1998: Staying Alive: The Body in Balance

In the first of her lectures, Nancy Rothwell reveals how we are endowed with a multitude of sensors that help us regulate our bodies. This process of regulation – known as 'homeostasis' – is sensitive to even the slightest change in our environment. How we respond to these changes determines how well we fare in different situations. Nancy puts her own blood under the microscope to show the cells keeping her body in balance. Plus, Olympic champion Chris Boardman gets back on a bike to demonstrate the effect of exercise on our brain and blood.

In her second lecture, Nancy Rothwell explores how much energy is in the different foods we eat, and what happens to our body weight when we eat it. Different people need to eat different amounts of food, and each of us burns energy at different rates. The human body expends energy even when we’re sitting still, keeping warm. So how do we know how much energy we require?

In the third of her Christmas Lectures, Nancy Rothwell reveals how humans and animals alike have evolved to keep their body temperatures constant, even when the temperature of their habitats is changing. After journeying down to the chilly depths of the ocean to tell us how sharks keep warm, Nancy returns to the warm climes of the Arabian desert to explain why some Bedouins still wear dark robes despite knowing that black absorbs more heat than white.

In her fourth lecture, Nancy Rothwell explores how our bodies and those of animals are trained by sunlight. From summer to winter, and land to ocean, Nancy explores nature's most unique examples of timing, including why Cicadas emerge from the nest after exactly 17 years, and how the Iguana can tell whether it’s daytime even with its eyes shut.

In her final Christmas Lecture, Nancy Rothwell reveals some of the incredible adaptations that animals have evolved to cope with life in the extremes. From anti-freeze blood to double-layered fur, each animal has found its own way to overcome the extremes. We also learn what it takes for humans to survive in these locations – from the perilously cold conditions confronted by Antarctic explorers to the extreme forces experienced by fighter pilots.