Brain and Behavior Exam 2

action potential

brief and dramatic depolarization of the membrane of an axon; message sent down axons

cation

positively charged ion

anion

negatively charged ion

ion channel

pore through which ionsmay pass into or out of the cell; embedded in the membrane of the cell

sodium (Na+)

When no signl is traveling down an axon, ______ ions have a higher concentration outside the cell than inside the cell

Potassium (K+)

When no signal is traveling down an axon, _____ ions have a higher concentration inside the cell than outside the cell

diffusion

tendency for molelcules to distribute themselves evenly

electrostatic pressure

opposite charges attract; like charges repel; thus, ions tend to move to an area with its opposite charge

1. Na+ ion channels open

2. Na+ ions move inside the axon

3. K+ ion channels open

4. K+ ions move outside the axon

four steps of action potential

voltmeter

registers the difference in electrical charge between the inside and outside of the cell (membrane potential)

oscilloscope

records the changes in membrane potential over time

membrane potential

difference in electrical charge (in millivolts) between the inside and outside of a cell; in reference to axon potential it is the difference in electrical charge between the inside and outside of an axon

resting potential

membrane potential in the absence of stimulation or an action potential; it is a condition of polarization

negatively; -70mV

At resting potential the inside of the axon is ______ charged with respect to the outside. About how many millivolts?

graded potential

small voltage fluctuations across the membrane (between the inside and outside) of an axon

depolarization

when the inside of an axon is less negative than it was at resting potential

hyperpolarization

when the inside of an axon is more negative than it was at resting potential

threshold of excitation

minimum amount of depolarization needed in order for an action potential to occur

reversed polarization

a condition where the membrane potential has a positive value; occurs at the peak of an action potential “spike: when the membrane potential is a positive value

repolarization

when the membrane potential is retruning back to the resting potential after the peak of the action potential “spike”; occurs due to potassium (K+) ions axiting the ion

slatatory conduction

refers to the fast movement of a signal in a mylinated axon; action potentials only occur in the nodes of ranvier

decreases signaling (action potentials) in sensory neurons; decreases signaling by blocking sodium (Na+) ion channels in the senory neuron axons

How does lidocane work?

synapse

spatial junction between one neuron and another; forms the information transfer site between two neurons

microtubules

anatomy of a synapse:

long structures containing muscle fibers that extend from the soma to the terminal buttons; transport synaptic vesicles to the terminal buttons

synaptic vesicles

anatomy of a synapse:

spherical structures that contain the chemical messengers

neurotransmitter molecules

anatomy of a synapse:

chemical messengers used for communication between the presynaptic membrane and postsynaptic membrane

synaptic gap (cleft)

anatomy of a synapse:

space between presynaptic and postsynaptic membrane

presynaptic membrane

anatomy of a synapse:

at the very end of the terminal button;  place from which chemical messengers are released from the presynaptic neuron

postsynaptic membrane

anatomy of a synapse:

the place on the postsynaptic neuron that recieves chemical messengers

postsynaptic receptors

anatomy of a synapse:

protein complexes embedded in the postsynaptic membrane; contain binding sites for chemical messengers

reuptake transporters

anatomy of a synapse:

proteins embedded in the postsynaptic membrane; each contain a channel (pore) through which chemical messengers are brought back into the presynaptic neuron after brief exposure in the synaptic gap

steps of a synaptic transmisson

neural integration

refers to the combining of excititory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs) by the dendrites and somas of postsynaptic neurons

whether or not an action potential occurs in the axon of a postsynaptic neuron

What does the result of neural integration determine?

postsynaptic potentials

________ are graded potentials occuring in the postsynaptic membrane (of a postsynaptic neuron)

excititory postsynaptic potenials (EPSPs)

associated with the opening of ion channels that allow for the flow of sodium (Na+) ions to the inside of the cell, producing a decrease in the membrane potential (less lenagtive than before)

inhibitory postsynaptic potentials (IPSPs)

associated with the opening of ion channels to allow for the flow of potassium (K+) to the outside of the cell, or ion channels that allow for the flow of chloride (Cl-) ions to the inside of the cell, producing increase in membrane potenial (more negative than before)

efficacy

maximum effect obtainable, with additional doses producing no effect

affinity

how tightly a drug binds to its receptor

agonist

mimics a neurotransmitter; acts like the neurotransmitter it replaces

antagonist

blocks neuro transmitter function

blindsight

exhibit cortical blindness (are not conciously aware of what they see) due to damage in area V1 in the occipital lobe

Balint’s syndrome

person may exhibit a wide variety of difficulties related to spatial cognition