Histology of Resp. System

Question 1

what are the three regions of the nasal cavity?

Answer 1

nasal vesitbule (dilated space inside nostrils)

resp. region (2/3, lined with resp. mucosa)

olfactory region (apex of each cavity - olfactory mucosa)

Question 2

what type of cells line the nasal cavity respiratory system - respiratory mucosa?
what are the 3 different types?^

what is role? (2)

Answer 2

respiratory mucosa:
- ciliated, pseudostratified columnar epithelium
a) goblet cells - tall columnar cells producing mucous
b) brush cells - bear short microvilli
c) basal cells - stem cells

role:
warms, moistens and filters the inspired air

Question 3

where do you find the ciliated pseudostratified columnar resp. epithelium?

Answer 3

covers most ofthe parts of the conducting system!

Question 4

Answer 4

Question 5

what lies below the ciliated pseudostratified columnar resp. epithelium of nasal cavity in resp system?

Answer 5

below pseudostratified columnar resp. epithelium = lamina propria (thin layer of connective tissue that forms part of the moist linings known as mucous membranes or mucosa)

in the lamina propria:
seromucous glands - drain to surface.
CT
and blood vessels

Question 6

explain structure of olfactory epithelium

Answer 6

• still ciliated pseudostratified columnar resp. epithelium - but thicker.
• *- NO GOBLET CELLs !!
• olfactory cells:have sense receptor cilia on surface. connect toolfactory nerve
• olfactory (Bowmans) glands**: secrete serous secretion that serves as a trap and solvent for odiferous substances

Question 7

how does respiratory and olfactory epithelium differ? / how can you tell the difference? (2)

Answer 7

olfactory epithelium is thicker (but still not stratified)!!
AND
nerve fibres in olfactory lamina propria

Question 8

Answer 8

Question 9

describe the histology of the pharynx (nasopharnx (2) and the oropharnynx and hypopharnxy (1))

what is found in lamina propria? (2)

Answer 9

- nasopharynx: ciliated resp epithilium & stratified squamous epithelium

- oropharynx & hypopharynx: non-keritinised stratified squamous epithelium

- laminia propria: connective tissue with mucous gland & elastic layer

Question 10

what are the true vocal fold / cords histology like? what is the underlying skeltal muscles called?

Answer 10

vocal cords:

• lined with both
  a) non-keratinised stratified squamous epithelium
  b) ciliated columnar epithlium cells
• underlying layer: vocalis muscles

Question 11

describe the histology of the ventricular folds / false vocal cords

• *- what are they covered with?**
• function?
• underyling CT has what?

Answer 11

• covered with: respiratory mucosa
• function: sound resonance
• underyling CT has: mucous glands

Question 12

what are the blue and black arrows pointing to here in larynx ?

Answer 12

1 = vocalis muscle

2 = mucous glands

3 = ventricular folds

Question 13

label 1-5 of larynx

Answer 13

1 = vocalis muscle

2 = vocal fold

3 = ventricles

4 = ventricular fold

5 = mucous glands

Question 14

what are the 4 layers of the trachea?

Answer 14

- mucosa: ciliated pseudo. columnar epithelium and elastic rich lamina propria

• submucosa: serous and mucous glands, BV and nerve fibres

- cartilaginous layer: c shaped hyaline cartilage (!). joined posteriorly by bands of SM called trachealis muscle

- adventitia- CT that binds trachea

Question 15

label 1-5 of trachea

Answer 15

1. Endothelium of trachea
2. Seromucous glands
3. Lamina propria and submucosa
4. Hyaline cartilage

5 adventita

Question 16

Answer 16

Question 17

label 1-3

Answer 17

C- Hyaline cartilage. This can be seen as a C-shaped ring (stained blue) which support the tracheal mucosa and prevent its collapse during inspiration

T- Trachealis muscle / Smooth muscle. These bands of smooth muscle join the free ends of the C-shaped hyaline cartilage ring posteriorly. Contraction of the trachealis muscle reduces tracheal diameter and thereby assists in raising intrathoracic pressure during coughing.

LM – Longitudinal muscle. A few strands of longitudinal muscle can be seen behind the trachealis muscle

Question 18

tracheal epithelium:

consists of which cells? (5)

Answer 18

• *- ciliated cels
• mucous (goblet cells)**
• brush cells (have blunt, squat microvill)
• small granule cells (secrete various hormones)
• *- basal cells**

Question 19

how do you tell the histological difference between trachea and bronchi?

Answer 19

• *bronchi =** cartilage chips
• *trachea =** cartialge c ring (picture shows this - c)

Question 20

5 differences between structure of trachea and bronchi?

Answer 20

1. Respiratory epithelium is not as tall in the bronchi, and contains fewer goblet cells.
2. The lamina propria has more elastic tissue than the trachea
3. A muscularis mucosae begins to take shape between the lamina propria and submucosa
4. There are fewer submucosal, seromucous glands
5. Cartilage is found in plates rather than rings

Question 21

explain structure of bronchi - 5 layers ?

Answer 21

• mucosa (resp. epithelium)
• muscularis - SMC
• submucosa - glands, CT
• cartilage layer (chips)
• advenitia

Question 22

diffference between bronchi and bronchioles?

Answer 22

bronchi = **cartilage present**
bronchiole = **no cartilage**

Question 23

what do bronchioles have instead of cartilage?

what is the epithelial layer of bronchioles like?

are there goblet cells?

Answer 23

cartilage = NO. instead = thick layer of smooth muscle cell & folded mucosa

epithelial layer = simple ciliated columnar / cuboidal epitheliam

NO GOBLET CELLS

Question 24

what are goblet cells replaced by in bronchioles?

what is the function of ^?

Answer 24

goblet cell = NO. instead = clara cells

function:

• watery surface. prevents luminal adhesian if wall of airway collapses
• *- secretory protein C16 - associated with pathologies like COPD and asthma
• detoxyifying compound, cytochrome p450 - regenerates epithelium of small airways when damaged**

Question 25

what are alveolar ducts ? what are alveolar sacs? what are alvelolar cells aka?

Answer 25

* *alveolar ducts:** elongated airways with almost no walls of alveoli * *alveolar sacs:** spaces surrounded by clusters of alveoli **alveolar cells aka:** **_pneumocytes_**

Question 26

**what are the two types of pneumocytes? explain the difference in strucutre which is the majority?** which divide? what does one of them make?

Answer 26

* *pneumocytes I:** - flat sqaumous cells - 95 % of surface of alveoli - do not divide * *pneumocytes II:** - cuboidal cells - 5% - synthesize surfactant - stem cell like - replace type I after injury the epithelium is a mix of these cells

Question 27

how do you tell between type I and II avlevolar cells? what else do you see around alveolar?

Answer 27

pneumocytes is that **type 1 pneumocytes are thin** and **flattened** alveolar cells responsible for the gas exchange between alveoli and capillaries, **type 2 pneumocytes** are **cuboidal alveolar cells** that are responsible for the secretion of pulmonary surfactants that reduce surface tension in the alveoli. also get **pulmonary macrophages in the alveoli BUT not within the walls**

Question 28

what are the 4 layers that exist between the bllod and inspired air in the blood-air barrier?

Answer 28

**capillary endothelium fused basal lamina alveolar epithelium (type 1 pnemocyte\_ surfactant**

Question 29

to which layers in resp. aiways do we get: - goblet cells - ciliated cells, - glands - hyaline cart - smooth muscle - elastic fibres

Answer 29

Question 30

which part of resp system is this?

Answer 30

bronchiole (no cart, thick smooth muscle and folded of the mucosa)

Question 31

fill in the table xox

Answer 31

Question 32

what is pleura histology like?

Answer 32

Question 33

label the alveoli :)

Answer 33

## Footnote **P1- Type 1 pneumocyte, P2- Type 2 pneumocyte, RBC – Red blood cells, C – capaillary, E – endothelial cell**

Question 34

label this bronchus slide

Answer 34

**_1 : Smooth muscle._** The lamina propria of the segmental bronchi are completely encircled by smooth muscle, which is disposed in a spiral manner. This arrangement permits contraction of the bronchi in both length and diameter during expiration. **_2= Small aggregates of lymphocytes (2)_** which are part of the MALT (mucosa-associated lymphoid tissue) are seen in the adventitia. **_3- Seromucous glands_**. These are sparser in segmental bronchi submucosa. These glands are rarely found in the smaller airways, as you descend down the airway the number decrease gradually. **4- Cartilage framework.** The cartilage here is reduced to a few irregular plates. Cartilage does not usually extend beyond segmental bronchi. **5- Submucosa.** Note that the submucosa merges with the surrounding adventitia.