Cellular Neuroscience Flashcards by Joseph Lyman

basic unit of organization of the nervous system

Neuron

How well did you know this?

Not at all

Perfectly

part of the neuron that contains the nucleus and genetic information for protein synthesis.

Soma (cell body)

How well did you know this?

Not at all

Perfectly

Materials move from the cell body along _____ and _____ by a process called _____.

microtubules
neurofilaments
axoplasmic transport

How well did you know this?

Not at all

Perfectly

Highly branched outgrowths from the cell body

dendrites

How well did you know this?

Not at all

Perfectly

In some cells (spinal motor neurons) the surface area of dendrites accounts for over ____ of the total neuronal surface area available for synaptic contact.

90%

How well did you know this?

Not at all

Perfectly

Single process extending from the cell body that carries action potentials away from the cell body.

axon

How well did you know this?

Not at all

Perfectly

____ axons conduct action potentials at a higher velocity than ____ axons.

Myelinated, unmyelinated

How well did you know this?

Not at all

Perfectly

Myelin is formed by ____ cells and is not considered part of the neuron itself.

glial

How well did you know this?

Not at all

Perfectly

Spaces between myelin-forming cells are called ____.

nodes of ranvier

How well did you know this?

Not at all

Perfectly

____ are branches of axons which enable the neuron to activate more than one effector cell at a time

Axon collaterals

How well did you know this?

Not at all

Perfectly

____ contain synaptic vesicles of chemical substances (____) for transmitting signals at the synapse.

Axon terminals

neurotransmitters

How well did you know this?

Not at all

Perfectly

The nature of the action of a neuron on another cell type is determined by the ____ for the neurotransmitter.

post-synaptic receptor

How well did you know this?

Not at all

Perfectly

Ion channels that allow negatively charged ions to flow into the cell will _____ the cell.

hyperpolarize or inhibit

How well did you know this?

Not at all

Perfectly

Ion channels that allow positively charged ions to flow into the cell will _____ the cell.

depolarize or excite

How well did you know this?

Not at all

Perfectly

Two types of summation of inputs that can also determine output of the post-synaptic cell are ____.

Spatial and Temporal summation

How well did you know this?

Not at all

Perfectly

4 Types of Neurons are:

Unipolar
Pseudounipolar
Bipolar
Multipolar

How well did you know this?

Not at all

Perfectly

____ have large dendritic trees and receive input from many sources (spinal motor neurons, purkinje cells in cerebellum)

Multipolar neurons

How well did you know this?

Not at all

Perfectly

____ make up peripheral sensory afferents. Unique because they have 2 axons.

Psuedounipolar neurons

How well did you know this?

Not at all

Perfectly

____ are found in special sensory systems (retina, auditory and vestibular systems)

Bipolar neurons

How well did you know this?

Not at all

Perfectly

____ are found in invertebrates.

Unipolar neurons

How well did you know this?

Not at all

Perfectly

____ neurons have receptors at their peripheral endings that respond to physical or chemical changes in their environment and cause electrical signals to be generated in the neurons.

Afferent

How well did you know this?

Not at all

Perfectly

____ neurons transmit electrical signals from the CNS out to effector cells (muscle or gland)

Efferent

How well did you know this?

Not at all

Perfectly

____ are found entirely within the CNS. These cells, which account for about 99% of all neurons, integrate inputs from many sources and are important components of reflex pathways and of pattern-generating circuits.

Interneurons

How well did you know this?

Not at all

Perfectly

Functionally related groups of neuronal cell bodies are clustered together to form ____ and ____.

nuclei and ganglia

How well did you know this?

Not at all

Perfectly

Terms to describe bundles of white matter include:

tract, fasciculus, lemniscus Several tracts together form a funiculus

Neurons may also be described by the action of their neurotransmitter. Some of those groups are:

noradrenergic, cholinergic, dopaminergic, serotenergic, glutaminergic, GABAergic, glycinergic, peptidergic

Some glial cells called ____ may be excitable.

astrocytes

____ form the myelin sheath in the CNS

Oligodendrocytes

____ surround every CNS blood vessel and provide structural support for neurons.

Astrocytes

Astrocytes also secrete ____ which is vital for neurons.

growth factors

____ line the ventricles, cerebral aqueduct and central canal of the spinal cord and produce some CSF.

Ependymal cells

____ are the resident macrophages of the CNS. They are the first line of defense and carry out the immune response of the brain.

Microglia

____ form the myelin sheath in the PNS.

Schwann Cells (myelinating type)

____ surround cell bodies of neurons in sensory and autonomic ganglia.

Satellite cells

Provide trophic support to regenerating motor axons in the PNS following denervation.

Schwann Cells (non-myelinating type)

Resting cell membrane potential is approximately ____ mV.

-70 to -90

__ concentration is greater on the outside of the cell while __ concentration is greater on the inside.

Na+, K+

A ____ is a transient change in membrane potential that decays both over time and distance from the point of origin.

graded potential

If the cell membrane depolarizes a small amount (i.e. from -70mV to -60mV) this is termed.

Excitatory Post Synaptic Potential

If the cell membrane potential hyperpolarizes a small amount (i.e. from -70mV to -80mV) this is termed.

Inhibitory Post Synaptic Potential.

Multiple graded potentials occurring at a single synapse in rapid succession becoming additive is ____.

Temporal Summation

Multiple graded potentials occurring at different synapses at the same time becoming additive is called ____.

Spatial Summation

If the cell's threshold for firing is met (around ___mV) an all or one action potential will result.

-55

During the action potential the membrane permeability to __ increases dramatically.

Sodium (Na+)

The membrane potential is reduced from approximately -70mV toward 0mV and even goes past the 0mV mark to approximately +20mV called the ____.

overshoot potential.

Repolarization of membrane potential is caused by the __ efflux from the neuron.

potassium (K+)

Repolarization is followed by a period of hyper polarization that is termed the ____ which limits the frequency of action potentials.

refractory period

Ionic gradients are restored to the resting state following the action potential by the action of ____ pumps, fueled by ATP.

sodium potassium

In the CNS, ____ help remove some excess K+ ions from the extracellular environment to prevent the accumulation of K+ ions.

astrocytes

Some neurons also develop ____ which are relatively prolonged (but not slow) depolarizations mediated by calcium entry into the neuron.

plateau potentials

Plateau potentials are thought to contribute to ____, a condition characterized by severe muscle cramps.

myotonia congenita

It is proposed that plateau potentials may underlie ____ an aberrant discharge of motor neurons with resultant uncontrolled muscle contraction following spinal cord injury and stroke.

spasticity

The first portion of the axon, plus the region of the cell body from which the axon leaves, is the ____.

axon hillock

The axon hillock has the ___ threshold for excitation and contains the ____ density of voltage-sensitive Na+ channels.

lowest | highest

The action potential is conducted throughout the neuron by one of two methods. They are:

local current flow | saltatory conduction

In a myelinated axon, voltage gated Na+ channels are concentrated at the ____.

nodes of ranvier

Conduction velocity along a myelinated axon can reach up to ____ meters/second which is about __ times faster than unmyelinated axons.

120 | 50

Diameter affects conduction velocity. ____ axons go faster while ____ go slower. This is due to resistance

Larger | smaller

Conduction in the normal direction of action potentials is called _____.

Orthodromic conduction

Conduction in the opposite direction of the normal action potential is called ____.

antidromic conduction

The process of passing a signal from one neuron to another or from a motor neuron to a muscle cell is called ____.

synaptic transmission

There are three different types of synapses:

axosomatic, axodendritic, axoaxonic

Synapses on the soma tend to be ____ whereas those on dendrites tend to be ____.

inhibitory (produce an IPSP) | excitatory (produce an EPSP)

The ____ of pre-synaptic neurons have synaptic vesicles containing neurotransmitters.

axon terminals

As the action potential travels down the axon, it depolarizes the axon terminal. This causes voltage-gated ____ channels to open in the terminals.

calcium

Entry of calcium into the axon terminal causes the synaptic vesicles to do 3 things:

1. move to the presynaptic terminal 2. fuse their membranes with the presynaptic terminal 3. release their contents into the synaptic cleft

When a neurotransmitter binds with a receptor in a synaptic cleft, the resulting action is dependent upon the type of ____.

receptor

If the receptor is linked to an ion channel then the action depends on what type of ____ are subsequently opened in the post synaptic membrane.

ion channel

The entry of negatively charged species into the post-synaptic cell causes ____ whereas the entry of positively charged species causes ____.

hyperpolarization | depolarization

If the post-synaptic membrane becomes more polarized or more negative than the resting potential, the resulting membrane potential is called an ____.

inhibitory post-synaptic potential

If the post-synaptic membrane becomes less polarized or more positive than the resting potential, the resulting membrane potential is called an ____.

excitory post-synaptic potential

Mechanisms for ending the process at the synapse depends on the type of neurotransmitter at the synapse. Three types of synaptic transmission termination are:

1. Neurotransmitter may diffuse away from the synapse 2. Neurotransmitter may be inactivated by specific enzymes 3. Neurotransmitter may be taken back up into the presynaptic axon terminal for storage or release at another time.

An IPSP never occurs at the synapse between an alpha motor neuron and its post synaptic cell, a ____ cell.

skeletal muscle

Inhibition of muscle occur through IPSP's in the soma and dendrites of the alpha motor neuron in the CNS. At the neuromuscular junction, their is either ____ or ____.

no activation or an EPSP

The EPSP at the neuromuscular junction is called the ____ and is normally above the threshold.

endplate potential

For every action potential in an alpha motor neuron, there will be an action potential in the muscle cell innervated by that motor neuron, this is termed ____.

excitation-contraction coupling

5 things characterize a neurotransmitter. They are:

1. synthesized by neurons 2. stored in vesicles at nerve terminals 3. released following depolarization into synaptic cleft 4. bind to receptors (leading to conformational change of receptor) 5. Binding results in altered physiology or chemistry in post-synaptic cell

5 Classes of neurotransmitters are:

1. Monoamines 2. Cholinergic 3. Amino Acids 4. Neuropeptides 5. Nontraditional neurotransmitters

Monoamine neurotransmitters are:

``` a. catecholamines norepinephrine epinephrine dopamine b. serotonin ```

A cholinergic neurotransmitter is:

acetylcholine

Amino acid neurotransmitters are:

a. GABA b. glycine c. glutamate and other excitatory amino acids

Neuropeptide neurotransmitters are:

endorphins, calcitonin gene-related peptide, substance P.

Nontraditional neurotransmitters are:

NO and CO2

Two broad classes of receptors are:

Ionotropic | Metabotropic

Characteristics of Ionotropic receptors:

- Form a channel in the membrane - Neurotransmitter binds to receptor and causes a conformational change int he transmembrane proteins that open up an ion channel

Characteristics of metabotropic receptors:

- Initiate a range of chemical changes - Neurotransmitter binds to the receptor and changes its shape - G-protein is activated resulting in 3 potential effects: 1. open ion channels 2. activate genes 3. modulate intracellular calcium concentrations

``` Acetylcholine: Area of concentration? Receptor? Action? Action Termination? ```

NMJ, Autonomic NS, motor nuclei of CN's Ionotropic and metabotropic Excitatory (Ionotropic), Excitatory or inhibitory (Metabotropic) Enzymatic degredation

``` Norepinephrine: Area of concentration? Receptor? Action? Action Termination? ```

Sympathetic NS, locus ceruleus Metabotropic Excitatory or inhibitory Passive diffusion, reuptake and enzymatic degradation

``` Dopamine: Area of concentration? Receptor? Action? Action Termination? ```

Basal ganglia, hypothalamus, ventral tegmental area Metabotropic Excitatory or inhibitory Passive diffusion, reuptake and enzymatic degredation

``` Serotonin: Area of concentration? Receptor? Action? Action Termination? ```

Parasympathetic neurons, pineal gland, raphe nucleus Ionotropic and Metabotropic Excitatory and Excitatory or inhibitory Reuptake

``` Glutamate: Area of concentration? Receptor? Action? Action Termination? ```

Cortex, cerebellum, brainstem, hippocampus, spinal cord Ionotropic and Metabotropic Excitatory only Reuptake and diffusion

``` GABA Area of concentration? Receptor? Action? Action Termination? ```

Cortex, cerebellum, hippocampus Ionotropic and metabotropic Inhibitory only Reuptake (neurons and glia)