If I cut myself boning chicken, or saw my hand when I'm cutting wood, or stick a needle in my hand when I'm sewing (it happens everytime I sew) I just deal with it. No problem. The odd time I've needed stitches I've chatted away to the medical staff while watching them do the needlework.

But when the nurse takes a blood sample the tunnel vision starts, the clammy forehead kicks in, BP drops to 1 over zero and I really struggle to stay conscious. I've never actually passed out, but I've come close.

What's the difference?

When I wake up, the white of my left eye is always slightly pink. This isn't the result of blood pooling on the left side of my body as I invariably sleep on my right side. After 10 minutes my left eye is back to the same white as my right eye. My left eye can start out even pinker if I have drunk too much alcohol the night before, but it still reverts to white after 10 minutes. I'm not concerned - it has been like this for years - but what is the cause?

Norman Hood, Salisbury, Wiltshire, UK

We're all no doubt familiar with the somewhat metallic taste of blood, but seeing as the tongue has a healthy supply of the stuff, how can it detect it at all?  Surely the tongue should be so used to the presence of blood that any extra should effectively taste of nothing at all?

Most of us will be familiar with the somewhat metallic taste of blood, but how are we able to detect the taste of blood at all, when the tongue already has a healthy supply of the stuff?  Surely with this blood supply adding itself to the taste of everything we, er, taste, then blood itself would effectively taste of nothing?

Being a regular athlete, i have visible veins standing out from both my arms. However, many more veins protude from my right arm than my left, and those that do, protude further. I can only assume that this means i have greater blood circulation in my right arm. I am right handed - could these 2 facts be linked? I have noticed this in other people too, with all having more veins in their favoured arm. Does the hand we favour need more oxygen to function, or does the factc that the arm has more oxygen make the arm ones favourite?