Pulmonary - Histology

bronchioles are how wide in diameter?

less than 1 mm

what is the main function of the conducting/respiratory epithelium?

to warm, moisten and sterilize the air

the conducting/respiratory epithelium is present in which areas?

nasal cavity

larynx, trachea

bronchi

intrapulmonary bronchi

the conducting/respiratory epithelium is what type of epithelium?

pseudostratified, ciliated, columnar epithelium with goblet cells and then progresses to simple non-ciliated cuboidal epithelium in deeper passageways

what cells types will you find in the gas exchange epithelium?

type I and type II alveolar cells (pneumocytes)

olfactory cells are what type of neuron?

bipolar

what are sustentacular cells? where are they found?

support cells, apical surface forming a line

where are Bowman's glands found? what is their role?

they are found in the connective tissue of olfactory epithelium and they are pure serous glands that secrete fluid in which odor molecules will be dissolved so we can smell

non-mobile cilia are found where?

olfactory epithelium

normally, neurons do not regenerate. what is the exception?

olfactory epithelium

What effect does Parkinson's and Alzheimer's have on olfactory nerves?

the regenerative capability of the neurons is reduced which reduces odor discrimination

how do Bowman's glands appear histologically?

- perfectly round nuclei (serous)

- dark staining cytoplasm

- lumen in the middle

how do we warm incoming air?

blood vessels/capillaries

what is found at the anterior portion of the trachea?

c-shaped hyaline cartilage

what is found at the posterior portion of the trachea?

trachealis muscle

what is the role of the trachealis?

- gives space to the esophagus

- stabilizes the airway and prevents collapse, for example, in the case of a cough

T or F: older adults will sometimes develop bone in place of their tracheal cartilage as a result of age

TRUE

will you find muscularis mucosae in the trachea?

NO

why is there no muscle in the trachea?

the trachea needs to be rigid (cartilage) to maintain its circular, tube-like shape. the diameter of the trachea should not change

the trachea is lined with...

pseudostratified ciliated columnar epithelium

- respiratory epithelium

the hyaline cartilage of the trachea is located in what layer?

adventitia

how do you determine the cartilage in a histological image of the trachea?

- back-to-back "double-D" in a milky matrix

what color do basal bodies stain? why?

pink due to basal bodies being a complex of proteins

how do you differentiate between goblet cells and ciliated columnar cells?

if there is a discontinuation in the cilia, a goblet cells is present in the discontinuation

does respiration (gas exchange) happen in respiratory epithelium?

NO

will you see smooth muscle in the intrapulmonary bronchus?

Yes, to change the diameter

will you see cartilage in the intrapulmonary bronchus?

NO, you will see smooth muscle, if there was cartilage, we would not be able to change the diameter

in what areas of the respiratory tract will you find structures that are 1mm or less in diameter?

starting at the bronchioles

T or F: there are mucosal glands in bronchioles

FALSE

will you find club cells in bronchioles?

YES, number increases distally

will you find goblet cells in bronchioles?

YES, but the amount decreases distally

what is the purpose of club cells?

they secrete bronchiole surfactants to keep the bronchioles from collapsing

- inhibit inflammation/fibrosis

- since there is no cartilage to maintain the shape (only trachea)

what happens in asthma?

airway becomes inflamed, narrows, swells and produces extra mucus, making it difficult to breathe

- bronchiolar epithelium contains and increased number of goblet cells (typically, numbers decrease distally)

elevation of excretory product of club cells in the plasma may be indicative of what?

epithelial injury

in a normal cell, under normal circumstances, how does cystic fibrosis transmembrane conductance regulator (CFTR) work?

in encodes a chloride channel protein that is responsible for moving chloride ions from inside the cell to the lumen where water will follow and dilute mucus secretions

in cystic fibrosis what happens?

chloride ion channels are defective due to mutation and this prevents chloridie from being removed from the cell, which prevent water from leaving the cell and makes the mucus in the lumen increasingly viscous and the cilia cannot move

type I cells cover how much alveolar surface area? how abundant are they?

they cover 95% of SA but are only 40% abundant

type II cells cover how much alveolar surface area? how abundant are they?

they cover 5% of surface area but make up most of the cells of the alveoli at 60%

what type of epithelial cell are type I cells?

simple squamous

- type II are round

which cell type in the alveoli produce surfactant?

type II

what is surfactant?

a mixture of lipids, proteins and carbs that reduces the surface tension at the air-blood interface. this helps to maintain the shape of the alveoli and prevent them from collapsing during expiration

at what gestational age do fetuses start producing surfactant?

6 months

when might respiratory ditress syndrome occur?

with premature babies that have insufficient surfactant

- administration of corticosteroids will increase the surfactant levels

what is a way to increase the amount of surfactant in fetuses that are suffering from respiratory distress syndrome?

administer a corticosteroid

aside from surfactant, what else helps the alveoli to maintain their shape/function?

they have elastic fibers

what are type I pneumocytes? what is their role?

extremely thin squamous cells that line 95% of the alveolar surface and form the barrier between the air space and the septal wall

T or F: type I pneumocytes are mitotic cells that can easily replace each other after injury

FALSE

- type I pneumocytes are post-mitotic cells and are replaced by type II pneumocytes

alveolar macrophages are also known as...

dust cells