The screaming was incessant until finally the tourniquet was in place and fiercely tightened.

What I was watching was a training exercise at Camp Bastion, with most of the screaming coming from instructor, Sergeant Lee Melvin.

His job is to prepare new troops in Afghanistan for what they may encounter out on the battlefield and he makes it as realistic as possible.

War has always driven innovation in medicine and science, and the reason I was out in Afghanistan was because we were filming the documentary Frontline Medicine, which I'm presenting for BBC Two, to find out what has been learnt from recent conflicts.

Jane Aldous, the series executive producer, has made numerous series with the military, including the Bafta-winning Wounded and The Bomb Squad - so I thought her excellent contacts would mean making this series would be straightforward - but I quickly learned it was far more complicated than I had realised.

There were issues to be ironed out about filming patients who were critically injured or unconscious and who weren't able to give informed consent.

An added complication was the fact that Camp Bastion Hospital, although run by the British, had medical staff and patients from a variety of other countries.

Protracted negotiations followed with the Ministry of Defence, the Pentagon and the American Navy to name just a few, before we even started filming.

There were safety briefings and hostile environment courses to be got through, but finally in May 2011 we took off on an ageing airplane from Brize Norton in Oxfordshire for Afghanistan.

We were only allocated four seats, which meant the assistant producer, Blythe, also had to cover the job of a sound recordist.

Fortunately she's experienced, because trying to record decent sound in a busy battlefield hospital is a real challenge.

We were also fortunate to have cameraman, Andrew Thompson, who as well as a great sense of humour has plenty of experience of Afghanistan, having been out there filming with Ross Kemp.

The hospital we filmed in is in Camp Bastion, where they treat injured troops of all nationalities from all over southern Afghanistan.

They deal with some of the most extreme injuries you'll see anywhere.

Despite this they manage to save the lives of up to 90% of the wounded, the highest success rate in the history of warfare.

One reason for this is that they are incredibly well set up.

I was there for a couple of weeks and in that time watched dozens and dozens of badly wounded people (and a couple of bomb sniffer dogs) being treated.

Gunshot wounds, soldiers cut to pieces by shrapnel, burns and numerous amputations caused by improvised explosive devices (IEDs) were a regular occurrence.

I saw a lot of badly injured people in Bastion, but only one that reduced me to tears.

He was a young US marine called Chuck who had had his left leg partially amputated by a bomb blast.

Although he had been treated on the helicopter, he was still in a lot of pain.

Chuck was fortunate because the anaesthetist at Bastion, Surgeon Commander Dan Connor is very skilful at pain management and he's particularly good at a technique which the military have been refining over recent years.

Instead of just giving morphine, Dan carefully inserted a fine catheter into the area near Chuck's popliteal nerve, the nerve that provides pain signals from the foot.

He then connected it to a pump that keeps a regular flow of local anesthetic to the nerve.

When I saw Chuck that evening he was completely pain free. With the apparatus in place he was flown back to the US for further surgery.

Continuous nerve blocks, like the one he had, are increasingly being used in the NHS for procedures like knee replacements.

Getting out of Afghanistan was harder than getting in. The RAF told us they could not guarantee our return date and I was a bit desperate.

Fortunately we found a plane flying to Dubai, which we boarded at dead of night.

My trip to Afghanistan was just the beginning of a long and fascinating journey to find out more about medical innovations that have emerged from recent military-funded research.

You'll see in episode two that we got access to a range of such research, including trials of new prosthetics and devices that allow blinded soldiers to "see" with their tongues.

The cost of this war, for civilians and military, has been exceptionally high.

But I do believe some good will come out of so much suffering and because of what we've learnt, future lives will be saved.

Michael Mosley is the presenter of Frontline Medicine.

Comments made by writers on the BBC TV blog are their own opinions and not necessarily those of the BBC.

Altruistic individuals would leave their bodies for students, like me, to tremblingly dissect.

These days you can get a more intimate and revealing understanding of the workings of the body by other methods.

This is largely thanks to improvements in scanning technology and far more sophisticated microscopy.

Inside The Human Body, a series I have just finished making for BBC One, does what it says in the title. We decided to turn our cameras on the animal we love best - ourselves.

I was chosen to present the series because I have a background in medicine.

I trained as a doctor and have more than 20 years experience as a science journalist. I've presented a number of series for the BBC, including recently, The Young Ones and Blood And Guts: A History Of Surgery.

In this series we showcase the latest scientific images of the body, including a fabulous sequence of a human face forming inside the womb.

We also reveal some of the more unusual and surprising ways in which your body, minute-by-minute, struggles to keep you alive.

To illustrate the latest science we also filmed people who have managed to get their bodies to do some pretty amazing things, like breaking the world free-diving record or teaching their eyes to see with perfect clarity deep underwater.

I was particularly impressed by a magician who could do the most unbelievable tricks with his hyper-flexible hands.

The series covers the human experience from conception to death.

So, not only do you see the moment when sperm enters egg, detonating a series of violent explosions, viewers also see the moment when 84-year-old Gerald, surrounded by his family, draws his last breath.

In the programme that features Gerald, First To Last, we learn about all the things that the body does to keep itself in balance (homeostasis), and what happens when this balance is lost.

Gerald had terminal cancer but what ultimately killed him was probably his body's inability to maintain his red blood cell count.

Gerald agreed to be filmed because he thought it would be helpful to show that it is possible to pass away painlessly, at home, surrounded by your loved ones.

It's a series I greatly enjoyed making, partly because of the people in it like Gerald, partly because I learnt so much about the workings of my own body. I hope you get the time to watch.

Michael Mosley is the presenter of Inside The Human Body.

Comments made by writers on the BBC TV blog are their own opinions and not necessarily those of the BBC.