Bioelectricity& Excitable Tissue

BIOELECTRICITY AND EXCITABLE TISSUE THE ORIGIN OF BIOELECTRICITY AND HOW NERVES WORK www.freelivedoctor.com

THE RESTING CELL ,[object Object],[object Object],[object Object],[object Object],[object Object],www.freelivedoctor.com

BIOELECTRICITY THE ORIGIN OF THE MEMBRANE POTENTIAL www.freelivedoctor.com

MOBILITY OF IONS DEPENDS ON HYDRATED SIZE ,[object Object],[object Object],[object Object],www.freelivedoctor.com

IONS MOVE WITH THEIR HYDRATION SHELLS - + - + Hydration Shells - + - + - + - + - + - + - + - + - + www.freelivedoctor.com Na + - + - + Cl - - + - + - + - + - + - + - + - + - + - + - + - + - +

ELECTRONEUTRAL DIFFUSSION HIGH SALT CONCEMTRATION LOW SALT CONCEMTRATION BARRIER SEPARATES THE TWO SOLUTIONS www.freelivedoctor.com + - + - + - + - + - + - + - + -

ELECTRONEUTRAL DIFFUSSION + - CHARGE SEPARATION = ELECTRICAL POTENTIAL www.freelivedoctor.com HIGH SALT CONCEMTRATION LOW SALT CONCEMTRATION + - BARRIER REMOVED + - + - + - + - + - + - + -

ELECTRICAL POTENTIAL=CHARGE SEPARATION In water, without a membrane hydrated Chloride is smaller than hydrated Sodium, therefore faster: Cl - Na + The resulting separation of charge is called an ELECTRICAL POTENTIAL + - www.freelivedoctor.com

THE MEMBRANE POTENTIAL M E M B R A N E Extracellular Fluid Intracellular Fluid Na + K + Sodium channel is less open causing sodium to be slower Potassium channel is more open causing potassium to be faster + - MEMRANE POTENTIAL (ABOUT 90 -120 mv) www.freelivedoctor.com

THE ORIGIN OF BIOELECTRICITY ,[object Object],[object Object],[object Object],[object Object],www.freelivedoctor.com

ACTIVE TRANSPORT ADP ATP www.freelivedoctor.com

ACTIVE TRANSPORT REQUIRES AN INPUT OF ENERGY ,[object Object],[object Object],[object Object],[object Object],www.freelivedoctor.com

EXCITABLE TISSUES ,[object Object],[object Object],[object Object],[object Object],[object Object],www.freelivedoctor.com

THE NERVE CELL CELL BODY DENDRITES AXON AXON HILLOCK AXON TERMINALS www.freelivedoctor.com

EXCITABLE TISSUES:THE ACTION POTENTIAL ,[object Object],[object Object],[object Object],www.freelivedoctor.com

EQUILIBRIUM POTENTIALS FOR IONS FOR EACH CONCENTRATION DIFFERENCE ACROSS THE MEMBRANE THERE IS AN ELECTRIC POTENTIAL DIFFERENCE WHICH WILL PRODUCE EQUILIBRIUM. AT EQUILIBRIUM NO NET ION FLOW OCCURS www.freelivedoctor.com

THE EQUILIBRIUM MEMBRANE POTENTIAL FOR POTASSIUM IS -90 mV + - CONCENTRATION POTENTIAL K + K + IN www.freelivedoctor.com

THE EQUILIBRIUM MEMBRANE POTENTIAL FOR SODIUM IS + 60 mV Na + Na + + - CONCENTRATION POTENTIAL IN OUT www.freelivedoctor.com

THE RESTING POTENTIAL IS NEAR THE POTASSIUM EQUILIBRIUM POTENTIAL ,[object Object],[object Object],www.freelivedoctor.com

EVENTS DURING EXCITATION ,[object Object],[object Object],[object Object],[object Object],[object Object],www.freelivedoctor.com

OPENING THE SODIUM CHANNELS ALLOWS SODIUM TO RUSH IN ,[object Object],[object Object],[object Object],www.freelivedoctor.com

GRADED VS ALL OR NONE ,[object Object],[object Object],www.freelivedoctor.com

PROPAGATION OF THE ACTION POTENTIAL +++++ -------- --------------------- +++++++++++++ AXON MEMBRANE INSIDE OUTSIDE ACTION POTENTIAL DEPOLARIZING CURRENT www.freelivedoctor.com

PROPAGATION OF THE ACTION POTENTIAL --+++ ++------ +++------------------ ---++++++++++ AXON MEMBRANE INSIDE OUTSIDE ACTION POTENTIAL DEPOLARIZING CURRENT www.freelivedoctor.com

PROPAGATION OF THE ACTION POTENTIAL -------- +++++ ++++++------- -----------++++ AXON MEMBRANE INSIDE OUTSIDE ACTION POTENTIAL DEPOLARIZING CURRENT www.freelivedoctor.com

SALTATORY CONDUCTION +++++ -------- -------- +++++ AXON MEMBRANE INSIDE OUTSIDE ACTION POTENTIAL DEPOLARIZING CURRENT MYELIN NODE OF RANVIER NODE OF RANVIER www.freelivedoctor.com

NORMALLY A NERVE IS EXCITED BY A SYNAPSE OR BY A RECEPTOR ,[object Object],[object Object],[object Object],www.freelivedoctor.com

THE SYNAPSE ,[object Object],[object Object],[object Object],[object Object],[object Object],www.freelivedoctor.com

THE SYNAPSE SYNAPTIC VESSICLES ••• ••• ••• ••• ••• ••• ••• ••• ••• INCOMING ACTION POTENTIAL CALCIUM CHANNEL ION CHANNEL RECEPTOR ENZYME www.freelivedoctor.com

THE SYNAPSE SYNAPTIC VESSICLES ••• ••• ••• ••• ••• ••• ••• ••• ••• CALCIUM CHANNEL ION CHANNEL RECEPTOR ENZYME www.freelivedoctor.com

THE SYNAPSE SYNAPTIC VESSICLES ••• ••• ••• ••• ••• ••• ••• ••• ••• CALCIUM CHANNEL ION CHANNEL RECEPTOR ENZYME ••• www.freelivedoctor.com

POSTSYNAPTIC POTENTIALS RESTING POTENTIAL EPSP TIME www.freelivedoctor.com IPSP

TEMPORAL SUMMATION TIME TOO FAR APART IN TIME: NO SUMMATION www.freelivedoctor.com

TEMPORAL SUMMATION TIME CLOSER IN TIME: SUMMATION BUT BELOW THRESHOLD THRESHOLD www.freelivedoctor.com

TEMPORAL SUMMATION TIME STILL CLOSER IN TIME: ABOVE THRESHOLD THRESHOLD www.freelivedoctor.com

SPATIAL SUMMATION TIME SIMULTANEOUS INPUT FROM TWO SYNAPSES: ABOVE THRESHOLD THRESHOLD www.freelivedoctor.com

EPSP-IPSP CANCELLATION www.freelivedoctor.com

NEURO TRANSMITTERS ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],www.freelivedoctor.com

Bioelectricity& Excitable Tissue

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