Respiratory System Part 2 Flashcards
where is MALT found
throughout the respiratory tract
MALT is lymphoid —-
aggregates
BALT or MALT are found in
lamina propria
lamina propria
layer of subepithelial connective tissue
1’ function of MALT is
secretion of IgA onto mucosal surface
IgA secretion onto mucosal surface provides
provides protection from micro-organisms
Deep to mucosa is smooth Mm layer,
muscularis mucosae
Prominent in smaller airways of respiratory bronchioles & alveolar ducts as — —
alveolar rings
function of muscular mucosae (3)
Controls luminal diameter of airways & resistance to airflow, regulates alveolar air movement, takes over support function of cartilage
alveolar ducts & alveoli lined by
simple squamous epithelium
Alveoli are thin-walled structures surrounded by rich
capillary network
what are alveoli supplied by?
supplied by pulmonary A
Walls between alveoli called
alveolar septa
Septa contain
alveolar pores
alveolar pores
communicating spaces between alveoli
~95% of alveolar surface area covered by simple squamous epithelium consisting of
Type I pneumocytes
Type I pneumocytes
flattened epithelial cells modified for gas exchange
Air within alveolus separated
from blood within capillaries
by 2 cell layers—so-called
air-
blood barrier
air-blood barrier consists of (3)
Type I pneumocytes of alveoli, endothelial cells lining capillaries, & shared, fused basement membrane
~5% of surface area of lung lined by
Type II pneumocytes
Type II pneumocytes
larger, rounded, dome-shaped cells
Type II pneumocyte can differentiate into
Type I cells
type 2 pneumocytes possess intracytoplasmic granules, called — —, containing —
lamellar bodies
phospholipid
Contents of type 2 pneumocyets secreted as
surfactant
surfactant, a —, which (2)
phospholipid
decreases surface tension & keeps cells moist for gas exchange
respiratory distress syndrome, 1’ respiratory problem for
lack of surfactant, premature infants
Throughout lung are small to
moderate #’s of
alveolar macrophages
= dust cells
dust cells
Phagocytize particulate
matter & microorganisms
dust cells are eliminated from lung at rate of ~50 million/day, via
mucocilliary ladder
No direct lymphatic drainage of alveoli—only
indirect, via
interstitium of interalveolar septa
Second system of pleural
lymphatics within visceral pleura
drains
pleural space
Lymphatic obstruction can lead to (2)
pleural effusion or pulmonary edema
pleural effusion
fluid within pleural space between lungs results in horizontal fluid line
pulmonary edema
fluid within alveoli of lungs
results in interstitial pattern
Both common with
pneumonia
pneumonia
bacterial &/or viral
infection of lung with increase
inflammatory cell infiltrate esp. neutrophils & macrophages
Infections associated with
pneumonia may decrease production of
pleural fluid
damage to the pleura
pleurisy
Adhesions between visceral & parietal pleura results in
connective
tissue tags
originally seen in coal miners, from inhaling “anthracite” coal dust; now common in urban environments
Anthracosis
Silicosis & asbestosis
silicosis from inhaled silica particles
primary source of silicosis & asbestosis
coal dust & asbestos
silicosis & asbestosis
sharp crystals, difficult to phagocytose
Sharp crystals, difficult to phagocytose results in — — due to accumulation of silicic acid in lungs, which stimulates (2)
pulmonary fibrosis
fibroblast proliferation & collagen production
Asbestos inhalation has also
been linked to benign and
malignant
mesothelioma
Tuberculosis (TB) bacteria
Mycobacterium tuberculinum
TB
formation of multifocal nodules or tubercles
Bacterial foci surrounded by inflammatory cells,
especially macrophages, walled off by
fibrotic
capsule
Highly contagious, especially among
primates
Mucus production — in response to smoking
increases
Smoking impairs
cilia
how does smoking impair cilia?
first lose synchronicity, then die
Mucus accumulation results in
“smoker’s hack”
Bronchitis
fibrosis, thickening of airways
Over time, normal pseudostratified, ciliated, columnar epithelium of URT replaced by
stratified squamous epithelium
metaplasia
replacement of one tissue type by another
More resist to
physical stress
Can be incited by (3)
physical trauma (chronic coughing), chemical, or thermal insult (smoking)
Metaplasia may be first step in
neoplasia (cancer)—cigarettes also contain carcinogens
1’ cause of lung cancer is
smoking
emphysema is characterized by
permanent enlargement of alveoli
permanent enlargement of alveoli
bulla formation
Caused by chronic obstruction of air flow results in
destruction of alveolar septa & decrease surface area for gas exchange
what is emphysema initiated by
chronic inhalation of particulate matter (dust, smoke), mucus accumulation
chronic inhalation of particulate matter (dust, smoke), mucus accumulation results in
destruction of alveolar wall
destruction of alveolar wall is due to
release of lysosomal enzymes from neutrophils & macrophages
most common cause of emphysema
smoking
Bronchitis, asthma, & emphysema collectively referred to as
COPD (chronic obstructive pulmonary disease)
Asthma characterized by (4)
chronic airway obstruction, inflammation or irritation & increased responsiveness
asthma results in exaggerated
bronchoconstriction
how is asthma initiated
by formation of Ag-Ab complexes on cell membranes, require phagocytosis
Mast cells & eosinophils present in large #’s in — in asthmatics
submucosa
can be present with other inflammatory cells
Increased respiration, irritation causes mast cells to release (2)
histamine & SRS
Increased respiration, irritation causes mast cells to release histamine& SRS results in smooth Mm contraction of (2)
bronchioles & vasodilation
acute asthma attack
smooth Mm contractionof bronchioles & vasodilation
Eosinophils counteract effects of histamine with (2)
histaminase (neutralizes histamine), & eosinophil derived inhibitor (inhibits mast cell degranulation), etc.
