Chapter 4

Neuroscience 3300 with Wee at Tulane University

About this deck

By: Olivia Mahler-Haug
Textbook:

Biopsychology (8th Edition)
Created: 2012-01-31
Size: 38 flashcards
Views: 80

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Membrane Potential

the difference in electrical charge between the inside and the outside of a cell.

Resting potential

In a neuron that is polarized, the amount the inside and outside voltage differs (e.g. -70 inside the neuron says that the potential inside the resting neuron is 70 less than that outside the neuron)

Factors- Even distribution of ions

Random motion --> chemical gradient

Electrostatic pressure --> electrostatic pressure

Exocytosis

the process of neurotransmitter release

Relative Refractory Period

The period during which it is possible to fire the neuron again, but only by applying higher-than-normal levels of stimulation

Absolute Refractory Period

The brief period of about 1 to 2 milliseconds after the initiation of an action potential during which it is impossible to elicit a second one.

Resting Potential

A steady membrane potential of about -70 mV

Membrane Potential

The difference in electrical charge between the inside and the outside of a cell

Depolarize

decrease the resting membrane potential from -70 to -67 mV

Hyperpolarize

increase the resting membrane potential from -70 to -72 mV

millivolts

Excitatory Postsynaptic Potentials (EPSPs)

postsynaptic depolarizations, they increase the likelihood that the neuron will fire

Graded Response

Inhibitory Postsynaptic Potentials (IPSPs)

postsynaptic hyperpolarizations, they decrease the likelihood that the neuron will fire

Graded Response

Action Potential

Is a massive but momentary reversal (1 millisecond) of the membrane potential from about -70 to about +50 mV

All-or-none response

Graded Response

strong signals elicit large postsynaptic potentials and weak signals elicit small ones

Voltage-Activated Ion Channels

Ion channels that open or close in response to changes in the level of the membrane potential

Transporters

mechanisms in the membrane of a cell that activly transport ions or molecules across the membrane

Axon hillock

The conical structure at the junction between the cell body and the axon

threshold of excitation

The level at which the sum of the depolarizations and the hyperpolarizations reach the section of the axon hillock at any time is sufficient to depolarize the membrane to a level.

Integration

adding or combining a number of individual signals into one overall signal

Spatial summation

the summation of graded potentials as a result of stimuli presented from two different presynaptic sites at the same time; best summation results from close stimuli

Temporal summation

the summation of two or more graded potentials as a result of two or more stimuli presented with separation in time

nodes of Ranvier

the gaps between adjacent myelin segments.

In myelinated axons, ions can pass through the axonal membrane only at this point

saltatory conduction

Conduction along the the mylenated sections are the axon are passive, it occurs instantly, and the signal jumps along the axon from node to node.

Dendritic spines

nodules of various shapes that are located on the surface of many dendrites

Directed synapse

synapses at this the site of neurotransmitter release and the sire of neurotransmitter reception are in close proximity

Nondirected synapses

Synapses at which the site of release is at some distance from the site of reception.

Gap junctions

Narrow spaces between adjacent neurons, bridged by fine tubular channels containing cytoplasm

electrical synapses made of protein

Advantages of Gap junctions over chemical

Two advantages over chemical synapses because they are so close together:

- Fast communication across junction

- Bidirectional communication (unlike chemical synapses)

Four criteria for identifying neurotransmitters

Chemical must be synthesized or present in neuron

When released chemical must produce response in target cell

Same response must be obtained when chemical is experimentally placed on target

There must be a mechanism for removal after chemical’s work is done

Excitatory NT (functional)

NT is going to cause a depolarization (EPSP) in the synaptic gap and increases the likelihood that a AP will happen

ex Glutamate (amino acid)

Inhibitory NT (functional)

NT that is going to cause a hyperpolarization (IPSP) in the synaptic gap and decreases the likelihood that a AP will happen

ex GABA (amino acid)

Peptides

strings of amino acids (structure of hormones and endorphins)

Neuropeptide neurotransmitters

much bigger than small molecule neurotransmitters

Co-localization

presence of two or more neurotransmitters in same axon terminal

usually different stimuli cause release of diff NTS in different vesicles (big or small)

Synthesis & packaging

enzymes can synthesize different NTs and pack them into vesicle

Transport to axon terminals

vesicles packaged--> brought down to the axon terminals to be released

When you make a peptide, you need to make it in the cell body where there are rhybosomes you cannot make it in the axon.

About this deck

By: Olivia Mahler-Haug
Textbook:

Biopsychology (8th Edition)
Created: 2012-01-31
Size: 38 flashcards
Views: 80

About StudyBlue

“Simply amazing. The flash cards are smooth, there are many different types of studying tools, and there is a great search engine. I praise you on the awesomeness.”
Dennis