histo of respiratory tract2

8/8/2019 Histo of respiratory tract2

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istology of Respiratory Trac

Asst. Prof. Wisuit PradidarcheepAsst. Prof. Wisuit PradidarcheepDepartment of Anatomy, Faculty of MedicineDepartment of Anatomy, Faculty of Medicine

Srinakharinwirot University, ThailandSrinakharinwirot University, Thailand


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Respiratory Tract: Clinic

upper respiratorytract

nose, mouth,

pharynx, epiglottis,larynx and (trachea)

lower respiratory

tract

bronchial tree and

lungs


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Respiratory Tract: Anatomy

Nasal cavity

Terminal bronchioles

Respiratory bronchioles

Alveoli

Pharynx

Larynx

Trachea

Bronchus

Primary bronchiole

Alveolar duct

Alveolar sac

* Pseudostratified

ciliaed columnar

with goblet cells

* Simple squamous

*Most area

*Most area


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Epithelium of Respiratory Tract

1.Conducting portion nasal cavity terminal bronchiole* Most area:Pseudostratified ciliated columnar

epithelium with goblet cells = respiratoryepithelium

2. Respiratory portion respiratory bronchiole alveoli* Most area:Simple squamous epithelium


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Functions of Conduction Portions

. Cleaning of air

. Humidification of air

. Warming or cooling air

. Olfaction

. Phonation

1-3 is for conditioned the inspired air.


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Functions of Respiratory Portions

. Air-blood barrier (exchange) provide oxygen to blood and remove CO2 from it.

. Secrete surfactant

. Phagocytosis


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Nasal Cavity


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Nasal Cavity

3 area

1. Vestibule area

keratinized epithelium

2. Respiratory area pseudostratified columnar cilia

epithelium with goblet cells

3. Olfactory areaolfactory epithelium


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Respiratory area : Inferior concha


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spiratory area: Respiratory Epitheliu

Nasal Conchae

- Pseudostratified ciliated columnar epithelium with goblet cells- Serous and mucous gland = mixed gland- Large thin walls veins lie under the epithelium


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Medical fact: The mucosa of the nose hasmany thin-walled veins. During a viral infection t

hese become dilated, causing a blocked nose


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spiratory Epithelium with Goblet Cel

Muco-ciliary escalator

The mucociliary escalator coversmost of the bronchi, bronchiolesand nose. It is composed of twobasic parts;

1. the mucus-producing goblet cells2. the ciliated epithelium

The mucociliaryescalator is a majorbarrier against infection.


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Olfactory Area

2.5 cm2

Olfactory area lies with

olfactory epithelium

Olfactory area is located on both

medial and lateral walls ofthe superior concha


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The olfactory mucosa is served by a richly vascularized

lamina propria that also contains the olfactory

nerves and numerous serous glands.

Tall Respiratory Epithelium without Goblet Cells

Nerve

GlandGland


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3 Olfactory Epithelial Cell Types


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3 OlfactoryEpithelial

Cell Types

1. Supportingcell

2. Olfactory cell(bipolar

neuron)3. Basal cell

Bowmans gland

Fila Olfactoria (unmyelinated NF)

Myelinated NF (CN5)

Nasal cavity

Cribiform plate

P l i i


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Paranasal air sinus

Respiratory epithelium + few goblet cells

Thin lamina propria


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Pharynx

stratified squamous epithelium

stratified squamous epithelium

respiratory epithelium

Type of epithelial lining ofthe pharynx depends onregions.


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Mixed seromucous glands

Epiglottis

Su

periors

urf

ace In

f

eri o

rsu

rfa

ce

Elastic cartilage

Larynx


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Larynx

TC

CC

VM

C l S ti Th h th L


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epiglottis (E), false vocal folds (FVF), true vocal folds (VF),

thyroid cartilage (TC), cricoid cartilage (CC),lateral saccule (LS) and trachea (T).

Coronal Section Through the Larynx


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Epiglottis (E) at the top, false vocal folds (FVF), true vocal folds (VF),

lateral saccule (LS), vocalis muscle (VM) which is a skeletal muscle, andthyroid hyaline cartilage (TC).

VVocal fold (cord) region of the larynxocal fold (cord) region of the larynx


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Medical fact: Cigarette smoking causes irritation to

the mucosa of the larynx, resulting in changes of theepithelium. The respiratory epithelium will change into

squamous epithelium, and if the irritation continues thi

s will change into squamous cell carcinoma.

Metaplasia


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Bronchus

Bronchiole

Alveolar ductAlveolar sac

Alveoli

TracheaLung

-Pleura


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Trachea


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Trachealis muscle = smooth muscleTrachealis muscle = smooth muscle

Cartilage ring= C- shaped hyaline cartilage

h


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C-shape hyaline cartilage

Trachealis muscle

Trachea

Ch t i ti f T h


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a. Mucosal epithelium - respiratorepithelium

b. Lamina propria containsmany

lymphocytes that aresupported by a meshwork

of

elastic and reticular fibers.

c. The submucosa iscomposed of

loose connective tissue andcontains the secretorycomponents ofserous and

mucous glands whose ductsempty into the tracheal

lumen.

Characteristics of Trachea

* Trachealis muscle (smoothmuscle) connects the ends ofthe C formed by the cartilagerings.

d. -C-shaped rings of hyalinecartilage

-Trachealis muscle

* The cartilage and musclemake the trachea a very rigidstructure.


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Fibro-elastic CT


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Trachea


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Lung (mouse)

Visceral pleura


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Visceral pleura

AS

Vi l l f h l


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1. Alveolus

2. Blood vessel

3. Mesothelial cells

4. Pleura

5. Collagen fibers

6. Interalveolarseptum

Visceral pleura of the lung.


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Medical fact:Medical fact: The walls of the pleural cavityThe walls of the pleural cavity

are very permeable to water and other substaare very permeable to water and other substances, and therefore fluid accumulation (pleurances, and therefore fluid accumulation (pleura

l effusion) occurs frequentlyl effusion) occurs frequently


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Bronchus

Bronchiole

Alveolar ductAlveolar sac

Alveoli

TracheaLung

-Pleura

Bronchus


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Bronchus

B h


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Bronchus

a. Cartilage rings are

reduced to irregular platesof cartilage.

b. A band of spirally woundsmooth muscle present inlamina propria. Some textsmay call this smoothmuscle layer the mucularismucosa (probably not agood name for it).

c. Goblet cells in theepithelium become less

numerous.

d. Epithelium becomesreduced in height with lesscilia.

e. Lymphatic nodules may beresent in lamina ro ria,

Bronchus


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Bronchus


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Medical fact: The whole respiratory system is very exposedto infection. The bronchi have abundant lymphoid tissues in

he form of nodules containing B- and T- lymphocytes. These

interact with the lung macrophages. This is called BALT (bro

nchus-associated lymphoid tissue).

Bronchioles


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The bronchioles are the first airwaybranches that no longer contain cartilage.

They are branches of the bronchi, and are

smaller than one millimeter in diameter.

- Primary bronchiole

- Terminal bronchiole- Respiratory bronchiole

Bronchioles


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* Epithelium is simple columnar to simplecuboidal with fewer cilia.

* Non-ciliated Clara cells are present inepithelium.

* No goblet cells and no glands insubmucosa.

* Only smooth muscle layer is present.

* Bronchioles lack of cartilage.

Characteristics of Bronchioles

Bronchiole


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Bronchiole

Primaryb

ronc

hiole

Primary Bronchiole


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Primary Bronchiole

Terminal bronchiole


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Terminal bronchiole

Respiratory Bronchiole


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Respiratory Bronchiole


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Epithelium of

Primary bronchiole

- Low respiratory

epithelium + few

goblet cells

(simple ciliated columnar


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Epithelium ofTerminal bronchiole

- Simple ciliated

columnar or cuboid

- Clara cells


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Epithelium ofRespiratory Bronchiole- Simple ciliated cuboid+ Clara cell

Clara cell: Bronchiole


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Clara cell: Bronchiole

lara cells were originally described by Max Clara in 193

Clara cells are non-mucous and non-ciliated secretory

cells found in the bronchioles of the lungs.-

Epithelium of bronchiole


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Epithelium of bronchiole


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Immunohistochemistry using a rabbit polyclonal antibody labeling CC10 (Clara

cell specific 10 kD) protein discloses numerous clara cells in the bronchiolar epi

thelium of Sprague-Dawley rats with characteristic apical cytoplasmic protrusio

Functions of Clara cells in Bronchiole


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- Protect the bronchiolar epithelium

- Clara cell secretory protein (CCSP) :: inhibit pulmonary inflammation

- Lung surfactant

- Responsible for detoxifying harmful substances

inhaled into the lungs- Cytochrome P450 enzymes found in

their smooth endoplasmic reticulum

- Multiply and differentiate into ciliated cells to

regenerate the bronchiolar epithelium

Functions of Clara cells in Bronchiole

Pathol Res Pract. 1999;195(7):487-

Th diff d i il iti b t th t h


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The differences and similarities between the trachea,

bronchus and bronchiole can be summarized as follows:Histologicalcomponent

Trachea Bronchus Bronchiole

Epithelium Respiratory Respiratory Columnar

Elastic tissue Present as laminaelastica

Longitudinal bands Fibres only

Cartilage C-shaped Plates None

Glands Goblet and insubmucosa

Goblet and betweenmuscle and cartilage

None

Clara cells Absent Absent Present


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Medical fact: Contraction of bronchiolar smooth

muscle is an important factor in asthma, causingincreased airway resistance. In small babies the

smooth muscle is not well developed, therefore

medications acting on the smooth muscle is not

effective in treating babies with bronchiolitis.


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Pulmonary lobule


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Respiratory bronchiole

Alveolar duct

Alveolar sac

Alveoli

Respiratory Bronchiole, Alveolar Duct,


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Respiratory Bronchiole, Alveolar Duct,

Alveolar Sac and Alveoli

Respiratory Portions


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Respiratory Portions

Respiratory Bronchiole Alveolar Duct


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Respiratory Bronchiole, Alveolar Duct


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Smooth muscle , elastic fibers


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Alveoli


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eo

Interalveolar septum


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1.Collagen fibers2.Elastic fibers

3.Capillaries4.Alveolar

epithelium



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1. Alveolar epithelium2. Elastic fibers

3. Collagen fibers

4. Capillary lumen

5. Endothelial cells6. Alveolus


Alveolar Epithelium


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Alveolar Epithelium


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p

Alveolar Epithelium


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Type I pneumocyte (blue) ~ 95%

Type II pneumocyte = septal cell (green) ~ 5%

Macrophage = dust cell (red)

30 Microns

p


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The alveoli bring RBCs into close proximity with inspired air.

The cuboidal Type II pneumocytes (green) secrete surfactant

that reduces surface tension and prevents atelectasis.

Type I pneumocytes (blue) are the squamous cells type

that form a component of the air-blood barrier.

30Microns

Air-blood barrier


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Air-blood barrier


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Thickness ~ 300 nm.

a. The blood-air barrier prevents air

in gaseous form from mixing with theblood.

b. In certain situations, the blood airbarrier may be broken

* Called an embolism (arterial or

venous gas embolism).

* Can result in the release ofgaseous air into the bloodcirculatory system

* These air bubbles can causeblockages of blood circulation in


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Alveolus

Surfactant

Epithelium

Basal lamina of epithelium

Basal lamina of endotheliumEndothelium

Lumen

Red blood cell

Air-blood barrier

Alveolar Pore (of Kohn)


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Medical fact: The pneumocytes type II produce surfactant. A

deficiency of surfactant causes respiratory distress syndrome in newborns, and is associated with prematurity. It is the leading caus

e of death in premature babies. In the normal newborn, the onset

of breathing is associated with a massive release of stored surfact

ant, which lowers the surface tension in the alveoli. Surfactant als

o has a bactericidal effect.


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Medical fact: Alveolar pores and Lambert sinuses

are very important safety mechanisms in the

lungs. If a specific area in the lung is obstructed (

e.g., carcinoma in a bronchus), air can still reachthe affected area through these short circuits. It a

lso helps to equalize the pressure in various area

s of the lungs.


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Cleaning of air:

muco-ciliary escalator

Humidification of air:

serous from submucosal glandWarming or cooling air:

blood flowing in the venous plexus

Olfaction

Phonation



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. Air-blood barrier Type I pneumocyte and endothelium

. Secrete surfactant

Type II pneumocyte

. Phagocytosis

Alveolar macrophage

http://www.up.ac.za/academic/medicine/

telemed/Hist/lugwee/index3.html


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http://www.youtube.com/watch?

v=U6LqEr4vVis&feature=related

histo of respiratory tract2

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