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The patency of the respiratory system is maintained by what elements
Bone, cartilage, and fibrous tissues
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What components make up the respiratory portion of the respiratory system
- Bronchioles
- Alveolar ducts and sacs
- Alveoli
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What are the three parts of the nasal cavity
- Vestibule
- Respiratory segment
- Olfactory segment
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What cell type is the vestibule lined by
Stratified squamous epithelium, continuous with the outside skin
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What are the stiff hairs in the vestibule called
Vibrissae, they trap large particulate matter
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What is in the dermis of the vestibule that assists in trapping foreign particulate
Sebaceous and sweat glands which secretions aide in catching particles
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What lies just posterior to the nasal cavity
Three bony shelves called nasal conchae (turbinates)
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What is the function of the nasal conchae
They warm the air, moisten the air, clean the air, and create a turbulence in the air.
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What happens to the type of epithelium posterior to the vestibule
It transitions from stratified squamous to respiratory epithelium
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Where does the respiratory epithelium cover
From just behind the vestibule to the small bronchioles
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What is respiratory epithelium composed of
Ciliated pseudostratified columnar epithelium with goblet cells
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Almost all of the nose is covered by the respiratory epithelium except
Vestibule and chemosensory area
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What are the five cell types found in the respiratory epithelium (Pseudostratified ciliated columnar epithelium)
- Ciliated columnar
- Mucous goblet cells
- Brush cells
- Basal cells
- Small granule cells
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What is unique about the ciliated cells in the respiratory epithelium
They all beat in unison
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What is the job of the goblet cells in the respiratory epithelium
They secrete mucus which acts as a blanket over the ciliated cells
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What act as the anchoring site for ciliary axonemes
Basal bodies
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When there are abundant cilia, what other organelle must be close
Mitochondria for ATP production
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What is kartageners syndrome
- Immotile cilia due to a lack of dynein
- Make men sterile and mucus airways don't clear well
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What is the job of a brush cell
They have several microvilli that act as sensory receptors
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Microvilli on brush cells can be mistaken for
Cilia, BUT THEY ARE NOT THE SAME
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What is the purpose of basal cells in the respiratory epithelium
They can differentiate into sustentacular cells and olfactory cells
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What is the purpose of the granule (enteroendocrine) cells
They secrete bombesin and seritonin that control the functioning of other cells in the respiratory epithelium
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What can granules be mistaken for
Basal cells but are differentiated by the many granules inside
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What is beleived to be the function of bombesin and seritonin in the lungs and where else can they be found
Regulate smooth muscle tone, bronchial flow, and airway secretions. They can also be found in the GI tract
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What type of epithelium are the olfactory epithelium
Pseudostratified columnar epithelium (different form respiratory epithelium)
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What cells are in the olfactory epithelium
- Olfactory receptor cells (neurons)
- Supporting cells (sustentacular)
- Basal cells
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The nasal cavity is usually divided into what three parts
- Vestibule
- Respiratory segment
- Olfactory segment
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What are the two conditions that must be met for a compound to have a smell or odor
- Volatile
- High enough concentration to interact with olfactory receptors
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What compounds have the widest range of odors
Organic
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What happens to an olfactory receptor when an odor binds to it
It undergoes a structural change then binds and activates the olfactory-type G protein on the inside of the olfactory receptor neuron
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What is the structure of an olfactory sensory neuron
It has modified immotile cilia on their free surface containing odorant receptor proteins and a single axon extending to the brain
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How long does one olfactory neuron live
Around a month
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What makes new olfactory neurons
Basal cells
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What is the significant of Olfactory cells
- Bipolar neurons
- Spans the breadth of the whole epithelium
- Nucleus is centrally located
- 2 cytoplasmic processes (dendritic and proximal)
- Cilia on its surface
- Only neurons in the body exposed directly to the external environment
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What bone must the axons of the olfactory neurons penetrate to reach the olfactory bulb
Cribriform bone
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Sustentacular cells (supporting cells) have what characteristics
- Ovoid cells
- Nucleus on apical end
- Narrow base broad apex
- Microvilli
- Yellow brown pigment
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What is the job of the supporting (sustenacular) cells
They provide physical and metabolic support to olfactory cells
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What are bowmans glands and their job
Olfactory glands. Serous secreting glands which act as a solvent for odorous substances to be cleared for new ones to be brought in
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How are the olfactory neurons different then all other neurons
- They are subjected to the outside world
- They attach many molecules instead of just one
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Each olfactory neuron expresses how many receptors
Just one
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Olfactory receptors are coupled to what and act on what channels
G protein acting on ion channels
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Olfactory cells synapse on what cells
Mitral cells in the olfactory bulb
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Naegleria fowleri
The brain eating amoeba that enters the nasal cavity and into the olfactory bulb
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What is the difference in epithelial types from the nasopharynx and the oral and laryngeal pharynx
- Naso is lined by respiratory epithelium
- Oral and Laryngeal are lined by stratified squamous epithelium
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What is the job of the larynx
- Voice box
- Control of air pathway separating it from food
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True vocal chords consist of
- Stratified squamous epithelium
- Vocal ligament
- Vocal muscle
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The false vocal cords are made of
- Respiratory epithelium
- Lamina propria (w/many exocrine glands)
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Metaplasia
The reversible replacement of one cell type to another (not the same as dysplasia)
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Dysplasia
Abnormal development of cells, usually indicates beginning of neoplasia
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The trachea is surrounded by C rings and attached at their ends by
- Smooth muscle
- Dense fibroelastic ligament (attaches other rings)
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The open cartilage C rings in the trachea face what structure
Esophagus
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In what layer of the trachea are the seromucous glands located
Submucosa
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What are the three layers of the trachea
- Mucosa
- Submucosa
- Adventitia
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What makes up the mucosa of the trachea
- Respiratory Epithelium
- Thick basal lamina
- Lamina propria
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What is the lamina propria of the trachea rich in
Elastic fibers and lymphocytes
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As the airways get smaller what gets more prevalent and what gets less prevalent
- Smooth muscle is more prevalent
- Cartilage, Glands, goblet cells, and height of epithelial cells gets diminished
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Lamina propria is another name for
Basement membrane
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What happens to the cartilaginous rings of the bronchi when they enter the lungs
They are no longer C shaped rings but become a cartilaginous plate of irregular shape
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When do the bronchi become bronchioles
When the cartilaginous plates disappear
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What are the effects of the parasympathetic and sympathetic innervation on the bronchioles
- Para - Contraction
- Symp - Relaxation
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Bronchioles contain no
Cartilage or seromucous glands
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Clara cells
- Dome shape cells with short microvilli found only in the bronchioles
- They are identified by their bulging apical cytoplasm
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What is the function of the Clara cells
- To protect the bronchiole epithelium
- Detoxify harmful substances
- Divide and differentiate to form ciliated and non ciliated epithelial cells
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What substances in the Clara cells are secreted that protect the bronchioles
- Clara cell secretory protein (CCSP) a product of lung
- surfactant
- Glycosaminoglycans (GAG's) that prevent luminal adhesion
- Both decrease inflammatory response
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How do the Clara cells detoxify harmful substances
They contain Cytochrome P450 that metabolizes airborne toxins often contained in the ER
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Clara cells do not form ciliated cells in the
Respiratory epithelium
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Gas exchange in the lungs happens where
In the Alveoli only
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The wall of the aveolar ducts which seperate the aveoli are made up of
Elastic, collagen, and smooth muscle fibers
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What is the only portion of the respiratory tree that doesn't contain smooth muscle
Alveolar sacs (but it is in the ducts)
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What type of cells are found on the alveoli
- Alveolar cells (pneumocytes) Type I and II
- Alveolar macrophages
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What is the purpose of the two types of alveolar cells
- Type I gas exchange
- Type II secrete surfactant
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What kind of cells are pneumocyte type I
- Simple squamous epithelial cells
- Joined by tight junctions
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What are type I pneumocytes made by
- Type II
- They don't divide on their own
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What are type II pneumocytes made up of
Cuboidal cells
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What is the purpose of surfactant
Reduces the surface tension at the blood air barrier and prevents collapse of alveoli
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Surfactant is rich in
Phospholipids and phosphotidylcholine
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What happens when there is not enough surfactant in the body
It leads to cyanosis and respiratory distress syndrome (RDS) happens most frequently in children
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What are newborns treated with that are low in surfactant
Synthetic surfactant and glucocorticoid therapy which can cross the placenta
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How does glucocorticoid therapy treat low surfactant
It stimulates type II pneumocytes to secrete surfactant
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What are the components of the blood air barrier
- Alveolar epithelial cells
- Basal lamina of alveolar epithelium
- Basal lamina of capillary endothelium
- Endothelial cell of capillary network
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Alveolar macrophages are also called
Dust cells
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Where do the alveolar macrophages do their work
- In the air space and the interalveolar septum
- Uniquely they move between air and liquid
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How are alveolar macrophages often removed
They are moved up the bronchioles by the ciliary tract and swallowed getting destroyed in the stomach
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Alveoli have pores that have what function and name
- The pores of Kohn
- Found in the interalveolar septum
- They equalize the pressure in the alveoli and allow macrophages in
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What happens to the lungs in emphysema
Destruction of the interalveolar wall making fewer but larger alveoli
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Many people with COPD also have
Chronic bronchitis and emphysema
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