The Context of Harvey's Discovery

Hello.

My name is Andrew Gregory and I'm professor

of History of Science at University College,

London.

This module is on William Harvey, who discovered the circulation of the blood

and is part of the medicine. Through Time course.

William Harvey lived from 15 78 to 16 57.

He went to University of Cambridge and then to the University of Padua,

which is the major centre for anatomy and physiology in Europe at the time.

His major work is exercises on the Motion of the Heart

and Blood in Animals that was published in 16 28.

Harvey was also physician to King James the first,

so he had quite a good medical career as well.

And we're going to look at the nature of his discovery, why it was important

and what was actually quite a difficult discovery to make.

And to do that to start with,

I'm going to go into some of the background to the discovery.

The key figure here, in many ways is a character called Andreas Vesalius,

who lived in the 16th century

and published his major work on the fabric of the human body in 15 43.

This is an important and groundbreaking work because up until this time,

everyone had relied on an ancient author called Galen,

who lived in the second century A D

and was taken to be absolutely authoritative on matters of anatomy,

medicine and treatment.

Now, what's important about Vesalius

is that he was the first person to start

questioning whether Galen was actually correct or not.

So his work on the fabric of the human body largely follows Galen,

but also questions a few things that Galen had to say.

Now the issue here is largely this

that Galen was an excellent scientist and

an excellent doctor and an excellent anatomist.

But in the ancient world, there's a taboo against dissecting the human body.

So you weren't allowed to cut up life humans.

But you weren't allowed to cut up dead humans either.

And this put quite a break on Galen's research,

and what Gayle intended to do instead was to dissect

higher mammals and assume that these were like human beings.

What Vesalius was the first person to realise

was that while Galen's descriptions were fairly good,

they weren't absolutely perfect.

So, for instance, gallons description of the human hand

is a good description of the human hand and a

brilliant description of the hand of a Barbary ape.

What Vesalius recognised was is actually describing

a Barbary ape rather than the human.

And there are small differences.

So Vesalius was able to show that there were differences

between True Anatomy and what was received from Galen.

The cell uses also groundbreaking in

using very detailed and very good diagrams in his work on anatomy.

And it is thought that either he used Titian or

some of the students a petition to do the diagrams.

And this was very important in making anatomy much more interesting

and much more widespread a science than it was.

And there's quite a demand from the artists of the time who

are seeking to depict the human body in ever more naturalistic ways

for there to be this more accurate anatomy

and physiology.

So if you say this is very important here in breaking this ground and

setting up a new way of looking at anatomy looking at the human body.

One of Vesalius, these students was a fellow called Fabric IUs,

who's Harvey studied with fabricas took up Vesalius programme

of looking at Galen's works and trying to find errors in

it and to improve our understanding of the human body.

Now FABRICAS is important to Harvey for two reasons.

Firstly, Harvey said that FABRICAS had completed the project of Anatomy

apart from the heart

and it was harvest project,

then to look at the heart and to look at it in great detail and to see if

we could come up with an improved account of

the heart and also of the circulation of the blood

as well.

The other thing that's important here

is that fabricas discovered

little valves

in the human veins,

and these are called Venus valves.

They are little

cups inside the valves,

and when the blood is flowing in one direction,

the blood tends to push these little membranes up against

the walls of the vein and allow blood to flow.

If blood tries to pass in the other direction,

these little valves will

open up and stop the flow of blood

in the direction in that direction so blood

can flow in one direction along the veins.

But these little valves will stop it flowing

in the other direction along the veins.

Now, initially,

it was thought that these valves were organised

to stop blood pooling at the lower extremities of the body.

Effectively, they were gravity oriented. So it's thought that

and these little cups face upwards in the legs

in order to stop blood pooling

at your feet.

And

what Harvey recognised was that that's not, in fact, the case,

and that these little cups are organised cardio centric Lee that is organised

oriented

in the direction of the heart.

And we'll talk about that a little bit more in the next section

when we talk about Harvey's actual discovery of the circulation of the blood.