Image copyright Tracey Jolliffe Image caption Tracey Jolliffe is calling on others to give a kidney

Tracey Jolliffe has already donated a kidney, 16 eggs and 80 pints of blood, and intends to leave her brain to science. She is now hoping to give away part of her liver to a person she may never meet.

"If I had another spare kidney, I'd do it again," Tracey tells the BBC's Victoria Derbyshire programme.

She is what is known as an "altruistic donor" - someone willing to give away an organ to potentially help save the life of a complete stranger.

A microbiologist in the NHS, and the daughter of two nurses, she has spent her life learning about the importance of healthcare from a professional standpoint.

But she has also been keen to make a difference on a personal level.

"I signed up to donate blood, and to the bone marrow register, when I was 18," she says.

Now 50, her wish to donate has become gradually more expansive.

In 2012, she was one of fewer than 100 people that year to donate a kidney without knowing the recipient's identity - and now supports the charity Give A Kidney, encouraging others to do the same.

As of 30 September 2016, 5,126 people remain on the NHS kidney transplant waiting list.

Image copyright Getty Images Image caption About 3,000 kidney transplants are carried out each year

Tracey's kidney donation, in all likelihood, will have saved someone's life.

"I remind myself of it every day when I wake up," she says, rightly proud of her life-changing actions.

It was not, however, a decision taken on the spur of a moment.

Donating a kidney is an "involved process", she says, with suitability assessments taking at least three months to complete.

Tests leading up to the transplant include X-rays, heart tracing and a special test of kidney function, which involves an injection and a series of blood tests.

"It is not something to do if you're scared of needles," she jokes.

The risks associated with donating, however, are relatively low for those deemed healthy enough to proceed, with a mortality rate of about one in 3,000 - roughly the same as having an appendix removed.

Compared with the general public, NHS Blood and Transplant says, most kidney donors have equivalent - or better - life expectancy than the average person.

Tracey says she was in hospital for five days after her operation but felt "back to normal" within six weeks.

Kidney transplants: The facts

More than 53,000 people in the UK are being treated for kidney failure

90% of people on the transplant list are waiting for a kidney, with 3,000 kidney transplants carried out each year

Unlike many other types of organ donation, it is possible to donate a kidney while still alive because we need only one kidney to survive

The average waiting time for a kidney transplant is three to four years

60% of recipients of live donor kidneys can expect to survive for about 15 years

Source: Kidney Research UK

As well as helping to save lives - including through 80 pints worth of blood donations - Tracey has also helped families create them too.

She has donated 16 of her eggs, allowing three couples to have children.

It was a simple decision to take, she says.

"I have no desire to have children of my own, so I thought, 'I'm healthy, why not?'"

Image copyright Thinkstock

The next step, she hopes, could be to donate part of her liver - once again, to someone she has never met. But she is aware of the dangers involved.

"It's a much riskier operation than donating your kidney," she says.

The rate of death for those donating the right lobe is estimated at one in 200. For the left lobe, it is one in 500.

But many donators live a long and healthy life, with the organ having an "amazing capacity to regenerate", as Tracey describes it.

Almost immediately after an operation, the remaining liver begins to enlarge in a process known as hypertrophy, continuing for up to eight weeks.

Image caption Brain tissue is a vital research resource

Tracey will undoubtedly continue to donate for as long as she can - and is hoping to pass on her organs once she dies.

"I signed up to donate my brain for medical science when I go," she says.

Brain donations are usually performed within 24 hours of death, to be used for medical research into conditions such as dementia.

Taking such decisions can be difficult, but Tracey says her friends and family "accept I'm going to do what I want to do".

Her reasons for donating organs - whether it be a brain or a kidney - are both humbling and understated.

"I think it's part of my nature, my opportunity to do something nice," she says.

But the difference such decisions can make to others is huge.

For information on how to make a living donation, visit the NHS Blood and Transplant website.

Watch the Victoria Derbyshire programme on weekdays between 09:00 and 11:00 on BBC Two and the BBC News channel.