Drive - defense (barrier and immunity)

Question 1

What is the purpose of respiratory epithelium?

Answer 1

To moisten and protect the airways.

Acts as a barrier to potential pathogens

Prevents infection by action of the mucociliary escalator

Question 2

What type of epithelium (specifically) is respiratory epithelium?

Answer 2

Ciliated pseudostratified columnar epithelium

Question 3

How do skin glands, salivary glands and lacrimal glands form part of the surface defence mechanism?

Answer 3

By secreting antimicrobial chemicals (e.g. antibodies, lysozymes, lactoferrin, mucus)

Question 4

What is meant by the escalator mechanism?

Answer 4

Where particulates (and pathogens) that are stuck to the respiratory epithelium are swept by ciliary action up into the pharynx where they are then swallowed.

Question 5

Physical barriers utilised by the lungs:

Answer 5

Coughing

Mucus

Question 6

Describe the mechanism of coughing:

Answer 6

Deep inhalation

Epiglottis close and vocal cords shut tightly (air is trapped in lungs)

Abdominal muscle contract forcefully pushing the diaphragm upwards

Pressure in the lungs rises to 100mmHg or more

Increased intrathoracic pressure causes narrowing of the trachea

Vocal chords and epiglottis suddenly open wide

Large pressure differential (and trachea narrowing) produces rapid flow rate through the trachea

Air is expelled

Question 7

What sort of velocities are reached (by the air) when coughing?

Answer 7

75 to 100 mph

Question 8

Why are alcoholics more susceptible to choking and pneumonia?

Answer 8

As alcohol inhibits the cough reflex

Question 9

What is the respiratory mucus secreted from?

Answer 9

The goblet cells of the airway surface epithelium and the submucosal glands

Question 10

What does airways mucus consist of?

Answer 10

A viscoelastic gel containing water, carbohydrate, proteins and lipids.

Question 11

What occurs after an epithelial injury (when the epithelium is damaged)?

Answer 11

Epithelium regenerates itself to form a full repair. Due to a level of function plasticity.

Question 12

What causes pulmonary diseases?

Answer 12

Most are characterised by epithelia and thus sufferers have impaired host defence.

Question 13

What causes the formation of mucus plugs and what do/can these cause?

Answer 13

As a result of excessive mucus production (due to bronchoconstriction. They can completely obstruct airways and are often fatal

Question 14

What type of specialist tissue resident macrophage is found in the lungs?

Answer 14

Alveolar macrophages

Question 15

What are the precursor cells to macrophages and where are they produced?

Answer 15

Monocytes - produced in the bone marrow.

Question 16

What are the functions of the alveolar macrophages?

Answer 16

Resident phagocyte of the lungs

Co-ordinates the inflammatory response

Induction and clearance of apoptotic cells.

Destroy bacteria in the alveoli swiftly without inducing a massive immune response

Question 17

If the macrophages cannot get rid of the pathogen what happens next?

Answer 17

Illicit a huge immune response - calling in neutrophils. This results in pneumonia.

Question 18

What do primary granules contain?

Answer 18

Myeloperoxidase, elastase, cathepsins and defensins.

Question 19

What do secondary granules contain?

Answer 19

Receptors, lysosome, collagenase.

Question 20

Describe the mechanism of action by neutrophils: (5)

Answer 20

Identify the threat - through receptors

Activation

Adhesion

Migration/chemotaxis

Phagocytosis + bacterial killing

Question 21

What occurs in necrosis?

Answer 21

Cells swell, lyse and reactive oxygen species and other enzymes are released.

Can cause damage to the surrounding tissue

Results in inflammation and phagocytosis of necrosed cell

Question 22

What occurs in apoptosis?

Answer 22

(More controlled than necrosis)

Cell is turned off and packaged

Phagocytosed by neutrophils

No damage to the surrounding tissue

Question 23

What type of antibody are made in an allergic reaction?

Answer 23

IgE

Question 24

Name 2 possible causes of a type 1 IgE reaction

Answer 24

Acute anaphylaxis and hayfever

Question 25

What type of immune reaction do pigeon fanciers lung sufferers have?

Answer 25

Type 3 - IgG