- Nasal cavities
- Oropharynx, nasopharynx, larynx
- 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
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?
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?
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?
- 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?
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:
2. Submucosa (with glands)
3. Cartilage (and trachealis)
What are the wall layers of the intrapulmonary bronchi?
(i.e. bronchi within the lungs) - there are five:
3. Subucosa (with glands)
What are the wall layers of the bronchioles?
Least complex - only three layers:
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....
- 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
- Largest type of bronchiole
- Gives rise to the terminal bronchiole
- Each terminal bronchiole gives rise to several branches of 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
6. Club (AKA Clara) cells (found in smaller bronchioles)
What layers will you find in a terminal bronchiole?
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?
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
- 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
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?
- Type I alveolar cells
- Basal laminae of cells above and below
- Endothelial cells