ICL 1.3: Respiratory Histology

Question 1

what is dermatophagoides pteronyssinus?

Answer 1

common house dust mite!

he eats dead skin cells and we need him for it!

he’s also one of the most potent allergens for bronchiole asthma!

Question 2

what is bronchial asthma?

Answer 2

hyperresponsive airways leading to episodic reversible bronchoconstriction

immediate phase: bronchospasm (cough, wheeze)

late phase: inflammation, edema, airway remodel

asthma is a chronic inflammatory disorder of the airways likely caused by imbalance between proinflammatory and tissue protective cytokines

Question 3

what is COPD?

Answer 3

generally thought to be some biased combination of chronic bronchitis (blue bloater) and emphysema (pink puffer)

patients have progressive dyspnea which ranges in severity from mild difficulty to failure

Question 4

what is are the general functions of the respiratory tract?

Answer 4

PRIMARY

1. gas exchange
2. ventilation
3. external respiration

SECONDARY

1. conditions air
2. olfaction
3. phonation

Question 5

what are the major divisions of the respiratory tract?

Answer 5

1. conduction portion = nasal cavity to bronchioles

2. respiratory portion = respiratory bronchioles, alveolar ducts and sacs –> where external respiration happens

Question 6

what are the 2 major types of epithelium in the respiratory tract?

Answer 6

1. stratified squamous epithelium

usually just in the respiratory tract where the tissue is exposed to constant insult like eating food!

2. ciliated pseudostratified epithelium with goblet cells

Question 7

which cells types are in the respiratory epithelium?

Answer 7

in the pseudo stratified ciliated columnar epithelium there are the following cells joined apically by tight junctions:
1. ciliated columnar cells

2. goblet cells
3. brush cells
4. serious cells
5. small granule cells/DNES

Question 8

what are basal cells?

Answer 8

part of the respitory epithelium

stem cells for goblet cells

Question 9

what are ciliated columnar cells?

Answer 9

part of the respitory epithelium

they have 300 cilia/cell that beat to form the mucociliary escalator to clear things from the respitory tract

Question 10

what are brush cells?

Answer 10

part of the respitory epithelium

narrow columnar cells that have a microvillus border

we don’t really know what they do

Question 11

what are small granule cells?

Answer 11

part of the respitory epithelium

diffuse neuroendocrine cells

important for secreting hormones and biogenic amines that regulate blood flow through the respiratory system

Question 12

what are serous cells?

Answer 12

part of the respitory epithelium

columnar cells that have a microvillus border electron dense apical granules

they secrete a water substance but we don’t really know their function

Question 13

what is Kartagener’s Syndrome? how does it effect the respiratory system?

Answer 13

mutation in dynein

primary ciliary dyskinesia (PCD), also called immotile ciliary syndrome or Kartagener’s syndrome, is a rare, ciliopathic, autosomal recessive genetic disorder that causes defects in the action of cilia lining the respiratory tract and sinuses

non-motile cilia can cause symptoms like frequent respiratory infections that can lead to severe lung damage, chronic nasal congestion, frequent sinus infections

they will also have situs inverses and infertility

Question 14

what are bronchial carcinoid tumors?

Answer 14

a type of gastroenteropancreatic neuroendocrine tumor

females&raquo_space; males

it’s a Kulchitsky cell tumor that is NOT related to smoking

these cells proliferate and metastasize to the liver and dump vasoactive compounds into the circulation – patients will experience flushing, diarrhea and bronchodilation

Question 15

what are the 3 general layers of tissue in the respiratory tract?

Answer 15

1. mucosa + lamina propria = epithelium
2. smooth muscle and connective tissue layer
3. adventitia with collagen, connective tissue and cartilage

Question 16

what tissue types are in all the parts of the respitory system all the way down to the alveoli?

Answer 16

1. elastic fibers

2. smooth muscles

Question 17

what are the functions of the conduction portion of the resiratory system?

Answer 17

1. airway
2. warms
3. humidifies
4. sanitizes
5. olfaction
6. phonation

Question 18

what are the anatomical structures in the nasal cavity?

Answer 18

1. external nares = hairs in the nose that help filter particles in the air
2. vestibule = keratinized stratified squamous epithelium, sweat and sebaceous glands and hair follicles

the nasal cavity and paranasal sinuses contain standard respiratory epithelium and olfactory epithelium

lamina propria contains seromucus glands to clean and humidify, arterial plexuses and venous sinuses (Swell bodies) to warm and humidify the air!

Question 19

where is the olfactory epithelium?

Answer 19

the roof of the epithelium

the olfactory cells are able to contact the CN 1 through the cribriform plate to convey information

Question 20

what are the cell types in the olfactory epithelium?

Answer 20

1. thick pseudostratified epithelium with cilia
2. basal lamina
3. lamina propria = contains Bowmna’s glands
4. Bowman’s glands and ducts –> produce a fluid to hydrate olfactory epithelium and wash the stereocilia to get rid of olfactory molecules
5. olfactory cells = bipolar neurons with 6-8 very long non-motile cilia decorated with odor receptors
6. sustentacular cells = support cells that help electrically isolate the different olfactory cells
7. basal cells = they replace both olfactory and sustentacular cells

NO goblet cells!

Question 21

where are the tonsils located?

Answer 21

oropharynx

the lamina propria of the naso and oropharymx contains lymphoid tissue nodules: pharyngeal tonsils (adenoids) and palatine/lingual tonsils

Question 22

what cell type is the epiglottis?

Answer 22

it’s part of the oropharynx

this is because when you swallow the tongue pushes down the epiglottis so that food goes down the pharynx – so food is contacting the oropharynx so it has a non-karatinized stratified squamous epithelium due to all this mechanical insult

Question 23

what cells types are in the nasopharynx?

Answer 23

it contains typical respitory epithelium

Question 24

what is the larynx?

Answer 24

a laryngeal structure comprised of largely hyaline thyroid, cricoid, arytenoid, corniculate and cuneiform cartilages and largely elastic epiglottis cartilage, elastic vocal cords and skeletal muscle

the larynx is lined with typical respiratory epithelium EXCEPT that covering lingual surface of epiglottis and true vocal folds

Question 25

what happens to the respitory epithelium in a smoker?

Answer 25

metaplasia

there’s a great expansion of stratified squamous epithelium OR remodeling of the normal epithelium so that you have more goblet cells and less celiated cells = more mucous but less cilia to clear it = smokers cough

Question 26

how does the structure of bronchi change as they go from primary to tertiary etc.

Answer 26

airways with progressively smaller diameter exhibit less cartilage with an increase in elastic fibers and smooth muscle

Question 27

how does the tissue structure change in someone with asthma?

Answer 27

1. expansion in the number of goblet cells
2. thickening of the lamina propria
3. congestion of blood

Question 28

what is the composition of bronchioles?

Answer 28

NO cartilage and NO glands!

they’re smooth muscle arranged in discrete bundles

so you’ve transitioned from pseudostratified columnar with scattered goblet cells to low columnar or cuboidal with or without cilia

Question 29

what are clara cells?

Answer 29

cells in bronchioles and terminal bronchioles with no cilia

they produce a surfactant = oily substance to reduce surface tension

they also have a detox system to degrade different toxins

super important to bronchiole health!

Question 30

what cells compose alveoli?

Answer 30

1. type I pneumocytes = simple squamous cells where gas exchange occurs
2. type II pneumocytes = secrete alveolar fluid containing surfactant and replace type I and II cells
3. alveolar dust cells = macrophages

Question 31

what is acute neonatal respitory distress syndrome?

Answer 31

1. surfactant coat is not present or produced in low amounts in a premature infant
2. the alveolar surface tension increases
3. hypoventilation causes low oxygen and retention of CO2
4. pulmonary hypo perfusion
5. endothelial cell damage
6. fibrin and other proteins form a hyaline membrane exudate

net effect is the reduced ability of gas exchange

Question 32

what are alveolar macrophages?

Answer 32

scavenger cells derived from blood-borne monocytes

they’re also called dust cells or heart failure cells!

Question 33

what is emphysema?

Answer 33

abnormal permanent enlargement of the airspaces distal to the terminal bronchiole (alveoli), accompanied by destruction of their walls

reduced elasticity and FEV so you can’t push the air out of the air pockets

associated with heavy cigarette smoking

Question 34

what are the causes of emphysema?

Answer 34

1. protease-antiprotease hypothesis- emphysema results from the destructive effect of high protease (elastase) activity in patients with low antiprotease activity
2. homozygous alpha-1-antitrypsin deficiency
3. smoking stimulates release of elastase from neutrophils