Histology and Pathology

Question 1

Name the functions of the respiratory system

Answer 1

• supplies oxygen to the blood for delivery to cells throughout the body
• removes carbon dioxide that has been accumulated in the blood from the tissues of the body
• phonation
• olfaction
• lungs function in blood pressure control via renin-angiotensin system

Question 2

Describe the lining of the nasal cavity

Answer 2

• the initial part of the nasal cavity, the vestibule, is lined by keratinised stratified squamous epithelium
• deeper into the nasal cavity, the keratin is lost and deeper still it changes again to respiratory epithelium

Question 3

What is respiratory epithelium?

Answer 3

Pseudostratified ciliated columnar epithelium with goblet cells

Question 4

What is underneath the respiratory epithelium?

Answer 4

The lamina propria

Question 5

What is the lamina propria?

Answer 5

A band of loose connective tissue containing seromucous glands and thin-walled venous sinuses which can quickly engorge with blood and block the nose

Question 6

What is the oropharynx lined with?

Answer 6

Non-keratinised stratified squamous epithelium

Question 7

Describe the lining of the epiglottis

Answer 7

• anterior surface is lined with squamous epithelium

- posterior surface transitions to respiratory epithelium

Question 8

Describe the lining of the larynx

Answer 8

The walls are made up of cartilage and muscles with respiratory epithelium lining its surfaces with the exception of the vocal cords and adjacent structures

Question 9

How many c shaped cartilages does the trachea have?

Answer 9

15 to 20

Question 10

What is the open side of the ‘c’ shaped cartilage composed of?

Answer 10

Fibroelastic tissue and smooth muscle (trachealis muscle)

Question 11

The rings of hyaline cartilage are replaced by what in the bronchi?

Answer 11

Irregularly shaped cartilage plates

Question 12

The smallest bronchioles that lack respiratory function as referred to as what?

Answer 12

Terminal bronchioles

Question 13

The smooth muscle of the bronchioles respond to what?

Answer 13

Parasympathetic innervation, histamine and other factors by contracting and constricting the diameter of the bronchiole

Question 14

What are terminal bronchioles lined with?

Answer 14

Cuboidal ciliated epithelium and contain non-ciliated club cells that project above the level of adjacent ciliated cells

Question 15

Name the functions of club cells

Answer 15

• stem cells
• detoxification
• immune modulation
• surfactant production

Question 16

What is responsible for the spongy nature of the lungs?

Answer 16

The alveoli

Question 17

Alveoli are lined with an epithelium which contain what?

Answer 17

Type 1 and type 2 alveolar cells (pneumocytes)

Question 18

Describe type 1 alveolar cells

Answer 18

• simple squamous epithelium that lines the alveolar surfaces covering 90% of the alveolar surface
• these cells provide a barrier of minimal thickness that is permeable to gases

Question 19

Describe type 2 alveolar cells

Answer 19

• polygonal in shape the free surface is covered by microvilli and the cytoplasm displays dense membrane bound lamellar bodies which contain surfactant

Question 20

How is surfactant released?

Answer 20

Through exocytosis.

Question 21

Define pneumonia

Answer 21

Infection involving the distal airspaces usually with inflammatory exudation, localised oedema. Fluid filled spaced lead to consolidation

Question 22

How can pneumonia be classified?

Answer 22

• by location eg. hospital acquired or community acquired
• by organism eg. mycoplasma, pneumococcal etc
• by morphology eg. lobar pneumonia, bronchopneumonia

Question 23

Describe lobar pneumonia

Answer 23

• confluent consolidation involving a complete lung lobe
• most often due to streptococcus pneumoniae
• can be seen with other organisms (klebsiella, legionella)

Question 24

Describe the pathology of pneumonia

Answer 24

• a classical acute inflammatory response; exudation of fibrin-rich fluid, neutrophil infiltration, macrophage infiltration leading to resolution
• immune system play a part, antibodies lead to opsonisation, phagocytosis of bacteria

Question 25

Name the complications of scarring

Answer 25

- organisation (fibrous scarring) - abscess - bronchiectasis - empyema

Question 26

Define bronchopneumonia

Answer 26

- infection starting in the airways and spreading to adjacent alveolar lung - most often seen in the context of pre-existing disease, doesn't develop as an epidemic

Question 27

Name the organisms associated with bronchopneumonia

Answer 27

- strep. peumoniae - haemophilus influenza - staphylococcus - anaerobes - coliforms

Question 28

Describe lung abscesses

Answer 28

- localised collection of pus, mass lesion - tumour like - chronic malaise and fever - context- aspiration

Question 29

Define bronchiectasis

Answer 29

- abnormal fixed dilation of the bronchi - usually due to fibrosis scarring following infection (pneumonia, TB, cystic fibrosis) - also seen with chronic obstruction - cystic fibrosis in children- repeated bronchopneumonia's leading to bronchiectasis

Question 30

Describe immunity and hypersensitivity in relation to TB

Answer 30

- T cell response to organism enhances macrophage ability to kill mycobacteria, this ability constitutes immunity - T cell response causes granulomatous inflammation., tissue necrosis and scarring, this is hypersensitivity (type 4) - commonly both processes occur together

Question 31

Why is the TB pathogen able to avoid phagocytosis?

Answer 31

Due to its waxy coat

Question 32

Describe the tissues changes that occur in TB

Answer 32

- primary; small focus (ghon focus) in periphery of mid zon of lung - large hilar nodes (granulomatous) - secondary; fibrosing and cavitating apical lesion

Question 33

Why does the TB pathogen reactivate?

Answer 33

- decreased T cell function; age, coincident disease (HIV), immuno-suppressive therapy (steroids, cancer chemotherapy) - reinfection at high dose or with more virulent organism

Question 34

Names some causes of interstitial lung disease

Answer 34

- environmental; minerals, drugs, radiations, post-ARDS, hypersensitivity - unknown (idiopathic); connective tissue diseases, idiopathic pulmonary fibrosis - diagnosis based on clinical features often with biopsy

Question 35

What is the late stage of interstitial lung disease characterised by?

Answer 35

Fibrosis

Question 36

Name some chronic interstitial disease

Answer 36

- idiopathic pulmonary fibrosis - sarcoidosis - hypersensitivity pneumonitis - pneumoconiosis - connective tissue diseases

Question 37

Describe idiopathic pulmonary fibrosis

Answer 37

- aka cryptogenic fibrosing alveolitis, usual interstitial pneumonia - progressive interstitial fibrosis of unknown cause - variable associated inflammation - finger clubbing `

Question 38

Describe the pathology of idiopathic pulmonary fibrosis

Answer 38

- subpleural and basal fibrosis, affects peripheral areas of the lung - inflammatory component variable - terminal lung structure replaced by dilated spaces surrounded by fibrous walls

Question 39

Describe hypersensitivity pneumonitis

Answer 39

- chronic inflammatory disease | - allergic origin

Question 40

Describe the causes of hypersensitivity pneumonitis

Answer 40

- thermophilic bacteria; farmers lung - avian proteins; bird fanciers lung - fungi; malt workers lung - precipitins (antibodies) often detectable in serum. Unusual cases come to biopsy

Question 41

Describe sarcoidosis

Answer 41

- multisystem granulomatous disorder of unknown cause (defined by histological means) - pulmonary involvement is common - most cases mild and self-limiting

Question 42

Name the other manifestations of sarcoidosis

Answer 42

- uveitis - erythema nodosum - lymphadenopathy - hypercalcaemia