Respiratory tract

Question 1

What consists of the conducting zone?

Answer 1

Nasal passages, pharynx, larynx, trachea, bronchi and most of the bronchioles as far as the terminal bronchioles.

Question 2

What is the purpose of the conducting zone?

Answer 2

Warm, moisten, filter and deliver inspired air to the gas-exchanging or respiratory zone of the lungs

Question 3

What consists of the respiratory zone?

Answer 3

Respiratory bronchioles, alveolar ducts and definitive alveoli

Question 4

What is the purpose of the respiratory zone?

Answer 4

Exchange of gases between the air and blood

Question 5

How is the conducting portion of airways adapted for removal and delivery of air?

Answer 5

Opening of airways maintained by bone, cartilage, elastic and collagen fibres and smooth muscle (provides flexibility)

Lining of epithelial cells with glands, secretory and protective functions

Question 6

How is respiratory portion of airways adapted to gas exchange?

Answer 6

Thin walled pouches and cellular membranes with rich capillary network

Question 7

What is the conducting portion lined with?

Answer 7

Mucous membrane

Question 8

What does mucous membrane consist of?

Answer 8

Respiratory epithelium (mainly pseudocolumnar epithelium) and lamina propria (connective tissue) below it

Question 9

What does mucous membrane do?

Answer 9

Warm and humidify inspired air

Provide sense of smell via olfactory epithelium

Cover and protects (ciliary clearing mechanism and immunological defence)

Question 10

What is found beneath the mucous membrane?

Answer 10

Submucosa and adventitia

Question 11

What seperates submucosa and mucous layer?

Answer 11

Elastic layer

Question 12

What sort of epithelium makes up respiratory airways?

Answer 12

Ciliated pseudostratified columnar epithelium

Question 13

What do all 5 cell types of respiratory airways do?

Answer 13

Reach basement membrane

Question 14

What are the five types of cells in respiratory epithelium?

Answer 14

Ciliated columnar cells 
Mucous goblet cells 
Small granule (K cells)
Basal cells 
Brush cells

Question 15

What do ciliated columnar cells do?

Answer 15

Cilia on apical surface beat up and out to shift mucous out of respiratory tract

Question 16

What facilitates cilia beating in ciliated columnar cells?

Answer 16

Beneath cilia are small mitochondria golgi, RER

Question 17

What makes up the structure of cilia?

Answer 17

Cytoskeleton, 9x2+2 microtubule core (axoneme) dyenin arms supply motor movements

Question 18

What is the name of action that moves mucus towards pharynx from respiratory tract?

Answer 18

Mucocilary escalator

Question 19

What do goblet cells make?

Answer 19

Mucus

Question 20

What does mucus do?

Answer 20

Trap particulate matter and pollutants lining respiratory tract as far as bronchi

Question 21

What defines viscosity of mucus?

Answer 21

Contributions from goblet glands (cellular glands) and seromucus glands

Question 22

What are basal cells?

Answer 22

Stem cells of respiratory epithelium (diff into other cell types)

Question 23

What are brush cells?

Answer 23

Narrow columnar cells, have afferent nerve endings so are sensory receptors

Question 24

What are small granule cells aka K cells?

Answer 24

Neuroendocrine cells with small granules containing neuroendocrine hormones

Question 25

What is the lamina propria?

Answer 25

Loose connective tissue supporting the respiratory epithelia

Question 26

What does lamina propria contain (5 things)?

Answer 26

``` Mucous gland Serous gland MALT Rich blood supply Elastic fibres ```

Question 27

What do serous glands do?

Answer 27

Watery secretions that dilute mucus and humidify inspired air. Also contain lysozyme and protease inhibitors for defence against bacteria

Question 28

What is MALT? Give an example.

Answer 28

Mucosa associarted lymphoid tissue e.g BALT in bronchi (diffuse aggregates of lymphoid tissue providing specific immunity involving lymphocyte, neutrophils etc.)

Question 29

What does air blood barrier consist of?

Answer 29

Fused basal laminae of epithelial layer and capillary endothelial cells Capillary endothelial cells and single layered type 1 alveolar epithelial cells

Question 30

What sort of alveoli cells form the ABB?

Answer 30

Type 1, squamous alveolar cells

Question 31

What seperates adjacent alveoli?

Answer 31

Interalveolar septum

Question 32

What does interalveolar septum consist of?

Answer 32

2 squamous epithelial layers from 2 alvoeli sandwiching connective tissue matrix and dense capillary network, many lymphoid cells and macrophages

Question 33

What are interalveolar pores of Kohn, why are the useful?

Answer 33

Openings in interalveolar septum allowing communicaiton between alveoli and movement of gases betweeen alveoli in local brochiolar obstruction

Question 34

What structurally supports the alveoli?

Answer 34

Elastic fibres

Question 35

What are type 1 pneumocytes/alvoeli cells for?

Answer 35

Make up 90% alveolar epithelium Absorb surfactant promoting its turnover Form occluding junctions with each other preventing seepage of extracellular fluid into alveolar lumen

Question 36

Describe structure of type 1 alveoli cells (junctions, width)

Answer 36

Squamous epithelial cells Wide cells Form occluding junctions with each other

Question 37

From what cells can type 1 cells develop?

Answer 37

Type 2 cells

Question 38

Where are type 2 cells positioned?

Answer 38

Dispersed among the type 1 cells

Question 39

Describe the structure of type 2 cells (shape, junctions)

Answer 39

Cuboidal | Form occluding junctions with type 1 cells

Question 40

How are type 2 pneumocytes a stem cell population?

Answer 40

Can diff into type 1 or 2 cells if alveolar epithelium damaged

Question 41

What do type 2 cells do?

Answer 41

Secrete surfactant

Question 42

What does surfactant do?

Answer 42

Maintains alveolar stability and lower alveolar surface tension (prevent collapse of alveoli in exhalation) Minimise work required to inflate lungs

Question 43

What are alveolar macrophages known as? What are they derived from?

Answer 43

Dust cells | Derived from monocytes in the blood

Question 44

What is a serous membrane?

Answer 44

Thin, double layered membrane that secretes serous fluid

Question 45

What are the 2 layers of serous membrane?

Answer 45

Inner membrane covers organs, visceral membrane Second layer lines body wall, parietal layer

Question 46

Where are serous membrane found?

Answer 46

Lining pericardial cavity Pleura Peritoneum (surrounding some abdominal organs)

Question 47

Why is serous fluid beneficial?

Answer 47

Reduces friction

Question 48

Difference between where mucous and serous membranes found?

Answer 48

Serous: line internal cavities Mucous: line cavities that connect to exterior

Question 49

Describe development of the alveolar epithelial surface

Answer 49

Endodermally derived epithelium (from respiratory diverticulum) which differentiates into respiratory epithelium that lines the airways and specialized epithelium that lines the alveoli.

Question 50

What layer of the embryo are lungs derived from?

Answer 50

Endoderm

Question 51

When are the primitive alveoli formed?

Answer 51

Week 36

Question 52

When do alveoli mature?

Answer 52

After birth

Question 53

What is the function of the nasal cavity and paranasal sinus surface?

Answer 53

Warming and moistening air

Question 54

What three types of epithelium make up the nasopharynx?

Answer 54

Respiratory epithelium (pseudostratified columnar) Stratified squamous epithelium Olfactory epithelium

Question 55

What three cell types make up the olfactory epithelium?

Answer 55

Olfactory receptor neurons, primary sensory neurons for smell perception, bipolar neurons whose apical end forms olfactory vesicle, cilia have odor receptors. Sustentacular cells (supporting cells). Basal cells, small stem cells at base replace other cell types.

Question 56

What are vibrissae and what is their role?

Answer 56

Nasal hairs that filter out particulate matter (defence)

Question 57

Are there goblet cells in bronchioles?

Answer 57

No

Question 58

What do goblet cells get replaced by in the bronchioles?

Answer 58

Clara (club) cells

Question 59

What is the role of Clara cells?

Answer 59

Domed apical surface. Function of the Club cells is to secrete proteins that reduce the stickiness of the mucus produced by larger diameter airways and to produce lysozyme and immunoglobulins.

Question 60

What are acini?

Answer 60

Includes all components capable of facilitating gas exchange. It consists of respiratory bronchioles alveolar ducts and alveoli.

Question 61

Between pneumocytes and pulmonary endothelial cells ...

Answer 61

The basement membranes are fused

Question 62

Which cell types other than pneumocytes are commonly found in the walls of alveoli?

Answer 62

Macrophages