Autonomic Pharmacology (Ar) - Lec 02 - Adrenergic Receptors
Summary
TLDRThis educational video script delves into the intricate world of adrenergic receptors, highlighting their crucial roles in the body's sympathetic system. It explains pre-synaptic and post-synaptic receptors, the concept of second messengers, and the unique functions of different adrenergic receptors, such as Alpha 1, Alpha 2, Beta 1, Beta 2, and Beta 3. The script provides insights into how these receptors influence various physiological processes, from muscle contractions to heart rate, and discusses the implications for medical treatments, including the development of selective drugs targeting specific receptor subtypes.
Takeaways
- đ§ Pre-synaptic and post-synaptic receptors are distinguished by their location relative to the synapse, with pre-synaptic receptors regulating neurotransmitter release from the neuron and post-synaptic receptors receiving the signal on the target cell.
- đ The concept of second messengers is crucial as they are intermediaries that help receptors perform their functions, except for ion channel-linked receptors like the nicotinic acetylcholine receptor, which produce immediate outcomes without them.
- đ Adrenergic receptors are significant, with 70% of all receptors in the body being G protein-linked receptors, including the adrenergic receptors discussed in the script.
- đ Alpha-1 receptors are primarily associated with vasoconstriction in blood vessels, but they can also cause contraction in the uterus and dilation of the pupil, with the exception of causing relaxation in the gastrointestinal tract and urinary bladder due to the presence of a specific potassium channel.
- đ Alpha-2 receptors are predominantly pre-synaptic, regulating the release of norepinephrine and contributing to a calming effect, with over 90% of them located on nerve terminals.
- â€ïž Beta-1 receptors are most notably found in the heart, where they increase cardiac properties, making them potential targets for drugs treating arrhythmias or tachycardia.
- đ Beta-2 receptors are vital for the 'fight or flight' response, increasing blood flow to muscles, facilitating neuromuscular transmission, and causing bronchodilation, among other effects.
- đïž Beta-3 receptors are mainly found in adipose tissue, where they stimulate lipolysis, breaking down fat cells, but their uneven distribution makes them less useful for weight loss therapies.
- đ The activation of beta receptors increases cyclic AMP (cAMP) within cells, which then triggers various cellular responses depending on the specific enzymes and effectors present in different tissues.
- đ The development of drugs targeting specific subtypes of receptors, such as Alpha-1D for urinary retention without affecting blood pressure, highlights the importance of receptor specificity in minimizing side effects.
- đ Understanding the subtypes and functions of adrenergic receptors is essential for medical professionals to make informed decisions about treatments and potential drug developments.
Q & A
What are the two main concepts introduced at the beginning of the script?
-The two main concepts introduced are pre-synaptic and post-synaptic receptors, and the term 'second messenger' in the context of adrenergic receptors.
What is the difference between pre-synaptic and post-synaptic receptors?
-Pre-synaptic receptors are located on the neuron or nerve terminal that releases the chemical transmitter, and their function is to regulate the release of transmitters. Post-synaptic receptors are located on the receiving cell or tissue and are responsible for the response to the transmitter.
What is a second messenger in the context of cell signaling?
-A second messenger is a molecule that is part of a signaling pathway and is activated by a primary messenger, such as a hormone or neurotransmitter. It often functions within the cell to amplify the signal and trigger a cellular response.
What is unique about the nicotinic acetylcholine receptor compared to other receptors?
-The nicotinic acetylcholine receptor is unique because its activation can lead to an immediate outcome without the need for a second messenger. It is an ion channel-linked receptor that, when activated, opens a gate allowing sodium ions to enter, leading to depolarization.
What percentage of receptors in the body are G protein-linked receptors?
-Approximately 70 percent of the receptors in the body are G protein-linked receptors.
What are the five common types of adrenergic receptors that adrenaline or noradrenaline can act upon?
-The five common types of adrenergic receptors are Alpha One, Alpha Two, Beta One, Beta Two, and Beta Three.
What is the primary function of Alpha One receptors in blood vessels?
-The primary function of Alpha One receptors in blood vessels is to cause vasoconstriction, which narrows the blood vessels.
How does the activation of Alpha One receptors lead to vasoconstriction?
-Activation of Alpha One receptors leads to the activation of G protein (Gq), which increases inositol trisphosphate (IP3) levels, resulting in increased calcium levels. This increase in calcium causes contraction of the blood vessels.
What is the primary location and function of Alpha Two receptors in the body?
-More than 90 percent of Alpha Two receptors are pre-synaptic, primarily located on nerve terminals, where they regulate the release of neurotransmitters, often inhibiting their release.
What are the main functions of Beta Two receptors in the body during physical activity, such as running?
-Beta Two receptors are responsible for vasodilation in skeletal muscle blood vessels, facilitation of neuromuscular transmission, increasing potassium stores in muscles, bronchodilation, increasing blood glucose levels, and adjusting intraocular pressure during changes in external air pressure.
Why are Beta 3 receptors not ideal for treating obesity despite their role in lipolysis?
-Beta 3 receptors are not ideal for treating obesity because they are not evenly distributed throughout the body. They are more prevalent in the upper half of the body and face, and less so in areas like the belly, which limits their effectiveness in uniformly reducing body fat.
What is the common second messenger activated by all types of beta receptors?
-The common second messenger activated by all types of beta receptors is cyclic AMP (cAMP).
How do beta receptors, despite increasing cyclic AMP, result in different cellular responses?
-Different cellular responses occur because the increase in cyclic AMP activates different protein kinases and subcellular components depending on the cell type, leading to varied effects despite the common second messenger.
Outlines
đ Introduction to Adrenergic Receptors
The script begins by introducing the topic of adrenergic receptors, emphasizing the importance of understanding pre-synaptic versus post-synaptic receptors and the concept of second messengers. It explains that pre-synaptic receptors regulate the release of neurotransmitters from the neuron or nerve terminal, while post-synaptic receptors are found on the receiving cell and are influenced by the neurotransmitter. The script also highlights the unique role of ion channel-linked receptors, such as the nicotinic acetylcholine receptor, which produce immediate outcomes without the need for second messengers.
đ Exploring Adrenergic Receptor Subtypes
This paragraph delves into the different subtypes of adrenergic receptors, including Alpha 1, Alpha 2, Beta 1, Beta 2, and Beta 3. It clarifies that 70% of receptors in the body are G protein-linked receptors, which act through second messengers. The paragraph also discusses the specific functions and locations of Alpha 1 receptors, such as causing vasoconstriction in blood vessels, contraction in the uterus, and dilation of the pupil in the eye. It mentions the subtypes of Alpha 1 receptors and their distinct roles in different tissues.
đ The Role of Alpha 1 Receptors and Second Messengers
The script explains the molecular mechanisms behind the actions of Alpha 1 receptors, focusing on their activation of G protein (Gq), which in turn increases inositol trisphosphate (IP3) and calcium levels. This increase in calcium leads to contraction in various tissues, such as blood vessels, the uterus, and the radial muscles of the eye, resulting in mydriasis. However, in the gastrointestinal and urinary tracts, the presence of a calcium-dependent potassium channel leads to relaxation instead of contraction when Alpha 1 receptors are activated.
đĄïž Alpha 2 Receptors: Pre-Synaptic Inhibition
This section discusses the role of Alpha 2 receptors, which are predominantly pre-synaptic and function to regulate the release of norepinephrine. By inhibiting the release of neurotransmitters, Alpha 2 receptors have a calming effect on the body. The script suggests that drugs that activate Alpha 2 receptors can be used to treat anxiety and stress by reducing the release of norepinephrine, leading to a more relaxed state.
đââïž Beta 2 Receptors: Enhancing Performance
The script highlights Beta 2 receptors as essential for enhancing physical performance during activities like running. Beta 2 receptors increase blood flow to muscles, facilitate neuromuscular transmission, and promote potassium shift from the blood into muscle cells. They also cause bronchodilation for easier breathing and increase blood glucose levels for energy. Additionally, they are involved in the secretion of aqueous humor in the eyes, which is crucial for maintaining intraocular pressure during activities that increase air pressure on the eyes.
đ€° Beta 2 Receptors in the Uterus: Protection During Stress
This paragraph explains the protective role of Beta 2 receptors in the uterus during times of stress. Beta 2 receptors cause uterine relaxation, which can prevent the risk of abortion if a pregnant woman experiences fear or stress. The script also touches on the potential side effects of Beta 2 receptor activation, such as tremors due to facilitated neuromuscular transmission, which can be mitigated with beta blockers.
đ„ Beta 3 Receptors: Fat Melting Controversy
The script addresses the misconception about Beta 3 receptors and their role in fat melting. While Beta 3 receptors do induce lipolysis in adipose tissue, their uneven distribution in the body limits their potential for weight loss. The paragraph clarifies that stimulating Beta 3 receptors would not result in uniform fat loss across the body, which is why there are no Beta 3 agonists among drugs treating obesity.
đŹ Beta Receptor Function and Cyclic AMP
The final paragraph wraps up the discussion on adrenergic receptors by explaining the common second messenger activated by all Beta receptors, cyclic AMP (cAMP). It clarifies that the different functions of Beta 1, 2, and 3 receptors are due to the specific enzymes and effectors activated by the increased levels of cAMP in their respective cells. The script emphasizes that the ultimate effects of receptor activation are determined by the subcellular components that respond to the second messenger.
Mindmap
Keywords
đĄAdrenergic receptors
đĄPre-synaptic and post-synaptic receptors
đĄSecond messenger
đĄNicotinic acetylcholine receptor
đĄG protein-linked receptors
đĄAlpha-1 receptors
đĄBeta-2 receptors
đĄBeta-3 receptors
đĄCyclic AMP (cAMP)
đĄVasoconstriction
Highlights
Introduction to adrenergic receptors and the importance of understanding pre-synaptic and post-synaptic receptors.
Explanation of the concept of second messengers in the context of receptor function.
Distinction between pre-synaptic receptors regulating neurotransmitter release and their unrelatedness to the function of the target tissue.
The unique role of nicotinic acetylcholine receptors as the only type acting without a second messenger for immediate response.
Overview of the four main types of adrenergic receptors and their prevalence, particularly the dominance of G protein-coupled receptors.
Detailed discussion on Alpha 1 receptors, their subtypes, and their effects on various body parts such as blood vessels and the eye.
The role of Alpha 1 receptors in causing vasoconstriction and the underlying mechanism involving G protein and calcium levels.
Exception to the rule: Alpha 1 receptors causing relaxation in the gastrointestinal and urinary tracts due to the presence of a specific potassium channel.
Alpha 2 receptors' predominant location on pre-synaptic terminals and their regulatory function on norepinephrine release.
The therapeutic use of drugs that activate Alpha 2 receptors for calming effects and potential applications in treating anxiety.
Beta 1 receptors' significant impact on cardiac function, including increasing heart rate and contractility.
Beta 2 receptors' multifaceted role in facilitating physical activity, including vasodilation in muscles and bronchodilation.
Beta 2 receptors' contribution to muscle performance by increasing potassium levels within muscle cells and its side effect of hypokalemia.
Beta 3 receptors' specific role in adipose tissue and the scientific understanding of their distribution affecting the potential for weight loss therapies.
The common second messenger, cyclic AMP, utilized by beta receptors and the varying effects due to different cellular responses.
Final concepts on the diversity of adrenergic receptor functions and the complexity of their interactions at the subcellular level.
Transcripts
hello everyone we will specify this video for illustration of adrenergic receptors before I
start explaining this adrenergic receptors I want to mention two concepts the first concept I want
you to know is pre-synaptic receptors versus postsynaptic receptors what does pre-synaptic
and postsynaptic mean because you will hear about these terms very often while you study number two
we want to discuss a term called second messenger what the second messenger mean let's start with
the first concept pre-synaptic and postsynaptic consider this any nerve fiber this is the nerve
body and it's connecting to another nerve body anywhere either in CNS or prayfully if there is
a receptor present here let's call it Alpha 2 or beta2 and if the same receptor is also
present here Alpha 2 and beta2 remember that this attachment or the space here is called
synapse which of these are called postsynaptic and which are pre-synaptic look at the direction
of the chemical transmitter from where it comes and to where it goes if the chemical transmitter
is moving in this direction from the sill to this one or let's assume this is a tissue instead and
this is a nerve terminal and signal is moving in this direction then the receptors present
on the neuron or nerve terminal which releases the transmitter is called pre-synaptic pre because the
space is called synapse and it's located before so it's pre-synaptic on the same principle the other
receptors present on the cell or this tissue are called postsynaptic this is for the terms pre-ampo
synaptic okay now before we dwell into details may I ask you does this presynaptic receptor has in
anything to do with this tissue or its function is only about its own nerve cell its function
stops in here so the spray synaptic receptor present on any nerve terminal or any neuron
releasing transmitters if you say pre-synaptic then you'll mean that its only function is to
regulate the release of transmitters from this nerve terminal or this cell releasing transmitters
however it has nothing to do with the tissue itself or the responder on the other hand if
we say that the transmitter is released from here to here in this direction this is the receptor is
called pre-synaptic and this one is a postsynaptic to avoid any confusion if you hear the term
pre-synaptic receptor from now till we finish all of the lectures when you hear pre-synaptic
then it means these are the receptors located at presynaptic membrane its function is to regulate
transmitters release so some of them increase others decrease as we will see now for now if
you hear pre-synaptic then its function is not in the tissue but it's too regulate transmitter's
release this is the first concept second one is something called second messenger naturally we
will specify a huge part in general pharmacology chapter only for receptors we will discuss them
in detail but for now at least you know most of the receptors are present on cell membrane
if this is a cell then the receptor is here on cell membrane the receptor doesn't ever perform
any function when it bind to its Agonist it can only act through something called second messenger
the second messenger might be a g protein it might be a kinase protein kinase it might be tyrosine
kinase and so on or this receptor might be working through ION channel in other words there is no
receptor working directly like this except for focus on this one except for only one type of
receptors its activation can lead to immediate outcome do you know which one this might be let me
remind you do you remember ganglia from the post video this ganglia contains acetylcholine when
released it opens a gate do you remember its name this gets called nicotinic acetylcholine receptor
this receptor here called nicotinic acetylcholine receptor is the only type of receptors which by
its activation the gate opens resulting in sodium ion influx leading to depolarization of tissue so
the only type producing immediate outcome and acts quickly without second messenger
is this type called ION channel linked receptor if you have any skill question State on this
the only type of receptors that has no second messenger then it is the first type of receptors
naturally we will explain all of this in detail on General chapter but for now at least you have an
idea about it so it is the first type called iron Channel LinkedIn receptor except for this one any
other type of receptors X through second messenger now how many types of receptors are present
in your body you have four types I won't discuss them in detail now however you should know that 70
percent offers receptors in your body 70 percent of the overall number of receptors present inside
your body are something called G protein LinkedIn receptors so 70 percent of receptors inside your
body are G protein linked receptors like this one we are explaining in this video which is
adrenergic receptors all of the other energy receptors are G protein LinkedIn receptors [Music]
don't forget this 70 percent receptors we have are G protein LinkedIn receptors acting through
second messenger the second messenger might be a geoprotein protein kinase ION channel or whatever
this is the second concept let's now talk about the types of adrenergic receptors and discuss
them in detail in the past video physiology introduction I told you that adrenergic system
or sympathetic System main transmitter is more adrenaline or nor epinephrine and when it is
released it can affect or activate five types of receptors first type is Alpha One Second times
Alpha two third is beta1 fourth is beta2 and the last one is beta 3. those are the five common
types of adrenergic receptors that adrenaline or noradrenaline can act on and as I told you
any tissue has one type of this as predominant one it it may indeed have more than one type
but only one is the predominant exert in the most Market influence let's talk about this Alpha One
firstly discussing its sites functions and its second messenger which type of second messenger
this Alpha One before anything you should know that recently there is nothing called Alpha One
anymore it's divided into subtypes we now have subtype a b d and there are more but only keep
these three in mind Alpha 2 is divided into a b and c we can no longer say Alpha One and stop
instead we say that a certain tissue has Alpha One a specifically they are slightly different
from another tissue with Alpha 1D and so on the first and the most important side for
this Alpha receptor is blood vessels most of blood vessels you have contain Alpha and its
activation results in vasoconstriction if you want to be more scientifically exact it is one alpha a
specifically most blood vessels contain Alpha 1 a receptor its function is vasoconstriction
number two is the uterus Alpha receptors in the uterus also cause contraction however it's
somehow weak in there so I don't want someone to say that we can make use of this receptor to
induce an abortion in a pregnant woman it does cause contraction but not so strong that it
could lead to abortion consider this effect to be theoretical theoretically it can cause contraction
third side is the eye he is the eye this is the pupil here is something called radial muscles
that you call dilator pure Pele this is a little pupily contain Alpha One when it is activated it
leads to contraction note that alpha 1 is always causing contraction or constriction and you will
see the reason when this Alpha is activated in the eye it leads to contraction of the radial
muscles of the eye so the pupil dilates and when the pupil dilates it's called mydriasis as you
know from physiology when someone experiences sympathetic stimulation his people must dilate
for a better Vision in order to face the danger fourth site for all sound receptors this is git
and this is a urinary tract let's talk about them as one in both of them we always have a hole and
we always have a sphincter Alpha One if it's found in the wall then it causes relaxation and
this is an exception because I told you although causes contraction if it's found in the wall of
the urinary system it also causes relaxation but in sphincters it causes contraction if you
want to be more scientifically exact here in this sphincter we have Alpha One a and Alpha
1D so in this sphincter we have Alpha One a and the cause and contraction why are we saying this
that's because when we discuss the drugs I'll tell you that whenever you invent a drug it's
better to Target only one specific subtype why because if you want to act on blood vessels only
then you should Target Alpha 1A if you want to act on sphincter you have Alpha One A and E then
you should choose a drug that acts on Alpha 1DÂ considering that this subtype is not very common
except in sphincters so if you have a patient complaining of hearing retention which one is
accused of course it is the alpha receptor so we should give him Alpha blocker when we
block this Alpha receptor the sphincter opens and urine come out and the post we used to do
this not very far in the past but about 20Â years ago when someone complained of hearing
retention we used to give him Alpha blocker do you know what did these people complain
of these patients who received alpha blockers complain firstly of dizziness do you know why
was he dizzy it's simple as you can see when IÂ give him Alpha blocker to block Alpha here which
was responsible for sphincter contract action and urine retention this Alpha blocker I gave
it to the patient was non-selective so it looked Alpha here and it did solve this problem however
it also blocked Alpha receptors and blood vessels leading to loss of vasoconstriction resulting in
low blood pressure so if you are smart enough and you want to invent a drug that only acts on
the sphincter without affecting blood pressure the new inventor drug that blocks only Alpha 1D
why this Alpha 1D we cause its present only in sphincters blood vessels doesn't have Alpha 1D
this is the progress in medicine and these are the new drugs but don't mind with their names now
I only want to show you how important subtype functions can be a new subtype discovery means
that a new drug is on the way which is more selective this High selectivity decreases its
side effects on other tissue these are most of the parts in your body that contain Alpha
receptors there is only one place left which we don't care about that much but let's have
a quick Glimpse on it anyway do you remember in the past video when I told you about sweat glands
do you remember the autonomic supply of sweet glands is it sympathetic or parasympathetic yes
they are supplied by sympathetic system but when IÂ told you although they are supplied by sympathetic
their transmitter is acetylcholine that's why we called the nerves applying these sweat glands
sympathetic cholinergic so The receptors in this glands should respond to acetylcholine accordingly
they are not supposed to belong to this family of adrenergic receptors however some of the sweat
glands especially those in the palms and forehead still obey the rule in other words they are
supplied by sympathetic and their nerve endings released nor adrenaline and the responders that
respond to it and make your hand and foreign so we have two types of sweet glands in our body one
that's cholinergic and this is the most common all over the body and one that's adrenergic present in
the forehead and the Palms because its nerve is sympathetic release another adrenaline which acts
on Alpha One again if we want to enumerate the size of Alpha One receptors they are present in
blood vessels causing vasoconstriction they are present in the uterus their effect is weak but
still contraction they are present and the radial muscles of the IV cause contraction but be aware
of this for McQ they don't cause contraction of the pupil they indeed cause contraction but
not for the pupil they cause contraction of the radial muscles of the eye they are also present
in the role of git and urinary tract causing relaxation they are present in the sphincters
causing contraction we are missing only one thing which you may be wondering about now [Music]
in all of these places why do alpha 1 receptors cause contraction everywhere except in the role
of git and urinary tract where they cause relaxation here we need to return to the
concept of second messenger that I told you about at the start of the video this is explained by
second messenger regarding Alpha One if this is a sill and this is Alpha 1 receptor present on
cell membrane when it's activated it activates something called G protein queue time we have
three types of G protein and maybe there are more than just three as you know from biochemistry we
have three types of G protein g stimulatory g inhibitory and third type is called GQ is short
for query or questionable when this GQ works it increases something called inocetyl triphosphate
or ip3 and when ip3 increase it increases calcium you know from physiology that this calcium is an
incinerator calcium never acts for the sake of common good it's never possible for calcium to
increase causing relaxation increased calcium level in any cell if that cell was contractile
it leads to contraction this is why blood vessels contract you know that when alpha
one works it leads to vasoconstriction this is explained on the molecular level by these steps
Alpha One activation turns on GQ increase in ip3Â level which increases calcium level this increased
calcium and the reason behind vasoconstriction okay so much so that when we want to induce
relaxation in any tissue we use drugs I'll tell you about later they are called calcium channel
blockers calcium blockers because you know that the calcium always leads to contraction but then
what drives gltm urinal bladder to deviate from this rule it's suppose that the alpha activates GQ
increase in ip3 includes in calcium do you know why Joy can urinal Builder rules deviate from
the rule it's very simple reason if we assume this to be a sill from git wall when calcium
level is increased within the cell of git wall it opens a certain type of potassium Channel called
calcium dependent potassium Channel originally increased calcium level leads to activation
of a certain enzyme called don't bother with the name but anyway it's called myosin light
chain kinase this myosin like chinkinis is the one causing contraction however
in the whole of the git and urinary tract this enzyme is absent instead there is a
certain potassium Channel when calcium level is increased it opens this type of potassium
Channel and you know what when potassium channels open this cell is somehow paralyzed
this cell now is paralyzed and this paralysis in medical terms is called relaxation again
if some examiner wants to intimidate you you're an oral exam like this dear student can you tell
me why doesn't this Alpha have any good intentions tell him indeed it doesn't because it always cause
contraction he will then ask you but why tell him because it turns on GQ and GQ increased
ip3 leading to increased level of calcium if he wants to pressurize you further he would then ask
you and what does calcium do tell him it acts on enzyme called myosin lyching kinase causing
contraction he would then say but I think it can cause relaxation git and urinary bladder rules
tell him that this is right because the rules doesn't have this enzyme instead they have a
potassium Channel called calcium dependent potassium channel that opens in response to
increased calcium leading to hyperpolarization of the wall resulting in relaxation for now this is
all what we need to know about this Alpha so let's start discussing alpha 2. alpha 2 is too kind
that it won't take too much time I'll only tell you one word and leave you to your own devices
if I tell you that most of Alpha 2 in your body more than 90 percent of this Alpha 2 distributed
in your body or pre-synaptic that's it I'm saying no more I'm leaving you to your own devices what
does pre-synaptic mean it means it's present on the nerve terminal if this is a nerve terminal and
this is a tissue and this is synapse does alpha 2Â act on tissue or on its nerve terminal of course
on the nerve terminal its function is regulatory as I told you before and this Alpha 2 is nearly
always opposite of alpha one this one was far from good always contraction and so on on the
other hand this one is inhibitory it decreased lower epinephrine release calming you down
patience relax humans relax who in the nervous one he is the one with malfunctioning Alpha 2
and since Alpha 2 is malfunctioning then this one is releasing more than enough norepinephrine
such conditions when someone complains of always feeling nervous and you want to calm him down give
him a drug that activates Alpha too we invented drugs for this purpose to activate this Alpha
too for example if a drug addict came to us now he has repented open the cigarette booth
and he is no longer taking drugs he may come to you complaining of an anxiety and tension
in this situation if you want to calm him down you tell him that instead of taking substance
for relaxation stop this and I'll give you a drug that stimulates Alpha 2 receptors
when I stimulate your Alpha 2 and the brain and peripheral nerves it's a pre-synaptic receptor
that decreases nor epinephrine release so you will be calmer and more relaxed this is the best use
of these drugs that activates Alpha 2 and we call them selective Alpha two agonists or stimulants we
have Alpha 2 and many other tissue it's also present postsynaptic but it's somehow weak
I told you that more than 90 percent of them are pre-synaptic for regulator nor epinephrine release
decrease in norepinephrine release okay now let's shift to betalon beta1 is the commander of the
heart so that it's called cardiac beta1 its most well-known place is the heart and its activation
leads to increase all of the cardiac properties count with me from heart rate to automaticity
rhythmicity contractility and so on it increases all of the cardiac properties and when you have a
patient complaining of arrhythmia or tachycardia this bet alone could be responsible for this
then you have to give him a beta blocker until now we don't know if it has subtypes or not let's hope
to discover its subtype soon I'm sure it has subtitles but this is not important for you so
Peter 1 is present in the heart not only there but it is also present in the kid D if you want
to Target this beta 1 in the heart search for its subtypes and invent a drug targeting them
in order to be more selective those are the most well-known places for beta1 it's present in the
kidneys and it's present in the heart this beta one is also present in liposites or adipocytes fat
tissue cells however beta 3 is the predominant type there so if someone asks you whether your
adipose tissue have bitter one then the answer is yes but when we talk about adipocytes or fat
cells it's always the beta 3 that has the most of the effect there it is their specialty the
playground of beta 3 is adipocytes if betalon is mentioned just don't forget it's present in the
heart and in the kidney this is all what I want you to know now beta2 beta2 is called the kind
beta2 why the kind by the way receptor is taken number two are always kind and considerate and
receptors taken number one are almost always Rogue now why are beta 2 called the coin beta2 because
it's the one responsible for running this is the hero 7u when God forbid a dog chases you or while
you are climbing the stairs perish the thought a habit cat runs into you in the dark this beta 2
is the one saving you on such occasions in Egypt when we Face something terrify we say that Ronin
is half of their carriage and this beta2 is the one responsible for this carriage's half but why
number one if I am facing a threat and I need to run away what is the first thing I need it
is skeletal muscles correct I need skeletal muscle cells so this beta2 dilates your blood
vessels present in skeletal muscles to give them more blood so you can run do you know why it's
because if beta 2 didn't do this Alpha One would cause vasoconstriction and this is very bad if you
try to run you would have a cram however this beta2 prevent this one from affecting skeletal
muscles skeletal muscles blood vessels are dilated under the effect of beta 1 not only this but do
you remember when I told you that skeletal muscles have nerve endings releasing a style
cooling do you remember the name of the receptor respondent for acetylcholine from the post video
it's a gate called nicotinic acylcholine receptor muscular type do you remember this word this one
is supposed to be acetylcholine then what is the rule of beta2 beta 2 makes this receptor
cool nicotine cell cooling receptor become more sensitive to acetylcholine why we need it to be
more sensitive so we can run quickly so we can depend on our muscles this is the term that you
read and wonder about its meaning this is called facilitation of the neuromuscular transmission
this term means that beta2 increases blood flow to the muscles and also makes this receptor that
respond to a style cooling become more sensitive resulting in a quicker and better response these
are two functions within the muscles still we have a third one but before the third one let me remind
you with something you had in physiology in order for a cell to have action potential one sodium ion
gets inside for exchange of one potassium ion you call this action potential and depolarization now
in order for muscle to contract cause a muscular contraction shouldn't sodium get inside cells
potassium get out and this process occur very rapidly so we can run but if you don't have
potassium in your muscles can you run if potassium stores in muscles are low can you start running
sodium get inside muscle cells cause interpolarization but it wouldn't find
potassium to get out for exit change this can result in disruption of the action potential and
this is the rule of beta2 receptors these beta2Â receptors Drive potassium ions from blood into the
cells causing something known as potassium shift it quickly draws potassium ions from the blood
and push them inside muscle cells so they have sufficient potassium stores for Action potentials
facilitate muscle contraction muscle contracts quicker without fatigue they increased potassium
levels in cells but they decreased its level in the blood resulting in hypokalemia potassium is
not sufficient in the blood be careful not to mix these effects with each other I want you to
understand when I tell you how does beta 2 affect potassium if you say it causes hypokalemia you're
right although it didn't mean to cause hypokalemia beta 2 didn't intend to cause hypokalemia
specifically it only intends to increase potassium ions inside the muscles so it draws them from
Blood In other words beta 2 had good intentions it only wanted to facilitate muscle contraction
but it didn't intend to cause hypokalemia these are three effects on the level of muscles it
increases blood flow it facilitates neuromuscular transmission and it draws potassium from blood
into the muscles causing hypokalemia not only this but you know that when we are running we need our
heart right heart rate is increased and this beta 1 supposed to increase contractility this
beta2 helps beta 1 through coronary dilocation dilation of the coronary artery so its causing
dilatation in two places skeletal muscle blood vessels and coronary arteries both of them you
need during running these two places has nothing to do with Alpha for now during running skeletal
muscles and Corners are under beta 2 controlled which causes vasodilation we didn't finish it
while you are running you need to paint so what do you think happened to broncoi do you think
they constrict you will die then beta 2 causes bronchodilatation so you can breathe easily
during running [Music] and when you run don't you need high blood sugar so you can think a muscle
can contract where can you give the sugar from from the liver liver is stored in sugar in the
form called glycogen okay this beta2 dissolves some of this July cushion releasing glucose into
blood to enhance muscle performance and cognition function so you can react you can decide how to
escape from this dog which root is the best sugar helps you in this count with me all
of these functions I don't memorize them so let's try to remember them together it has three effects
on muscles it causes vasodilation of skeletal muscles blood vessels and it cause facilitation
of neuromuscular transmission resulting bitter muscular performance and it increased potassium
stores inside muscles from where does it come from blood number four it increases blood
glucose level from where from liver hell or is analysis number five it cause bronchodilatation
so you can take good breaths while you're out number six while you run air pressure
can affect the eye if you are running quickly air pressure is increased on the eyes [Music]
let's assume this is an eye this is cornea and this is scalero this is front image
this is the iris this is a lens this is suspensory ligament of the lens this is a ciliary body
anchoroid here is something called ciliary epithelium this ciliary epithelium which has
beta-2 receptor it's responsible for secretion of the fluid inside your eye which preserves
intraocular attention URI contain fluid in the interior and posterior Chambers both of
them are filled with fluid cooled aqueous humor where does it come from from epithelium line and
ciliary body called ciliary epithelium it has beta-2 responsible for secretion of this fluid
what does this have to do with running while you run air pressure on the ice is increased and we
cannot live discontinue here are pressure sensors they sense the pressure once they feel increased
air pressure they activate B tattoo receptor to increase equals human secretion it doesn't
intend to harm you with increasing equals humor but to confront this increase in the air pressure
during running now you stop and air pressure is back to normal then this equals humor is absorbed
and drained through something called angle of the eye to Canal of Islam to the episcular veins and
lymphatics that's okay all of this and we didn't deviate from the word running running is half of
the carriage this beta 2 is the hero responsible for this Carriage okay is there anything else yes
there is something else imagine if you have a pregnant woman in your clinic who was unable
to conceive for many years 15 years or so then she finally was able to get pregnant now she's praying
for God every day and doing charity because she's now pregnant imagine if this brilliant woman is
being chased by a stray dog what a nurse at this if she was frightened and ran away she would
likely have an abortion that's why God's blessing her with B tattoo receptors in the uterus do you
remember when I told you that uterusalem but it's effects on remarkable on the other hand the tattoo
effect on the uterus is Extreme really powerful it causes you to rain relaxation during danger
to avoid abortion do you get it now why we are calling this kind B tattoo receptor so be careful
during exams as some examiner may try to deceive you and ask you do you know a drug that can block
beta-2 receptor tell him I can understand if you want a drug block on all types of receptors
together but why Peter 2 specifically it didn't do anything bad maybe the only answerable effect
of it is when it improves muscle contraction by facilitation of the neuromuscular Transmission in
order to improve performance it might sometimes cause handshake this facilitation can sometimes
result in this Chic which we call tremors this may be the only undesirable effect of beta2
sometimes people can complain to you of hand shaking especially those working in a shooting
range these people may complain of shaky hands during targeting tell him it's because of beta
2 in your hands it's slightly overactive in your hands during their facilitation of the
neuromuscular transmission and this is what causes these Tremors this is the only answerable effect
and I can prescribe a beta blocker in this situation to remove these trimmers if this
man wants to cheat he may have a shooting test and he wants a steady hands during this test give
him a bit of looker blocking beta receptors which causes this Tremor so his hand Can Be
steady and he can pass so all in all beta 2 is always kind and doesn't mean to cause any harm
except for these trimmers this is a very simple effect now we only have beta 3 left
and you already know something about it by the way this beta 3 could be considered a different
type of beta 2 is scientifically considered as a subtitle of beta2 however it's present
in the Edibles tissue causing lipolysis melting the fat needless to say once you hear that it
melts the fat people who are watching this video right now will say that's it we have found it you
are thinking about weight loss aren't you this is good you have a sound mind and you are trying to
make good application of signs however allow me to destroy your happiness why because if beta 3 had
been uniformly distributed all over your fat if it had been present in the fat of my face hence all
of my body evenly I would have invented a drug stimulating it causing lipolysis allowing us to
get rid of this fat without much effort but sadly enough this beta 3 receptors are present more in
the upper half of the body they are present more in the face hands but they are not present in
the belly fat accordingly if you stimulate beta3Â receptors certain area of your body lose fat but
other areas don't your face would be thinner but your belly fat will dream in the sea that's why
we couldn't make much benefit from them so if you see a question in exam asking why don't we have
beta 3 agonists as this receptor are supposed to induce lipolysis so why don't we have a beta
3 against among drugs treating obesity pick this peculiar sentence from the choices because it is
not evenly distributed throughout the body this is the answer there is only one last concept
before we end this video I told you that Alpha One Second messenger is which type of messenger
I told you that Alpha on Activision turns on a protein called GQ do you remember all types of
beta receptors when they are activated they turn on the same second messenger called cyclic amb
when cyclic amp is increased inside sales it causes all of these effects which we discussed so
why don't they all have the same function why are beta 1 2 and 3 though in different functions it's
because when cyclic amb is increased it activates other subcellular components other Kinesis kinase
here is different from the one here and here again so you don't miss this concept if someone asks you
what type are beta receptors present in your body tell him G protein LinkedIn receptors but how does
this beta receptor function tell him it increases cyclic amp inside cells but then why beton
receptors in the heart increase contractility while betatuku's relaxation although both of
them increase their theme cyclic MP tell him it is not all about cyclic amb but what's present behind
this cyclic amb when cyclic amp is increased and the harder it activates a certain protein kinase
which is a different from the kinase present in the cells that are under the effect of bit data 3
so it's not all about the receptor it's not all about G protein however it's all about further
enzymes final effectors at the subcerial level remember this so no one can trap you during oral
exams now we have finished the main Concepts about adrenergic receptors see you in the next video
5.0 / 5 (0 votes)