summarize this for a 3 year old:

The pacemaker current (If, or IKf, also called funny current) is an electric current in the heart that flows through the HCN channel or pacemaker channel. Such channels are important parts of the electrical conduction system of the heart and form a component of the natural pacemaker.

First described in the late 1970s in Purkinje fibers and sinoatrial myocytes, the cardiac pacemaker "funny" (If) current has been extensively characterized and its role in cardiac pacemaking has been investigated.[1][2][3] Among the unusual features which justified the name "funny" are mixed Na+ and K+ permeability, activation on hyperpolarization, and very slow kinetics.[1]
Function

The funny current is highly expressed in spontaneously active cardiac regions, such as the sinoatrial node (SAN, the natural pacemaker region), the atrioventricular node (AVN) and the Purkinje fibres of conduction tissue. The funny current is a mixed sodium–potassium current that activates upon hyperpolarization at voltages in the diastolic range (normally from −60/−70 mV to −40 mV). When, at the end of a sinoatrial action potential, the membrane repolarizes below the If threshold (about −40/−50 mV), the funny current is activated and supplies inward current, which is responsible for starting the diastolic depolarization phase (DD); by this mechanism, the funny current controls the rate of spontaneous activity of sinoatrial myocytes, and thus the cardiac rate. Another unusual feature of If is its dual activation by voltage and by cyclic nucleotides. Cyclic adenosine monophosphate (cAMP) molecules bind directly to f-channels and increase their open probability.[4] cAMP dependence is a particularly relevant physiological property, since it underlies the If-dependent autonomic regulation of heart rate. Sympathetic stimulation raises the level of cAMP-molecules which bind to f-channels and shift the If activation range to more positive voltages; this mechanism leads to an increase of the current at diastolic voltages and therefore to an increase of the steepness of DD and heart rate acceleration. Parasympathetic stimulation (which acts to increase probability of potassium channels opening but decreases the probability of calcium channel opening) decreases the heart rate by the opposite action, that is by shifting the If activation curve towards more negative voltages. When vagally-released acetylcholine (ACh) binds to muscarinic M2 receptors, which promotes dissociation of βγ subunit complexes, leading to direct opening of the G-protein–gated inwardly rectifying K+ channel (Girk/Kir) IKACh.[5] 
system
ek 3 saal kii umr ke liye ise sankshep main bataaen:

pesamekar karant (yadi, yaa aikeef, jise phani karant bhi kaha jaataa he) dil main ek vidyut pravaah he jo echsien channel yaa pesamekar channel ke madhyam se bahata he.aise channel hriday ke vidyut chaalan pranali ke mahatvapurn bhaag hai or prakritik pesamekar kaa ek ghatak banaate hai.

pehali baar 1970 ke dashak ke uttarardh main parkinaje fibre or sinoetrial myosites main varnit, cardiyak pesamekar "phani" (ief) karant ko bade paimaane par chitrit kiya gaya he or cardiyak pesameking main isaki bhoomika kii jaanch kii gai he. [1] [2] [3]asaamaanya visheshtaon main, jinhone "phani" naam ko sahi tehraaya, ve mishrit naa+ or ke+ pargamyata, hyperpolarigeshan par sakriyan, or bahut dhimi kenetiks hai. [1]
samaaroh

mazaakia vartmaan ko sahaj rup se sakriy hriday kshetron main vyakt kiya jaataa he, jaise ki sinoatrial node (san, prakritik pesamekar kshetra), etrioventricular node (evien) or chaalan utak ke parkinaje fibre.mjedaar vartmaan ek mishrit sodium -potacium karant he jo diastolic range main voltage par hyperpolarigeshan par sakriy hota he (aam taur par −60/−70 mV se −40 mV se).jab, ek sinoatrial ection kshamta ke ant main, jhilli IF threshold (lagbhag −40/−50 mv) ke neeche doharaata he, to ajeeb vartmaan sakriy hota he or aavak vartmaan kii aapurti karata he, jo diastolic dapoligeshan charan (DD) shuru karne ke liye jimmedaar he.;is tantra dwaara, mjedaar vartmaan Sinoatrial myosites kii sahaj gatividhi kii dar ko niyantrit karata he, or is prakaar hriday kii dar.IF kii ek or asaamaanya visheshta voltage dwaara or chakree newcliotide dwaara isaki dohari sakriyata he.chakree adenosin monophosphate (siempi) anu sidhe epa-channel se baandhte hai or unki khuli sambhaavna ko badhaate hai. [4]siempi nirbharta ek vishesh rup se praasangik shaareerik sampatti he, kyonki yah hriday gati ke ief-nirbhar swytt viniman ko rekhaankit karata he.sahanubhuti uttejnaa siempi-anuon ke str ko badhaati he jo epa-channel ko baandhte hai or yadi sakriyan seemaa ko adhik sakaaratmak voltage main sthanantarit karte hai;yah tantra diastolic voltage main vartmaan main vruddhi kii ore jaataa he or isliye didi or hriday gati twaran kii sthirataa main vruddhi hoti he.parachimpethetic uttejnaa (jo potacium channelon ke khulne kii sambhaavna ko badhaane ke liye kaary karti he, lekin calcium channel kholane kii sambhaavna ko kam kar detii he) vipareet karrwai dwaara hriday gati ko kam kar detii he, jo ki adhik nakaaratmak voltage kii ore sakriyan vakr ko sthanantarit karke he.jab yoni-relised acetilecoline (ACH) muscarinic M2 receptors ko baandhta he, jo βγ subunit complex ke pruthakkaran ko badhaava detaa he, jisase ji-protein-gated ke pratyaksh rup se K+ channel (GIRK/KIR) ikach ko sudhaarney ke liye agrani hota he. [5]
user
aapke dil main ek "mjedaar vartmaan" kaha jaataa he jo ise haraane main madad karata he.yah bijli kii tarah he jo aapke dil main channelon ke madhyam se bahati he.apane dil kii lay ko sthir rakhane ke liye yah mahatvapurn he.jab vartmaan sakriy ho jaataa he, to yah ek aisa charan shuru karata he jo aapke dil ko niyamit rup se dhadkane main madad karata he.yah aapke sharir main rasayanon kii tarah alag -alag chizon se niyantrit hota he, jo aapke dil ko teji se yaa dhimaa kar saktaa he.
assistant
<|system|>
</s>
<|user|>
ek 3 saal kii umr ke liye ise sankshep main bataaen:

pesamekar karant (yadi, yaa aikeef, jise phani karant bhi kaha jaataa he) dil main ek vidyut pravaah he jo echsien channel yaa pesamekar channel ke madhyam se bahata he.aise channel hriday ke vidyut chaalan pranali ke mahatvapurn bhaag hai or prakritik pesamekar kaa ek ghatak banaate hai.

pehali baar 1970 ke dashak ke uttarardh main parkinaje fibre or sinoetrial myosites main varnit, cardiyak pesamekar "phani" (ief) karant ko bade paimaane par chitrit kiya gaya he or cardiyak pesameking main isaki bhoomika kii jaanch kii gai he. [1] [2] [3]asaamaanya visheshtaon main, jinhone "phani" naam ko sahi tehraaya, ve mishrit naa+ or ke+ pargamyata, hyperpolarigeshan par sakriyan, or bahut dhimi kenetiks hai. [1]
samaaroh

mazaakia vartmaan ko sahaj rup se sakriy hriday kshetron main vyakt kiya jaataa he, jaise ki sinoatrial node (san, prakritik pesamekar kshetra), etrioventricular node (evien) or chaalan utak ke parkinaje fibre.mjedaar vartmaan ek mishrit sodium -potacium karant he jo diastolic range main voltage par hyperpolarigeshan par sakriy hota he (aam taur par −60/−70 mV se −40 mV se).jab, ek sinoatrial ection kshamta ke ant main, jhilli IF threshold (lagbhag −40/−50 mv) ke neeche doharaata he, to ajeeb vartmaan sakriy hota he or aavak vartmaan kii aapurti karata he, jo diastolic dapoligeshan charan (DD) shuru karne ke liye jimmedaar he.;is tantra dwaara, mjedaar vartmaan Sinoatrial myosites kii sahaj gatividhi kii dar ko niyantrit karata he, or is prakaar hriday kii dar.IF kii ek or asaamaanya visheshta voltage dwaara or chakree newcliotide dwaara isaki dohari sakriyata he.chakree adenosin monophosphate (siempi) anu sidhe epa-channel se baandhte hai or unki khuli sambhaavna ko badhaate hai. [4]siempi nirbharta ek vishesh rup se praasangik shaareerik sampatti he, kyonki yah hriday gati ke ief-nirbhar swytt viniman ko rekhaankit karata he.sahanubhuti uttejnaa siempi-anuon ke str ko badhaati he jo epa-channel ko baandhte hai or yadi sakriyan seemaa ko adhik sakaaratmak voltage main sthanantarit karte hai;yah tantra diastolic voltage main vartmaan main vruddhi kii ore jaataa he or isliye didi or hriday gati twaran kii sthirataa main vruddhi hoti he.parachimpethetic uttejnaa (jo potacium channelon ke khulne kii sambhaavna ko badhaane ke liye kaary karti he, lekin calcium channel kholane kii sambhaavna ko kam kar detii he) vipareet karrwai dwaara hriday gati ko kam kar detii he, jo ki adhik nakaaratmak voltage kii ore sakriyan vakr ko sthanantarit karke he.jab yoni-relised acetilecoline (ACH) muscarinic M2 receptors ko baandhta he, jo βγ subunit complex ke pruthakkaran ko badhaava detaa he, jisase ji-protein-gated ke pratyaksh rup se K+ channel (GIRK/KIR) ikach ko sudhaarney ke liye agrani hota he. [5]</s>
<|assistant|>
aapke dil main ek "mjedaar vartmaan" kaha jaataa he jo ise haraane main madad karata he.yah bijli kii tarah he jo aapke dil main channelon ke madhyam se bahati he.apane dil kii lay ko sthir rakhane ke liye yah mahatvapurn he.jab vartmaan sakriy ho jaataa he, to yah ek aisa charan shuru karata he jo aapke dil ko niyamit rup se dhadkane main madad karata he.yah aapke sharir main rasayanon kii tarah alag -alag chizon se niyantrit hota he, jo aapke dil ko teji se yaa dhimaa kar saktaa he.</s>
