Module 1A: Histology Of Respiratory System

Question 1

What is the type of epithelium in the respiratory epithelium?

Answer 1

Pseudostratified columnar ciliated epithelium with numerous goblet cells

Question 2

What is the function of respiratory epithelium?

Answer 2

Function:
a) To warm the inspired air- it has blood vessels
b) To trap small particles- it secretes mucus
c) To humidify the inspired air- it secretes serum

Question 3

Why is the lamina propria important to the respiratory epithelium?

Answer 3

Lamina propria is rich in blood vessels and serous and mucous glands

Question 4

Where is the olfactory epithelium located?

Answer 4

• Roof of nasal cavity
• Upper part of nasal septum
• The superior turbinate

Question 5

What is the olfactory epithelium made of?

Answer 5

“pseudostratified” – made of olfactory cells, supporting cells and basal cells

Question 6

What do olfactory cells/ receptor cells do?
Supporting cells?
Basal cells?

Answer 6

• Olfactory cells/ receptor cell: Bipolar nerve cells with nonmotile olfactory cilia that function as odor receptors

• Supporting cells: Have many microvilli

• Basal cells: Located deeper in the epithelium, supported by a basal lamina, function as the stem cells for other cell types

Question 7

What are the Bowman glands? Where is it located?

Answer 7

Bowman glands : Serous glands present in the olfactory epithelium

Olfactory Epithelium- Bowman’s glands
• Bowman’s glands (serous gland) that secrete thin watery secretion (serum) to the
surface via narrow ducts
• Dissolves substances of odor and flushes the epithelium, refreshes the receptors
for a new odor

Question 8

What do goblet cells do?

Answer 8

secrete mucus to protect the mucous membranes

Serum and mucus secretions contain mucins, immunoglobulins, lysozymes, and antiproteases that disable bacterial functions.

Question 9

How are olfactory cilia arranged?

Answer 9

they have 9+2 arrangement of microtubules.
But they are non-motile.
There are 12 or more olfactory cilia per neuron.
They lack the dynein arms necessary for movement and are thus rendered immotile.

Question 10

What do the microvilli do in the olfactory epithelium?

Answer 10

The microvilli of the supporting cells provide increased surface area of the odor reception by the cilia. Odorants have more area to land on given by the microvilli and the cilia basically create a mesh with these microvilli- thus they come in contact with odorants.

Question 11

What do Bowman glands/olfactory glands do?

Answer 11

secret thin watery secretion (serum) — to surface via narrow ducts — to dissolve substances of odor sense & to flush and refresh the receptors for new odor.

Question 12

What is the difference between conducting zone vs respiratory zone?

Answer 12

Conducting zone
• The airways (nasal passages, pharynx, larynx, trachea, bronchii and terminal bronchioles
• Deliver air to the respiratory
zone

Respiratory zone
• Respiratory bronchioles
• Alveolar ducts
• Alveolar sacs
• Alveoli
• Carry out O2 – CO 2 exchange

Question 13

What is the function of the conducting zone function? What are the alternate functions?

Answer 13

Function: to warm, moisten & filter the inhaled air before it enters the respiratory zone

a) Olfactory mucosa: smell reception
b) Larynx: to generate sound (the vocal cords)

Question 14

What are the 3 turbinates arise from the lateral walls?

Answer 14

Three turbinates arise from the lateral walls
1) Superior turbinate: covered by olfactory mucosa
2) Middle turbinate: covered with respiratory mucosa
3) Inferior turbinate: covered with respiratory mucosa

Question 15

What is the nasopharynx lined with? What does the laminate propria contain? What is the submucosa of nasopharynx has large masses of lymphoid tissue called?

Answer 15

• Lined by respiratory epithelium
• Lamina propria contains mucus and serous glands
• Submucosa of nasopharynx has large masses of lymphoid tissue, called
the nasopharyngeal tonsil

Question 16

What is laryngitis?

Answer 16

• Typically, due to viral infection and is usually accompanied by edema or swelling of the organ’s lamina propria.
• This changes the shape of the vocal folds or other parts of the larynx, producing hoarseness or complete loss of voice .

Question 17

What are the features of the trachea?

Answer 17

• Incomplete rings of hyaline cartilage
• Posterior ends of cartilage are joined by Trachealis muscle (smooth muscle)
• Wall: a series of c-shape hyaline cartilage + trachealis muscle
• Fibro-elastic tissue fills in between consecutive cartilage rings
• Mucosa is made of respiratory epithelium+ lamina propria
• Submucosa has a lot of seromucus glands

Question 18

What are some of the brochopulmonary segments?

Answer 18

Pulmonary artery (from heart) - always accompanies the branching pattern of the bronchial tree

Pulmonary veins - lie in the septa (between segments) and drain blood towards heart

Lymphatic vessels also found between the segments

Question 19

Where are there less goblet cells?

Answer 19

Primary (main) bronchus

Question 20

How does cigarette smoke effect cilia?

Answer 20

Cilia are very fragile and can be destroyed by cigarette smoke, fumes or bacterial and viral infections

Question 21

Where are the Clara cells found?

Answer 21

Terminal bronchiole

Question 22

What are the structures in terminal bronchioles?

Answer 22

• Columnar epithelium with fewer goblet cells
• Some Clara cells found in the epithelium
• Cartilage and submucosal glands are absent

Question 23

What are Clara cells?

Answer 23

• Non-ciliated cells, with dome-shaped apical surface - Secrete a lipoprotein (CC16)- similar to surfactant
• Also act as stem cells for bronchial epithelium

Question 24

What is the blood supply of the terminal bronchioles?

Answer 24

Branch of the pulmonary artery

Question 25

What is the last segment of the conducting zone?

Answer 25

Terminal bronchioles

Question 26

What is the first segment of the respiratory zone?

Answer 26

Respiratory bronchioles

Question 27

What are the respiratory bronchioles made up of?

Answer 27

Cuboidal epithelium- no goblet cells, more clara cells

Question 28

What is bronchiolitis?

Answer 28

• Air passages are affected most often, especially in young children, by the measles virus or adenovirus, both of which can cause bronchiolitis. • Mucus clogs the bronchioles • If persistent, the inflammation produced by either infection can lead to obliterative bronchiolitis, complete or partial closure of the airway lumen due to fibrosis in the wall

Question 29

What is the end portion of the respiratory tree?

Answer 29

Alveolar ducts terminate as alveolar sacs that opens into several alveoli

Question 30

What is the surface epithelium of alveolar wall?

Answer 30

Pneumocyte type I (P1) • 95% of surface area • Simple squamous • Gaseous exchange • Amitotic Pneumocyte type II (P2) • 5% of surface area • Rounded cells • Produce surfactant- have granular cytoplasm • Can differentiate in to P1 and P2 Supporting tissue- Collagen, elastic fibers, fibroblasts Extensive capillary plexus- walls made of endothelial cells Capillary: • Receives blood from branches of pulmonary artery • After gas exchange - deliver oxygenated blood via pulmonary vein - to heart

Question 31

What is emphysema?

Answer 31

• Chronic lung disease is most commonly caused by cigarette smoking • Emphysema is characterized by the permanent destruction of alveolar structures, enlargement of the alveolar airspaces distal to the terminal bronchioles, and loss of elasticity of the lung tissue without obvious fibrosis.

Question 32

What is the Blood-Air barrier?

Answer 32

Basement membranes of the Endothelial cells of the capillaries and the Pneumocyte type I fuse