Respiratory Flashcards
What does conducting portion contain?
Nasal cavities, pharynx, larynx, trachea, primary bronchi, bronchiole tree
What does respiratory portion contain?
Respiratory bronchioles, alveolar ducts, sacs, alveoli
What is the nasal vestibule lined with?
Stratified squamous keratinized, posteriorly pseudostratified columnar ciliated
What is respiratory region lined with?
Pseudostratified columnar ciliated with goblet cells
Define mucoperiosteum?
Lamina propria firmly attached to periosteum of bone
What is olfactory region lined with?
Pseudostratified columnar non motile cilia and no goblet cells
What does lamina propria of respiratory region contain?
CT, cells, capillary plexuses at right angles to airflow (warms air), mucus glands with serous demilunes
What do mucus serous demilunes do in respiratory region?
Trap particulate matter in air, matter is swept into pharynx by ciliary action
What gives olfactory epithelium yellow color?
Pigmentation and bowmans glands, lipofuscin granules are predominant in bowmans glands
Describe structure of olfactory receptor cells?
Bipolar neurons, single dendritic process that leads to olfactory vesicle, long thin non motile cilia extend from vesicle, axonal process leave from base of cell
What is lifespan of olfactory receptor cells?
1 month
What cells replenish olfactory receptor cells and supporting cells?
Basal stem cells
Is loss of olfactory sensation permanent?
No, cells replenish on monthly basis
Receptors on non motile cilia of olfactory vesicle bind with?
OBP, odorant binding protein
What do supporting cells of olfactory region secrete?
OBP, odorant binding protein
What is OBP?
Molecular carrier for already dissolved odorants and deliver them to olfactory receptors
Supporting cells makes what kind of junctions with olfactory cells?
Adherent junctions
What do supporting cells of olfactory region provide?
Physical and metabolic support to olfactory cells
Describe process of OBP binding
OBP bind with G protein couple receptors on olfactory vesicles, stimulus takes place. Adenyl cyclase gets activated and produces cAMP. cAMP binds with sodium and calcium channels, this influx starts depolarization.
What do brush cells function as in olfactory region?
Function as general sensory of olfactory mucosa, via afferent of trigeminal nerve
What does lamina propria of olfactory region contain?
Olfactory glands=bowmans glands, unmyelinated nerves and blood vessels
What are the oropharynx and laryngopharynx lined with?
Stratified squamous non keratinized
What is nasopharynx lined with?
Pseudostratified columnar ciliated
What is nasopharynx connected to in the ear?
Connected to middle ear by the auditory tube
What level does trachea divide into two main primary bronchi?
T4/T5
How does trachea lumen stay open?
Due to arrangement of C shaped hyaline cartilaginous rings
What bridges the gap between free ends of hyaline cartilage in the trachea?
Fibroelastic tissue and smooth muscle (trachealis muscle)
What is the trachea mucosa lined with?
Pseudostratified columnar ciliated with goblet cells
What does the submucosa of trachea contain?
CT, mucus glands with serous demilunes
What does the adventitia of trachea contain?
Dense CT that binds trachea to adjacent structures
What do ciliated columnar cells of trachea mucosa do?
Help remove small inhaled particles towards the pharynx
What is the dark line immediately below cilia in trachea mucosa?
Basal bodies
What is the mucouscilliary function?
Function to beat and remove particles trapped in cilia mucus
What is primary ciliary dyskinesia/ICS?
Autosomal recessive disease, abnormal ciliary motion and impaired mucocilliary clearance
What can ICS lead to ?
Recurrent respiratory infections, sinusitis, otitis media, male infertility
What complication is 50% of ICS patients associated with?
Situs inversus
What is Kartagener syndrome?
Dyenin arms are absent in the cilia and leads to abnormal ciliary function, Characterized by triad of situs inversus, chronic sinusitis, and bronchiectasis
What are brush cells in the trachea mucosa?
Considered a receptor cell, in contact with afferent nerve endings for general sensation for mucosa
What are small granule cells/Kulchitsky cells?
Part of DNES, diffuse neuroendocrine system, secrete paracrine hormones that act locally
What are Kulchitsky cells sensitive to?
Nicotine, known to be involved in small cell lung cancer
What are DNES cells in contact with in trachea mucosa?
Nerve fibers, known as pulmonary neuroepithelial bodies
What do DNES pulmonary neuroepithelial bodies do?
Monitor local tissue hypoxia, alert respiratory center of brain to increase respiration
What do basal cells do in trachea mucosa?
Maintain individual cell replacement in the epithelium
Is basal lamina in trachea prominent?
Yes very, more prominent in smokers and asthmatics
What does lamina propria of trachea consist of?
Loose CT, diffused lymphocytes that infiltrate epithelium, BALT
What is BALT?
Bronchus associated lymphatic tissue
What separates lamina propria from underlying submucosa in trachea mucosa?
Band of elastic fibers (elastic membrane)
What does trachea submucosa consist of?
Loose CT, diffuse lymphatic tissue and nodules, large vessels and lymphatics, seromucous submucosal glands
What are seromucous submucosal glands?
Mucus secreting acini with serous demilunes, ducts with simple cuboidal
What does trachea adventitia consist of?
CT, largest blood vessels, nerves, and lymphatics, some adipose tissue
Trachea divides into two main primary bronchi with two parts?
Extrapulmonary bronchi, same structure as trachea
Intrapulmonary bronchi, cartilage plates with circumferential smooth muscle layer
Intrapulmonary bronchi divide into?
Secondary and tertiary bronchi
What is mucosa of intrapulmonary bronchi lined with?
Pseudostratified columnar ciliated with goblet cells
What does lamina propria consist of in intrapulmonary bronchi?
CT, cells, BALT
Is basal lamina prominent in secondary or tertiary bronchi?
Not visible, discrete
What does muscularis of intrapulmonary bronchi consist of?
Continuous layer of smooth muscle, contraction regulates diameter of airway
What function does muscularis of intrapulmonary bronchi perform?
Contraction regulates diameter of airway
What does submucosa of intrapulmonary bronchi consist of?
Loose CT, serous glands, adipose tissue
What does adventitia of intrapulmonary bronchi consist of?
Dense CT
Terminal bronchioles are?
Smallest conducting bronchioles
What are terminal bronchioles lined with?
Simple cuboidal ciliated and non ciliated club cells
Function of respiratory bronchioles?
Air conduction and gas exchange
Are goblet cells present in terminal or respiratory bronchioles?
No, they are present in smokers and asthmatics
When do club cells increase in number?
Along the length of the bronchiole
What do secretory vesicles of club cells have?
Surface active agent, a lipoprotein that prevents luminal adhesion if airway collapsed
What does the club cell secrete?
Protein CC16, protects against oxidative stress and inflammation
Decreases in asthma and COPD patients
What type of mucus does club cells secrete?
Mucus 5B, gene is called MUC5B
What happens to club cells during asthma?
They transform to goblet cells and produce mucus 5C
Cytoplasm of club cells contain?
Numerous cisternae of sER that contain cytochrome P450 enzyme system
Lysosomes active against bacteria
What does P450 enzyme system do?
Detoxifies harmful compounds in air
Where can P450 enzyme system be found?
Club cells and liver cells
What are respiratory bronchioles line with?
Simple cuboidal with ciliated cells and club cells
What does thick region of respiratory bronchiole have?
Large amount of club cells and smooth muscle bundles
What does thin region of respiratory bronchioles have?
Few club cells and thin smooth muscle
What controls diameter of alveoli in respiratory bronchioles?
Elastic fibers, help expand during inspiration and recoil during expiration
Alveoli septal wall is vascularized with what?
Richest capillary network
Alveoli septal wall contains what?
Fibroblasts and ECM
What does alveoli septal wall ECM consist of?
Elastic fibers-help control diameter of the alveoli
Reticular fibers-protection from over-expansion, prevents collapsing, provides support
What are alveolar pores of Kohn?
Pores that connect neighboring alveoli, equalize air pressure and permit collateral circulation when a bronchiole is obstructed
Alveoli septal wall is the site of what?
Air blood barrier
What happens in thin segment of air blood barrier?
Gas exchange, thin layer of surfactant here
What happens in thick segment of air blood barrier?
Site of tissue fluid accumulation, contains CT cells and fibers between basal laminae, macrophages are present here
Gas diffusion sequence for thin segment?
Type I pneumocyte-fused basal lamina of pneumocyte and capillary-endothelial capillary
Gas diffusion sequence for thick segment?
Type I pneumocyte-basal lamina of pneumocyte- connective tissue- basal lamina of capillary-endothelial capillary
Type I pneumocyte/Type I alveolar cell
Main function is gas exchange, joined by occluding junctions to prevent leakage of fluid into air space, no cell division
Type II pneumocyte/Type II alveolar cell
Progenitors for type I pneumocyte, contains lamellar body granules in cytoplasm
Lamellar bodies granules contain?
phospholipids, neutral lipids, proteins
What do lamellar bodies secrete?
Surfactant layer
What do type II pneumocytes use to synthesize surfactant?
Choline
What does pulmonary surfactant provide?
Reduces surface tension in alveoli, helps prevent collapsing, eases breathing, modulates alveolar immune responses due to bacterial properties
What is RDS?
Respiratory distress syndrome
When is RDS common?
Premature babies, humans that have a gene mutation of surfactant gene
What is surfactant removed by?
Alveolar macrophages and type I pneumocytes
Where are alveolar macrophages derived from?
Monocytes
What are dust cells?
Macrophages that scavenge surface to remove inhaled particles like dust
Where do alveolar macrophages function?
CT of the alveolar septum and in air space of alveolus
What are heart failure cells?
Macrophages that phagocytize red blood cells and have hemosidrin that may enter the alveoli in heart failure
Why do smokers have large dust cells?
Nicotine particles
What are receptors called on type II pneumocytes?
ACE2 receptors
What do ACE2 receptors control?
Blood pressure
Explain high blood pressure and ACE2 receptors
Renin is produced in kidneys, sent into circulation which converts angiotensin to angiotensin I, endothelial cells of the capillaries convert angiotensin I to angiotensin II which increases blood pressure, ACE2 receptors bind with angiotensin II and modify effects of high blood pressure.
Explain COVID 19 and ACE2 receptors
COVID spike proteins fit perfectly in ACE2 receptors, the virus is internalized and replicates its mRNA. Alveoli collapse, gas exchange is reduced, fluid accumulation in alveoli and bronchioles, type II cell does not produce surfactant, blood pressure increases.
What is emphysema?
Enlargement of air spaces and destruction of alveolar wall, leads to reduced gas exchange
What cells are effected in emphysema?
Type II pneumocytes
What does alveolar cell death lead to in emphysema cases?
Destruction of alveolar wall, reduced surface area for gas exchange
What are causes of emphysema?
Chronic smoking, air pollutants, genetic factors like Alpha I Antitrypsin
What is process of Alpha I Antitrypsin?
Protein is created in rER but transport to golgi fails. Since it is the “off switch” to producing neutrophil elastase, excess of the neutrophil elastase takes place, excess destroys normal tissue, air space is destroyed and large air spaces occur with permanent damage. (Leads to emphysema)
What happens to asthmatic bronchioles?
Inflammation of bronchioles and smooth muscle constricts, contains large amounts of goblet cells and mucus is produced
Where does mucus from asthmatics get coughed up from?
Deep bronchioles, whereas mucus from bronchitis is coughed up from upper respiratory passages
