Autophagy derived from latin words “self eating” is a normal regulated cell process where cytoplasmic materials are degraded through the lysosomal machinery and the contents reused by the cell.

During this process, organelles like mitochondria together with long-lived proteins are sequestred in a double-membrane vesicle delivered and degrade in lysosomes inside the cell.

Autophagy is activated in case of nutrient deprivation and plays a crucial role in the destruction of bacteria, viruses, and unnecessary proteins aggregates in cell.


An allergen is usually an inert substance (e.g. pollen, house dust mite faeces) that in some individuals can trigger the generation of an (inappropriate) antigenic response. Mediated by TH2 lymphocytes, it causes B-Lymphocytes to produce lgE.

Subsequent exposure of a sensitized individual to the allergen is therefore able to cross-link IgE antibodies on the surface of mast cells and trigger an immune response and histamine release.


Arousal is a state of vigilance regulated by subcortical parts of the nervous system, especially connections between the nuclei of the amygdala, the hypothalamus and the brain stem.

These unconscious responses prepare the body for action. In terms of sleep/wake regulation, the arousal systems are those that have highest activity during wake, for example the aminergic (noradrenaline, 5-HT, histamine) systems.

The arousal systems inhibit, and are themselves inhibited by the GABAergic system emanating from the ventrolateral preoptic nucleus (VLPO), in a so-called “flip flop” arrangement that is stabilised via orexinergic activity.