Q Doc, could you explain the process of losing one's virginity? I am a 19-year-old woman and I think I may well have sex at some stage during the next couple of years.

I have been told by my friends that there is some 'obstacle' in a woman's vagina, which is present in virgins. Furthermore, they say that when a woman loses her virginity, this obstacle somehow 'gives way'.

Is this true? If there really is an 'obstacle' there, I do not understand how females can pass urine or have menses.

A Please don't be in too much of a hurry to lose your virginity. You obviously don't know a lot about sex. It would be unwise for you to put your health in danger by exposing yourself to the many dangers of intercourse. These include sexually transmitted infections such as HIV, chlamydia and gonorrhoea.

Also, you could easily become pregnant, particularly if you don't know much about contraception, which I suspect is the case.

In addition, do you realise that early sex can lead, after an interval of years, to cancer of the cervix? This disease can be fatal.

My advice to you and other young women is to hang on to your virginity as long as possible.

This 'obstacle' is a thin pink membrane called the hymen. This 'door' does not prevent women from passing urine. Why? Because it's farther into the vagina than the urinary opening so there is no way that it can block the flow.

The hymen has a small hole in it that allows the flow of menses. However, in very rare cases there is no hole in the hymen. This condition becomes apparent at puberty, when the unfortunate girl develops all the symptoms of a period, including a lot of pain - but has no bleeding. Happily, this unusual problem can be addressed by a surgeon, who will cut through the hymen.

When a woman first has sex, the tip of the guy's penis breaks through it. It is then gone for ever and generally all that is left are some tiny 'bumps' on the vaginal walls showing where it was.

However, these days, the hymen is often broken in other ways. For instance, girls who use tampons will normally break the hymen as they push the little device in for the first time.

Also, the process of 'love play' or 'petting' will often break the hymen if (as is common) the man uses his finger. Furthermore, many females accidentally break their own hymens by engaging in masturbation. Vigorous activity such as gymnastics is also believed to break the hymen.

Young women are often very fearful of the moment when the hymen breaks because they may have been told that this is intensely painful. In most cases, that is just not true. Surveys have shown that usually there is only slight pain, or even none at all. Generally, there is a small amount of bleeding when the hymen breaks.

Q I would like to know some ways in which I could gain weight. I am five feet 10 inches tall and weigh 127 lb. I think I look thin. I want to gain some weight to look healthier. Am I am underweight?

A Well, you don't say whether you are male or female. However, the height/weight tables which are produced by life insurance experts say that a guy of your height has a 'desirable weight' of between 151 lb and 163 lb. If you are a woman, the tables suggest that your desirable weight is between 142 lb and 156 lb.

So either way, you are indeed a little underweight. By my calculations, your body mass index is somewhat below normal.

Are there hereditary trends to watch? For instance, if your mother and father were both very slim, it would be very likely that their children would be lightweights.

I feel that your next move should be to go to a doc for a medical check-up. He will be particularly interested to know if you have lost weight recently, because there are some disorders that cause weight loss, notably diabetes ('sugar'), anorexia and tuberculosis.

Assuming that the doc has found nothing wrong, what can you do? Well, I hope he will give you a diet sheet containing a list of nutritious foods that would build you up. In particular, it would be reasonable for you to eat slightly more fatty foods, since these contain more calories. However, try to avoid the ones which contain 'saturated' fats, since these are not good for the heart.

It is traditional for doctors to advise underweight patients to drink a pint of milk a day. That's not a bad idea once your cholesterol level is not high. Also, doctors have traditionally told underweight people to drink a well-known brand of stout. I am not keen on encouraging people to drink alcohol, but if your doc advises it, I suggest you limit your intake to two units per day.

Finally, working out in a gym would help you bulk up your muscles.

Q I am a young woman who needs your help. Over the last year, I have been feeling dizzy. I have also been feeling 'electric shocks' throughout my body. I also get pains in my arms, legs and back. I know I am not anaemic, because I get my periods rarely.

A That does NOT prove that you are not anaemic. It is clear that you need a full check-up from a doc, probably including blood tests.

Also, the doc needs to investigate the fact that your menses are 'rare'. I wish you well.

Q I have been told that I have 'bad blood'. What does this mean?

A. This is an old phrase. It usually means that there is a positive blood test for either syphilis or for an infection called yaws which used to be common in rural Jamaica. You need to have several different blood tests to find out precisely what is wrong and whether you need antibiotic treatment.

Email your questions for Doc to saturdaylife@gleanerjm.com.