What makes me feel hungry?

Wednesday 22nd July 2009
Submitted by Luis Villazon
Laura Finnegan, Ballinasloe

The vagus nerve sends information about the fullness of the stomach to the hypothalamus in the brain. Hunger is also controlled by hormones, including insulin, leptin, ghrelin and cholecystokinin. Levels of these change according to the levels of various nutrients in the blood and digestive tract.

Why does breathing pure oxygen kill you?
previous qanda Article
What is pins and needles?
next qanda Article
Q&A Tabs

Phlegm is the mucous secretion of the respiratory passages. The cilia cells that line these passages are continually driving the phlegm upward to the throat, where it triggers the swallow reflex...

Beard hair is quite different to head hair; it is coarser, curlier and doesn't fall out as we get older. Comparatively little work has been done on the genetics of human hair colour, but it is...

 When a nuclear bomb explodes on Earth, the huge release of radiation triggers the rapid expansion of air around it, causing the intense blast wave that wreaks so much destruction. In the...

Height in humans is about 70 per cent genetic and 30 per cent environmental, but there are many different genes that all contribute to your final height. Women generally stop growing any taller...

Ordinary glass absorbs 97 per cent of the UVB rays that cause sunburn and some skin cancers, and 37 per cent of the less harmful UVA radiation. This translates to a protection of about SPF30, so...

All female mammals have a clitoris, the sole purpose of which is to react to sexual stimulation, and presumably this stimulation has evolved to be pleasurable for most species. But establishing...

To create a sound, we have to set matter - whether it's a gas like air, a liquid or even a solid material - in regular motion, creating a wave of specific frequencies, which we hear as a sound of...

Mirrors don’t reverse left and right either – that’s just our interpretation of what happens. Your reflection in the mirror is actually reversed front to back – if you have...

Discovered by an American student named Gary Flandro in the mid-1960s, the slingshot manoeuvre usually involves spacecraft briefly 'coat-tailing' a planet orbiting the Sun, extracting some of the...

The ice disappears because the wind blows away water molecules that have evaporated or 'sublimed' from the ice, so the ice slowly shrinks in size. The molecules that escape are those with the...