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0:00
Hello, and welcome back to
The Fundamentals of
Human Physiology.
My name is Jessica Briffa
and I'm a postdoctoral fellow in
the Department of
Anatomy and Physiology
at the University of Melbourne
in Melbourne, Australia.
I'll be delivering a series
of four lectures on
kidney function,
where we'll cover
the basic functions
of the kidney in the
first two lectures,
and then go on to the
mechanisms of sodium and
water reabsorption in
the last two lectures.
0:30
Similarly to what Charles
has done in his lectures,
I've also included
these stop and think
questions throughout
my lectures with
the aim to help you track
how you're doing and set
up some ideas for future
questions and activities.
Let's think about this
basic principle in
kidney function as I run down
the timer and then I'll
give you the answer.
What is urine mostly made of?
If you consider that the
kidneys main function is to
filter waste products from
the blood and balance
your body's fluids,
you'll appreciate that urine
is mostly comprised of plasma.
This is because blood filtration
leads to a mass movement of
water and solutes from the
plasma into the renal tubule,
which goes on to form urine.
Approximately 20%
of plasma volume
is filtered at any given time,
which equates to
around 180 litres
of fluid being filtered
by the kidneys daily.
While this is produced by
the filtration of blood,
no blood is typically present in
the urine unless there's an
underlying health condition.
The mechanisms by which
this occurs will be
described in more details
in subsequent slides.
