Asthma

Question 1

What is FEV_1?

Answer 1

Forced Expiratory Volume in a second - used in the diagnosis of restrictive and obstructive respiratory diseases.
*This should be around 3/4 of the FVC (Forced vital capacity)

Question 2

What is PEFR?

Answer 2

Peak Expiratory Flow Rate - how much the patient can blow out in one breath.

*At the same time - explain how you would take a peak flow - clinical skills

Question 3

What is the definition of Asthma? (5)

Answer 3

intermittent attacks of bronchoconstriction due to a pathological change to the bronchioles that results from long standing inflammation.

1. Increased mass of smooth muscle (hyperplasia and hypertrophy)
2. accumulation of interstitial fluid (oedema)
3. increase in secretion of mucus
4. epithelial damage- exposes the nerve endings
5. sub-epithelial fibrosis.

Question 4

What happens to the airways in asthma (general)

Answer 4

Narrowing of the airways caused by inflammation and bronchoconstriction increases the airway resistance and decreases the FEV_1 and PEFR.

Question 5

What type of nerve fibres are exposed (due to epithelial damage) and contribute to bronchial hyper-responsiveness?

Answer 5

Sensory fibres - C fibres, irritant receptors

Question 6

What are the 2 components to bronchial hyper-responsiveness in asthma?

Answer 6

1. Hypersensitivity

2. Hyper-reactivity

Question 7

inhaled bronchoconstrictors are also known as…

Answer 7

Spasmogen

Question 8

Give examples of spasmogens (2) and which receptors they act upon.

Answer 8

Histamine - activate the ASM H1 Receptors

Methacholine - activiate the ASM M3 Receptors

Question 9

During an asthma attack bronchospasms are ______ action

Answer 9

an immediate

Question 10

During an asthma attack an inflammatory reactions are ______ action

Answer 10

a delayed

Question 11

A type 1 Hypersensitivity reaction is _____

Answer 11

early phase - bronchospasm and acute inflammation

Question 12

A type 4 Hypersensitivity reaction is ______

Answer 12

Late phase - bronchospasm and delayed inflammation

Question 13

Hyper-reactivity: Asthma as an immune imbalance - what two pathways does this involved on presentation of an allergen?

Answer 13

Non-atopic: low level TH1 response cell mediated immune response involving IgG and macrophages

Atopic: Strong TH2 response antibody mediated immune response involving IgE

Question 14

What is TH1 response?

Answer 14

TH1 cell mediated response

Question 15

MHC II cells are ____________

5

Answer 15

present on antigen presenting cells only
bind exogenous antigens
present the antigen to helper T-Cells
binds the CD4 adhesion molecules on helper T-Cells
presence of foreign bodies induces antibody production and attracts immune cells (EOINSPHILS) to the area of infection

Question 16

TH2 response causes….

Answer 16

(Induction phase) maturation of TH0 cells into TH2 cells which under the influence of IL-4 and binding to B-cells causes them to mature to IgE secreting P cells

Question 17

The effector phase in development of allergic asthma is…..

Answer 17

Eosinophil differentiation and activation in response to IL-5 released from TH2 cells.

Question 18

Mast cells in airway smooth tissue express IgE receptors in response to…

Answer 18

IL-4 and IL-13 released from TH2 Cells.

Question 19

Phase 3 in allergic asthma development involves:

Answer 19

Activation of mast cells in the airway smooth muscle Subesquent presentation of the antigen and cross -links in IgE receptors stimulates calcium entry into mast cells and also the release of calcium from intracellular cells

Question 20

The release of Calcium from intracellular stores in phase 3 causes _______________

Answer 20

the release of secretory granules containing preformed histamine and production and release of other agents - Leukotrienes LTC4 and LTD4 - ASM contraction

Question 21

What are LTC4 and LTD 4 and their effects?

Answer 21

Leukotrienes - primary cause in bronchoconstriction in the airways (asthma)
in more severe cases - eosinophils cause bronchoconstriction (are attracted to the area by the leukotrienes)

Question 22

Leukotrienes can both

Answer 22

trigger asthma attacks and are also an important part in causing long term hypersensitivity in chronic asthma.

Question 23

True or False? Drugs are now produced to interfere in the action of Leukotrienes

Answer 23

True but they only provide protection not as effective once an asthma attack is in place.

Prevent the Leukotriene release from mast cells and eosinophil production - in turn prevents bronchoconstriction, mucous secretion and oedema.