Anaphylaxis Flashcards

1
Q

What type of cell causes anaphylactic symptoms?

A

Mast cells

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2
Q

What binds to mast cells?

A

IgE

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3
Q

What are the main signalling molecules involved in anaphylaxis?

A

Histamines and leukotrienes which are found in mast cell granules

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4
Q

What do histamines act on?

A

Blood vessels and smooth muscle

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5
Q

What affect does histamines have on blood vessels?

A

In connective tissue - Causes the dilation of blood vessels leading to increased blood flow to the surface, and increased movement of fluid out the blood steam

In mucosa - causes constriction of airways and contraction of the smooth muscle in the walls of the intestine

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6
Q

What causes mast cell degranulation?

A

When the circulating antigen binds to the IgE which is bound to the mast cell via Fc receptor, this causes receptor cross linking leading to degranulation

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7
Q

How are IgE produced?

A

The CD4 T helper cells causes a class switch to IgE production

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8
Q

What is an allergen?

A

An antigen which causes an allergic type IgE-mediated response

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9
Q

What causes rashes and puffy skin seen in anaphylaxis?

A

Histamine causes vasodilation leading to red skin colour and oedema leading to raised appearance

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10
Q

What is skin rash called?

A

urticaria

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11
Q

When can the localised skin reaction seen in allergy be useful?

A

In skin prick tests to see if they caused a wheal-and-flare reaction

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12
Q

What is hay fever called?

A

Allergic Rhinitis

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13
Q

What causes Allergic Rhinitis?

A

Odema in the epithelia lining the nose resulting in general irritation and stimulation of mucus secretion

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14
Q

What causes asthma?

A

When the allergen reaches he bronchioles of the lungs, resulting in contraction of smooth muscles which reduces the diameter of the airways, leads to increased mucus production and difficulty breathing in and out

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15
Q

What causes food allergies?

A

When an allergen is ingested, it acts on the mucosal mast cells in the intestinal tract - leading to vomiting and diarrhoea

if absorbed into blood stream, can cause rashes or itching

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16
Q

What occurs in anaphylaxis which can be fatal and affect organ function?

A

A rapid decrease in blood pressure as the blood vessels dilate

17
Q

Why is adrenaline (epinephrine) given as an emergency treatment for anaphylaxis?

A

Epinephrine is a vasoconstrictor and therefore is aimed at trying to stabilize blood pressure

18
Q

After adrenaline, what medication is given following an anaphylactic shock?

A

Anti-histamines and anti-inflammatory corticosteroids like hydrocortisone

19
Q

Why do patients feel faint follow an anaphylactic shock?

A

Due to the dramatic loss of blood pressure - hypotension

20
Q

Why is blood pressure carefully measured after a shock?

A

Provides a reliable indication of recovery

21
Q

What is biphasic anaphylaxis?

A

When the symtpoms return within hours of the initial reactiom

22
Q

How long should patients with moderate respiratory/cardiovascular compromise should be observed before discharge?

A

8-10 hours