Lesson video

Hello, I'm Mr. Marchant, and thank you for joining me for today's history lesson.

My top priority today is to help guide you through all of our resources and make sure that you can meet today's learning objective.

Welcome to today's lesson, which is part of our Edexcel unit on "Medicine in Britain." By the end of today's lesson, you'll be able to explain how understanding of the causes of disease and illness has progressed since 1900.

There are three keywords which will help us navigate our way through today's lesson.

Those are lifestyle factor, inherit, and genes.

A lifestyle factor refers to the way that people live, including their diets and levels of exercise.

To inherit something, to have the same physical or mental characteristics as one of your biological parents or grandparents.

And genes are information that is passed on from a biological parent to a child which controls particular characteristics.

Today's lesson will be split into two parts, and we'll begin by focusing on lifestyle factors.

By 1900, scientists knew that microbes were responsible for causing infectious diseases.

However, there are many illnesses in diseases, including cancer and diabetes, which aren't caused by microbes.

Research during the 20th and 21st centuries has improved understanding of how lifestyle factors can also affect a person's health.

Diets have been linked to people's health for many centuries.

Indeed, in accordance with the theory of the four humours, mediaeval physicians usually recommended that their patients maintain a balanced diet to remain healthy by keeping their humours in balance.

Although doctors continue to emphasise the importance of a balanced diet, they now do so based on improved knowledge of the substances different foods contain and how these affect the body.

For instance, it is known that a diet which is very rich in sugar can increase the risk of a person developing type 2 diabetes.

Likewise, it is understood that fatty diets can increase the risk of a person developing heart disease, especially if they do not exercise regularly.

Other substances contained in foods were only discovered during the 20th century.

For example, vitamins were first discovered in the 1910s.

Since making this discovery, doctors have been able to explain how a lack of certain vitamins can affect a person's health.

For example, anaemia, which can cause tiredness and increase of infection is now known to be caused by a lack of iron.

Consequently, foods like spinach are often recommended to groups like women who are at greater risk of suffering from anaemia.

So let's check our understanding of what we've heard so far.

An excess of which substance in foods can cause type 2 diabetes? Is it fat, protein, or sugar? Pause the video here and press play when you're ready to see the right answer.

Now, okay, well done to everybody who said the correct answer was C.

An excess of sugar in food can lead to type 2 diabetes.

And now we have a statement on the screen which reads, "Maintaining a balanced diet was not considered important before the modern period," but is that statement true or false? Pause the video here and press play when you're ready to see the right answer.

Now, okay, well done to everybody who said that that statement was false, but we need to be able to justify our response.

So why is it that that original statement was incorrect? Pause the video here and press play when you're ready to check your answer.

Okay, well done to everybody who said, "Mediaeval physicians believed a balanced diet would keep people healthy by maintaining a balance between the body's humours." This shows that the idea of a balanced diet has existed for many centuries, not just as an important health measure in the modern period.

And let's try one more question.

How can eating foods like spinach prevent anaemia? Is it that these foods contain high amounts of iron, that these foods contain low amounts of iron, that these foods contain high amounts of sugar, or that these foods contain low amounts of sugar? Pause the video here and press play when you're ready to see the correct answer.

Okay, well done to everybody who said the correct answer was A.

Foods like spinach can help prevent anaemia because they contain high amounts of iron.

The medical impact of other lifestyle factors also became better understood in the 20th century.

For example, by the 1950s, scientific studies had clearly demonstrated that smoking was associated with conditions such as lung cancer, high blood pressure, and heart disease.

These studies convinced groups like the Royal College of Physicians to issue their own public warnings about the dangers of smoking tobacco.

Similarly, it was only in the 1970s that scientists discovered that toxins contained in secondhand smoke from cigarettes can cause cancer in non-smokers.

Modern research has also helped doctors understand how high levels of alcohol consumption can cause liver and kidney diseases, and how activities such as unprotected sex can lead to the spread of sexually transmitted infections, or STIs, like chlamydia.

So let's check our understanding of what we've just heard.

I want you to write the missing word for the following sentence, which reads, "After the 1950s, the Royal College of Physicians began warning that, blank, increased people's risk of developing conditions like lung cancer and high blood pressure.

But what's the missing word? Pause the video here and press play when you're ready to check your answer.

Okay, well done to everybody who said that the missing word was smoking.

After the 1950s, the Royal College of Physicians began warning that smoking increased people's risk of developing conditions like lung cancer and high blood pressure.

So we are now in a good position to put all of our knowledge about lifestyle factors into practise.

Firstly, for each of the health conditions shown in the table, I want you to identify a lifestyle factor which can cause it to develop.

One has been done for you.

So for heart disease, you can see that we've said eating too much fatty food and a lack of exercise can lead to people developing it.

So you need to do the same for chlamydia, kidney disease, lung cancer, and type 2 diabetes.

Pause the video here and press play when you're ready to reflect on your responses.

Okay, well done for all of your hard work on that part of task A.

So we had some health conditions and I asked you to identify a lifestyle factor which could lead to each of them being developed.

For chlamydia, you may have identified unprotected sex.

For kidney disease, you may have identified drinking too much alcohol.

For lung cancer, you may have said smoking tobacco and breathing secondhand smoke.

And for type 2 diabetes, you may have talked about eating too much sugary food.

And so now we can move on to the second part of task A.

I would now like you to describe one similarity between mediaeval and modern understandings of the impact of diets.

You should ensure that you provide specific examples for both periods as part of your answer.

So pause the video here and press play when you're ready to reflect on your response.

Okay, well done for all of your effort on that part of task A.

So I asked you to describe one similarity between mediaeval and modern understandings of the impact of diets.

And your answer may have included.

Both mediaeval physicians and modern doctors shared the belief that a balanced diet can help people protect their health.

In the mediaeval period, it was believed that a balanced diet would help keep people's humours in balance.

In a modern period, it is understood that a balanced diet ensures people's bodies get a range of substances such as vitamins which they need to remain healthy.

For example, iron-rich foods are often recommended to groups who suffer from anaemia.

So well done if your own response looks something like that model which we've just seen.

And so now we're ready to move on to the second part of our lesson for today, where we are going to think about the role of genetics.

Aside from lifestyle factors, modern research has also focused on the role genetics play in causing illness and disease.

This research has often aimed to explain how some people are born with particular health conditions or seem to inherit these conditions from their biological parents.

By 1900, there was increasing research focused on inheritance.

In particular, there was interest in understanding how certain characteristics of parents appeared to be inherited by their children.

One scientist, Gregor Mendel, talked of invisible forces which came in pairs, one from each parent, that influenced a person's own characteristics.

These invisible forces would later be referred to as genetic information or genes.

Another scientist, Archibald Garrod, built on this work suggesting that some diseases might be hereditary caused by a child inheriting particular genes from their biological parents.

The theories of both Mendel and Garrod were correct.

A person's characteristics aren't determined by their genes.

These genes are inherited from parents and carried by a chemical substance known as DNA.

However, neither Mendel nor Garrod could prove their theories were correct in the early 20th century, as existing technology was not powerful enough to identify DNA.

However, by 1951, Rosalind Franklin's work on x-ray imaging allowed her to produce the first photographs of DNA.

Franklin's photographs were then used by two other scientists, James Watson and Francis Crick, to model the structure of DNA.

Watson and Crick discovered that DNA was shaped as a double helix, and that this shape allows DNA to make copies of itself and pass genes from a parent to a child.

So thinking about what we've just heard, why was scientists in the early 20th century unable to prove that certain diseases were genetic? Was it because governments banned genetic research, because most believed it was impossible to inherit a disease, or because they could not observe and identify DNA? Pause the video here and press play when you're ready to see the right answer.

Okay, well done to everybody who said the correct answer was C.

Scientists in the early 20th century were unable to prove that certain diseases were genetic because they could not observe and identify DNA.

And let's try another question.

Who produced the first x-ray photograph of DNA? Pause the video here and press play when you're ready to see the right answer.

Okay, well done to everybody who said that Rosalind Franklin produced the first x-ray photograph of DNA.

Once the structure of DNA was understood, further investigation became possible.

For instance, scientists identified the genes responsible for Down syndrome and haemophilia, proving that these conditions were genetic and hereditary.

In 1990, the Human Genome Project began, involving teams of scientists from across the world.

The project was an attempt to map the entire human genome, meaning the full set of genetic information contained in human DNA.

Because of its scale, the project cost billions to run, but it received large amounts of funding from the US government to complete its work.

The Human Genome Project was complete in 2003, and its findings were made free and public.

This ensured that all scientists could benefit from it.

Using information from the project, scientists have been able to identify a gene that is sometimes present in women who suffer from breast cancer.

This has enabled some women who have that gene to protect themselves from breast cancer by choosing to have a mastectomy, a surgery which involves removing one or both breasts.

In the 21st century, continued research into DNA and the role of genetics has benefited from the use of electron microscopes.

These microscopes are capable of producing clear images at up to 5,000 times greater magnification than optical microscopes, allowing DNA to be viewed in greater clarity, offering more insight into its structure and its functions.

So let's make sure we have a secure understanding of everything we've just had.

I want you to identify two diseases which can be genetic.

You can choose from breast cancer, cholera, haemophilia, and smallpox.

So pause the video here and press play when you're ready to see the right answers.

Okay, well done to everybody who said that breast cancer and haemophilia can both be genetic diseases.

And this time, we have a statement on the screen which reads, "Most funding for the Human Genome Project was provided by businesses." But is that statement true or false? Pause the video here and press play when you are ready to see the correct answer.

Okay, well done to everybody who said that that statement was false, but we need to be able to justify our response.

So why is it that that original statement was incorrect? Pause the video here and press play when you're ready to check your answer.

Okay, well done to everybody who said, most of the funding for the Human Genome Project was provided by the US government.

So we are now in a good position to put all of our knowledge about the role of genetics into practise.

I want you to explain two reasons why understanding of genetics advanced after 1900.

You may consider the influence of factors such as individuals, government, or technology.

So pause the video here and press play when you're ready to reflect on your responses.

Okay, well done for all of your hard work on that task.

So I asked you to explain two reasons why understanding of genetics advanced after 1900, and your answer may have included, one reason why understanding of genetics advanced after 1900 was because of the contribution of individuals such as Rosalind Franklin, James Watson, and Francis Crick.

Franklin's work on x-ray photography produced the first images of DNA in 1951, and these were used by Watson and Crick to produce a model of DNA's double helix structure two years later.

This work was important for genetics because once DNA structure was understood, it was easier for scientists to identify the genetic causes of certain diseases, including haemophilia and Down syndrome.

Your answer may also have included, another reason why understanding a genetics advanced after 1900 was because of developments in technology.

For example, improvements in x-ray photography allowed DNA to be photographed for the first time in 1951.

Prior to this, it had been difficult for scientists to understand the structure of DNA.

Similarly, the development of electron microscopes has also helped support modern research into genetics.

Electron microscopes can produce clear images with 5,000 times greater magnification than optical microscopes, allowing DNA and its functions to be studied in more detail.

And your answer may also have included, another reason why understanding of genetics advanced after 1900 was because of the support governments provided for scientific research.

For instance, the Human Genome Project involved teams of scientists from many countries who worked to map the human genome.

This project cost billions, but was made possible with funding that came mainly for the US government.

The work of the Human Genome Project allowed new advances to be made, including identification of a gene associated with breast cancer in women.

So really well done if your own responses look something similar to those models, which we've just seen.

And so now we've reached the end of today's lesson, which puts us in a good position to summarise our learning about modern advances in understanding the causes of illness and disease.

We've seen that lifestyle factors such as drinking, smoking, and diet all affect people's health.

In the 20th century, understanding of lifestyle factors became more scientific, such as with the discovery of vitamins in food.

People's characteristics, including whether they suffer from certain diseases, are determined by genes which they inherit from parents.

The double helix structure of DNA was discovered in the 1950s.

And further research, including the Human Genome Project, has helped identify genes which can cause particular diseases like breast cancer.

So really well done for all of your effort during today's lesson.

It's been a pleasure to help guide you through our resources today, and I look forward to seeing you again in future, as we continue to think about medicine in Britain.