Introduction to the lungs (28)

Question 1

How does the structure of the left and right lung differ?

Answer 1

• right lung has 3 lobes: superior lobe, middle lobe and inferior lobe
• left lung has 2: superior lobe and inferior lobe

Question 2

What is the name of the type of branching in the airways?

Answer 2

dichotomous

Question 3

What is the carina?

Answer 3

the point at which the trachea splits into the 2 main bronchi (left- more vertical, and right)

Question 4

When do the bronchioles occur?

Answer 4

after the first 3 generations of bronchi

• -> airways narrow
• -> no cartilage
• -> conducting bronchioles, terminal bronchioles, respiratory bronchioles (–> alveolar ducts)

Question 5

What are the basic functions of the respiratory airways?

Answer 5

conduit/pipes to
- conduct oxygen to the alveoli
and - conduct CO2 out of the lung
^gas exchange

Question 6

What is the structure of the alveolar wall?

Answer 6

• no cilia or smooth muscle

- pneumocytes: type 1 and type 2

Question 7

What is the structure of the alveolar wall?

Answer 7

• no cilia or smooth muscle
• pneumocytes: type 1 (fewer, but cover most of wall) and type 2
• alveolar macrophages (can engulf pathogens and move up to mucociliary escalator)

Question 8

What glues together the pneumocytes and capillaries at the alveoli?

Answer 8

basement membrane

Question 9

What is the pharynx?

Answer 9

a common passageway for food, liquids, and air

Question 10

What are the nasal conchae?

Answer 10

• highly vascular

- contribute to warming and humidification of intranasally inhaled air

Question 11

What is the purpose of the nasal hairs?

Answer 11

to trap large particles of dust and pollen, as well as bacteria

Question 12

What are the 3 regions of the pharynx?

Answer 12

• nasopharynx
• oropharynx
• laryngopharynx

Question 13

What is the organisation inside the airway walls?

Answer 13

• layer of mucus
• cilia
• columnar ciliated epithelium w/ goblet cells (fewer)
• basement membrane
• submucosal gland
• smooth muscle (when it contracts, it squeezes mucosal glands)

Question 14

What are the lining cells in the airways?

Answer 14

• ciliated
• intermediate
• brush
• basal

Question 15

What are the contractile cells in the airways?

Answer 15

• smooth muscle (airway, vasculature)

Question 16

What are the secretory cells in the airways?

Answer 16

• goblet (epithelium)
• mucous
• serous (glands)

Question 17

What are the connective tissue cells in the airways?

Answer 17

• fibroblast

- interstitial cell (elastin, collagen, cartilage)

Question 18

What are the neuroendocrine cells in the airways?

Answer 18

• nerves
• ganglia
• neuroendocrine cells
• neuroepithelial bodies

Question 19

What are the vascular cells in the airways?

Answer 19

• endothelial
• pericyte
• plasma cell (+ smooth muscle)

Question 20

What are the immune cells in the airways?

Answer 20

• mast cell
• dendritic cell
• lymphocyte
• eosinophil
• macrophage
• neutrophil

Question 21

What is the arrangement of the submucosal glands in the airways?

Answer 21

• mucus cells (in the submucosal gland) secrete mucus
• serous cells in the gland secrete anti-bacterial enzymes
• water and salts also secreted

Question 22

What are the functions of the airway epithelium?

Answer 22

• secretion of the components of mucus: mucins, water and electrolytes
• movement of mucus by cilia (mucociliary clearance)
• physical barrier
• production of regulatory and inflammatory mediators: NO, CO, arachidonic acid metabolites, chemokines and cytokines, proteases

Question 23

What is the 9+2 relationship in individual cilia?

Answer 23

• 9 pairs of microtubules on outside, bound together

- 2 pairs of microtubules in middle, not bound together

Question 24

How do cilia beat?

Answer 24

in a metachronal rhythm
- hydrolysis of ATP causes thin dynein arms to take steps towards the minus end of the neighbouring doublet, generating a sliding force that can slide doublets apart if crosslinks are removed

Question 25

What are the 3 main functions of airway smooth muscle?

Answer 25

- structure: inflammation stimulates proliferation--> hypertrophy and hyperplasia - tone: contraction/relaxation - secretion: inflammatory mediators, cytokines, chemokines

Question 26

What do smooth muscle cells secrete in response to cytokines?

Answer 26

- NOS--> produce NO - COS--> produce prostaglandins ^^inflammatory mediators - immune cell recruiters: cytokines, chemokines, adhesion molecules

Question 27

What blood vessels return to the heart from tracheal circulation?

Answer 27

systemic veins

Question 28

What blood vessels return to the heart from bronchial circulation?

Answer 28

bronchial and pulmonary veins

Question 29

What are the functions of the tracheo-bronchial circulation?

Answer 29

- good gas exchange between airway tissues and the blood (N.B. not pulmonary circulation ) - warming of inspired air - humidification of inspired air - clears inflammatory mediators - clears inhaled drugs - supplies airway tissue+ lumen w/ inflammatory cells and proteinaceous plasma

Question 30

What is the effect of adrenaline on airways?

Answer 30

relaxation bc in response to stress, need to breathe more deeply

Question 31

What is the effect of NO on airway smooth muscle?

Answer 31

relaxation

Question 32

What is the effect of acetylcholine on the airway?

Answer 32

relaxation/dilation

Question 33

What respiratory diseases are associated with loss of airway control?

Answer 33

asthma, COPD, CF

Question 34

What is asthma?

Answer 34

a clinical syndrome characterised by increased airway 'responsiveness' to a variety of stimuli--> airway obstruction- varies over short periods of time, reversible spontaneously or w/ drugs - dyspnoea (shortness of breath), wheezing and cough (mild to severe) - airway inflammation--> airway remodelling

Question 35

What is airway remodelling?

Answer 35

- structural changes due to/alongside chronic airway inflammation - alterations in the airway epithelium, lamina propria, and submucosa--> leading to thickening of airway wall

Question 36

How does an asthmatic bronchial layer differ from a normal one?

Answer 36

- inc. mucus and goblet cells - inc. eosinophils in mucus and tissue - thicker basement membrane - inc. mast cells in lamina propria--> more histamine - inc. neutrophils--> inflammation - smooth muscle cell hypertrophy

Question 37

What are the 3 main characteristics of asthma?

Answer 37

- airflow obstruction - bronchohyperresponsiveness - inflammation

Question 38

What are symptoms of asthma?

Answer 38

- shortness of breath - wheeze - chest tightness - dry, irritating cough

Question 39

What is the role of T-helper 2 cells in asthma?

Answer 39

promote humoral immunity--> IgE antibody production--> inc. mast cell activity