Histology: Respiratory System

Front 1

Which structures make up the Conduit System?

Back 1

nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles
(in that order)

Front 2

What is the primary function of the Conduit System?

Back 2

transports air to alveoli for gas exchange (functions as "anatomic dead space")
-filters, cleans, moistens, warms air before it gets to the lower respiratory tract

Front 3

What do most elements of the conduit system (below the larynx) include?

Back 3

smooth muscle (which allows for constriction) and elastic fibers (which give recoil) within their walls

Front 4

What structures do the bronchi branch into?

Back 4

bronchioles then terminal bronchioles then respiratory bronchioles

Front 5

What are the three functions of the Respiratory Tract?

Back 5

1) Ventilation
2) Conduction
3) Gas Exchange

Front 6

What is the germ layer origin of the respiratory tract?

Back 6

endodermal diverticulum of the foregut

Front 7

What is the process that describes the respiratory tract epithelial tube development?

Back 7

It is an epithelial tube that undergoes branching morphogenesis.

Front 8

What tissues is the respiratory tract composed of?

Back 8

The respiratory tract is a series of tubes with an epithelial lining, a lamina propria, connective tissue with glands (and sometimes cartilage); smooth muscle, and an adventitia (connective tissue).

Front 9

Which cells make up the "resipiratory epithelium" of the conduit system?

Back 9

pseudostratified ciliated columnar epithelium with goblet cells.
function: filter, trap, and move particulate matter (which will then be swallowed)

Front 10

Which structures make up the Respiratory Portion of the respiratory system?

Back 10

respiratory bronchioles, the alveolar duct and its associated alveolar sacs and alveoli

Front 11

What is the function of the Respiratory Portion of the respiratory system?

Back 11

Gas exchange (the alveolar-blood interface provides an extensive surface area for gas exchange)

Front 12

Do the parts of the respiratory tract distal to the bronchi contain cartilage?

Back 12

No.

(the trachea and bronchi contain complete or incomplete rings of hyaline cartilage while those parts distal to the bronchi do not have cartilage)

Front 13

What type of cells can be found in the respiratory portion of the respiratory tract?

Back 13

Simple squamous

Most gas exchange occurs in the alveoli. The thinness of the epithelium allows for rapid gas exchange with capillaries.

Front 14

The ______ is a cartilage-bound space connecting the pharynx to the trachea.

Back 14

Larynx

Front 15

Name the major structures of the larynx.

Back 15

epiglottis, thyroid cartilage, cricoid cartilage, and arytenoid cartilages.

(All but the epiglottis are made of hyaline cartilage)

Front 16

What are the two functions of the larynx?

Back 16

1) phonation (speech)
2) control of the air pathway (so that only air – and not food or liquid – reaches the lower airway)

Front 17

What are the three main histological features of the epiglottis?

Back 17

1) stratified squamous epithelium - on upper lingual surface (lower has respiratory epithelium)
2) elastic cartilage core - main support surrounded by perichondrium
3) exocrine glands - found in lamina propia

Front 18

What is the function of the epiglottis?

Back 18

a flap-like structure that prevents food or fluid from entering the respiratory tree
(prevents choking)

Front 19

About how long is the trachea?

Back 19

~10cm

Front 20

What is the trachea composed of?

Back 20

lined with “pseudostratified ciliated” respiratory epithelium
loose connective tissue
16-20 "C-shaped" hyaline cartilage rings (dorsally connected by smooth muscle)

Front 21

Which respiratory structures have "O-shaped" rings of hyaline cartilage?

Back 21

Bronchi

Front 22

Which structures are involved in respiratory Ventilation?

Back 22

diaphragm, intercostal & abdominal muscles

Front 23

Which respiratory function is responsible for conveying air to the alveoli while warming, moistening, and cleaning of mucus and debris along the way?

Back 23

Conduction

Front 24

At which point does the trachea divide into two primary bronchi (which then enter the lung)?

Back 24

at the Hilum

Front 25

What will the primary bronchi divide into?

Back 25

smaller secondary (or lobar) bronchi

(three on the right and two on the left)

Front 26

What type of cartilage do the secondary bronchi have?

Back 26

irregular plates of hyaline cartilage (appear oval-shaped vs. "O" or "C" shaped)

also have abundant elastic fibers

Front 27

In bronchioles, cartilage is replaced by ____________.

Back 27

smooth muscle

Front 28

What is the transition of epithelium cells as you move from the conducting portion to the respiratory portion of the respiratory tract?

Back 28

pseudostratified columnar ciliated with goblet cells -
simple ciliated cuboidal or columnar -
simple squamous

Front 29

What are the distinguishing features of the bronchioles?

Back 29

they have no cartilage and no glands (do have smooth muscle)

may have pseudostratified ciliated epithelium or simple ciliary columnar/cuboidal

Front 30

What happens to the height of the epithelium as the branching of the respiratory tract continues to smaller airways?

Back 30

It gets lower

Front 31

In the terminal bronchioles, ____ cells are located between ciliated cells.

Back 31

Clara cells

secretory (potentially for lubricant, surfactant, immune resistance)

Front 32

What are the terminal bronchioles?

Back 32

last of the "conducting airway" before gas-exchange region

contain simple cuboidal cells, some ciliated (no cartilage and few Goblet cells)

Front 33

What is the diameter of the terminal bronchioles?

Back 33

<1mm in diameter

Front 34

How are the terminal bronchioles innervated?

Back 34

via the autonomic nervous system (smooth muscle)

Front 35

Which section of the respiratory tract is affected during an asthma attack?

Back 35

terminal bronchioles (smooth muscle) - parasympathetic nervous system promotes constriction while asthma drugs initiate dilation through sympathetic innervation

Front 36

Bronchioles are associated with a pulmonary _______.

Back 36

artery

(Note: vessels that are not in close proximity to bronchi or bronchioles are the pulmonary veins – they are found in the interalveolar septa.)

Front 37

Respiratory bronchioles can be considered as short tubes that serve as a ________ between the conducting and the respiratory portions of the respiratory tract.

Back 37

transition

Front 38

What type of epithelium is at the bronchiole/alveolar duct junction?

Back 38

simple squamous
(transition from simple cuboidal)

Front 39

What are the walls of the respiratory bronchioles "interrupted" by?

Back 39

alveolar pouches
(opening into gas-exchange regions)

Front 40

What does the functional unit of the lung include?

Back 40

alveolar ducts, the atria, alveolar sacs, and alveoli

Front 41

What are the sac-like structures that are the final parts of the bronchial tree?

Back 41

alveoli

Front 42

What surrounds each alveolar "sac"?

Back 42

a network of capillaries

Front 43

About how many alveoli does the human lung have?

Back 43

~300 million alveoli

Front 44

Adjacent alveoli are connected by small pores (Pores of Kohn) that help to _____ .

Back 44

equalize air pressure between them

Front 45

What are the alveolar ducts?

Back 45

short tubes (of elastic and collagen fibers) that open into numerous alveoli

separated by smooth muscle "knobs"

Front 46

What are the atria?

Back 46

the last portion of the alveolar duct

opens into the Atrium

Front 47

What are the three main types of cells in the alveolar wall?

Back 47

1) endothelial cells of blood capillaries (these are continuous and nonfenestrated),
2) squamous Type I epithelial cells,
3) secretory (Type II) alveolar cells.

Front 48

A common ______ is found between alveolar cells and endothelial cells.

Back 48

basal lamina
(a basement membrane)

Front 49

What are the characteristics of Alveolar Type I pneumocytes?

Back 49

simple squamous epithelial cells that make up ~97% of the lining.

attached by desmosomes and zonula occludens

Front 50

What is another name for the "dust cells" that remove debris from the lumen and interstitium in the gas exchange region?

Back 50

Alveolar macrophages

Front 51

What is the purpose of surfactant?

Back 51

Surfactant coats alveolar linings and lowers the surface tension to zero, preventing alveolar collapse.

Front 52

What is the name of the structure found in Type II pneumocytes that contain surfactant?

Back 52

osmiophilic lamellar bodies

Front 53

Why might premature babies suffer from respiratory distress syndrome?

Back 53

They lack surfactant

Front 54

What are the two layers of surfactant?

Back 54

- Hypophase (the proteinaceous aqueous basal layer)
- Phospholipid phase (dipalmitoyl lecithin)

Front 55

What is the disease that results from destruction of lung tissue around alveoli that makes the air sacs unable to hold their functional shape upon exhalation?

Back 55

Emphysema

Front 56

What is the shape of the Type II pneumocytes?

Back 56

simple cuboidal

Front 57

Where are Type II pneumocytes found?

Back 57

At the junctions (septae) between alveolar walls.

Front 58

What do the osmiophilic lamellar bodies contain?

Back 58

phospholipids, GAGs, phosphatidyl choline, and sphingomyelin

Front 59

What can happen during pulmonary hypertension where the ratio of alveoli: capillaries is compromised?

Back 59

ventilation perfusion ratio compromised

perfusion - blood vessel branching alongside the airways (alveolar space)

Front 60

Explain the layers of the air-blood interface (how a molecule of oxygen gets to the blood).

Back 60

alvelolar lumen - cytoplasm of Type I cell - basal lamina of Type I cell - basal lamina of capillary endothelial cell - cytoplasm of capillary endo cell - blood

Front 61

If the lining of the lungs is damaged which type of cells have the ability to re-generate and re-differentiate?

Back 61

Type II alveolar cells can re-generate to make more of themselves and de-differentiate and re-differentiate to become squamous lining cells.