BIO270H1 Lecture Notes - Juxtacrine Signalling, Hydrophile, Secretion

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Published on 31 Jan 2013
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Wednesday, October 21, 2009
BIO270 Lecture 1
-This is the second half of 270 – the professor is David Lovejoy & he will be teaching us until the end. He is
also the course coordinator for this course. He has been involved in the behind the scenes stuff we
haven’t seen him but the subtle hand of activity has been involved.
-Just before he starts the class, we are getting an overview of the next 6 weeks & there are a few things he
wants to get through.
-He’s asking about the midterm. The class average (unofficial) was 67% which statistically is where the
cohort should be. Every once in a while there is an anomaly where we have really high marks or years with
low marks but this is exactly where it has been – the worst year was around 50%. He doesn’t have anything
to do with that midterm so we talk to Dr. Forder if we have problems unless there is a really serious
problem, but if there are no serious problems then she looks after it.
-The final exam which this year is interesting because it will only be on the second half of the course, on
Lovejoy’s lectures. He was going to offer to put in other questions if we thought his stuff was boring. The
class average for his section is consistently higher than 67, but it’s not 95 so however he tries to make this
as painless as possible & hopefully we learn something, to get us excited about the next section.
-He’s joking about how hormones can affect personality change when some guy in the audience made
gorilla sounds. He has a course in the 4th year called endocrinology of transformation & it’s about how
hormones can change an individual.
-A couple of other housekeeping issues. We had our lab reports & they’re going to be handed back in the
next week or so & there was a bit of an issue he wants to bring up about 10% of the lab reports received
has material on them from previous lab reports. This happens in every university but it’s considered a form
of fraud. Those lab reports are going to be scrutinized much closer so please don’t do that. We are free to
get info from wherever we want but rules & regulations of this course say that this is considered an
unauthorized teaching aid. We shouldn’t do that & it makes everyone’s lives easier & the last thing they
want to do is to grill us in a backroom which they had to do occasionally.
-There were only 200 when he started the course years ago we’re proliferating. He is asking why we’re
taking this course so how many are interested in graduate work, how many want to pursue a career in
medicine, business & law, etc.
-His day job is a professor; his night job is operating a biotech company. Apparently he got “picked up” by
a prof & stuck into a graduate program.
-The number is for an absolute emergency. The person we’re dealing with on a regular basis are the TAs
we go to them first, the second person is Peggy Salmon who handles logistics for this course & he is the
coordinator but Salmon does all the real work. If the problem is so big of an issue then we can see him – he
has office hours but he will be holding them posted on blackboard.
-Somebody asked him if the lectures will go up – the lectures should be up, the entire set should be up. This
is the first year they got them all up before the class began.
-His office hours will be from 11 to 1 on Wednesdays so we can come & talk about issues – they are usually
referred to I’m having difficulty with the subject material, other issues can be talked about so select issues
wisely. There were 500 students last year & only 7 students showed up for these office hours over the 6
week period, but everyone did well so everyone probably understood the subject material at least he
assumes.
-This brings us to the subject material. He wants to ask another question, & it’s about Professor Forder. He’s
asking how many thought she did a good job, he is now making excuses for her, & we haven’t seen the
exam yet.
-What he will be talking about is endocrinology in the big scheme so a little bit about his background – he is
an endocrinologist, he started off as a comparative endocrinologist & his laboratory & research over the last
20 or 30 years encompasses everything from genes to behaviour to even some ecosystem work. He worked
with a variety of species: flies, worms, Tunicates, starfish, & just about every vertebrate class so he wants
to think that he is reasonably comfortable with it. Now he’s doing clinical work as well so things have
expanded. He is looking at it in terms of pure discovery & in terms of applications as well, so it has been a
very fun ride, a lot of fun. Now one of the things that really struck him with endocrinology.
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-He is telling us a story – he has a friend who is a punk rocker, this guy is older – we imagine the geezer on
stage & he is also a university professor as well which is scary. He met him a number of years ago after a
long period when they didn’t talk. He told him he was doing endocrine research & he looked at our prof &
said GLANDS, GLANDS. But that reflected the historical understanding of what endocrinology was
there was no concept of endocrinology really until the first glands were discovered & what a gland was.
There were these ductless secretions that came out of glands & that was called endo-for internal secretions
& so that is where the word came from.
- So we’re going to use the word endocrinology in a couple of different
contexts. On one hand, we will talk about it really as an internal secretion
so something from the pancreas that is released to the blood. Insulin
comes to mind we can’t possibly go through U of T without learning
about insulin but it is a good example of a hormone.
- Endocrinology, because that was the first thing that was discovered,
those ductless secretions, those internal secretions, because they were the
first things that were ever discovered. It has gone on to mean a whole
gamut (series/range) of different secretions. So we also talk about
autocrine, paracrine, intercrine type secretions & juxtacrine which is the
newest -crine that has been added. But each of those has different
meanings, very discreet meanings. We think of endocrinology as a very
discreet thing but also encompassing the entire field as well.
- One of the things that is really interesting about endocrinology he thinks
is the communication system. First & foremost it is a communication
system these hormones exist because they have to convey information
from one cell to another cell. So we know a little bit about the brain the
brain sends out all these various nerves to certain areas but it is impossible
for the brain to send a nerve to every single cluster of cells, it just can’t
happen. The brain uses not only nervous connections but it also uses what
are called neuroendocrine secretions which we will talk about. But how do
all of those other tissues in the body communicate back to the brain? The
brain says okay look, muscle do this, look pancreas I want more insulin or
whatever. But those tissues then have to feed back to the brain but not just
the brain, it has to tell everything what is going on.
- Imagine you’re in a community & you have a bunch of nosy neighbours
& they’re all looking through your window & asking so what is going on,
did you know this person got gout? Cells need to do the same thing – they
need to know what their neighbours are doing, they need to know what the
head honcho, the brain, is doing & so the only way they can communicate
is by releasing these chemical messengers. There are hundreds if not
thousands of these things, tens of thousands of these things from many,
many different classes & every cell in your body is bathed in these things.
- Some of these hormones are more potent than others. His field of
research which is involved in designing new hormones is all about tricking
cells into thinking that they’re supposed to be doing something else.
They’re not doing what they’re doing so we’re going to trick them into
doing something else. Just by manipulating these chemical factors can
have a profound effect on the organism – it can change the developmental
profile allowing them to develop into something very different. In
humans, can change personality entirely – it is very profound & the secret
is presumably to keep these things balanced.
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- Having said all that, this is what we’re going to be covering. Now these
lectures have been laid out as 8 lectures. Some of us may be panicking, &
doesn’t he know there are only 6 classes left? Yes, he does know that.
Lectures are based around subjects & not around time constraints so some
of the lectures are a little short, some are a little bit long so there won’t be
a day-to-day correspondence of each lecture. Lecture 2 will follow lecture
1 & so on & so forth.
- However we will get through all of the material – if we don’t get through
all the material then we won’t be responsible for material he didn’t cover
since we won’t be punished for his inabilities.
- He will just tell us that upfront because around December, people panic
& say Dr. Lovejoy, you haven’t covered this or that topic if it’s not
covered then it is not on the test; if the test is already made up, he will tell
us to ignore those questions. There is a certain reason for how this is laid
out.
- The other thing he wants to say is that these lectures correspond exactly
to what is in the text, & he added extra material to help us understand
what is in the text. The exam, the questions will be based on his lectures
which follow the text & the text material. Now we’re starting to get a little
bit of sophistication in knowledge. Some professors love to discuss
conceptual things, some professors love to go into the nitty gritty detail so
students are trying to figure out whether to focus on concepts or details
he is in the middle, & his details are related directly to the questions. One
of the things he will not be asking are small niggly details we wouldn’t
even learn as a scientist, for example which version of the alpha receptor
is responsible for communicating with cyclic AMP in glucagon, when the
animals are in the dark phase or something like that. He won’t ask
questions like that but questions he may ask are: what are the 3 subunits of
a G protein coupled receptor? Those are basic things we should know. It
will seem more obvious as we go on.
- This is laid out in what he thinks is a logical way of going about it.
Today we will be talking about hormones & just what are they, some of
the structural classes & how they work, so basic things. Then we explore
what they look like & how they act, how they do their thing. How do they
turn on cells, how do cells get excited about it? Once we have that basic
concept, we will talk about different circuits; there are a number of
different circuits that are out there. He wants to think of the first 3 lectures
as structural elements of endocrinology & they’re applicable to any field,
any physiology this will be practical for. After that, once we’ve got that
we dive into reproductive endocrinology why do we do that? Well
because we have a reproductive endocrinology lab so we try to do it
earlier as opposed to later.
- Now he’s asking when the lab is. We’re going to talk about steroids
today. Then from there we start looking at energy metabolism this if
anything reproductive endocrinology & if we look at the textbook
reproductive endocrinology tend to go at the end of books since they’re
complex but we won’t go into that kind of complexity – there are plenty of
courses that are offered if we’re interested.
- He used to teach a third year course called endocrinology (endocrine
physiology) it is still on the books, it’s going on as we speak & some
people may be taking it. It’s a very different course, he doesn’t lecture
anymore & then he does a fourth year course which does have a fair
amount of reproductive endocrinology. Our third year course, we used to
cover a number of things in detail about reproductive endocrinology &
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