Respiratory System Flashcards
What are the functions of the respiratory system? x4
Air conduction (transport) to and from alveoli:
- ventilation - moving air in/out of lungs
- carry olfactory stimuli
-moving air past larynx to generate speech
Conditioning the air
Air Filtration
Mechanical respiration
What are the components of the respiratory system?
Extrapulmonary portions
Intrapulmonary portions
What are not part of the respiratory tract or path of air?
CT stroma - divides lungs into lobes
Visceral and parietal pleurae - define and lubricate pleural caivty
Muscles of respiration
What is the conducting portion of the respiratory system?
Extrapulmonary
Intrapulmonary - secondary bronchi to terminal bronchioles
What is the respiratory portion of the tract?
Structures associated with alveoli and where gas exchange with blood actually occurs
Respiratory bronchioles to alveoli
What structures are part of the conducting portion?
Trachea
Primary bronchi (1 per lung)
Secondary bronchi (1 per lobe)
Tertiary bronchi
Small bronchi
Bronchioles
Terminal bronchioles
What structures are part of the respiratory portion?
Respiratory bronchioles
Alveolar duct
Alveolar sac
Alveolus
Either these structures are alveoli or they have alveoli budding off of them
What are the general layers of tracts?
Mucosa - surface epithelium, lamina propria (loose CT with glands), muscularis mucosae (smooth muscle)
Submucosa - more loose CT with glands
Muscularis externa - smooth muscle
Adventitia or serosa - covering
What are the layers of the respiratory tract?
Mucosa
- surface epithelium
-lamina propria - areolar or fibroelastic CT
-muscularis - smooth muscle
Submucosa - dense irregular fibroelastic CT
Adventitia
What is the function of the muscularis layer of the respiratory tract?
Regulates diameter of airways
Sometimes provides structural support
What is the function of the adventitia of the respiratory tract?
Covering or anchoring
May contain cartilage that keeps large airways patent
What is the only layer of the olfactory region? What are its characteristics?
Olfactory mucosa - olfactory epithelium and lamina propria
This mucosa sits on periosteum of the cribiform plate in roof of nasal cavity
What are the characteristics of the olfactory epithelium of the olfactory region?
Pseudostratified ciliated columnar - no goblet cells
Olfactory receptor cells
What are the characteristics of the lamina propria of the olfactory mucosa?
Supporting CT - areolar CT
Vessels - arteries, lymph, and swell bodies (small venous plexuses)
Nerves - unmyelinated axons from olfactory receptor cells form bundles called CN I (Olfactory nerve)
Olfactory glands (Bowman’s glands) - serous glands whose secretions trap and dissolve odorants
What are the characteristics of the olfactory receptor cell, dendrite bulb and cilia?
Long nonmotile cilia lie flat on epithelia surface (facing cavity)
Olfactory receptors are cell membranes of cilia
What are the characteristics of the olfactory receptor cell?
bipolar neuron
Unmyelinated axons
Axons form bundles in the LP (CN I) and bundles pass through holes in ethmoid bone to reach olfactory bulb
What are the characteristics of the supporting cell (sustentacular cell) of the olfactory region?
Glial cells that support, nourish, and physically separate neurons
Secrete odorant binding proteins
What are the characteristics of the basal cell and brush cell of the olfactory region?
Basal cell - stem cell
Brush cell - columnar with microvilli, general sensory reception via CN V
Explain how viruses entering olfactory receptor cells can trigger apoptosis.
Olfactory receptor cells are exposed to circulating air in the nasa cavity
Their axons are on route to CNS that allows pathogens to bypass the blood brain barrier
What is the respiratory epithelium cells?
Pseudostratified columnar epithelium with cilia and goblet cells
What cells are part of the respiratory epithelium? What do they do? x6
Goblet cells - secrete mucus, which traps dust, particles, and pathogens
Ciliated columnar cells - cilia move mucus towards mouth
Basal cells - stem cells
Brush cells - general sensory receptors
Neuroendocrine cells (Kulchitsky cells, small granule cells) - secrete hormones like catecholamines, serotonin, calcitonin
Mast cells and intraepithelial lymphocytes (T lymph)
What is numerous in fetal lungs but decreases after birth? Also it may proliferate during certain pulmonary diseases?
Neuroendocrine cells (kulchitsky cells)
Explain mucociliary clearance
If mucus becomes too thick, cilia have much more difficult time clearing it or unable to do so
What is the mucosa of the nasal cavity, sinuses, and nasopharynx?
Nasal mucosa - respiratory epithelium and lamina propria
Lamina propria is well vascularized with many swell bodies - vessels and glands condition air by adding warmth and moisture
What ruptures during nose bleeds?
Swell bodies
What is the mucosa of the oral cavity, oropharynx, and laryngopharynx?
Mucosa is nonkeratinized stratified squamous epithelium and lamina propria
Need thicker epithelium because food more abrasive than air
What is the epithelium of the larynx?
Respiratory epithelium
Nonkeratinized stratified squamous epithelium on true vocal cords
Lamina propria - numerous mucous and seromucous glands (keeps air and mucosa moist)
Lacks muscularis and submucosa
Adventitia in most parts contains hyaline cartilage
Adventitia of epiglottis contains elastic cartilage - allows it to return to original position after swallowing
What are the trends for epithelium in respiratory tract?
More cell types of larger airways
Tall pseudostratified columnar in most of tract to simple squamous in alveoli
What are the trends of smooth muscle of muscularis of respiratory system?
Continuous sheets in larger bronchi and strips in smaller bronchi
Continuous sheets again in largest bronchioles and small circumferential strips in terminal and respiratory bronchioles
Absent in alveolar duct, alveolar sacs, and alveoli
What are the trends of elastic fibers (in LP and submucosa) in respiratory tract?
Fairly consistent throughout but especially in alveoli
What are the trends for cartilage in the respiratory tract?
Cartilage only in trachea and bronchi (adventitia)
Changes shape from trachea to smallest bronchi
Absent in bronchioles and alveoli
Describe the mucosa of the trachea and bronchi
Respiratory epithelium in trachea and all bronchi - BM thick in trachea, primary and secondary bronchi (harder for pathogens)
Lamina propria often contains seromucous glands and BALT (bronchus associated lymphoid tissue)
Muscularis - absent in trachea and primary bronchi, present in secondary and tertiary bronchi and in smaller bronchi
What is common in infant and if present in adults, usually associate with illness or smoking?
BALT
bronchus associated lymphoid tissue
What is present in the submucosa and adventitia of the trachea and bronchi?
Submucosa contains submucosal glands
Adventitia is in all bronchi and contains hyaline cartilage. Trachea and primary bronchi have C-rings of trachealis muscle that spans the ends of the C rings and contracts to bring the ends together. Secondary, tertiary, and smaller bronchi have irregular plates
What occurs to the bronchi when someone has asthma?
Bronchospasms constrict bronchi so trouble moving air in and move - short of breath and wheezing
Irritate bronchial mucosa - increased mucus production, inflammation of mucosa, muscularis, and submucosa in intrapulmonary bronchi
Edema and elevated WBCs in tissues
Repeated attacks cause increased number of goblet cells (more mucus) and permanent thickening of walls, especially in small bronchi
Describe the epithelium of bronchioles
Bronchiolar epithelium
Respiratory epithelium in largest bronchioles and simple cuboidal in respiratory bronchioles
Most bronchioles lack goblet cells
Have club cells
Lamina propria has no glands and no BALT, lots of elastic fibers
Muscularis thick in all bronchioles
What are club cells?
Present in bronchioles only and are stem cells and do secrete
Secrete surface antigen agent - prevents lumina adhesion and bronchiolar walls from collapsing
Secretes club cells secretory protein (CC16) - antioxidant and anti-inflammatory molecule
What is elevated when bronchioles are damaged?
Club cell secretory protein (CC16)
What is the epithelium of the terminal bronchioles?
Mucosa is a solid wall - no gaps in terminal bronchioles wall that open into lumens of surrounding alveoli
Short simple columnar epithelium. LP lacks glands
Muscularis in spiraling strips
No submucosa
Adventitia - fibroelastic CT
What are the terminal bronchioles?
Smallest and last airways in conducting division
Solid walls that do not open into alveoli
What are the respiratory bronchioles?
First airways in respiratory division
Walls have alveoli budding off them
Air can flow between respiratory bronchioles directly into alveoli and vice versa
Walls have cuboidal epithelium and smooth muscle
What are the walls of alveolar ducts?
Lack cuboidal epithelium, smooth muscle and have more gaps opening into alveoli
Each duct terminates in an alveolar sac
What are the alveoli?
Thin walled chambers where gas exchange with continuous capillaries occurs
Walls are alveolar epithelium
300-400 million alveoli in both lungs
Alveolar pores (pores of Kohn) - allow collateral gas circulation between adjacent alveoli when passages are blocked
What do disease like emphysema do to alveoli?
Lower surface area by destroying alveolar walls, specifically destroy elastic fibers in walls and reduce ability to get air out of lungs
Toxic particles in smoke recruit neutrophils which travel to alveolar surface and secrete elastases that destroy elastic fibers. Over time, the neutrophils destroy the walls
What part of the alveoli can serve as passageway for macrophages, exudates, and pathogens?
Alveolar pores (pores of Kohn)
Describe the alveolar epithelium
2 cells types:
- Type I alveolar cells = type I pneumocyte
- Type II alveolar cells = type II pneumocyte
What cells are not part of alveolar epithelium but are associated cells?
Alveolar macrophages - dust cells
Patrol surface of alveolar lumen
Patrol CT of alveolar septum
What is the function and structure of type I alveolar cells?
Simple squamous - gas exchange
95% of alveolar surface area
Cannot divide
Thin and delicate
What is the function and structure of type II alveolar cells?
Simple cuboidal with short microvilli
Stem cells that can divide into type I or type II
Secrete surfactant that reduces surface tensions and prevents moist alveolar walls from sticking to each other if alveolus collapses
What is neonatal respiratory distress syndrome (NRDS)?
Premature babies have underdeveloped lungs and type II cells have not produces enough surfactant to prevent alveolar collapse or even lung collapse (atelectasis)
Serial blood gasses show worsening hypoxemia and metabolic acidosis
What is the structure of the alveolar interstitium?
LP is pulmonary interstitium
CT is mostly elastic fibers with no glands
Elastic fibers allow alveoli to expand with inhalation and relax and return to shape during exhalation - passive way of getting air of out alveoli
No smooth muscle in alveolar wall
What is the blood-gas barrier?
Physical barrier that includes everything gasses must cross - more than just the alveolar wall
Permeable to oxygen, CO2, CO, and other gasses
Site of gas transfer between alveolus and RBCs in capillary
Prevents air bubbles from forming in blood - if gas embolisms form, they can block blood vessels
Prevents blood from entering alveoli - bleeding adds more thickness to barrier
