Nervous system

Action potential

Caused by voltage difference across the plasma membrane

Due to ionic composition Inside: more K+ than Na+

Outside: more Na+ than K+

Anions: primarily inside and composed of large molecules

Channels

Channels are responsible for the permeability of the membrane Voltage-gated ion channels Chemically-gated ion channels

Propagation of AP

Neuron is stimulatedVoltage-gated ion channels will openK will move outside due to conc gradientWill return due to electrical gradientNa reverse reaction of KResting membrane potential of -70mV

rather than -85mV

REMEMBER!!!!!!!!!!!!!!!

Dissipation of membrane potential is hindered due to the presence of the sodium potassium pump

The very important graph

The very important terms……

Polarization- creation of different charges inside/outside the cell membrane

Depolarization- membrane is more positive (dec in electrical gradient)

Hyperpolarization- membrane is more negative (inc electrical gradient)

Terms pa rin……..

Threshold potential- amount of potential difference needed to create an action potential

Action potential- electrical stimulus that creates signal/message in an axon

Hyperpolarization- do not produce action potential

Graded potential if it is dependent on the amount of stimulus

Action potential in case of neurons that need to meet the threshold potential

AP is the nerve impulse

TANDAAN!!!!!! Nongraded all or none response/event

Ang pagbabalik…….

Ano ba nangyayari?

Start with voltage-gated ion channel K- one gate; closed-resting, opens slowly during

depolarization Na- two gates; activation gate- closed-resting, opens

rapidly during depolarizationinactivation gate- open when resting, closes

slowly due to depolarization

Huh?

K is responsible for hyperpolarization because they remain open during repolarization

Na is responsible for depolarization

synapse

VoltageChemical

EPSP vs IPSP

Excitatory postsynaptic potentialInhibitory postsynaptic potential

Temporal vs summation

Magbasa……..

Magbasa ng mga neurotransmitter at different kinds ng organization of nervous system

Hyperpolarization

Responsible for the unidirectional movement of the action potential