Flashcards in Respiratory System Deck (80):
What are the functions of the respiratory system?
- air conduction/gas exchange
- heat regulation
- air "conditioning" (temp and moisture control)
- acid-base regulation
- hormone conversion
What are the subdivisions of the respiratory system?
- conductive system
- transitional system
- gas exchange system
What structures are part of the conductive system?
nasal cavity, pharynx, larynx, trachea, and bronchi
What structures are part of the transitional system?
What structures are part of the gas exchange system?
respiratory bronchioles and alveoli
What does the conducting system do?
- brings air to the respiratory portion
- cleanses, moistens and warms incoming air
- blood in venous plexuses in mucous membrane of nasal cavity regulates temperature of inhaled air
- hair and secretions in the nasal cavity trap particulate matter
What is the transitional system?
a transition zone between the conducting (ciliated) and the gas exchange (alveolar system) areas of the respiratory tree
- consists exclusively of terminal bronchioles
What are the terminal bronchioles lined by?
- clara cells
- non-ciliated secretory cells
- only a few ciliated cells
- healthy bronchioles do not have goblet cells
What is the exchange system composed of?
alveoli; thin walled structures enveloped by a rich network of capillaries: the pulmonary capillaries.
What are alveoli lined by?
epithelial type I (membranous) and type II pneumonocytes (also known as pneumocytes)
What is the path of air into the lungs?
Nasal cavity -> nasopharynx -> larynx -> trachea -> bronchi -> bronchioles -> respiratory bronchioles -> alveolar ducts -> alveolar sacs -> alveoli
What are the non-specific defense mechanisms of the respiratory system? (non immune mediated)
- mucous trapping
- Mucociliary clearance (mucociliary escalator)
- Air turbulence (generated by coughing and sneezing)
What are the specific (immune-mediated) defense mechanisms of the respiratory system?
- antibody production
- antibody-mediated phagocytosis
- Cell-mediated immunity
What lines the nasal cavity, pharynx, larynx, trachea, and bronchi?
pseudostratified ciliated columnar epithelium with secretory goblet cells and submucosal serous cells
What does the lamina propria of the nasal cavity contain?
tubulo-alveolar glands, mainly serous with lesser numbers of mucous and mixed glands
What does the olfactory epithelium of the nasal cavity contain?
olfactory sensory cells
What is the nasal cavity?
bone supported cavity within the skull divided by nasal cartilaginous septum into two halves: left and right.
What are the three regions of the nasal cavities?
- vestibular region
- respiratory region
- olfactory region
What is the vestibular region of the nasal cavity?
initial external part of the nasal cavity that has a cutaneous mucous membrane, haired skin and glands
What is the vestibular region lined by?
stratified squamous keratinized epithelium
What is the respiratory region of the nasal cavity? What is it lined by?
the largest part of the nasal cavity lined with pseudostratified columnar ciliated epithelium with goblet cells.
What is the mucociliary apparatus and what is it responsible for?
combination of pseudostratified columnar ciliated epithelium with goblet cells that is responsible for clearance
- movement of cilia removes mucus with trapped airborne particles such as dust and microorganisms.
- cleaning apparatus of upper respiratory system
What are the projections from the lateral wall of the nasal cavity (respiratory region) called? What do they do?
conchae turbinates - narrow the lumen of the nasal cavity and increase the area of contact of inhaled air with respiratory mucous membrane, thus regulating the quality and quantity of inhaled air
Where are goblet cells found in the upper respiratory tract?
present along the airways to the level of the large bronchioles
What traps particulate matter in the upper respiratory tract?
secretion from the goblet cells
How does the respiratory system react to injury of the upper respiratory tract?
- increase numbers of goblet cells (hyperplasia) (eg: in smokers)
- metaplasia (a change from ciliated stratified epithelium to squamous stratified epithelium
What is present on the tips of the cilia in the URT?
claws of dynein
What is kartagener's syndrome?
dysfunction caused by immotile cilia syndrome - dynein claws missing
What is the olfactory region lined by? Where is it located?
lined with olfactory epithelium, much thicker than respiratory epithelium and lacks goblet cells
- located in the dorsal part of the nasal cavity (olfactory region)
What are the cells present in the olfactory region? What do they do?
- olfactory neurons - smell=olfaction
- supporting (sustentacular cells)
- Basal cells - stem cells for others
What does the lamina propria of the olfactory region contain?
serous olfactory glands and non-myelinated axons of olfactory neurons from nerve bundles Cr N 1
What are swell bodies and where are they located?
they are regions rich in venous plesxuses (distended with blood) and are found in the olfactory and respiratory regions
What are the cells found in the nasal cavity?
- ciliated columnar epithelial cells
- goblet cells - secrete mucous
- basal cells - stem cells for other types
- neuroendocrine cells
- brush cell - microvilli
- olfactory epithelium
What is the vomero-nasal organ used for?
chemoreception and sexual behavior
What lines the larynx?
initial part is lined by stratified squamous epithelium
- after vocal chords the lining changes to pseudostratified ciliated columnar epithelium
What structures make up the larynx?
cartilage, vocal folds, skeletal muscle
What is the trachea lined by?
ciliated pseudostratified columnar epithelium with serous glands in the lamina propria/submucosa
True or False? The trachea has a clearly defined lamina propria and submucosa.
False. They are not clearly demarcated in the trachea
What supports the trachea wall?
rings of cartilage (incomplete dorsally - excet in birds who have complete rings)
What completes the wall of the trachea?
connective tissue adventitia completes the wall of the trachea
What type of cartilage is found in the bronchus?
What are bronchi lined by?
ciliated pseudostratified columnar epithelium
What surrounds the lamina propria of the bronchus?
smooth muscle followed externally by connective tissue containing mixed bronchial glands and plates of hyaline cartilage
What do mixed seromucous glands secrete?
mucin, lactoferrin, and lysozyme (bacteriostatic/cidal)
What are the bronchioles always close to?
What do bronchioles lack?
cartilage and glands
What are bronchioles subdivided into?
terminal bronchioles and respiratory bronchioles
What are terminal bronchioles lined by?
ciliated cuboidal cells with few to no goblet cells
True or False? a muscularis mucosae is still present in terminal bronchioles.
What are clara cells and where are they found?
Cells located in terminal and respiratory bronchioles that bulge at the surface
- found in mucous membrane (inner epithelial layer)
What are the functions of clara cells?
- are a source of surfactant-like substance which aids in maintaining patency of airway
- metabolize airborne toxins, may have immune function
What is the function of the respiratory bronchiole?
conduction and gas exchange
What are respiratory bronchioles lined with?
ciliated cuboidal epithelium which becomes flattened distally
True or false? Respiratory bronchioles have a complete muscularis mucosae.
False, it is incomplete
What do alveolar ducts do? What are they?
are part of the exchange system and they empty into alveolar sacs and alveoli
What are the walls of alveolar ducts composed of?
entirely composed of alveoli lined by simple squamous epithelial cells
What is contained within the edges surrounding the openings of each alveoli of an alveolar duct?
smooth muscle cells - gives the lip of the alveolus a knob-like appearance
Alveolar ducts branch into alveolar sacs which lack __________
What are alveoli lined by?
two distinct epithelial cells:
- pneumocytes type I
- Pneumocytes type II
What happens during a pulmonary edema?
alveolar spaces filled with proteinacious fluid
How do neighboring alveoli connect to one another and why?
connect with each other via pores, providing equalization of pressure and collateral ventilation if a bronchiole is obstructed.
What do the pores allow the passage of? (between alveoli)
What cells are found in the alveolar septum and interstium?
- fibroblasts, capillaries
- DUST cells (actually macrophages)
- collagen type III is present in alveolar wall
- collagen type I present in conducting airways
- elastic fibers
Where are pneumocytes Type I found and what are their characteristics?
- form walls of alveoli and are extremely thin with occluding junctions which prevent fluid passage
- organelles are grouped around the nucleus
- are not mitotic - so no regeneration
- compose 95% of the alveolar sufaces
What is the function of a type I pneumocyte cell?
What type of capillaries are found in the alveoli?
What are type II pneumocytes and what are their characteristics?
- account for 5% of alveolar surface area
- secretory cells (more granular in appearance)
- surfactant is produced via lamellar bodies
- can be mitotic --> produces both type I and II pneumocytes (if damage is not continuous and severe)
What do the lamellar granules of type II pneumocytes contain?
What is surfactant?
mono-molecular layer of phospholipoprotein that functions to reduce surface tension, reducing the effort needed to inflate the alveoli, thus preventing alveolar collapse (known as atelectasis)
- constantly produced by type II pneumocytes
What stimulates the production of surfactant in the fetus just prior to parturition?
What is atelectasis?
What is hyaline membrane disease?
absence of surfactant in newborns
What is the blood-air barrier composed of?
- 2 fused basal laminae of alveolar epithelium and endothelium of capillary
- cytoplasm of type I pneumocyte covered by surfactant
What are PAMs and PIMs?
PAMs = alveolar macrophages (dust cells)
PIMS = intravascular macrophages
Where are macrophages found?
in tissues and organs: loose CT, liver, Lungs, Spleen and lymph nodes, serous cavities, nervous tissue and bone
True or false? There are lymphatic vessels in the alveolar walls.
Where do the lymphatic vessels of the respiratory system drain towards?
What are the lungs lined by and covered by and what is it composed of?
- Lined by simple squamous epithelium
- covered by the visceral pleura which is composed of connective tissue
What does the connective tissue surrounding the lung do?
supports the bronchial tree and separates the lung into lobes