0:03 okay so now that we've got that under
0:05 our belt the next thing that we need to
0:08 do is just take a little look at the
0:10 histamine one
0:12 receptor and the reason I say that
0:16 histamine one is because anti-histamines
0:19 work on the histamine one receptor
0:21 recall that there's a histamine 2
0:24 receptor it's the receptor in the
0:27 stomach in the parietal cells remember
0:29 in module one when we were talking about
0:33 the parietal cells there's uh in order
0:37 to secrete the acid the parietal cell
0:39 needs stimulation from a couple different
0:41 different
0:43 neurotransmitters but one of them is histamine
0:45 histamine
0:47 2 but we're not talking about the
0:49 histamine 2 receptor now it's the
0:51 histamine one receptor that we're
0:55 talking about and as we've seen that
0:59 histamine 1 receptor is in the periphery
1:02 but it's all also in the brain we also
1:04 have a histamine one receptor in the
1:07 brain it's a
1:09 neurotransmitter in the brain so it
1:11 doesn't do any of the things that
1:13 histamine does out in the periphery and
1:15 of course that's a really good thing you
1:18 know it doesn't do those things because
1:20 otherwise we'd have brain hemorrhages
1:21 and itchy
1:25 brain well obviously it it doesn't do
1:27 those things because first of all
1:30 histamine receptors in the brain are not
1:32 on the blood vessels in the brain and of
1:34 course the blood vessels in the brain
1:36 are tight junctions the the blood
1:39 vessels have tight junctions rather than
1:41 those loose Junctions that are necessary
1:45 for dilation and increased permeability
1:49 so we don't have that type of of uh
1:52 blood vessel in the brain and of course
1:55 uh histamine cannot actually cause an
1:57 itchy brain because there are no pain or
2:00 itch receptors in the brain so in the
2:02 brain it doesn't do any of the things
2:05 that it does out in the periphery in the
2:08 brain the only role is that of a
2:11 neurotransmitter but it's got two
2:14 different spots if you will uh of it's
2:16 two different responsibilities main
2:19 responsibilities as a
2:21 neurotransmitter so one of the primary
2:24 sites of histamine being used as a
2:26 neurotransmitter in the brain is at the
2:30 vomiting Center if you ever had motion
2:32 sickness it probably you know you
2:33 probably noticed that it didn't come on
2:36 immediately as soon as soon as the boat
2:38 started a rock you probably got a little
2:40 bit more and more nauseous for a while
2:44 and then finally started to vomit well
2:46 what what's happening there what's what
2:48 how is that happening well the
2:51 vestibular portion of the vestibular
2:54 cular nerve starts sending these
2:58 messages to the vomiting Center and the
3:01 way that the message is received is that the
3:02 the
3:04 histamine is one of those
3:06 neurotransmitters we'll discuss the
3:08 other neurotransmitter in just a minute
3:10 um but it's one of the two
3:12 neurotransmitters that is sending that
3:15 message it's basically the messenger
3:18 that says oh more and more um more and
3:20 more motion we're going to have to start
3:23 getting sick now it's one of the two
3:26 main neurotransmitters that are involved
3:29 are involved in that motion sickness so
3:31 given think about this right now and put
3:34 it on the chatboard what do you think an
3:39 ideal motion sickness medication would
3:43 be okay yes an antihistamine but exactly
3:46 what kind what kind of antihistamine
3:49 would be the best or would be the one
3:52 that would be useful yes yes one that
3:54 broke into the bloodb brain Barry and
3:55 what are those are those the first
3:58 generation or the second ones yes the
4:00 first generation
4:03 antihistamines the one that break into
4:06 the bloodb brain barrier and actually
4:09 have that antihistamine effect up there
4:13 at the between the vestibular cck
4:15 between the vestibular portion of the
4:18 vestibular cular nerve and the vomiting
4:22 Center so right there at that point
4:24 there's going to be the anti-histamine
4:27 is going to jump onto those receptors
4:30 and say nope histamine uh you
4:32 neurotransmitter don't get don't bind
4:35 onto these receptors and that of course
4:39 decreases the motion
4:42 sickness the ones that stay out in the
4:44 periphery are going to be pretty much no
4:47 use at all I mean there's a little tiny
4:49 bit that gets into the blood brain
4:52 barrier from even the second generation
4:55 antihistamines the one that the ones
4:56 that quote unquote stay out in the
4:59 periphery well there's a little bit of a
5:02 crossover into the brain very little not
5:07 enough to actually U be effective at
5:10 reducing the nausea and vomiting from motion
5:11 motion
5:14 sickness just by the way just remember
5:17 that there's four different Pathways
5:19 from for motion
5:24 sickness the uh the nausea and vomiting
5:26 from for instance uh when there's an
5:29 actual bug in the stomach when there's
5:31 something that is affect directly
5:34 affecting the nerves in the stomach or
5:37 intestines that's one pathway and then
5:40 there's another pathway that's in the uh
5:43 the toxic uh in the chemo receptor
5:45 trigger Zone there's another pathway
5:48 from the higher brain Center you know
5:50 the kind of nausea and vomiting that
5:53 that you feel oh you just see see a mold
5:55 carcus of something and just get sick to
5:57 your stomach well that's a different
6:01 pathway the only only type of vomiting
6:06 that is going to be addressed by our
6:09 first generation antihistamines is the
6:12 one from motion sickness also there's
6:14 kind of uh some other things that are if
6:17 there's problems in the inner ear then
6:20 that can be affected too so the one
6:23 place that we're going to find histamine
6:25 one in the brain is at that Junction
6:26 between the vestibular portion the
6:29 vestibular cular nerve and the vomiting Center
6:30 Center
6:33 but histamine also has a role in a
6:36 number of physiological functions in the
6:39 brain such as the sleep wake cycle and
6:44 it helps maintain arousal and it helps
6:48 maintain cognition and helps maintain
6:52 memory so if you were to inject an
6:54 anti-histamine or histamine into the
6:56 bloodb brain barrier just before an
6:57 examination which one are you going to
7:00 choose well I mean you know you probably
7:02 wouldn't choose either that's a silly
7:05 scenario but you'd want lots and lots of
7:08 histamine you would want histamine
7:11 before an examination what you don't
7:13 want to do is take an
7:16 anti-histamine before an important quiz
7:19 or examination okay because it affects
7:22 histamine affects and maintains arousal
7:25 cognition and
7:28 memory and the first generation
7:30 anti-histamines are going to break into
7:32 the bloodb brain barrier and affect all
7:36 of those okay so just using what we've
7:39 learned right here with respect to
7:41 histamine what histamine does in the
7:44 brain please answer this question what
7:47 are the side effects and the
7:49 contraindications of
7:51 anti-histamines that go into the bloodb
7:54 brain barrier and you might as well
7:57 start thinking about this one as well
8:00 what are the additional indicat ations
8:02 of antihistamines that go into the blood
8:05 brain barrier so so think of side
8:07 effects Contra
8:10 contraindications and additional
8:13 indications of just think about the
8:14 brain here just about what's happening
8:17 in the brain and what's happening with
8:20 histamine receptors in the brain and and
8:22 say you know what are the side effects
8:24 what would the side effects be you can
8:26 use the chatboard
8:30 no yep yep drowsiness yeah defin
8:33 drowsiness a decrease in memory yep a
8:36 decrease in in cognition
8:40 yep oh actually no we wouldn't call
8:45 reducing nausea a side effect it is one
8:48 of the effects that it reduces nausea
8:51 from motion sickness but it's we
8:53 wouldn't call it a side effect a side
8:56 effect is a secondary typically
8:59 undesirable effect of a drug or or
9:01 medical treatment so so that's a side
9:04 effect yeah we're getting used to those
9:07 terms still getting used to those terms
9:10 but we've identified the ones the main
9:13 ones so the main side effects are going
9:16 to be a decrease in cognition a decrease
9:20 in memory and you're going to be a bit
9:24 drowsy and given that what do you think
9:26 that the first generation antihistamines
9:29 like dyen hydramine would be indicated
9:32 for something else aside what it's used
9:34 for in the periphery what else would it
9:38 be indicated for can anybody think of
9:42 why you would want to be drowsy for
9:45 instance yeah so follow that
9:51 on y yeah insomnia it's indicated in
9:59 contraindications yeah one of the contra
10:02 most important contraindications is
10:04 driving heavy machinery so it's
10:06 contraindicated in people who operate
10:09 heavy machinery and it would also of
10:12 course be contraindicated in some
10:14 professions where the person would have
10:17 to be alert so something like air
10:20 traffic controllers or you know students
10:28 thing and now we're ready for sub
10:30 question three
10:32 so the sub question three is briefly
10:35 explain the side effects and
10:37 contraindications we remember what those
10:39 terms mean side effects and
10:42 contraindications of Dien hydramine uh
10:45 due to its crossing the brain and acting
10:48 on the histamine one receptors I'm going
10:51 to give you just a few minutes U for
10:53 those of you who are listening to this
10:56 on tape uh just U so you'll have to
10:59 actually stop your tape okay I'll
11:02 I I'll cut out the minutes that I'm
11:06 giving the students who are right
11:11 here okay so sub question three will go
11:14 something like well Mrs Meyers Dien
11:16 hydramine and other first generation
11:19 antihistamines easily cross into the
11:22 brain and there they act like
11:24 neurotransmitters on what we call the
11:27 histamine one receptors the histamine
11:31 one receptor is important as a
11:33 neurotransmitter that's involved in
11:35 memory cognition and the sleep wake
11:38 cycle so therefore those first
11:40 Generations the the one that you're
11:43 taking the Dien hyamine is going to
11:44 decrease cognition it's going to
11:48 decrease memory and make you drowsy so
11:51 since uh since they decrease cognition
11:53 and make you drowsy they're
11:56 contraindicated in people operating
11:59 heavy heavy machinery so really Mrs
12:01 Myers you shouldn't be driving when
12:03 you're on those
12:06 medications so you kind of get the idea
12:09 of what we're looking for on that one
12:11 and then what I'm going to do is I'm
12:15 going to jump over to sub question four
12:16 for a
12:20 minute and that sub question is briefly
12:23 explain the indications of dyen
12:25 hydramine that are due to its ability to
12:29 cross into the blood brain barrier and
12:33 remember that this is briefly explain
12:36 the indications so just saying that Dien
12:40 hydramine is indicated for this and this
12:41 because of the fact that it goes into
12:43 the blood brain barrier is not going to
12:46 get you hardly any marks it's that
12:49 explanation that's
12:52 important and I'd answer with something
12:55 to the effect of now Mrs Myers if you
12:57 ever did find yourself needing an
13:00 antihistamine and at the same time you
13:01 needed a little something to help you
13:05 sleep or if you were ever on a boat and
13:08 you needed a medication to decrease
13:11 motion sickness well you could use dyen
13:14 hyamine at that time because what dyen
13:16 hyamine does is it goes into the brain
13:19 and works at the vomiting Center so it
13:22 decreases the messages to tell you that
13:26 you're moving too much it it's a a
13:28 specific kind of nausea the one that
13:32 makes you you sick from motion so it's
13:34 good for that it's not a general
13:38 um anti nausea medication but it also
13:41 works in another portion of the brain
13:44 that's important in the sleep wake cycle
13:47 so that's why it's good for insomnia if
13:50 you have insomnia and allergies at the
13:53 same time it would be good
13:56 then okay so that is pretty much what you
