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sal : in the previous video we talked about how an atp molecule can , in the presence of water , hydrolysis will take place , and one of the phosphoryl groups could be plunked off , and how that would release energy because these electrons are going to be able to go into a lower energy state . you could imagine that th...
it nabs just the hydrogen , then both of these electrons that are in this pair , that are in this bond i should say , go back to the oxygen to form , essentially you could think of this as a pair of electrons attached to that oxygen . then that gives the oxygen license to allow these two electrons to form a bond with t...
why does n't two or three phosphate groups pop off to form something like an ap or adenosine molecule ?
sal : in the previous video we talked about how an atp molecule can , in the presence of water , hydrolysis will take place , and one of the phosphoryl groups could be plunked off , and how that would release energy because these electrons are going to be able to go into a lower energy state . you could imagine that th...
and you can imagine maybe this thing breaks off and it could be viewed as a proton , or you could view this as a positive charged molecule , but either way this is the reaction that we just depicted . you have atp being , hydrolysis takes place . you 're left with adp , you 're left with a phosphate , a released phosph...
i came across few questions on atp and gtp hydrolysis in my exams which one has powerful molecular energy in the cell 1- atp hydrolysis move component from cytoplasmic to nucleus 2- gtp hydrolysis move component from cytoplasmic to nucleus 3- atp hydrolysis move component from nucleus to cytoplasmic 4- gtp hydrolysis m...
sal : in the previous video we talked about how an atp molecule can , in the presence of water , hydrolysis will take place , and one of the phosphoryl groups could be plunked off , and how that would release energy because these electrons are going to be able to go into a lower energy state . you could imagine that th...
that 's what i 'm going to do in this video . let 's start with our atp molecule , and let 's throw some water in there , h2o . let 's say this is water right here , oxygen with two hydrogens .
how does atp react with water ?
sal : in the previous video we talked about how an atp molecule can , in the presence of water , hydrolysis will take place , and one of the phosphoryl groups could be plunked off , and how that would release energy because these electrons are going to be able to go into a lower energy state . you could imagine that th...
it 's going to look like this . double bond to that oxygen . you have this oxygen right over here .
if phosphorus wants six bonds , should n't the addition of the bond from the oxygen from the water molecule make its ideal octet ?
sal : in the previous video we talked about how an atp molecule can , in the presence of water , hydrolysis will take place , and one of the phosphoryl groups could be plunked off , and how that would release energy because these electrons are going to be able to go into a lower energy state . you could imagine that th...
you have atp being , hydrolysis takes place . you 're left with adp , you 're left with a phosphate , a released phosphate molecule , and then you 're left with a positive charge . you could either view this as kind of a proton or the proton attaches and forms a hydronium ion right over here .
why then does the phosphate break off to form a lone phosphate group , which still just has five bonds , when it could remain in its ideal octet ?
sal : in the previous video we talked about how an atp molecule can , in the presence of water , hydrolysis will take place , and one of the phosphoryl groups could be plunked off , and how that would release energy because these electrons are going to be able to go into a lower energy state . you could imagine that th...
i 'll do the two pairs of oxygen that are n't in bonds right over here , in the outermost shell . actually let me draw one more water molecule right over here . there 's multiple way that you could actually depict this right over here .
where does the water come from ?
sal : in the previous video we talked about how an atp molecule can , in the presence of water , hydrolysis will take place , and one of the phosphoryl groups could be plunked off , and how that would release energy because these electrons are going to be able to go into a lower energy state . you could imagine that th...
sal : in the previous video we talked about how an atp molecule can , in the presence of water , hydrolysis will take place , and one of the phosphoryl groups could be plunked off , and how that would release energy because these electrons are going to be able to go into a lower energy state . you could imagine that th...
energy come for bonding adp with p ?
sal : in the previous video we talked about how an atp molecule can , in the presence of water , hydrolysis will take place , and one of the phosphoryl groups could be plunked off , and how that would release energy because these electrons are going to be able to go into a lower energy state . you could imagine that th...
let 's start with our atp molecule , and let 's throw some water in there , h2o . let 's say this is water right here , oxygen with two hydrogens . i 'll do the two pairs of oxygen that are n't in bonds right over here , in the outermost shell .
so basically , the two water molecules form hydronium and hydroxide ions and the hydroxide bonds with the triphosphate ?
sal : in the previous video we talked about how an atp molecule can , in the presence of water , hydrolysis will take place , and one of the phosphoryl groups could be plunked off , and how that would release energy because these electrons are going to be able to go into a lower energy state . you could imagine that th...
it 's going to look like this . double bond to that oxygen . you have this oxygen right over here .
why is energy released when the bond is broken in this case , but absorbed when we talk about enthalpy and chemical bonds being broken ?
sal : in the previous video we talked about how an atp molecule can , in the presence of water , hydrolysis will take place , and one of the phosphoryl groups could be plunked off , and how that would release energy because these electrons are going to be able to go into a lower energy state . you could imagine that th...
then that gives the oxygen license to allow these two electrons to form a bond with the phosphorous . the phosphorous is n't in the mood to form six bonds , it 's already got five , and this is a fairly uncomfortable situation for it . that allows these two electrons right over here to go , these two electrons to go to...
how come phosphorus can only make six bonds ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
up here , we have the upper esophageal sphincter . esophageal sphincter . and so , just to reiterate , a sphincter is just a circular localization of muscle , so just a bunch of muscle that sits in a ring right here , that makes sure that it 's closed unless we tell that muscle to relax so we can pass food along .
if the sphincter muscles does n't allow food to move back then how do we vomit ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
there 's a sheet of muscle that lines the connection between the thoracic cavity and the abdominal cavity . so you can imagine that you have a thoracic cavity above , things that would sit here would be your lungs and your heart . and then below , and i 'll draw that right here , you have an abdominal cavity .
can somebody please provide a simpler explanation of why we have heart burn ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
up here , we have the upper esophageal sphincter . esophageal sphincter . and so , just to reiterate , a sphincter is just a circular localization of muscle , so just a bunch of muscle that sits in a ring right here , that makes sure that it 's closed unless we tell that muscle to relax so we can pass food along .
does breathing affect whether the `` sphincter '' is open or closed ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
and the diaphragm is actually lower esophageal sphincter because it just sits there holding the esophagus in place . and that 's why over time , we can have what 's called a hiatal hernia . the esophagus can move upward and downward through this lower esophageal sphincter and we 'll have gastric acid from the stomach r...
also , when a hiatal hernia ( ) forms , does it affect whether this `` sphincter '' is open or closed , and this is why gastric acid can reflux up into the esophagus and cause heartburn ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
so it 's under our voluntary control . skeletal muscle . and so that 's 1/3 , i 'll say the top 1/3 of the esophagus .
is the heart the only structure in our bodies that is made of cardiac muscle ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
the esophagus can move upward and downward through this lower esophageal sphincter and we 'll have gastric acid from the stomach reflux upward and give us heartburn , or gastroesophageal reflux disease , g.r.d . so that 's why we have heartburn but rodents or horses do n't . rodents and horses actually have their own t...
is it possible to reduce or eliminate heartburn by simply strengthening the abdominal muscles ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
well , we actually have a sheet that kind of sits right here . there 's a sheet of muscle that lines the connection between the thoracic cavity and the abdominal cavity . so you can imagine that you have a thoracic cavity above , things that would sit here would be your lungs and your heart .
what is the thoracic cavity and the abdominal cavity ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
when it moves downward , the lungs inflate with air . so the diaphragm sits here and it actually makes a ring around this lower esophageal sphincter . and the diaphragm is actually lower esophageal sphincter because it just sits there holding the esophagus in place .
how does the heart pump and makes noise when it pumps ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
and that 's why over time , we can have what 's called a hiatal hernia . the esophagus can move upward and downward through this lower esophageal sphincter and we 'll have gastric acid from the stomach reflux upward and give us heartburn , or gastroesophageal reflux disease , g.r.d . so that 's why we have heartburn bu...
does n't the esophagus have `` muscles '' that will contract and relax to move the bolus down to the stomach ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
and then below , and i 'll draw that right here , you have an abdominal cavity . so the abdominal cavity that 's gon na have most of the gi tract . and this muscle that we have , that sits here , that 's going to be the diaphragm .
can you explain the swallowing reflex that is associated with the esophagus and the gi tract ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
up here , we have the upper esophageal sphincter . esophageal sphincter . and so , just to reiterate , a sphincter is just a circular localization of muscle , so just a bunch of muscle that sits in a ring right here , that makes sure that it 's closed unless we tell that muscle to relax so we can pass food along .
what is the difference between a valve and a sphincter ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
when it moves downward , the lungs inflate with air . so the diaphragm sits here and it actually makes a ring around this lower esophageal sphincter . and the diaphragm is actually lower esophageal sphincter because it just sits there holding the esophagus in place .
if the lower sphincter of the oesophagus is actually the diaphragm , then is the contraction of the diaphragm during exhalation is what that induces vomiting ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that .
so ... ..when we get sick , our esophagus sphincters will open and allow food with any virus out ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
up here , we have the upper esophageal sphincter . esophageal sphincter . and so , just to reiterate , a sphincter is just a circular localization of muscle , so just a bunch of muscle that sits in a ring right here , that makes sure that it 's closed unless we tell that muscle to relax so we can pass food along .
then why have we evolved not to have lower esophageal sphincter ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
peristalsis , and this is going to be an important term for the discussion of the rest of the gi tract . peristalsis is just the wave-like propulsion of food . wave-like propulsion .
how does food pipe pass through the diaphragm ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
and then smooth entirely for the last 1/3 . and that 's how our esophagus works , as well .
i read somewhere that people also have esophagus cancer ... ..how does that happen ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
skeletal muscle . and so that 's 1/3 , i 'll say the top 1/3 of the esophagus . in the middle right here , we actually have a mix .
i got confused when he started breaking the esophagus into 3 different `` one thirds '' ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
there 's a sheet of muscle that lines the connection between the thoracic cavity and the abdominal cavity . so you can imagine that you have a thoracic cavity above , things that would sit here would be your lungs and your heart . and then below , and i 'll draw that right here , you have an abdominal cavity .
in the picture , where do the lungs and heart sit ?
: after the food is swallowed , it leaves the mouth and then goes next to the esophagus . so , let 's focus on that . and just to make sure , we all know kind of how far the esophagus goes , i 'm gon na draw in some lines right here , to show where it starts up here , and then it ends right about there . and kind of w...
so it 's composed primarily of skeletal muscle . skeletal muscle , so it 's under voluntary control . and down here , i 'll draw a squiggly line , we have the lower esophageal sphincter .
sir said that the skeletal part of esophagus is in our control ... how ?
ablation studies , or experimental ablation , describes the method of deliberately destroying brain tissue or making brain lesions , so a wound or an injury , in order to observe the changes that this might have on an animal 's behavior . so for lesion studies , we 're studying brain function by purposefully destroyin...
another type of neurochemical lesion is created by a chemical called oxidopamine , or 6-hydroxydopamine . and this is a really useful chemical that selectively destroys dopaminergic neurons as well noradrenergic neurons , or neurons that release domamine and norepinephrine or adrenaline . so imagine you have a presynap...
why does cooling down neurons not kill the neurons ?
ablation studies , or experimental ablation , describes the method of deliberately destroying brain tissue or making brain lesions , so a wound or an injury , in order to observe the changes that this might have on an animal 's behavior . so for lesion studies , we 're studying brain function by purposefully destroyin...
because you can really only use it for removing structures on the surface of the brain . also , scientists are n't always interested in actually removing brain tissue . instead , they 're usually more interested in destroying the brain tissue in place , because usually this winds up being a lot less invasive .
would n't a researcher also be damaging other areas of the brain while passing through if they 're trying to insert an electrode or chemicals into a deeper area of the brain ?
ablation studies , or experimental ablation , describes the method of deliberately destroying brain tissue or making brain lesions , so a wound or an injury , in order to observe the changes that this might have on an animal 's behavior . so for lesion studies , we 're studying brain function by purposefully destroyin...
and the main idea here is that the functions that can no longer be performed after the damage are the ones that were controlled by those damaged regions . and i know i 've used a human brain to illustrate this , but i want to state right up front that this type of research is not done with humans . it is only done with...
how do they know whether their effects are a result of their experimental desires rather than the damage done to other areas as the electrode or chemicals are inserted into the brain ?
ablation studies , or experimental ablation , describes the method of deliberately destroying brain tissue or making brain lesions , so a wound or an injury , in order to observe the changes that this might have on an animal 's behavior . so for lesion studies , we 're studying brain function by purposefully destroyin...
another type of neurochemical lesion is created by a chemical called oxidopamine , or 6-hydroxydopamine . and this is a really useful chemical that selectively destroys dopaminergic neurons as well noradrenergic neurons , or neurons that release domamine and norepinephrine or adrenaline . so imagine you have a presynap...
does our brain have stem cells that are capable of regenerating neurons ?
ablation studies , or experimental ablation , describes the method of deliberately destroying brain tissue or making brain lesions , so a wound or an injury , in order to observe the changes that this might have on an animal 's behavior . so for lesion studies , we 're studying brain function by purposefully destroyin...
and so oxidopamine is also taken up by the reuptake channels . and then it kills those cells . and this is extremely useful , because it gives us a lot of control .
if not , are we capable of extracting stem cells from umbilical cords , or any other methodology , to make this possible ?
ablation studies , or experimental ablation , describes the method of deliberately destroying brain tissue or making brain lesions , so a wound or an injury , in order to observe the changes that this might have on an animal 's behavior . so for lesion studies , we 're studying brain function by purposefully destroyin...
because you can really only use it for removing structures on the surface of the brain . also , scientists are n't always interested in actually removing brain tissue . instead , they 're usually more interested in destroying the brain tissue in place , because usually this winds up being a lot less invasive .
so how can we make any inferences about damage to these areas in human brains if rat brains do n't have the same areas ?
( piano playing ) beth harris : so , let 's talk about mannerist . the mannerist style and how it appears in portrait painting . david drogin : okay . beth : so , this is by bronzino ? david : this is a painting by bronzino . this is called a portrait of a young man from around 1540 . we do n't know exactly who it is a...
beth : it 's so weird because we kind of look down at it . we think people are insincere . david : we have a different take on it , certainly .
how were mannerist paintings received by the people of the time ?
( piano playing ) beth harris : so , let 's talk about mannerist . the mannerist style and how it appears in portrait painting . david drogin : okay . beth : so , this is by bronzino ? david : this is a painting by bronzino . this is called a portrait of a young man from around 1540 . we do n't know exactly who it is a...
approximately the same date and also here in new york city . this is at the frick collection . beth : his fingers , those elongated boneless fingers are also very typical of mannerism .
the second portrait at the frick , is there not an obvious phallic image - the sword hilt strategically placed ?
( piano playing ) beth harris : so , let 's talk about mannerist . the mannerist style and how it appears in portrait painting . david drogin : okay . beth : so , this is by bronzino ? david : this is a painting by bronzino . this is called a portrait of a young man from around 1540 . we do n't know exactly who it is a...
david : this is a painting by bronzino . this is called a portrait of a young man from around 1540 . we do n't know exactly who it is and therefore it has that title and it 's located in new york city at the metropolitan museum of art .
who is the man 's name ?
( piano playing ) beth harris : so , let 's talk about mannerist . the mannerist style and how it appears in portrait painting . david drogin : okay . beth : so , this is by bronzino ? david : this is a painting by bronzino . this is called a portrait of a young man from around 1540 . we do n't know exactly who it is a...
david : but at the time , especially in the medici circles of this period , obviously artificiality was a goal of proper social behavior in elite circles . your identity was something that was to be performed . you presented yourself to be seen in a certain way .
perhaps the identity of his lover ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
and here we 're dealing with the population . we have n't thought about sampling yet . the square root of the population variance , what do we call this thing right over here ?
how do you know if you need to divide by n or n-1 ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
so we 're going to use mu . so what is the arithmetic mean here ? well , we just have to add all of these data points up and divide by 5 .
is there a difference between the arithmetic mean and the average ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
so you might be saying , sal , what do we call this thing that we just did ? the square root of the variance . and here we 're dealing with the population .
is 'var ' the short form of variance ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
i 'm using that yellow a little bit too much . this is the population standard deviation . it is a measure of how much the data is varying from the mean .
what does population standard deviation mean ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
the reason why we do it this way is it has neat statistical properties as we try to build on it . but that 's the population standard deviation , which gives us nice units -- meters . in the next video , we 'll think about the sample standard deviation .
so in this example the standard deviation is 0.562 meters , does that mean that the 5.5 meters of the original data set is a bit of an outlier since it 's not within the standard deviation of the mean ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
then , we will divide by the number of data points we have . and we get 0.316 . or if we want to write it , this is going to be 0.316 .
every car caries 0.316 sq m. from the mean ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
i 'm using that yellow a little bit too much . this is the population standard deviation . it is a measure of how much the data is varying from the mean .
what does standard deviation measure ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
i 'm using that yellow a little bit too much . this is the population standard deviation . it is a measure of how much the data is varying from the mean .
what is the difference between mean absolute deviation and standard deviation ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
and a big hint -- this comes out of just even the notation for variance . and it 's this sigma symbol squared . so why do n't we just take the square root of our variance ?
is standard deviation sigma squared or just sigma ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
i 'm using that yellow a little bit too much . this is the population standard deviation . it is a measure of how much the data is varying from the mean .
do n't you use mean standard deviation to find the variance ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
and then , square them . and then , take the mean of those two squared distances . so let 's do that .
why do n't we just take the absolute value of the average distance each number is away from the mean ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
i 'm using that yellow a little bit too much . this is the population standard deviation . it is a measure of how much the data is varying from the mean .
what is the difference of standard deviation and mean absolute deviation ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
i 'm using that yellow a little bit too much . this is the population standard deviation . it is a measure of how much the data is varying from the mean .
what would be the purpose of getting a variance if we could get the standard deviation instead ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
i 'm using that yellow a little bit too much . this is the population standard deviation . it is a measure of how much the data is varying from the mean .
does addition and subtraction affect standard deviation ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
i 'm using that yellow a little bit too much . this is the population standard deviation . it is a measure of how much the data is varying from the mean .
what are the correct values of the mean and the standard deviation ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths .
do smokers develop a higher incidence of lung cancer than people who are nonsmokers or never smokers ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
when i visualize it , i visualize dispersion or how varied they are in terms of meters , not meters squared . so what could we do ? and a big hint -- this comes out of just even the notation for variance .
how could the concept of variance be usefull in real life ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
i 'm using that yellow a little bit too much . this is the population standard deviation . it is a measure of how much the data is varying from the mean . in general , the larger this value , that means that the data is more varied from the population mean .
can we use the concepts of variance and standard deviation to calculate how much the data are generally dispersed from a certain point ( not the center ) for example , lets say i was interested in the length of the second car ( l2 ) so can i input the value ( l2 ) in place of the mean an get a measurement of how disper...
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths .
which depositor creates donuts with a more consistent weight ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
and here we 're dealing with the population . we have n't thought about sampling yet . the square root of the population variance , what do we call this thing right over here ?
what are the nice properties that sd has while mad does n't ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
i 'm using that yellow a little bit too much . this is the population standard deviation . it is a measure of how much the data is varying from the mean .
what 's the benefit of going through all that complex calculations to find the standard deviation when we can apply mad ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
i 'm using that yellow a little bit too much . this is the population standard deviation . it is a measure of how much the data is varying from the mean .
what is better as estimation set of data - standard deviation or variance ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
so the units here are going to be square meters . and so you might say , hey . that 's kind of a weird unit if we 're trying to visualize or think about how dispersed we are from the mean .
0 , did sal say `` mu '' or `` u '' or what ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
i 'm using that yellow a little bit too much . this is the population standard deviation . it is a measure of how much the data is varying from the mean .
what is the difference between standard deviation and mean absolute deviation ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
i 'm using that yellow a little bit too much . this is the population standard deviation . it is a measure of how much the data is varying from the mean .
is there any situation where it is better to use the mean absolute difference rather than standard deviation ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
so we 're going to do that for the population . so we 're going to use mu . so what is the arithmetic mean here ?
for example , 2 sal says `` we 're going to use 'mu ' '' what 's 'mu ' ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
i 'm using that yellow a little bit too much . this is the population standard deviation . it is a measure of how much the data is varying from the mean .
can we say that standard deviation is the root mean square of the following values ?
let 's say that you 're curious about studying the dimensions of the cars that happen to sit in the parking lot . and so you measure their lengths . let 's just make the computation simple . let 's say that there are five cars in the parking lot . the entire size of the population that we care about is 5 . and you go a...
so we 're going to use mu . so what is the arithmetic mean here ? well , we just have to add all of these data points up and divide by 5 .
what does the purple symbol mean ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
so let me draw those in . sodium channels . and there 's so many of them .
why would n't the ca2+ channels open when the potential in the cell reaches the threshold potential for ca2+ channels ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
so now that our cell is in positive territory , actually let me write in positive 20 or so , our potassium voltage-gated channels open up . so these voltage-gated channels open up . and you can guess what 's going to happen .
why ca2+ channels wait until later when cellular potential reaches the threshold the second time to open ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
so let me draw those in . sodium channels . and there 's so many of them .
can you explain the difference between the t-type and l-type calcium channels ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
and let 's draw that over here . so you have these calcium voltage-gated channel that allow calcium to come it . so you 've got calcium coming in , potassium leaving . now think about what will happen in this situation .
could you please explain the physiologic effect of calcium administration in cases of hyperkalemia ( high serum potassium ) .. what changes in action potentials does calcium do ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle .
are the cardiac myocytes the same thing as cardiac muscle cells ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
so i 'm going to draw for you the heart cycle , and specifically the cycle of an individual cell . this is what one cell is going to kind of go through over time . and the heart cycle , or the cycle for a cell , a heart cell , is going to be measured in millivolts . we 're going to use millivolts to think about this .
i know we are talking about just one cell , but are the voltage differentials all simultaneous for the millions and millions of heart cells ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
now what will happened to our membrane potential ? well it was negative 90 , but now that we 've got some positive ions sitting inside of our cell , our cell becomes a little bit more positive , right ? so it goes up to , let 's say , here .
are the potentials just for the individual ions or the sum of the positive and negative charge differences between the intracellular ad extra-cellular environment ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
and the membrane potential stays kind of around the same . and so it can just write something similar , something like positive 5 . just so we 're clear , these are also voltage-gated calcium channels .
are these voltages similar to the voltages created by the transfer of electrons in redox reactions ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
so compare that to how the action potential goes in the pacemaker cells , where it 's much slower . this fast action potential is a result of those really , really amazingly quick voltage-gated sodium channels .
or is this voltage potential different ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
and what happens is that the calcium channels actually close just as suddenly as they opened . so now you do n't have any more calcium coming in . and if calcium was the only thing that was keeping this membrane potential going flat -- you know , i said that the potassium makes it want to go down , but the calcium was ...
because calcium has a higher absolute value compared o k+ , should n't the cell be depolarizing , no matter how slowly ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
so let me draw those in . sodium channels . and there 's so many of them .
does it mean that some sodium ions can still enter the cell even without the voltage-gated sodium channels ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
but close to it , if not for the fact that these voltage-gated channels actually close down . so these sodium channels are voltage-gated . and they will actually close down just as quickly as they opened up .
what are voltage gated channels ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
and i 'm putting them really just as benchmarks just so you can kind of keep track of where things would like to be . so calcium would like to be at 123 millivolts . sodium at 67 .
if a person did n't have calcium , what would the heart do ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
when it gets to that point , we call that stage 0 . and then on the other side of stage 0 you have stage 1 , 2 , and 3 . so stage 1 is that point when just the potassium channels first open up , the voltage-gated ones .
i hope im correct in assuming that at stage 1 , 2 , and 3 , the potassium is actually entering the cell as apposed to leaving it ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
so now that our cell is in positive territory , actually let me write in positive 20 or so , our potassium voltage-gated channels open up . so these voltage-gated channels open up . and you can guess what 's going to happen .
in previous video you said no ion voltage gated channel will reopen until the whole process and repolarization occur but now k channels are open again ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
you get kind of a flatline . so because both events are happening , both potassium leaving the cell and calcium entering the cell , you get this kind of flatline . and the membrane potential stays kind of around the same .
but if all the potassium left the cell during the repolarisation phase then where does the potassium inside the cell come from ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
so this stuff starts leaking through the gap junctions , right ? now what will happened to our membrane potential ? well it was negative 90 , but now that we 've got some positive ions sitting inside of our cell , our cell becomes a little bit more positive , right ?
why does the membrane potential move downwards ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
and what that means is that if these were the only ions moving through , then sodium would like to keep things positive . and potassium , on the other hand , would like to make the membrane potential negative . so this scale is actually the scale for the membrane potential .
if the negative potential-ed potassium is moving out of the cell why does it not gain membrane potential ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
and because stage 0 is happening so rapidly , because this is so fast , we actually call this a fast action potential . so compare that to how the action potential goes in the pacemaker cells , where it 's much slower . this fast action potential is a result of those really , really amazingly quick voltage-gated sodium...
why is the intrinsic rate of the av node slower than the sa node ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
and what that means is that if these were the only ions moving through , then sodium would like to keep things positive . and potassium , on the other hand , would like to make the membrane potential negative . so this scale is actually the scale for the membrane potential .
how does potassium keep the membrane potential negative if it is a positively charged ion ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
so now that our cell is in positive territory , actually let me write in positive 20 or so , our potassium voltage-gated channels open up . so these voltage-gated channels open up . and you can guess what 's going to happen .
voltage gated means when the sa sends an electrical impulse , the na channels will open ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
so this is going to be the way that potassium 's going to flow . and it 's going to leave behind a negative membrane potential , right ? and let 's say potassium is the main ion for this cell , which it is .
why is it that when na or ca enter the cell the action potential goes towards the resting potential of na or ca , respectively , yet k seems to be the opposite that it needs to leave the cell in order to go towards the resting potential of k ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
so this is kind of the last stage , where those potassium channels are going back down . and those voltage-gated potassium channels also close at this point . so finally , they close down as well .
also , would n't potassium flow back into the cell at some point ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
well , if the sodium channels are n't gushing the sodium inwards and potassium is leaking outwards , now you 're going to have a downwards repolarization . so now potassium is causing the membrane potential to go back down . and let 's say it gets to about positive 5 .
so if potassium leaks out during phase 4 to cause the mv to increase , how does potassium leaking out cause it to decrease in phase 1 and 3 bring it back negative ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
so now that our cell is in positive territory , actually let me write in positive 20 or so , our potassium voltage-gated channels open up . so these voltage-gated channels open up . and you can guess what 's going to happen .
cardiac myocyte calcium voltage gated channels open at around +5mv , while pacemaker cells calcium voltage gate channels open at around -40mv ( from previous video - action potential in pacemaker cells ) , why is this so ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
and because stage 0 is happening so rapidly , because this is so fast , we actually call this a fast action potential . so compare that to how the action potential goes in the pacemaker cells , where it 's much slower . this fast action potential is a result of those really , really amazingly quick voltage-gated sodium...
why is there a need for action potential in cardiac myocytes while the action potential which travels through t tubules is enough to cause muscle contraction ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
but close to it , if not for the fact that these voltage-gated channels actually close down . so these sodium channels are voltage-gated . and they will actually close down just as quickly as they opened up .
if so , should they not have opened in phase 0 when the voltage initially reached ( and then surpassed ) that same voltage ( ~ +5mv ) ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level .
are the values such as +20mv or +5mv arbitrary ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
so let me draw those in . sodium channels . and there 's so many of them .
is the increase in ca due to the sarcoplasmic reticulum in phase 2 of the action potential or from the l-type ca channels ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle .
do myocytes contract as soon as the electrical impulse reaches them ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
and this is the key idea , right ? i do n't want to forget that this is potassium . so you still have potassium in the same over here .
why does n't ca+2 come in during the initial depolarization ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
this is what one cell is going to kind of go through over time . and the heart cycle , or the cycle for a cell , a heart cell , is going to be measured in millivolts . we 're going to use millivolts to think about this .
if the cycle keep repeating , wo n't the cell eventually run out of potassium ?
let 's figure out how a heart squeezes , exactly . and to do that , we have to actually get down to the cellular level . we have to think about the heart muscle cells . so we call them cardiac myocytes . these are the cells within the heart muscle . and these are the cells that actually do that squeezing . so if you ac...
so we have , let 's say , a potassium channel right here . we know the potassium likes to leave cells . so this is going to be the way that potassium 's going to flow .
when do the k gets into the cells ?