PBL 1

Question 1

What does anaphylaxis present as?

Answer 1

oedema to lips and neck, hypotension, severe bronchoconstricton, tachycardia

Question 2

what are the 2 types of histamine blockers?

Answer 2

first generation (have high lipid solubility so can cross blood-brain barriers) or second generation (have far less lipid solubility so have less cognitive and antimuscarinic side effects)

Question 3

how do histamine antagonists work?

where are histamine receptors mostly found?

Answer 3

they reversibly inhibit H1 receptors

predominantly found on endothelial cells, smooth muscle cells, sensory nerve endings and the brain.

Question 4

what is an example of the natural glucocorticoid we produce at the adrenal gland?

Answer 4

cortisol

Question 5

how are steroid hormones transported around in the blood?

Answer 5

by transcortin

Question 6

what are indications for glucocorticoids?

Answer 6

autoimmune diseases, allergies, asthma, adrenal insufficiency, cancer, heart failure and skin conditions

Question 7

what is the problem with long-term use of glucocorticoids?

Answer 7

it can cause immunosuppression and can lead to Cushing’s syndrome, it can also cause osteoporosis, weight gain, fluid retention

Question 8

how can long term use of glucocorticoids cause osteoporosis?

Answer 8

it inhibits osteoblast activity and promotes osteoclast activity so more bone is broken down than made

Question 9

how do we treat anaphylaxis?

Answer 9

Epinephrine (adrenaline) to reduce your body’s allergic response.
Oxygen, to help you breathe.
Intravenous (IV) antihistamines and cortisone to reduce inflammation of your air passages and improve breathing.
A beta-agonist (such as albuterol) to relieve breathing symptoms.

Question 10

what is self-tolerance?

Answer 10

the ability of the immune system to recognise self-produced antigens as a non-threat.

Question 11

why do we not normally develop immune responses to self-antigens?

Answer 11

in the bone marrow, B cells randomly get their antibody as its encoded by random re-arrangement of pre-existing gene segments. if it reacts to a self-protein then it will cause changes to the cell which will lead to cell death.

Question 12

what are Autoreactive lymphocytes?

Answer 12

lymphocytes which have receptors against self-antigens

Question 13

what is central tolerance?

Answer 13

also known as negative selection- the process of eliminating any developing T or B lymphocytes that are reactive to self within the primary lymphoid organs

Question 14

what is peripheral tolerance?

Answer 14

ensure that self-reactive T and B cells which escaped central tolerance do not cause autoimmune disease. - this negative selection occurs at the site of antigen-recognition sites

Question 15

why could failure of central tolerance occur?

Answer 15

some weakly self-reactive clones survive the negative selection
molecular mimicry
inappropriate expression of MHC 2 molecule can sensitise auto-reactive T cells
self-antigens not being expressed where negative selection occurs

Question 16

describe the process of hyposensitisation?

Answer 16

administration of gradually increasing quantities of specific allergens to patients until a dose is reached that is effective in reducing severity from natural exposure. it does this by directing the immune response away from humeral immunity and towards cellular immunity

Question 17

describe how B and T cells can also develop self-tolerance via positive selection?

Answer 17

pre-cells express receptors that interact with self-MHC proteins on epithelial cells. these cells survive, those that cannot recognise it will undergo apoptosis

Question 18

what is anergy?

Answer 18

absence of the normal immune response to a particular antigen or allergen

Question 19

what is an autoantibody?

Answer 19

an antibody produced by the immune system that is directed against one or more of the individual’s own proteins

Question 20

outline some of the ways that autoantibodies can cause disease?

Answer 20

mimic hormone stimulation of receptor
blockade of neural transmission 
induction of altered signalling
cell lysis
uncontrolled neutrophil action
induction of inflammation at site of autoantibody binding

Question 21

what does urticaria (hives) look like?

Answer 21

red spots or raised red patches. it is often itchy and can feel like a sting or burn

Question 22

what happens in Graves disease?

Answer 22

autoantibodies mimic thyroid stimulating hormone and stimulate secretion of thyroid hormones

Question 23

what happens in myasthenia gravis?

Answer 23

autoantibodies bind to and block ACh receptors causing muscle weakness

Question 24

what happens in type 1 diabetes mellitus?

Answer 24

T cells attack the insulin-producing pancreatic beta cells

Question 25

what happens in multiple sclerosis?

Answer 25

T cells attack myelin sheaths around axons of neurones

Question 26

what are the 2 ways in which autoimmune disease can come about?

Answer 26

autoantibodies

mis-directed T cells