SNPUC Fast Track Bridge Course - Day 10

Added: 2026-05-14

[00:00:50]Hello hello hello hello good evening Afifa good evening Sudamani good evening VA good evening good evening I hope everyone is fine Let's begin the class.

[00:01:15]Let's begin the class. Friend topic already.

[00:01:27]Topic name heat and temperature.

[00:01:31]Right.

[00:01:39]streaming raise the thumb.

[00:01:52]So topic important basic and before starting the chapter let me tell you one thing that heat and thermodynamics is a topic very very important for competitive. Yes. Fine.

[00:02:10]Heat and thermodynamics is a topic which is very very important for NET JWE KCT a very huge topic again important and lengthy topics heat and thermodynamics.

[00:02:28]So related basics basic regarding that. Okay.

[00:02:36]So let's start the classics.

[00:02:39]Let's begins with what is meant by heat and temperature. So heat let us discuss once again what is meant by heat right.

[00:03:03]What is the heat means?

[00:03:05]physics.

[00:03:07]What is the definition of heat? Heat is a form of energy. Yes. What is heat?

[00:03:13]Heat is a form of energy with transfer between two bodies due to difference in the temperature.

[00:03:22]Simple easiest.

[00:03:26]Heat is a form of energy. Heat energy form and heat can be transferred from one body to another body if there is a difference in the temperature.

[00:03:48]Now when you talk about which body to which body so next topic next line heat energy always flow from the body of higher temperature to the body of lower temperature. So what is the direction of heat?

[00:04:08]Heat direction.

[00:04:11]Yes. Heat direction.

[00:04:13]Heat always flows from a body at higher temperature towards the body at lower temperature.

[00:04:24]Are you getting the point? Heat is a quantity. Heat is a physical quantity.

[00:04:36]physicality.

[00:04:39]So what is the direction of heat? Heat flows from the body which is at higher temperature to the body at lower temperature. Okay.

[00:04:53]So higher temperature body lower temperature naturally naturally natural direction of heat.

[00:05:12]So direction of heat and heat and heat.

[00:05:32]Okay. Measurement. Measurement.

[00:05:38]Naturally heat body at higher temperature at lower temperature.

[00:06:04]I think last class sir class fundamental physical quantity seven fundamental physical quantity temperature measurement. So what is temperature?

[00:06:17]Temperature what is temperature? So temperature is a physical quantity which is the measurement of degrees of hotness or coldness of a body.

[00:06:28]S2 the measurement is called temperature.

[00:06:39]Temperature is a physical quantity which measures the degrees of hotness or coldness of a body.

[00:06:48]Temperature is a measurement.

[00:07:04]Temperature is a kind of measurement of physical quantity. I hope you understand things interesting.

[00:07:21]Now important line. The next line is it can be defined the thermal conditions of a body can also be defined.

[00:07:34]The thermal condition body which determines the ability to transfer heat to the other. So this is a definition another definition of temperature. A very very important Simple definition temperature is the physical quantity which measures the degrees of hotness or coldness of a body.

[00:07:56]It can also defined the thermal condition.

[00:08:01]Thermal conditional thermal temperature heat thermal heat.

[00:08:08]It can also be defined as the thermal condition of a body which determines the ability to transfer it to the other bodies.

[00:08:27]Condition which determines the ability of a body to transfer heat from one body to another body is also called as temperature.

[00:08:38]Second definition of temperature.

[00:08:47]So temperature the thermal condition of a body.

[00:09:05]Temperature temperature another one thermal condition of a body which determines the ability to transfer heat.

[00:09:14]Okay. For what extent at what extent heat should transfer from one to two be determined by the temperature right this is one another type of definition of a temperature sina okay next another definition what we have the property which determines the flow of heat between the bodies in contact with each other thermal contact with each Right now temperature one by one definition one by one temperature the physical quantity which is the measurement of degrees of hotness and coldness of a body. Next one it is also defined as the thermal condition which determines the ability of a body to transfer heat is a temperature. Next, it is a property which determines the direction of flow of heat between two bodies in the thermal contact with each other.

[00:10:30]Imagine you are holding a metal rod and Okay.

[00:10:49]Heat.

[00:11:10]slowly.

[00:11:14]A heat A is the end where the heat is given and B is the end where you are holding the hand holding the rod by your hand. So heat in the air.

[00:11:32]Yes.

[00:11:44]Thermal contact.

[00:11:56]Yes. Super.

[00:12:00]Good. A to B. A to B.

[00:12:06]Thermal contact. Thermal contact.

[00:12:11]Slowly.

[00:12:16]contact thermal contact.

[00:12:27]So temperature is the one which determines the direction of heat flow.

[00:12:36]Direction of heat flow.

[00:12:44]Imagine there are two bodies. A body and B body.

[00:12:50]There are two bodies. A body and B body.

[00:12:52]Okay. Now bodies a body temperature.

[00:12:58]A body temperature 10°.

[00:13:02]A body temperature 10° B 50°.

[00:13:10]So body simple which is the cold body which is the hot body.

[00:13:27]Which one is a cold body? Which one is a hot body?

[00:13:31]Comparison body A is cold, B is hot. Yes. Basis determine sir temperature. Looking at the temperature we decided yes A is less hot than B. Super super A temperature basis.

[00:14:10]Super super nice.

[00:14:13]Super nice heat.

[00:14:32]A b. Tell me by the using of a wireal body joint.

[00:14:52]Now this is we call as thermal contact.

[00:14:56]This is we call as thermal contact.

[00:15:06]Yes, already answer B to A. B to A. B to A. B to A. Why the heat flows from B to A?

[00:15:26]Yes. Temperature. Temperature decides the direction of heat flow. High to low temperature. Super heat always flow from high temperature to low temperature. So temperature decides temperature property which decides the direction of heat flow.

[00:15:55]temperature than a super super.

[00:15:59]Okay.

[00:16:01]So you might think that question basic perfect.

[00:16:31]So who will decide the direction of heat? Ultimately if I ask you the question who will decide the direction of heat?

[00:16:41]>> Heat.

[00:16:43]Direction decide ultimately temperature will decide the direction of heat flow.

[00:16:58]It is the property which determines it is a property which determines the direction of flow of heat between two bodies in thermal contact with each other. Thermal contact temperature it is the physical quantity which uh which is the measurement of degrees of hotness and coldness of a body. One definition you know it is the property which determines the ability of the body which determines the ability of body to transfer heat between two bodies in contact temperature.

[00:17:59]So who will decide the direction of heat flow?

[00:18:12]Heat flow concept clear temperature concept.

[00:18:23]Okay.

[00:18:25]Next line. A very very important line.

[00:18:30]Eat question when two bodies at same temperature.

[00:18:54]Okay.

[00:18:57]Suppose A2 temperature.

[00:19:18]What if the two bodies have same temperature?

[00:19:22]Body temperature 20°.

[00:19:28]Heat flow A to B to B to A flow.

[00:19:36]Can the heat flows from one body to another body? If two bodies are in thermal contact temperature will not flow from one body to another body.

[00:20:00]So, thermal equilibrium, thermal equilibrium.

[00:20:19]Thermal equilibrium.

[00:20:22]Thermal equilibrium.

[00:20:25]When two bodies are at same temperature which is in contact then heat does not flow from one body to another body. If the two bodies are in contact in thermal equilibrium situation thermal equilibrium two bodies are in contact are in thermal equilibrium means what? Means they have same temperature.

[00:20:52]It means what? It means heat does not flow from one body to another body.

[00:20:56]That's it. That's it. That is the meaning. So let us come to the slide.

[00:21:04]When two bodies are in at the same temperature then they are said to be in thermal equilibrium with each other. So it is when two bodies are in the same temperature then they are in thermal equilibrium.

[00:21:28]Which of the following statement is correct?

[00:21:44]remaining question.

[00:21:55]Okay.

[00:21:59]When two bodies are at same temperature, two bodies are in thermal equilibrium with each other.

[00:22:19]Question.

[00:22:24]Which of the following statement is correct on the type questions?

[00:22:29]Only one statement correct the remaining two wrong.

[00:22:40]Okay.

[00:22:48]body same temperature they are called as thermal equilibrium with each other question at thermal equilibrium at thermal at thermal equilibrium is it necessary that board both body have same amount of heat is it necessary yard body over yard body Thermal equilibrium contact layout they are in contact two bodies are in contact are in thermal equilibrium. Is it necessary that both carry or both have the same amount of heat?

[00:23:45]Degrness degrees of hotness.

[00:24:07]It is not necessary question.

[00:24:10]If the two bodies are in thermal equilibrium, they may or may not have the same amount of heat.

[00:24:19]They carry the same amount of heat. They may carry the same amount of heat or they may not be carry the same amount of heat.

[00:24:41]If two bodies are in thermal equilibrium meaning two bodies are inral temperature they are called as in thermal equilibrium with each other. But It may same or may not be same question.

[00:25:26]Yes to heat energy. Yes. Heat.

[00:25:51]A body size.

[00:25:56]Okay. They are in thermal equilibrium s body temperature. A body temperature sir 20° B 20° temperature same and what they are called as sir they are called as thermal equilibrium they are in thermal equilibrium with each other. So if two bodies are in thermal equilibrium with each other, they may or may not they may or may not have the same degrees of hotness or coldness.

[00:26:37]Why? Because of the difference in the masses. Difference in the masses same amount of degrees of hotness.

[00:26:50]So questions which of the following mod okay now which of the following is a true statement?

[00:27:01]Okay wrong statement again it is necessary that if the body two bodies are in thermal equilibrium then they must be have the same amount of heat. It is not necessary that they should have same amount of heat. So because mass is different different masses variable. So the equilibrium same amount of important question But a body temperature 20° temperature sir. A compared to compared to temperature but different okay just gap Concept the concept based this is concept you should understand the concept okay don't worry deepen Suddenly, don't worry.

[00:29:29]Okay, next temperature is a very very important line. Again it is called as macroscopic macro macro micro m i micro micro small macro micro Microscopic property of the body or the system. Okay.

[00:30:10]Macro large scale it is it is means large large scale property microscopic micron small IC micro small scale but temperature microscopic property sir from when will the offline classes will start probably it will start from 18 in a Don't worry.

[00:30:52]Temperature is a microscopic property of the body or the system body or the system.

[00:31:00]And no doubt no doubt temperature scalar quantity scalers and vectors Temperature is a scalar quantity.

[00:31:11]What about heat? What about heat? Tell me.

[00:31:24]Okay. Temperature is a scalar quantity.

[00:31:26]What about heat? Heat any sir? We have second board examination from it. Okay.

[00:31:32]Don't worry.

[00:31:36]No issues anything don't heat.

[00:31:53]What about heat? Heat is a vector quantity sir. Heat flow direction. Is it a vector? Yes, heat is also a scalar quantity because heat is a energy. Heat is a form of energy and energy scalar quantity.

[00:32:18]Heat is a scalar quantity. Heat is a form of energy. Heat for temperature difference but it is a scalar. Sorry I hope you understand this.

[00:32:49]Okay.

[00:32:51]Difference temperature differences.

[00:32:56]What are the differences between temperature and heat?

[00:33:00]Temperature is the thermal condition that determines the direction of heat flow. Temperature is the thermal condition that determines the direction of heat flow. And what is heat? Heat is the energy which transferred from body at higher temperature to body at lower temperature.

[00:33:19]Right. Next difference.

[00:33:21]Temperature is the average energy of the particles.

[00:33:27]Temperature average energy. Average energy of the particle is a temperature. And what is heat? Heat is a total energy of the particle.

[00:33:41]Total energy. But temperature average.

[00:33:47]Okay.

[00:33:49]Okay. Small small amount of sum divided by number.

[00:33:56]So temperature of all the energy of all the particles to average temperature total energy of the particle.

[00:34:08]Next temperature is the degrees of hotness or coldness but heat is a form of energy. And the last last difference is unit of temperature is temperature.

[00:34:34]degree. Sorry, not degree. It is okay.

[00:34:43]Heat can be measured in calories.

[00:34:54]I hope you understand the difference between heat and energy and the direction of heat. Who will decide?

[00:35:00]Decide the direction of heat flow?

[00:35:02]Temperature will decide the direction of heat flow. Temperature basic right.

[00:35:32]So MCQ MCQ answer heat is a form of energy between two bodies due to difference in Tell me the answer proper answer correct. Heat is a form of energy transferred between two bodies due to difference in what? Difference in dash.

[00:35:55]Heat is a form of energy transfer between two bodies due to difference in dash. Which is the correct answer?

[00:36:04]Which is correct answer?

[00:36:06]Option A, energy. Option B, temperature.

[00:36:10]Option C, mass. Option D, both A and B.

[00:36:14]Option D, both A and B. Correct.

[00:36:18]B C Heat is a form of energy transfer between two bodies. Now heat will decide.

[00:36:47]So correct answer is temperature due to difference in the temperature difference.

[00:36:56]Okay.

[00:37:03]Temperature difference in the temperature.

[00:37:10]Okay. Next question. Second MCQ.

[00:37:15]When two bodies have same dash then they are said to be in thermal equilibrium with each other.

[00:37:24]Options correct answer when two bodies have same dash then they are said to be in thermal equilibrium at each other with each other. Sorry.

[00:37:37]Density, temperature, pressure and surface area. Yes, correct answer is they should have same temperature. If body have same temperature then they are said to be in thermal equilibrium with each other. Super super temperature answer.

[00:38:08]Temperature is dash physical quantity.

[00:38:11]Temperature is dash physical quantity.

[00:38:14]Physical quantity vector scalar fundamental both B and C both B and C answer it is a scalar quantity think temperature is physicality yesifa abishek The right answer is both B and C and D is the right answer. So temperature is a fundamental quantity.

[00:39:09]So temperature independent quantity fundamental basic quantity.

[00:39:20]So correct answer B and C D is the right answer. I hope you understand. Serena, next most important topic.

[00:39:35]Yes.

[00:39:37]Measurement of temperature.

[00:39:40]Measurement of temperature. Most important topic.

[00:39:52]Measurement of temperature.

[00:39:55]So most important topic next chemistry.

[00:40:07]Now next class measurement of temperature most important topic next I will stop here and next class will be the chemistry. So, thank Okay. Good evening.

[00:43:07]Good evening everyone.

[00:43:14]Okay. Good evening. Good evening.

[00:43:33]Okay. Okay.

[00:43:36]Okay. Last class sales study three but we have discussed it in the last class.

[00:43:41]Hi.

[00:43:44]Okay.

[00:43:46]So we are discussed about the chemical bond or the so we already discussed this one. Okay.

[00:44:11]You're not listening me.

[00:44:15]idea.

[00:44:31]Okay. So last class topic.

[00:44:36]Okay.

[00:44:38]Okay. So last class we have discussed about the ionic bond or electroent bond.

[00:44:44]Ionic bond or electroent bond see. So reise last just 5 to 10 minutes revise.

[00:44:53]Right. So nature of chemical bond one is ionic bond or electroen. Okay. So ionic bond formation the ionic bond is formed.

[00:45:07]The ionic bond is formed between the positively charged cation and negatively charged ion. Right? Oppositely charged force of attraction ionic bond.

[00:45:22]So example we are taking sodium chloride. So sodium atom what is the nature of sodium atom? It is electropositive in nature. So they readily loses electrons. They are readily loses electron. They become cation means sodium ion. Sodium ion it loses its valence electron. How many valence electron present in the sodium atom? There is only one electron in in the 3s subshell. 3s subshell only the sodium atom only. Sodium atom containing only one electron in their valence shell. That electron undergo readily loses. So sodium normally neutral sodium atom become converted into sodium ion.

[00:46:07]Okay. Na plus like that chlorine atom is a non-metal. What is the nature of chlorine atom? Chlorine chlorine is a more electro negative atom. It it accept a is accept a electron. Okay means gain electron. It readily converted into Cl into Cl minus. Right?

[00:46:32]So Na+ and Cl minus they readily form. They readily form ion. How cation and anion are formed? Kion and the anion is formed by losing and gaining of electron. One metal atom electron.

[00:46:51]Another one is chlorine atom gain one electron become chloride ion. Right?

[00:46:58]There is a force of attraction between the oppositely charged ion leads to the formation of sodium chloride. The bond is formed between the oppositely charged ion. There is a electrostatic force of attraction between Na plus and Cl minus due to the formation of electroent bond or ionic bond. The next see how ionic bond is formed due to force of attraction between the oppositely charged ion means Na plus and the Cl minus. Okay. The next this is electrostatic force of attraction between oppositely charged ion. The next say Na get converted into Na plus oct what it says right those element are atom those element or atom having eight electron in their valence shell that atomic atom or element or ionic species are stable so that's why there is only one electron in their valence shell right in 3s orbital one electron in their valence shell that readily loses what is configuration of Na plus 28 right previous to 281 it loses its one electron so sodium become Na+ the next chlorine so chlorine needed one electron complete their octate so that's why having electron 2 8 and 8 right next due to the formation of Na Cl okay okay sodium ium chloride along with liberation of energy.

[00:48:42]Those chemical reaction is having liberation of energy is nothing but an exofothermic reaction that exothermic reaction. Formation of chlor sodium chloride is a exothermic process.

[00:48:56]Why? Due to the formation of ionic ionic compound with the liberation of energy with the liberation of energy it nothing but an latis energy latis enthalpy this is a thermodynamic word enthalpy it is a heat content okay next energy is nothing but amount of energy released when one of ionic bond is formed. Then next higher the latice energy greater will be the formation of crystal.

[00:49:44]Then next compound more stable right more amount of energy is released due to the formation of ionic ionic crystal and more stable will be the bond. Okay. The next definition of ionic bond the bond is formed by the complete transfer of sodium that sodium loses its complete one electron one or more electron from one atom to another atom leads to the formation of ion which are linked by electrostatic force of attraction is nothing but an ionic bond. Apart apart from NaCCl, what is another example?

[00:50:31]Formation of calcium chloride and formation of calcium fluoride. Right?

[00:50:37]Next to potassium chloride. Sodium chloride. Potassium chloride. Example.

[00:50:42]It is an example for ionic compound.

[00:50:45]Okay. Ionic compound. Then sodium hydroxide. Na. Right. Ca twice. Calcium hydroxide. What is the nature of bond between the two species? There is ionic bond. There is a formation of ions. The next information chlorine calcium is assigned positive charge. So it is alkaline earth metal carrying Cu2 plus because it loses its valence electron. Two valence electron. Ca becomes Ca2+. Like that chlorine atom gains electron. Chlorine atom is converted into Cl minus. Okay. Then next how ionic bond is formed. Ionic bond is formed by the formation of cation and formation of anion. Here cation. What is cation? Cation is positively charged species. Positively charged species.

[00:51:46]Okay. Who is going to be readily form cation? So group one and the group two.

[00:51:52]What is group one? Group one and group two are the alkali metal and alkaline earth metal. Okay, that is present in the left hand side of the periodic table. They are more reactive.

[00:52:04]They readily loses his electron valence electron. Okay, the next another point is there is having low values of ionization potential.

[00:52:16]What is ionization potential? What is ionization potential? Can anybody What is ionization potential?

[00:52:27]Okay.

[00:52:29]An ionization potential.

[00:52:32]Ionization potential or ionization energy.

[00:52:41]So for example Na become Na plus.

[00:52:48]So there is having low ionization potential. What is ionization potential?

[00:52:54]Say for example, sodium containing 281 electron. So this is positively charged nucleus. Then this is the first shell.

[00:53:03]This is the second shell. And this one is the third shell. Valency shell.

[00:53:08]That first shell containing two electron. Then next shell containing eight electron.

[00:53:14]3 4 5 6 7 8. Then last one containing the last one containing wait this one valence electron there is only one electron. Okay.

[00:53:34]So right the amount of energy right what is ionization potential amount of energy required to require to remove valence electron valence electron in there to remove valence electron amount of energy required to remove valence electron in the isolated gaseous atom. Isolated gaseous atom. Isolated gaseous atom electron.

[00:54:20]There is only one electron in there 3s shell. That electron is removed. That electron is removed. Electron required energy.

[00:54:32]That energy known as ionization energy.

[00:54:37]Only just 2 and 8. Okay.

[00:54:49]Along with the liberation of latis enthalpy. Along with the liberation of latis enthalpy. Okay. The formation of lowionization.

[00:55:01]Okay.

[00:55:06]bond we must require cation means positively charged species. The next formation of anion here formation of anion formation right annion is formed by group 15, group 16 and group 17 means B block element readily form anion because they are more electro negative in nature and as possesses high electron affinity or electron gain enthalpy. So they readily form anion. Okay.

[00:55:43]Next.

[00:55:51]So bond containing two types ionic bond. The one is ionic bond. The second one is coalent bond.

[00:56:10]Right.

[00:56:11]How ionic bond is formed? Ionic bond is formed by the force of attraction between the oppositeely charged ion.

[00:56:18]Example and minus the next coalent bond form right. Which type of compound is readily formed coalent compound especially organic compound readily form coalent bond.

[00:56:35]Which type of compound is readily form coalent compound? organic compound. Then ionic bond formation ionic bond is formed by formed by inorganic compounds. Right? Generally inorganic compound is formed by ionic bond and coalent bond is formed by organic compound. Right?

[00:57:00]So organic compound inorganic ionic. Okay. So coalent bond nature of chemical bond in that coalent bond. See see this sentence. When two atoms of similar electro negativity combine together. Right? See this definition.

[00:57:28]When two atoms of similar electro negativity electro negativity see what is electro negativity I'll explain electro negativity okay what is electro negativity electro negativity means tendency of an atom it is a properties of periodic table periodic table only elements in one of the property the one property is ionization potential. Another property is atomic radius. The third property is ionization potent sorry electron gain enthalpy. The another one is electro negativity. This is most important properties of periodic table element.

[00:58:11]What is electro negativity? Means tendency of an atom element. Tendency of atoms or elements attract the attracts the shared pair of electron attract the shared pair of electron towards itself towards itself. Right?

[00:58:36]Except for example I am taking hydrogen chloride. I'm taking hydrogen chloride.

[00:58:42]Then I am taking the examples of Cl2.

[00:58:45]Then I will taking the examples of H2.

[00:58:48]Okay.

[00:58:51]I'm taking HCl as an example. Right? So hydrogen containing one electron and chlorine containing 2 8 and 7 electron.

[00:59:01]Okay? 2 and 8 electron that atom or ionic species should be should be stable. Okay.

[00:59:26]So we can accommodate only two electron.

[00:59:30]Okay. One more electron. So two plate configuration the configuration is known as two plate because hydrogen containing only two electrons. Okay.

[00:59:45]Okay. No gas electronic configuration of helium 1 s2.

[00:59:56]So even no gas configuration that element should be stable but hydrogen extra because maximum two electron. Okay.

[01:00:13]So that is the reason hydrogen carrying two plate configuration. Okay.

[01:00:24]How many electron present in the chlorine? 2 8 and seven. So in this case chlorine atom require one electron to complete their octate. Right? Octate one elected hydrogen is also having one electrogen.

[01:00:46]Hydrogen atom one electron like that.

[01:00:50]Chlorine containing seven electron in their valence shell. Two 4 6 7. Okay.

[01:00:58]There are seven electron dot. The dot represents the electron. Valence electron. Veence electron represent.

[01:01:08]Okay. This dot is also represent valence electron. Okay.

[01:01:13]Clear. Then next hydrogen is carrying dupate configuration. Chlorine carrying octate configuration needed electron. Hydrogen required one electron. Chlorine is also require one electron. Chlorine electro.

[01:01:33]For that reason in both the atom share their veence electron share their valence electron to complete their noble gas configuration. Right? To obey the noble gas configuration. Hey hydrogen is share one electron and chlorine is also share one electron. Okay.

[01:02:00]Hydrogen.

[01:02:02]Hydrogen is also 8 electron. Sorry, two electron. Okay. So it is 2 electron.

[01:02:09]This is 8 electron configuration.

[01:02:15]Right.

[01:02:16]So the bond is formed by it require two electron. Okay. It require two electron. The bond between the hydrogen and chlorine is coalent bond. The bond is called coalent bond. Why it is called coalent bond? The bond is formed by the mutual sharing of electron.

[01:02:40]Dupate configuration like that chlorine chlorine atom is also having seven electron but it require one electron to complete their Mutual elect the bond is formed by the formed by the mutual sharing of electron between the two atom is nothing but an coalent bond is nothing but an coalent bond right but the bond is not completely coalent right so it is it has some ionic character he hydrogen and the chlorine The bond between the hydrogen and chlorine hydrogen present in the left hand side of the periodic table above the lithium atom like that chlorine is present in the right hand side of the periodic table. They are more reactive and also electrogative in nature. For that reason the bond is formed by the bond is formed by the mutual sharing of electron because of due to the electron withdrawing nature of chlorine means more electro negativity more electro negative in nature. More electro negative in nature. The whole shared pair of electron is more towards chlorine atom. Is more towards chlorine atom. The electron density more on chlorine atom. For that reason, for that reason, chlorine carrying partially negative charge completely I am using this symbol delta. What is the meaning of delta? Delta means partially partial right.

[01:04:34]So chlorine carrying partially negative charge and hydrogen carrying partially positive charge because hydrogen is lesser electrogative chlorine is more electrogative more electro negative right. So there is a opposite pole is create between the hydrogen atom and chlorine atom. So that's why it is called polarity right polarity. What is the nature of bond? Coalent bond. So that's why the nature of the bond is polar coalent bond. Polar coalent bond polar coalent bond. Okay.

[01:05:13]Polar coalent.

[01:05:16]The bond the mutual sharing of electron between the two different atom and one of the atom is more electrogative another atom is lesser electrogative.

[01:05:26]The nature of bond is polar coalent bond. Another one example I am taking hydrogen or I am taking chlorine. Okay. Hydrogen chlorine. Okay. Formation of chlorine molecule. Take chlorine molecule formation. Each chlorine containing seven veence electron 287 287. Right? Each chlorine atom containing seven veence electron. Veence 2 4 6 and 7 like that.

[01:05:58]2 4 6 7 seven electron in their valence shell. Okay. Then next each chlorine atom shared their valence electron because both chlorine atom but one electron is needed to complete their octate. Each chlorine atom share their electron towards another chlorine atom.

[01:06:26]elect this is also carrying eight electron.

[01:06:31]This chlorine atom is also carrying eight electron. Okay. But what is the nature of bond between the two chlorine atom? Means each chlorine atom is having one electro negativity. Same electro negativity because both chlorine atoms are same right electity because both atom is having similar electro negativity.

[01:07:00]There is no polarity between the two chlorine atom. So that's why the nature of bond is nonpolar coalent bond.

[01:07:09]Nonpolar coalent bond. If coalent bond type is there one is polar coalent bond another one is nonpolar coalent bond when the polar coalent is bond is formed there is electrogativity difference between the two atomity difference create nonpolarent right.

[01:07:55]Okay.

[01:07:58]I am taking another example. H2 then F_sub_2 then Br2 I2. Okay. These are the molecules. Then O2 then N2. What is the nature of coalent bond is that molecule nonpolar coalent bond nonpolar coalent bond okay non-polar coalent bond butcess the bond is formed by the mutual sharing of electron between the two similar atom and two dissimilar atom. So the coalent bond is formed. Hope you understand.

[01:08:43]So put your thumb in your chat box.

[01:09:02]Sir okay see this sentence then explain when two atoms of similar electro negativities are combined together. Okay. Then a bond is formed by how coalent bond is formed.

[01:09:24]Coalent bond is formed by the mutual sharing of electron because atom octate configuration in complete complete. So for that reason each atom share its valence electron towards another atom.

[01:09:39]Both are mutually shared. This is the second point how coalent bond is formed.

[01:09:44]Then third one examples when two atoms have similar electro negativities H2 N2 O2 CL2 and methane right next what is a coalent bonding definition the attractive force which exists due to to the mutual sharing of electron.

[01:10:17]Mutual the attractive force which exist due to the mutual sharing of electron between the atom of similar electro negativity are having a similar small difference in their electro negativity is called coalent bond. previous example say for example HCl then I am taking H2 then I'm taking HL2 then HBr okay then the bond between the H2O oxygen and hydrogen then bond between the N and H ammonia example coalent bond example nonpolar coalent bond what isent and bond definition the attractive force which exist due to the mutual sharing of oppositely charged force of attraction due to mutual sharing of electron between the two atoms of similar electro negativity similar electrogivity H2 CL2 O2 these two atoms are similar electron negativity or have small difference in their electro negativity. Small difference. Say for example there is a small difference in the electro negativity between the oxygen and hydrogen. There is a small electro negativity difference between the nitrogen and hydrogen. So main important point electro negativity means what is electro negativity? The tendency of an atom to withdraw the share share pair of electron towards itself.

[01:12:09]Group 15 group 17 groups 15 16 17 group means electro negativity.

[01:12:25]Okay.

[01:12:28]Coalent bond.

[01:12:32]Okay. The next see containing one electron each.

[01:12:46]How H2 molecule is exist for exist. H2 how H2 molecule will be exist hydrogen atom each hydrogen atom containing one one electron in their valence shell hydrogen shell one shell like that two electron because they complete their dupate they complete their duplet configuration. Dupate configuration means they containing two electron. Two electron element helium. Helium is a noble gas. Hydrogen gas configuration.

[01:13:33]Okay. The next this is how H2 molecule is formed.

[01:13:40]So force of attraction due to mutual sharing of electron between the two similar electro negativity atom. Okay, this is how H2 molecule is formed. The next coalent bonds are classified into two types. One is non-polar coalent bond.

[01:14:02]Another one is polar coalent. One is non-polar coalent bond and polar coalent bond. Yes. Excuse me sir. Yes. Tell me if you have any doubt put put in message put in comment box.

[01:14:32]No doubt.

[01:14:39]So coalent bonds we are classified into two types. One is sometimes hydrogen have two electron in it's right sometimes means uh isotopes. Okay one second say hydrogen having a two isotopes one h1 h2 one h3 right. So now hydrogen atomic 1 exact atomic mass of hydrogen average okay naturally exist three important isotopes and electron okay but hydrogen containing only one electron and one proton but is It containing two neutron and one neutron and two neutron. Hydrogen only one proton one neutron sorry one proton and one electron is there. Right? In dutarium one proton one neutron and one electron like that initium one proton two neutron and one electron. Okay.

[01:16:01]Formation.

[01:16:03]Okay.

[01:16:05]Sometimes they exist in two dupate configuration. Okay.

[01:16:16]Hope you clear.

[01:16:24]topic.

[01:16:27]Okay. Then types of coalent bond.

[01:16:31]Non-polar coalent bond and polar coalent bond. Non-polar coalent bond formation.

[01:16:36]Non-polar coalent bond is exist between the two similar electro negativity atom.

[01:16:41]Say for example between the hydrogen atom. See electron cloud. Okay. The next there is a small difference in their electro negativity between the hydrogen and florine between the hydrogen and florine. See florine is having a highest. See this picture. See this picture both hydrogen atom is having similar electro negativity. I electron density same in it. You see the picture number two. Polar coalent bond.

[01:17:13]In polar coalent bond hydrogen is hydrogen is lesser electrogative and florine is the more electrogative. So more electron density is more towards florine atom. So that's why florine carrying partially negative and hydrogen carrying partially positive. See this one florine carrying partially negative hydrogen carrying partially positive.

[01:17:37]Okay. The next this unymmetrical distribution of electron cloud make the molecule dipolar dipole opposite positive right then next such a molecule is termed as polar hydrogen fluoride ammonia water hydrogen chloride this type of molecule we call it as polar molecule Okay. The next there is a partial ionic character in coalent bond. Okay. Coalent bond.

[01:18:21]So it exist as not 100% ionic. Okay. It has some coalent. It has some ionic character. The reason is there is electro negativity differences between the two dissimilar item. Okay.

[01:18:38]So the coalent examples which there are six type of coalent bonds is formed okay types okay example one first type case number one single bond and nonpolar single bond single what is the nature of that single bond And it is a non-polar in nature. There is no charge sorry there is no electro negativity difference between the two atom. Okay. Example hydrogen molecule. See both each hydrogen carry one one electron.

[01:19:27]The next both both are combined. they form dupate configuration leads to the formation of single coalent bond electron only one coalent bond form. The next shared pair of shared pair that shared pair of electron we call it as bond pairs. Those electronic species which involved in the bond formation is known as bond pairs.

[01:19:54]The next case number two is the first case.

[01:20:00]This one is the first case single bond and non-polar. The next is case number two double bond and the non-polar. Double bond and the non-polar. Okay. First one is single bond and non-polar. The second case is double bond and non-polar.

[01:20:22]I'm taking oxygen atom. Oxygen atom is a group 16 element. That oxygen carrying six valence electron. Oxygen carrying six valence electron. And I am taking another oxygen atom. That oxygen atom is also containing six valence elect.

[01:20:49]See that oxygen required two electron to complete their octate.

[01:20:58]Each oxygen carrying two electron to complete their octate. For that reason each oxygen share its two electron share its electron towards another oxygen atom. Everything like this. Okay.

[01:21:14]Each oxygen share the two valence electron. Okay.

[01:21:22]Formation double.

[01:21:27]So electron two pairs of electron is not involved in bonding. That electron we call it as lone pair of electron.

[01:21:39]That we call it as bone pair. that two two pairs of electron is shared between shared between two oxygen atom like that share unpaired electrons lone pair. Okay.

[01:21:58]So third one case triple bond and non-polar triple bond and non-polar.

[01:22:06]See three bond he formation. See this one nitrogen carrying five veence electron and another nitrogen is also containing five veence electron. Okay.

[01:22:16]Each nitrogen electron.

[01:22:19]So each nitrogen share their three electron towards another nitrogen atom. See nitrogen atom 8 electron. This nitrogen is also carrying 8 electron and this nitrogen is also carrying 8 electron.

[01:22:36]Okay. The next so each nitrogen share its three pairs of electron. Three pairs means six electron in this pair is called lone pair. There is a differences between bond pair and loan pair. What is bond pair? Bond pair is nothing but an electron pair involved in bond formation. Bond pair. Those electron pair is not involved in bonding is called lone pair. Right? Nitrogen containing one lone pair of electron.

[01:23:05]Okay? This is how the coalent bond is formed. Okay, I'm ending this session.

[01:23:10]The next session will be biology. Okay, next class, next session.

[01:23:17]Okay, thank you.

[01:24:15]Hello my dear students very good evening for all of you.

[01:24:23]So myself Priti Raj I'll be handling you biology.

[01:24:30]So in this class we'll be discussing about a short small session on uh nervous system. Okay.

[01:24:38]Although it is a very big topic we'll be having uh very big unit in your first first PO we'll just talk a few gist of this uh topic. Okay. Hi all of you. Good evening. Very good evening all of you.

[01:25:01]Yes, without any delay we'll be starting. Uh so I'll start with the biology bridge bridge course that is your nervous system. Okay, so you have studied in your previous class that is in your SLC. Okay, you have in your 10th standard you had a chapter called as control and coordination. Do you remember in science you had a chapter called as control and coordination. I hope all of you remember this one.

[01:25:28]Please give me a thumbs up if you remember.

[01:25:36]Yes. Yeah. Anjali.

[01:25:40]Yes. All of you had right. Yeah.

[01:25:43]Definitely. It is a chapter in which you have a relation with your first P. So whatever you have studied the same topics but in more detailed version you are you will be studying in your first year P itself. Okay. In uh human physiology, so in human physiology you have a chapter called as neural control and coordination. Okay. And also you have a chapter called as chemical control and coordination.

[01:26:11]Okay. It's a very nice interesting chapter and it is a part of zoolology as you all know. So I'll be just talking about nervous system and what is the structure which you can see in this diagram or in this slide.

[01:26:26]So what is this structure?

[01:26:32]Yes. Anyone? What is this structure that you can see on your screen?

[01:26:42]Yes, it is a neuron. Yes, all of you.

[01:26:44]Yes, it is correct. So neuron, it is a structure of neuron. So that you can see in your uh screen. So neuron is a basic structural and functional unit of nervous system. Okay. So it is a basic structural and functional unit of nervous system. So that is your neuron.

[01:27:07]Okay. So before coming to that what you have understood until now that we will see. Okay. So what you have seen the as the chapter suggest you that is you're talking about control and coordination.

[01:27:29]Okay, control and coordination. So you know this control we are talking about the nervous system. Okay, the nervous system that is going to control your entire body physiology or metabolism that is going to happen in your body.

[01:27:45]Okay, that is done by your nervous system. The other thing which you have to know is coordination. Okay, coordination. So coordination is nothing but the process through which two or more organs interact and complement. Okay, they interact two or more organs interact and they complement each other. Okay. So they complement each other in their respective functions. So just remember just we'll be talking about a person. Okay. this this boy okay we'll talk about this boy uh this boy's name is safe for example he is Mr. or master chintu.

[01:28:27]Okay. So he is master chintu. Now what is uh why should I talk about this person? Okay. So in Chindu's home we uh he have a sister. Okay. So this is Chindu's sister and this is Chintu's mother and this is Chinto's father. Okay. So, Chintu's sister and this is Chinto's mother and this is Chinto's father. Okay. And this is Chinto himself and uh you you have one more character that is not in the picture.

[01:29:10]So she she is I mean she is say Chinto's grandmother for example. Okay, you can give any number of examples. Now, what happens in Chinto's home? Why we are talking about this uh Chinu? Because see, we we'll take a situation. Okay, understand?

[01:29:29]We'll take a situation.

[01:29:32]In this situation uh imagine Chindu's relatives are coming home. Okay. So, some uh guests are coming to Chindu's home. But what is the problem with this guest?

[01:29:50]So you know there will be some relatives they intentionally they will visit your home without informing okay they are coming to imagine they 10 minutes away okay they are in the outskirts of itself and they'll call you and then they'll call you and They'll tell that they will be coming to home in 10 minutes. Okay. In 10 or 10 to 15 minutes they'll be coming home.

[01:30:26]So then what they are going to do in their home. Okay. What you are going to do? Think yourself. So what you are going to do? You will distribute the work between yourself. Okay. You are I mean say here four four of them or five of them are there. So Chinto will tell that he will clean or he will do the mopping. Okay. And she sister she will tell that she will clean the say fridgen. Okay. Frigen clean or utensils and the uh whatever it is. Okay. The sink and all whatever you can see in this diagram.

[01:31:04]Okay. Now and uh Chintu's mother she will tell that she will broom the house.

[01:31:10]Okay. She will broom the house and Chintu's father she will I mean he tells him that I mean he will put the trash okay to the to outside okay trash okay then what they'll do the in the next thing is they have cleaned the entire house and what they'll do next is they will allot themselves some of the other works okay say uh they will uh pick up the clothes okay and they will put it in the cupboard and then say Chind's father will tell that okay he will bring some uh eatables okay eatables to the guest or the sweets or sweets or any other things for the coming arriving guest okay then mother tells him that okay she will cook the tea okay she'll make the tea for them or she'll cook something snacks or something like that and yeah like this they they're going to divide the work and Shindu himself he will tell that he will arrange the table for them.

[01:32:14]You are dividing the work between themsel. Okay, they are I mean they're dividing the work between themselves. So what they meant to say is all of them are doing what? See they are dividing their work so that the guest when they come in okay when when the guest come into their house they will be happy. Okay. So seeing that house is so clean.

[01:32:43]So they the guest will be very happy and they will go home and saying thank you.

[01:32:50]Okay. Right. So they'll be very happy to see the home very clean and they are it is very very well maintained and the father okay he had bought a lot of things to eat and she have cooked the cooked the snacks or I mean whatever she had made tea also so all those things so by they'll be impressed okay the guest will be impressed and the work is being done how the work is being done because of the coordinated effort efforts of each of the members. Okay, each of the members are doing their work.

[01:33:27]Hence, they are work I mean they are the guest are very happy. Okay, so guest happy when they work in the coordinated manner. Okay, when they work in a coordinated manner, the guest will be very happy. Hence, they will move away just saying thank you. Now what you have to understand here the same control and coordination is happening in our human body also or in any other organisms for that matter. Okay. So this control and coordination is nothing but control you know the nervous system controlling all the other activities. Okay. Coordination means there is a coordinated effort that is taken place taking place between organ to organ. Okay. Organ and organ organ to organ system. Okay. Organ to organ systems and they interact with each other. Organs will interact with each other and they complement. Okay.

[01:34:26]All of them are complementing so that they are presented very well. The work is done very nicely. Okay. Hence the there is a coordinated efforts of each of the persons of the family. Like that in our body each of the organs will take part to complete the work successfully.

[01:34:47]Okay. In a good manner, very good manner without any problem without creating any problem to your body. It will make sure that there is no problems or issues created for the body. That is what it is doing. Okay. So it is a process in which two or more organs interact and complement the functions of each other.

[01:35:08]Okay. complement the functions of each other. So all the functions why it should be coordinated why it should be controlled. Yeah.

[01:35:19]To maintain a very critical process called as homeostasis.

[01:35:26]Okay. So it is called as homeostas stasis. Okay. Homeostasis. So what is homeostasis? It is nothing but the maintenance of internal environment.

[01:35:38]Okay. What is this? It is the maintenance. Okay. Maintenance of the internal environment. Okay.

[01:35:49]Remember it is the internal environment of the body. Okay. So it is a maintenance of the internal environment of the body with respect to with respect to the everchanging. Okay. Ever changing ever changing external environment. Okay. Ever changing external environment. So the environment outside the body is always changing.

[01:36:21]There is a temperature change fluctuations in the temperature. You know it is very sweating nowadays because it is summer. Okay. In the winter it is again going to change.

[01:36:31]Again in this rainy season it will be very highly humid. The temperature will also be more. Okay. So at that time the temperature fluctuation should be maintained in your body. So whatever temperature outside the body it may be doesn't matter. So inside your body there should be a constant body temperature that is 36 or 37° C. Right?

[01:36:54]So that should be maintained in our body. So that is one of the example. So total environment the internal environment of the body should be maintained that is that work is done by your brain and your nervous system.

[01:37:08]Okay. So nervous system. Now so what you mean by nervous system and what is there? So that was a example which I gave you in a general manner.

[01:37:21]Okay. Say for example here we are taking any physical activity. Okay you are doing uh any physical exercises.

[01:37:32]So physical exercise.

[01:37:36]Okay. So you're doing something jumping jacks or something like that. You doing any physical exercises at that time what happens inside your body. Okay. Inside your body if you want to do any physical exercises you require more energy.

[01:37:51]there is a increased energy demand.

[01:37:55]Okay, increased energy demand will be created in your body. This increased energy demand that is created is due to the muscular activity. It is due to the muscular activity.

[01:38:13]Muscular activity there is increased energy demand. So now what happens in order to maintain this energy demand what your body is going to do there is there should be increase in the supply of oxygen. Supply of oxygen should be more in order to meet the demand of the energy. The supply of oxygen in your body should be more.

[01:38:42]So when you imagine you're jogging or you are going for a walk your uh respiration rate will increase. So supply of oxygen this will be taken care by the nerves. Okay. Take a note of the nerves. Now what the nerves will do? Nerves nerves can the nerves breathe? No. So nerves what it will do?

[01:39:07]It will send the signal to the lungs.

[01:39:11]Okay. Will send the signal to the lungs.

[01:39:18]So it should increase the rate of respiration.

[01:39:24]Rate of respiration.

[01:39:27]It should be increased. Okay. To increase the rate of respiration. Who will going to who is going to increase the respiration rate? That is your lungs is going to increase the respiration rate. So if there is a increase in the respiration rate so what happens the heart rate okay so remember the heart rate will increase. So if the heart rate increase there is a increase in the blood flow blood flow should increase and if the blood flow should increase it can move through the blood should move through blood vessels. Okay blood vessels through mater. See you can see here the nerves is taking part. Okay, obviously the nervous system is taking part and then you have the lungs as a organ and heart is an organ and you have the blood vessels also are taking part in case of your the moving of the blood.

[01:40:24]Okay, that is all these things are happening in your body. So there is a coordinated effort that is taking place between the nervous system and the lungs as well as the heart and the blood vessels. All of them together you are mean they are working together in order to facilitate your muscular activity. So whatever muscular activity you are doing to in order to facilitate that you are all these organs are coordinatedly I mean working in a coordinated manner.

[01:40:58]Okay. Who is taking care of care of all these things? That is your nervous system. Okay. Nervous system. So nervous system and uh here you can give other examples. Okay. These are the other examples you can also give. So when when this reverse takes place okay I mean you you have stopped the muscular activity stop what happens again the nervous system will send the message that it will it should require less amount of oxygen oxygen and blood flow. So blood flow.

[01:41:39]So blood flow if it increases more blood is purified. And who is going to purify your blood? That is your kidney. Okay.

[01:41:47]Kidney is going to purify the blood. So kidney is also taking part here. Okay.

[01:41:53]All these things coordinatedly working together in order to protect or in order to facilitate your activity, muscular activity. Okay. So remember that. So that's it.

[01:42:06]uh about the introduction that is your uh coordination. Okay. So here you will be uh you should know so both the nervous system okay nervous system and there is something called as endocrine system also. Okay this also you have studied introduction you have you know uh you have already studied. Okay. Here endocrine system controls the body through some certain chemicals you call call it as hormones. Okay. Hormones through control and nervous system you know you have two types of nervous system. I'll come to that. Okay. Nervous system CNS PNS central nervous system and peripheral nervous system. Okay.

[01:42:58]I'll come to that. So before so before that you know uh what is our uh nervous system neural system. So it is made up of what? Nervous system or neural tissue.

[01:43:16]Nervous tissue is made up of what? Is made up of what?

[01:43:24]You have already known this one. you have already told also it is nothing but your the cells called as neurons.

[01:43:31]So it is called as neurons. So here what you know about neurons. So as I told you it is the basic structural and functional units of nervous system. Okay. is the basic structural and functional unit of nervous system.

[01:44:01]So they are very highly specialized. Okay, remember they are very highly specialized cells. Okay, they are highly specialized cells. Now what they will do? What is their function which or it can detect? Okay. It can detect or receive and transmit the different kinds. Okay. Different kinds of kinds of information that you call it as stimuli.

[01:44:48]Okay. Stimulus stimuli. So response to stimuli already. Okay. Now it is a basic structural and functional element of nervous system. They are highly specialized cells. Okay. That is about your neuron. And it can detect as well as receive and transmit different kinds of stimulus that is going to be received. And one more thing you have to remember very important it cannot it cannot divide. Okay. It does not have the property of cell division. Cell division.

[01:45:27]Okay. It cannot divide itself. So hence the people see once your nervous tissue is lost that's all. See people have lots of neural disorders. You cannot treat neur neural disorders like Parkinson's disease or dementia like all the nervous disease which have neural disease which you know very problematic okay once the memory is lost it is permanently lost you cannot get it back because no new cells are formed the neurons once it is formed during the fetus stage Okay, that's all. It will never form again.

[01:46:20]You cannot get new cells. New cells are impossible. You cannot give or you cannot get new neuron cells. Once it is degenerated, it is degenerated. That's all. It cannot be taken back. Done. Now but one thing you all know the brain has got a disease. Okay. Brain has got a disease or uncontrolled cell division.

[01:46:45]You call it as a tumor formation.

[01:46:49]Brain tumor.

[01:46:52]But there is a brain tumor right?

[01:46:56]Yes. Tell me what is brain tumor. Now what do you call what do you mean by brain tumor?

[01:47:06]See tumors are nothing but cancerous cells. See which continuously it is going to divide divide again again it is going to divide. So tell me what you mean by a brain tumor little fast children.

[01:47:43]So which cells are going to divide then?

[01:47:46]I told you neurons will not divide.

[01:47:50]Then there is a situation or condition called as tumor also which are nothing but the cancer which is affecting your brain. So what do you mean by that?

[01:48:10]What do you mean by that?

[01:48:13]fast.

[01:48:40]Miss anyone?

[01:48:44]How is this possible? Brain tumor. How is this possible?

[01:48:53]See, it is because the nervous tissue, okay, nervous tissue is made up of neurons as well as one more type of cell. Okay, there is one more type of cell. You call it as neurogal cells. Okay, neurogal cells. Okay, it is called as neurogal cells. Now this neurogleal cells what happens to this means? What it is doing?

[01:49:22]Means it is the nurse cells. It is the nurse cells.

[01:49:30]So giving the nutrition for the neurons.

[01:49:33]Okay, giving the nutrition for the neurons and taking care of the neurons.

[01:49:36]basically it is taking care of the neurons. Now this nerve cells composed okay of 50% or more than 50% of your uh cells or nerve cells are made up of or the cells of the cells which is present in the nervous tissue is made up of neurogal cells. So this neurogal cells actually have the capacity of division.

[01:50:03]It can divide. Okay, it can divide.

[01:50:07]Hence there is a formation of tumor brain tumor formation.

[01:50:14]Okay, now that is why you can say you can say that there is a tumor formation in the brain. You cannot say with respect to your neurons but you can definitely say it with respect to your eurogal cells. Okay, remember that there is one more type of cells called as neurogal cells. Then so remember about these uh different uh types of cells and structure of neurons you know you know you have the dendrites okay you have the dendrites then so these are the dendrites branching uh this one okay branching filament-like structure you can see this one is your dendrites and there is a cell body that is this is your cell body called as cyto on then there is a nucleus and then you have a long threadlike structure you have a long threadlike structure you can call it as axon okay I'll come with a detailed uh structure okay when you come to the regular classes okay you'll have a very uh elongated structure called as axon and axon terminal okay it terminates to a axon terminal and then this axon is covered by a sheath called as myelin sheath. Okay, myelin sheath.

[01:51:37]So myelin is a lipid. Okay, myelin is a lipid which is secret secreted by your schwan cells. Okay, there is the cells called as schwan cells here. And in these schwan cells will secrete a sheath of lipids. Okay, sheath of lipids you call it as myelin sheath. Okay, remember that. And inside the cyon, okay, inside the cyon there are small granules. Okay, there are small granules you call it as Niss granules.

[01:52:10]Okay, it is called as Niss granules.

[01:52:14]Okay, you will study that and its function is to produce neurotransmitter.

[01:52:19]Okay, neurotransmitter production help neurotransmitter formation cells granular help. Okay, that is its function. nerve endings you have and uh axon terminal you can call as a terminal position you have a bulged portion okay this portion you can call it as axon terminal or and uh in that you have the terminal portion which is going to bulge you can call it as synaptic knob okay synaptic knob and inside that you have synaptic vesicles okay inside that you have a synaptic IC vesicles are present.

[01:53:02]Synaptic vesicles are present inside the synaptic nerve and it will give out the synaptic vesicles will have the neurotransmitter. Okay. neurotransmitter for example acetylcoline or do I mean dopamine can be a uh neurotransmitter or adrenaline your hormone can it can also act as a uh the hormone adrenaline or epinephrine what you call it as so it can also act as a neurotransmitter and this neurotransmitter it will have the connection there is a gap okay there is a gap between Two neurons you call it as synapse. Okay.

[01:53:43]Synapse encourage and in that gap there will be secretion of neurotransmitter.

[01:53:50]Okay. And this structure you can call it as synaptic cleft. Okay. Synaptic cleft.

[01:53:57]So detailed structure you will come to know when you come to the regular classes. Okay. We'll discuss it is a very uh interesting very interesting chapter and uh very easy chapter also.

[01:54:09]If you remember for that if you remember as a little terms okay biological terms if you remember that's enough okay you can easily get through all this uh chapters very easy chapters but uh very important chapters also from the point of view of KCB as well as your uh need is concerned okay as far as your need is concerned and then uh what else to talk yeah you have one more thing uh to show show you that is the nervous system. Okay. So this is the breakdown of your nervous system. So the nervous system are basically or of two divisions. Okay. Main two divisions that is your central nervous system that is CNS. Okay. It is CNS and this is your PNS. Peripheral nervous system. The central nervous system. The central nervous system. It includes Okay. It includes your brain. Okay, it includes brain as well as your spinal cord. Okay, spinal cord will be included here in this CNS, central nervous system and peripheral nervous system. It is made up of all the nerves. Okay, all the nerves. Now the nerves are nothing but uh it is a very simply if I want to define that it is bundle of neurons.

[01:55:37]Okay, it is nothing but a bundle of neurons together you can call it as nerves. Okay, for basic understanding you remember that. So nothing but a group or bunch of uh nerves and neurons you can call it as a nerves. So it includes the peripheral nervous system includes the nerves. All the nerves that is coming from CNS. Okay, from the CNS. So from the CNS you will have so in the CNS as I told you you have the brain you have the brain. So from the brain you will have you will see that there is a projection that you call it as spinal cord. Okay spinal cord and imagine this is a brain. Okay the brain and the now from the brain lot of nerves is going to arise. Okay. Lot of nerves are going to arise from the brain. Okay. From the brain there are lot of nerves are going to come. This you call it as this nerves are called as cranial nerves. Okay. It is called as cranial nerves. The nerve cranial nerves.

[01:56:53]How many it is? It is actually 12 pairs.

[01:56:56]Okay. 12 pairs of cranial nerves are present in your that is arising from the brain. Okay. Then if you come to the spinal cord. Okay. There is the spinal cord. So throughout the spinal cord you will see that there are number of nerves that is arising from the spinal cord.

[01:57:17]You can call it as you can call it as spinal nerves. Okay.

[01:57:23]We can call it as spinal nerves. So spinal nerves.

[01:57:29]How many spinal nerves are there?

[01:57:31]There's nothing but your 31 pairs of spinal nerves are present in a human body. So in a human body you have 31 pairs of spinal nerves and in a cranial nerves in a human body that is the nerves which are arising from the brain it is 12 pairs. Okay that is you call it as cranial nerves. See our human uh nervous system is much more complex.

[01:57:56]Okay, we belong to vertebrates. We belong to vertebrates and we have a more complexity and it is highly developed.

[01:58:05]Okay, it is highly developed in case of human beings. But in lower forms like a hydra or invertebrates, you take any invertebrates, it's very simple. Okay, it is very very simple and it is just uh only a few neurons will form a central nervous system. Okay, only few neurons you can call it as nervous system in some invertebrates. Okay, that is all you have. And then this peripheral nervous system is further divided into somatic nervous system and autonomic nervous system. Autonomic nervous system. Smatic nervous system and this somatic nervous system in which you can see that it controls your voluntary actions. Okay. Mostly okay.

[01:58:52]Mostly it will be controlling your voluntary actions.

[01:58:58]Voluntary actions.

[01:59:02]It will control your skeletal muscle.

[01:59:10]Okay, it is going to control your skeletal muscles. That is what here you have in case of somatic nervous system.

[01:59:17]Autonomous nervous system. Now autonomic nervous system see it is mostly your it is going to control your visceral organs. Okay, visceral organs are the main organs that is present. Okay, which you cannot it is not under your control.

[01:59:32]Say for example heart is not under your control. Okay. So visceral region you call it as visceral region inside the body we have a visa cavity cavity orans visceral organs.

[01:59:48]Okay now so visceral organs which are involuntary they are controlled by your autonomic nervous system and further it is divided into sympathetic and parasympathetic nervous system. So sympathetic nervous system only when you it is like your uh fight and fright. Okay. Flight and frigid.

[02:00:15]Fight means you are going to fight and frigid means very cold or at times you have you have got plight also. Okay.

[02:00:26]You are in danger. So danger, cold, sympathetic nervous system and parasympathetic nervous system it works during rest. Okay, it is during your resting period. So resting digestion it helps in digestion. So digest parasympathetic nervous system and then you have nervous system in detail that is that will be more complex for you at your level. So divisions you will be studying all this classification you will be studying in your chapter called as control sorry neural control and coordination then also you'll study endocrine systems in your chemical control and uh coordination. And yes sir time. Yeah I know. So we'll be winding up. That's all. That's all for today's discussion.

[02:01:23]I hope a very brief introduction of nervous system you have got you have understood from this uh session. Okay. I hope to see you in the next uh classes coming classes. We'll be having uh class tomorrow. The timings will be updated in the group. Please go through that. Okay. So thank you all. See you soon. Okay. So, bye all of us.