Review posters 03/05/2016 Flashcards
How is the supply of NAD+ recreated?
Anaerobic respiration creates NAD+ in the conversion of pyruvate to lactic acid.
Oxidative metabolism of pyruvate.
What is the purpose of the pyruvate dehydrogenase complex?
To catalyse the decarboxylation and oxidation of pyruvate to form the 2 carbon acetyl coA. (oxidative decarboxylation)
Is allosterically regulated by phosphorylation.
Actively determines glucose oxidation in well oxygenated tissues.
How does pyruvate enter the mitochondrial matrix?
H+ gradient created. Ion channel called the H+/pyruvate symporter allows facilitated diffusion of pyruvate into the mitochondrial matrix.
Which enzyme in the TCA cycle is not from the mitochondrial matrix?
Succinate dehydrogenase.
What is the net yield of one turn of the TCA cycle.
3 NADH + H+
1 FADH
1 ATP
Pyruvate dehydrogenase deficiency
Carried on the X chromosome.
Only occurs in females.
Causes mental retardation, seizures, poor muscle tone. persistent lactic acidosis and resp problems.
Fumarate dehydrogenase deficiency and hereditary leiomyomatoses and renal cell cancer (HLRCC)
Result from defect in fumarate dehydrogenase (TCA cycle enzyme).
Causes muiltiple systemic, benign and malignant tumours.
Type 1 hypersensitivity reactions are mediated by which antibodies.
IgE
Describe the hygiene hypothesis
Early exposure to microbes in the environment means children are less likely to develop allergies. Overly protected, sterile environments mean childrens immune systems are not mature enough to deal with the new antigens.
Describe the pathophysiology of a type I hypersensitivity reaction.
On first encounter: Allergen is in the body.
Mast cells bind to the allergens antigen via Fc receptors and destroy it. IgE antibody created by B cells specific to allergen.
On re-encounter: IgE antibody binds to allergen. Mass mast cell degranulation occurs (release of histamine, leukotriene D4 etc) to kill antigen.
Release of histamine causes smooth muscle spasm (bronchoconstriction), vasodilation (mass oedema) and leukocyte extravation.
Give examples of a type I hypersensitivity reaction.
Extrinsic asthma
Anaphylaxis
Food allergy
Drug allergy
How do you diagnose a type I hypersensitivity reaction?
Skin prick test
RAST test- measure amount of IgE in serum directed against specific antigen.
Anaphylaxis- mast cell tryptase (product of mast cell granules-wide spread degranulation of mast cells)
Treatment of a type I hypersensitivity reaction.
Avoid stimulus. Anti-histamines Adrenaline (for anaphylaxis)- mass vasoconstriciton Corticosteroids Sodium cromoglycate.
What is a type II hypersensitivity reaction.
Direct cell killing.
Describe the pathophysiology of a type II hypersensitivity reaction.
Macrophages and dendritic cells wrongly recognise a cell or antigen presenting cell. B cells then produce antibodies (IgG or IgM) which activates the complement cascade.
When complement is activated, C3 opsonises the cell to make it more attractive for phagocytosis whereas C5b forms the membrane attack complex which results in cell lysis.
Name the three main roles complement has.
Opsonisation
Formation of the membrane attack complex.
Increase permeability of blood vessels.
Name an example of a type II hypersensitivity reaction.
Blood transfusions
Goodpastures syndrome- affects basement membrane of cells in the lung.
Guillian Barre syndrome-antibodies bind to peripheral nerve glycoprotien.
Immediate haemolytic transfusion reaction.
Can occur if as little as 1ml of blood is transfused.
Pyrexia and rigors.
Tachycardia
Hypotension