13Respiratorysystem2txt

8/7/2019 13Respiratorysystem2txt

1/30

RESPIRATORY SYSTEM


2/30


3/30

2. RESPIRATORY PORTION

a. respiratory bronchioles

b. aveolar ducts

c. alveolae used for gas exchange

3. MUSCULOELASTIC VENTILATION APPARATUS - muscles, e.g.

intercostals and diaphragm, used for moving air in and out of the

lungs. This third portion will be dealt with more in your anatomyclasses.


4/30

C. In components of the respiratory tract including the trachea and structures below we may

find

1. Mucosa composed of

a. Epithelium of various types depending on what part of the respiratory tree

youre in

b. Lamina propria

2. Submucosa in upper portions of respiratory tree

3. Elastic and reticular fibers

a. Elastic fibers - allow for expansion followed by passive contraction.

4. Smooth muscle

a. Smooth muscle - provides for change in the diameter of passageways.


5/30


6/30

1. Trachea and primary bronchi

a. Mucosal epithelium - the majority

of the cells form a pseudostratified,

columnar, ciliated epithelium

Interspersed among the columnar,

ciliated epithelial cells are a

number of different cell types

including,

e.g.Goblet cells

Brush cells

Basal cells

Other types of cells

Well discuss these, and

others, later.

http://anatomy.utmb.edu/microanatomy/respiratory/olfactory_trachea.htm#Trachea


7/30

b. Lamina propria contains many

lymphocytes that are supported

by a meshwork ofelastic andreticular fibers.

c. A band of elastic fibers called

the membrana elastica interna

separates the mucosa from the

sub mucosa.

d. The submucosa is composed

of loose connective tissue and

contains the secretory

components ofserous and

mucous glands whose ducts

empty into the tracheal lumen.

http://www.lab.anhb.uwa.edu.au/mb140/


8/30

e. The adventitia - most prominent due

to presence of cartilage.

* dense connective tissue

* C-shaped rings of hyaline

cartilage

* Trachealis muscle (smooth

muscle) connects the ends of

the C formed by the cartilage

rings.

* The cartilage and muscle makethe trachea a very rigid

structure.

trachea


9/30

2. Intrapulmonary bronchi (also called

secondary bronchi)

a. 3 in right lung, 2 in left lung.

* These intrapulmonary bronchi each

each extend into a pulmonary lobe of

the lung and thus are sometimes

called lobar bronchi (3 lobes on the

right, 2 on the left).

* These and subsequent bronchiundergo repeated branching

culminating in the formation of

bronchioles.

b. The intrapulmonary bronchi are

histologically similar to the trachea and

primary bronchi.

Left lung


10/30

3. Tertiary and smaller bronchi. Differences in the histology develop as the bronchi

become smaller.

a. Cartilage rings are reduced to irregular plates of cartilage.

b. A band of spirally wound smooth muscle present in lamina propria. Some texts

may call this smooth muscle layer the mucularis mucosa (probably not a good

name for it).

c. Goblet cells in the epithelium become less numerous.

d. Epithelium becomes reduced in height and simple columnar with less cilia.

e. Lymphatic nodules may be present in lamina propria, particularly at branchingpoints opf bronchi.

http://www.finchcms.edu/anatomy/histology/organology/respiratory/o_r_6.html


11/30

Bronchi


12/30

4. Bronchioles - diameter 1 mm or less

a. Major characteristics

* Bronchioles lack cartilage

* Smooth muscle layer is relatively thicker (relative to lumen size).

* Non-ciliated Clara cells are present in epithelium.

* Epithelium is simple columnarto simple cuboidal with fewer cilia.

* No glands in submucosa

Clara cells


13/30

b. 3 types of bronchioles

* Large (muscular)

bronchioles - branch

repeatedly, final

branches are the

terminal bronchioles

*Epithelium is ciliated

simple columnar to

cuboidal with

interspersed clara cells

http://www.finchcms.edu/anatomy/histology/organology/respiratory/images/ff362.jpg


14/30

* Terminal bronchioles -

form connection

between larger

bronchioles and

respiratory bronchioles

** Epithelium

becomes simple

cuboidal with lots

of clara cells


15/30

http://www.udel.edu/Biology/Wags/histopage/colorpage/cre/crerbhm.GIF

* Respiratory bronchioles - form connection between terminal bronchioles and

alveolar ducts** This is the transitional structure connecting the conducting zone to the

respiratory zone.

** Alveoli open into this structure along its length with stretches of typical

bronchiole epithelium in between.

** Clara cells are abundant in epithelium. A few ciliated cells. No goblet cells.

http://www.udel.edu/Biology/Wags/histopage/colorpage/cre/crerbad2.GIF


16/30

5. Alveolar ducts - wall composed completely of alveoli opening into duct.

* Walls of the ducts consist entirely of alveolar openings.

* Epithelium is squamous - called alveolar epithelium

* Duct terminates in a cluster of alveoli that share a common, dilated chamber -

called an alveolar sac.

http://www.udel.edu/Biology/Wags/histopage/colorpage/cre/crerbad2.GIF


17/30


18/30

B. EIGHT TYPES OF CELLS FOUND

IN RESPIRATORY EPITHELIUM.

1. Goblet cells

a. Mucus secretion.

b. Plentiful in portions of

respiratory tree above the

smaller bronchi.

c. Function - mucus collects

particulate matter and absorbs

some noxious gases.

2. Ciliated columnar cells

a. Common in components

above the smaller respiratory

bronchioles

b. 300 cilia/cell. move mucusback toward oral area

c. Function - to move inhaled

debri trapped in mucous out of

respiratory tract.

goblet cell

ciliated

columnar cell cilia

basal cell


19/30

3. Columnar brush cells

a. Numerous microvilli on surface

b. Some have dendritic synapses on

basal surface

c. Thought to have endocrine or

sensory function.

goblet cell

brush cell

(microvilli)

ciliated

columnar cell

mucus

Scanning electron micrograph of

respiratory epithelium


20/30


21/30

5. Small granule cells

a. Look like basal cell, but have granules in cytoplasm.

b. Function - thought to be enteroendocrine (APUD) cells that secrete

hormones.


22/30

6. Clara cells

a. Secretory cell ultrastructure

b. Function - may secrete

surfactants that decrease surface

tension of fluid that moistens the

surface of lung epithelia.

c. Found in bronchioles

Clara

cell

Clara cells


23/30

7. Alveolar cells - Type I - squamous epithelial cells

8. Alvelolar Type II cells - bulge into lumen of alveolus

http://www.lab.anhb.uwa.edu.au/mb140/


24/30

III. The alveolus

Figures in text, pp. 283-285

A. The alveoli are lined by an exceedingly thin, simple squamous

epithelium.


25/30

B. Between the epithelia of adjacent alveoli are

1. The endothelium of the

capillaries - continuous, non-fenestrated endothelium.

2. Basal laminas of epithelia of

aveolar type I cells and capillary

endothelial cells that are fused at

some points.

3. Smooth muscle cells

4. Fibroblasts

5. Elastic and reticular fibers

6. Pores between adjacent alveoli


26/30

C. Cells of the alveolar wall

1. Alveolar type I cells - squamous epithelial cells

a. the cells across which gaseous transfer occurs, possibly at the

sites of fusion between this cells basal lamina and that of thecapillary endothelial cells.

b. Compose about 40% of the alveolar cells, but cover about 95%

of the alveolar surface area.


27/30


28/30

3. Also find alveolar macrophages called dust cells - usually free in the alveolar

lumen, but also in tissues between alveoli.

a. These cells act to clean fine inhaled debri from the alveolar free surface

of cells by endocytosing particles.

b. They are critical to lung function. Deficiency in function increases the

incidence and seriousness of lung disorders.


29/30

D. The blood-air barrier.

1. This refers to the substances/structures that lie between the air in the

alveolar sacs and the blood in the capillaries.

a. Starting in the alveolar lumen this

barrier consists of,

* Surfactant

* Type I alveolar cells lining the

alveolus

* Basal lamina of both alveolar

cells and capillary endothelial

cells (fused in some areas)

* Non-fenestrated (continuous)

endothelium of capillary

* In areas where basal lamina of

the two endothelial layers are not

fused, reticular and elastic fibers

are present.

Fig.

On p.

285 in

text


30/30

b. The blood-air barrier prevents air in gaseous form from mixing with the

blood.

c. In certain situations, the blood air barrier may be broken

* Called an embolism (arterial or venous gas embolism).

* Can result in the release of gaseous air into the blood circulatory

system

* These air bubbles can cause blockages of blood circulation in

capillaries in the brain that result in paralysis and/or death.

13Respiratorysystem2txt

Documents

Transcript of 13Respiratorysystem2txt