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Flashcards in Respiratory System Deck (44):

what are the respiratory system components?

-conduits for air passage
-muscles and CT for movement of gases to/from sites of exchange


respiratory system functions

-conduction of air
-conditioning of air
-gas exchange
-host defense



active at rest through contraction of external intercostals and diaphragm
-enlarges thoracic cavity with less pressure than outside, so air can come in



passive at rest through elastic recoil of CT in lungs and chest wall


air conditioning

-inspired air is filtered to prevent entry of pathogens or irritants
-warmed and humidified in conducting portions to promote gas exchange and to prevent tissue damage due to cold air or desiccation


gas exchange

in highly specialized epithelia
-maximize surface area, and minimize diffusion distance


respiratory epithelium

from upper nasal cavity to bronchioles
-conducting portion with pseudostratified columnar with cilia
-respiratory portion with simple squamous


what are the 5 cell types in respiratory epithelium, and what are their functions?

1. ciliated pseudostratified columnar epithelial cells (most abundant type; under the cilia are basal bodies)
2. goblet cells (most abundant in larynx and trachea, diminishing in number thru bronchi; extend from basement membrane to lumen to secrete mucous)
3. brush cells (extend from BM to lumen, with numerous microvilli sensory receptors that act as nerve endings on basal surface)
4. basal cells (lie on BM, but are short and rounded; regenerative cells that undergo mitosis to give rise to other cells)
5. granule cells (sit directly on BM; have numerous dense granules and may be part of neuroendocrine system to regulate mucous and secretions)


which respiratory epithelial cells extend to apical lumen, and which ones stay on basement membrane?

-ciliated, pseudostratified, columnar epithelial cells, goblet cells, and brush cells extend to lumen
-basal cells and granule cells stay on BM


mucociliary elevator

coordinated beating action of cilia propels mucous and trapped particles across aqueous layer towards mouth and nose to be swallowed or expectorated
-cilia go deeper in respiratory tract than goblet cells to prevent retrograde flow (so mucous doesn't go down wrong way)


how are mucous and water layered over epithelial cells?

directly on top of cells are aqueous layer that contain the cilia (secreted from glands to provide low resistance environment)
-mucous float on top of water to catch any particles


Kartagener syndrome

genetic disorder where dynein is dysfunctional or absent
-needed for microtubule sliding in cilia movement, so there is no ciliary beating, and there are recurrent respiratory infections



-transition from keratinized to respiratory epithelium
-sebaceous and sweat glands
-vibrissae (nose hair) for filtering particles


what are the parts of the nasal cavity?

-vestibule (nostril)


fossae and their components

chambers in skull separated by bony nasal septum
-3 conchae - bony projections covered with CT and epithelium
--venous plexus in CT to warm air via swell bodies
-3 meati - spaces between conhae for air passage
--forces turbulent air flow to humidify and warm air


what are the inferior, middle, and superior conchae lined with?

inferior and middle - respiratory epithelium
superior - olfactory epithelium


olfactory epithelium and cell/gland types

lines superior conchae (10 square cm)
-supporting cells - microvilli, NOT cilia, with apical nuclei
-olfactory cells - bipolar neurons, basal nuclei
-basal cells - small, round, at base of epithelium, with basal nuclei; regenerative
-olfactory (Bowman's) glands
-olfactory nerve bundle


olfactory glands

AKA Bowman's glands
-make proteinaceous serous secretions to clear cilia and ease access of new odorants
-tubuloalveolar glands are in superior meatus in olfactory epithelium


paranasal sinus

-chambers in frontal, maxillary, ethmoid, sphenoid bones
-lined with respiratory ciliated epithelium, goblet cells, small glands
-connected to nasal cavity through small passages


pharynx and what it's lined with

tube connecting oral and nasal passages
-lined with respiratory epithelium dorsally and stratified squamous epithelium ventrally



tube connecting pharynx and trachea
-epiglottis prevents food from entering trachea
-hyaline cartilage support (can be ossified)
-skeletal muscle articulates cartilage and allows phonation via vocal cords


2 types of vocal folds

vestibular/false vocal folds
-respiratory epithelium, with serous glands in lamina propria
-lie superior to vocal cords
-no dense ligaments or skeletal muscle

true vocal folds
-stratified squamous epithelium for protection and phonation
-vocal ligament (parallel fibroelastic fibers)
-vocalis muscle (skeletal, alters sounds)



10 cm tube connecting larynx and bronchi
-lined with respiratory epithelium, goblet cells, mixed serous and mucous glands
-limited elastic fibers
-16-20 incomplete rings of hyaline cartilage connected dorsally by smooth muscle and fibroelastic ligament


what are the laryngeal cartilages?

thyroid and cricoid
-subject to ossification, which can alter the tone of voice in old age



histologically similar to trachea
-1 primary per side; 3 lobar in right lung, 2 in left lung, then branch into smaller bronchi
-unlike trachea, cartilage is in irregular plates and much thicker
--smooth muscle in irregular bands, and postmortem constriction induces folds (wavy mucosa)


-type of epithelium and cells

regular, terminal, and respiratory; transition from conductive to respiratory regions
-epithelium transitions from respiratory to simple columnar/cuboidal
-NO cartilage, but smooth muscle is prominent in larger bronchioles, reactive, and regulatory
-few goblet cells or glands; replaced by Clara cells (secretory function)


regular bronchioles

usually ciliated columnar epithelium with folded intima
-have some goblet cells
-can be pseudostratified
-mucosa is wavy or folded due to post-mortem constriction of smooth muscle


where does regulation of ventilation occur?

at the level of the regular bronchioles
-due to large X-sectional area (in aggregate), lack of cartilage, and presence of smooth muscle


terminal bronchioles

usually non-ciliated columnar or cuboidal epithelium
-reduced levels of cilia can be found
-goblet cells replaced by Clara cells
-mucosa is smooth, not wavy, but less than found in regular bronchioles


Clara cells

tall cells that replace goblet cells in terminal bronchioles
-share the basement membrane with cuboidal epithelium
-extend taller than surrounding epithelium
-have dense granules in apical cytoplasm containing PRO that is secreted along with aqueous solution to moisten the epithelium


respiratory bronchiole

respiratory bronchiole; histologically identical to terminal bronchiole
-some cilia remain on cuboidal/columnar epithelium
-no goblet cells present
-reduced levels of smooth muscle compared with regular bronchioles
-outpockets of alveoli in bronchiole walls permit gas exchange


alveolar ducts and sacs

air passage completely lined with alveolar openings
-simple squamous epithelium, w/ NO cilia, goblet, or Clara cells
-sacs are common space shared by multiple openings
-smooth muscle in knob-like projections (cusps) of openings allow more regulation of ventilation


alveolar septum

thin wall adapted for gas exchange from air to blood


what is the diffusion path for gases into alveoli?

surfactant --> epithelium (2 membranes + cytoplasm) --> bused basement membrane (epithelial basal lamina and endothelial basal lamina fused as 1 basement membrane) --> endothelium (2 membranes + cytoplasm) --> RBC membrane


alveolar cells (pneumocytes) types, functions and percentages

Type I - squamous and squished, immediately next to airspace; 8% by number and 97% by surface area (forms majority of lung lining)
Type II - cuboidal surfactant source, regenerative; divde to replace both I and II; found at septal junctions; 16%
Capillary endothelial - very thin, crescent-shaped nuclei; 30%
Dust - macrophages that accumulate debris; found from capillary to outer epithelium; bone marrow origin, and differentiate on site; 10%
Fibroblasts and mast cells - 26%


acellular alveolar features

acellular interstitum - critical for respiratory mechanics (passive exhalation)
-type III collagen, elastic fibers, proteoglycans


pores of Kohn

penetrate alveolar wall
-equalize air pressure between alveoli
-promotes collateral air circulation


jobs of pulmonary circulation

nutrient (systemic)
-brings O2 and nutrients to lung tissue
-found in submucosa

functional (pulmonary)
-blood from pulmonary artery to be O2ated
-thin walled, low pressure
-follows bronchial tree
-branches to capillaries at sites of gas exchange


where does venous return of pulmonary circulation occur?

in parenchyma until exiting lobe, where it joins the bronchial tree


types of host defense in respiratory system

acid-base balance - regulate CO2, short term pH regulator
metabolic - pulmonary capillary endothelium
-inactivate bradykinin, serotonin, Ach, etc.
-convert AI to AII
immunologic - cellular and humoral


examples of cellular immunologic defenses

vibrissae, muco-ciliary elevator, alveolar macrophages


examples of humoral immunologic defenses

Igs A and E
monitor for specific Ag in respiratory tree (mast cells reactive to allergens)
BALT (bronchially associated lymphoid tissue)


lung pleura

serous membrane covering entire lung
-parietal and visceral layers, each with a mesothelium
-layers fuse at lung hilus
-space between layers fluid filled, permits lung movement


innervation of lungs

both sympathetic and parasympathetic
-regulate bronchial dilation (ventilation)
-poorly localizzed pain responses