P215 ~ Chapter 10: Graded Potentials

What are some changes that can occur in membrane potential?

depolarization, repolarization, hyperpolarization

What is depolarization?

the inside of the membrane becomes less negative

What is repolarization?

the membrane returns to its resting membrane potential (return to negative)

What is hyperpolarization?

inside of membrane becomes more negative

What is a graded potential?

small, short lasting changes in the membrane potential

T or F: a single graded potential is enough to cause an action potential

false; not enough

How does a graded potential occur?

ion channels opening/closing; ions can go in and out

Graded potential varies according to what?

stimulus strength

bigger stimulus =

more doors opening/closing

Graded potentials can lead to what?

action potentials

What prevents exocytosis?

botulism

What is hyperpolarization also referred to as?

inhibitory postsynaptic potential (IPSP)

What is an example of hyperpolarizing?

something that causes K+ efflux

What is depolarization referred to as?

excitatory postsynaptic potential (EPSP)

What is an example of depolarizing?

something that causes Na+ influx

Sodium: extracellular fluid = 142, intracellular fluid = 10

depolarization

Potassium: extracellular fluid = 4, intracellular fluid = 140

hyperpolarization

Calcium: extracellular fluid = 2, intracellular fluid = 0

depolarization

Magnesium: extracellular fluid = 1, intracellular fluid = 58

hyperpolarization

Chloride: extracellular fluid = 103, intracellular fluid = 4

hyperpolarization

Bicarbonate: extracellular fluid = 28, intracellular fluid = 10

hyperpolarization

What is summation?

the process of adding up postsynaptic potentials and responding to their net effect

What are the two types of summation?

temporal and spatial

What is temporal summation?

single neuron sends the same signal repeatedly over time

What is spatial summation?

multiple neurons send a signal at the same time

What is temporal AND spatial summation?

multiple neurons repeatedly send signals to another neuron

What can result from summation?

depolarizing or hyperpolarizing graded potential

How can a single neurotransmitter be excitatory at one synapse but inhibitory at another?

neurotransmitters open different ion channels in different locations